Status, Trends, and Advances in Earthworm Research and Vermitechnology
Status, Trends, and Advances in Earthworm Research and Vermitechnology
Status, Trends, and Advances in Earthworm Research and Vermitechnology
This is a special issue published in volume 2010 of Applied and Environmental Soil Science. All articles are open access articles
distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any
medium, provided the original work is properly cited.
Applied and Environmental Soil Science
Editorial Board
Lynette K. Abbott, Australia D. L. Jones, UK Amaresh K. Nayak, India
Joselito M. Arocena, Canada Matthias Kaestner, Germany Alessandro Piccolo, Italy
Nanthi Bolan, Australia Anastasios D. Karathanasis, USA Peter Shouse, USA
Robert L. Bradley, Canada Heike Knicker, Spain B. Singh, Australia
Artemi Cerda, Spain Takashi Kosaki, Japan Keith Smettem, Australia
Amarilis de Varennes, Portugal Rattan Lal, USA Marco Trevisan, Italy
Hong J. Di, New Zealand Yongchao Liang, China Antonio Violante, Italy
Oliver Dilly, Germany Bernard Ludwig, Germany Paul Voroney, Canada
Michael A. Fullen, UK Mallavarapu Megharaj, Australia Walter Willms, Canada
Ryusuke Hatano, Japan A. J. Melfi, Brazil Jianming Xu, China
William R. Horwath, USA Teodoro M. Miano, Italy Yong-Guan Zhu, China
Reinhard F. Huettl, Germany Jean Charles Munch, Germany
Contents
Status, Trends, and Advances in Earthworm Research and Vermitechnology, Natchimuthu Karmegam,
Radha D. Kale, Thilagavathy Daniel, M. Nurul Alam, and Martn Gerardo Rodrguez
Volume 2010, Article ID 962726, 2 pages
Charles Darwins Observations on the Behaviour of Earthworms and the Evolutionary History of a Giant
Endemic Species from Germany, Lumbricus badensis (Oligochaeta: Lumbricidae), U. Kutschera and
J. M. Elliott
Volume 2010, Article ID 823047, 11 pages
Basic Research Tools for Earthworm Ecology, Kevin R. Butt and Niki Grigoropoulou
Volume 2010, Article ID 562816, 12 pages
The Role of Earthworms in Tropics with Emphasis on Indian Ecosystems, Radha D. Kale and
Natchimuthu Karmegam
Volume 2010, Article ID 414356, 16 pages
Role of Earthworms in Soil Fertility Maintenance through the Production of Biogenic Structures,
Tunira Bhadauria and Krishan Gopal Saxena
Volume 2010, Article ID 816073, 7 pages
Casting Activity of Scherotheca gigas in No-Till Mediterranean Soils: Role in Organic Matter
Incorporation and Influence of Aridity, Paloma Bescansa, Inigo Virto, Oihane Fernandez-Ugalde,
Mara Jose Imaz, and Alberto Enrique
Volume 2010, Article ID 526934, 6 pages
Eect of Soil Physical State on the Earthworms in Hungary, Marta Birkas, Laszlo Bottlik, Attila Stingli,
Csaba Gyuricza, and Marton Jolankai
Volume 2010, Article ID 830853, 7 pages
The Eect of Earthworm (Lumbricus terrestris L.) Population Density and Soil Water Content
Interactions on Nitrous Oxide Emissions from Agricultural Soils, Andrew K. Evers, Tyler A. Demers,
Andrew M. Gordon, and Naresh V. Thevathasan
Volume 2010, Article ID 737096, 9 pages
Can We Predict How Earthworm Eects on Plant Growth Vary with Soil Properties?, Kam-Rigne Laossi,
Thibaud Decaens, Pascal Jouquet, and Sebastien Barot
Volume 2010, Article ID 784342, 6 pages
Earthworms and Plant Residues Modify Nematodes in Tropical Cropping Soils (Madagascar): A
Mesocosm Experiment, Cecile Villenave, Bodo Rabary, Emilie Kichenin, Djibril Djigal, and Eric Blanchart
Volume 2010, Article ID 323640, 7 pages
Eects of Pesticides on the Growth and Reproduction of Earthworm: A Review, Shahla Yasmin and
Doris DSouza
Volume 2010, Article ID 678360, 9 pages
Eect of Butachlor Herbicide on Earthworm Eisenia fetidaIts Histological Perspicuity,
Muthukaruppan Gobi and Paramasamy Gunasekaran
Volume 2010, Article ID 850758, 4 pages
Heavy Metal-Induced Oxidative DNA Damage in Earthworms: A Review, Takeshi Hirano and
Kazuyoshi Tamae
Volume 2010, Article ID 726946, 7 pages
Nutrient Status of Vermicompost of Urban Green Waste Processed by Three Earthworm SpeciesEisenia
fetida, Eudrilus eugeniae, and Perionyx excavatus, Swati Pattnaik and M. Vikram Reddy
Volume 2010, Article ID 967526, 13 pages
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 962726, 2 pages
doi:10.1155/2010/962726
Editorial
Special Issue on Status, Trends, and Advances in
Earthworm Research and Vermitechnology
The articles in this special issue reflect the developments Considerable research is in progress with regard to
in the fields of earthworm research and vermitechnology. significant role of earthworms and vermitechnology. This
Charles Darwins observation on earthworms is a milestone issue addresses the existing situations by providing complete,
in understanding the soil biology and enormous contribu- collective, and up-to-date knowledge and recent trends. It is
tion to some aspects of the genesis of humus and of its a compilation of research articles on ecology, behavior, and
role in soils. Earthworms are the best known soil inhabiting functional role of earthworms at organismic levels. There are
animals commonly called friends of farmers due to the also papers to highlight the cellular and molecular studies.
beneficial role they play in soil. The research on earthworms The first paper by U. Kutschera and J. M. Elliott points
has gained importance in India as well as in other countries. out the origin of earthworm research from the time of Dar-
In the year 1981, an international symposium entitled win (1881) that was responsible for the recent developments
Earthworm Ecology: Darwin to Vermiculture was held at in biogeographical studies. A very interesting point is about
Cumbria, UK, to commemorate the centenary celebration the lineage of the earthworms described in this paper.
of Darwins book The Formation of Vegetable Mould through K. R. Butt and N. Grigoropoulou have given a detailed
the Action of Worms, with Observations on Their Habits that description on the tools and methods to be adopted for
was published in 1881 by Murray, London, UK. In the studying the earthworms at field level. Their contribution
year 2000, Vermilleniuman international workshop and supports a number of suitable ecological methods and access
symposiumwas held at Kalamazoo, USA, to realize the to various tools to support earthworm research.
progress achieved in this field after a decade (since 1991). The paper by R. D. Kale and N. Karmegam highlights
Recently, Ninth International Symposium on Earthworm the research carried out by dierent scientists in India
Ecology (ISEE-9) that was held at Xalapa, Mexico, during the on aspects of earthworm population dynamics and species
5th to 10th of September 2010 clearly proved the importance diversity associated with other soil fauna and microflora.
of earthworms and vermitechnology by the participation of The paper also deals with the importance of earthworm
scientists from dierent countries. About 300 papers were activity on physicochemical properties of soil with reference
received from the researchers across the world. to India and other tropical countries. They laid stress
2 Applied and Environmental Soil Science
on the earthworm plant association and importance of on biomolecules that have significance in pharmacological
the secretions of earthworms as plant growth stimulators applications.
and their role as bioindicators. Several other papers on Finally, the molecular approach at DNA level is an
earthworm ecology are also included. The review article on important contribution to use earthworms as the tool to
the role of earthworms in soil fertility maintenance through understand the possible damage that can be caused by
the production of biogenic structures explains the eect of dierent metallic pollutants. These are entering into the food
farming practices on earthworm population (T. Bhadauria chains of higher animals including humans. Many of these
and K. G. Saxena). P. Bescansa et al. have reported the pollutants at dierent levels may cause damage to DNA
casting activity of an anecic earthworm, Scherotheca gigas in which may be cancerous. It is inspirable from the study of T.
no tillage Mediterranean soils (Ebro Valley in Navarre, NE, Hirano and K. Tamae that the earthworms can also be used
Spain) and its role in organic matter incorporation. Influence as model organisms for studying the carcinogenesis.
of the earthworm on aridity factors is also discussed. This Though more articles were expected on vermicom-
study gives an evidence for incorporation of organic matter posting and related studies, only one paper on nutrient
and in particular the most labile fractions to the soil by status of vermicompost derived from urban green waste
S. gigas. M. Birkas and coauthors have reported that the was submitted for publication. It is a comparative study to
earthworm density in Hungary is directly linked to physical identify the most ecient epigeic earthworm (S. Pattnaik and
characteristics and soil mulch. The same may hold good even M. V. Reddy).
for other geographical regions. The organization of the papers in this special issue
Nitrous oxide (N2 O) emission has been the threat for represents the landmark of earthworm and vermitechnol-
climatic changes. N. K. Evers and his coworkers have shown ogy research. Altogether the articles presented provide the
the direct correlation between density of earthworm (Lum- reader with descriptions of earthworm ecology and dierent
bricus terrestris L.) population and soil moisture content to approaches to study their role in ecosystems, physiology at
N2 O emissions in a controlled greenhouse experiments. They cellular level, and finally the vermicomposting. We hope
are of the opinion that the benefits that are normally seen that this issue would provide the resources necessary to
from earthworms in agricultural systems may be masked by understand and to promote advances in this important field.
their influence on facilitating the production of N2 O and We hope that the readers and the research workers will
in turn climate change. But various other factors like the find this as a useful source of information. We would like
associated microorganisms, and the levels of organic matter, to thank the reviewers who helped us in reviewing the
soil porosity for oxygen supply to soil layers have to be articles and timely recommendations. We also would like
studied in soils with and without earthworms to derive at any to thank the Chief-Editor, Dr. Siobhan Staunton, Director
conclusion. There is sucient scope to further the research in of Research from Ecologie Fonctionnelle et Biogeochimie
this regard. des Sols (Montpellier Cedex, France), and other sta of the
The influence of earthworms on plant growth may vary Editorial Section of Applied and Environmental Soil Science
depending on soil structure. K.-R. Laossi and coauthors (AESS), who had faith in us and cooperated at all stages
in their review article have suggested the experimental of compilation. Special thanks are due to Dr. Nada Ahmed
approaches to be developed to assess the influence of soil type who had coordinated all communications at all stages of
on response of plants in the presence of earthworms. This compilation of this special issue.
line of study is very essential to relate the animal, plant, and
edaphic factors. Natchimuthu Karmegam
Soil community is a complex food web. Earthworms, Radha D. Kale
being the major macro fauna, contribute to modification of Thilagavathy Daniel
the structure and functions of dierent decomposers and M. Nurul Alam
predators. The research paper of C. Villenave et al. depicts the Martn Gerardo Rodrguez
changes that occur in the abundance of bacterial and fungal
feeding nematodes in presence of the earthworm, Pontoscolex
corethrurus.
The agrochemicals are known to have adverse eect
at dierent levels on life and activities of soil organisms
including earthworms. Two papers that appear in this issue
describe the eect of pesticides and herbicide on growth and
reproduction of earthworms (S. Yasmin and D. DSouza) on
population growth and on histology and reproduction of
Eisenia fetida, respectively (M. Gobi and P. Gunasekaran).
Probably, earthworms are the most promising sources
to combat various physiological and pathological disorders
that are disturbing the human life in the near future. One
such product from earthworms is the protease enzyme. In
this regard, the extensive review on earthworm protease
compiled by R. Pan et al. gives an impetus to further research
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 823047, 11 pages
doi:10.1155/2010/823047
Review Article
Charles Darwins Observations on
the Behaviour of Earthworms and the Evolutionary History of
a Giant Endemic Species from Germany, Lumbricus badensis
(Oligochaeta: Lumbricidae)
Copyright 2010 U. Kutschera and J. M. Elliott. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
The British naturalist Charles Darwin (18091882) began and ended his almost 45-year-long career with observations,
experiments, and theories related to earthworms. About six months before his death, Darwin published his book on The Formation
of Vegetable Mould, through the Actions of Worms, With Observations on their Habits (1881). Here we describe the origin, content,
and impact of Darwins last publication on earthworms (subclass Oligochaeta, family Lumbricidae) and the role of these annelids
as global ecosystem reworkers (concept of bioturbation). In addition, we summarize our current knowledge on the reproductive
behaviour of the common European species Lumbricus terrestris. In the second part of our account we describe the biology
and evolution of the giant endemic species L. badensis from south western Germany with reference to the principle of niche
construction. Biogeographic studies have shown that the last common ancestor of L. badensis, and the much smaller sister-taxon,
the Atlantic-Mediterranean L. friendi, lived less than 10 000 years ago. Allopatric speciation occurred via geographically isolated
founder populations that were separated by the river Rhine so that today two earthworm species exist in dierent areas.
Figure 1: Charles Darwin as an earthworm scientist: caricature from the journal Punch, published in the year 1882.
Figure 2: Schematic drawing of common European earthworms (Lumbricus terrestris) in their natural habitat. The annelids live in self-made
burrows and forage by night on rotten leaves.
Applied and Environmental Soil Science 3
2. A Trivial Gardening Matter and Darwins texture. More recent work has shown that they also influence
Speech to the Geological Society of London soil pH and enrich the soil [11]. The processes of physical and
chemical decomposition occur in the earthworm gut, chiefly
Darwin first indicated the importance of earthworms in in the gizzard and crop. Darwin concluded that the ingestion
a lecture On the formation of mould to the Geological of the topsoil, and its mixing, grinding, and digestion in
Society of London on 1 November 1837. This was published the gut, continually exposed rock particles to chemical
in the following year [4] and does not appear to have alteration, increasing the amount of soil. This process, and
had a great impact on his colleagues [5]. Darwin probably the addition of faecal casts from the worms, builds up
realised this because he repeated his ideas in three following the humus-rich topsoil (Figure 3(a)) and buries various
publications (published in 1840, 1844, 1869) [68], the materials originally on the surface (e.g., seeds, pebbles,
last two being aimed at gardeners. The terms vegetable archaeological artifacts) down to depths of 2 m, depending
mould or plant earth were used by the Victorians to upon the depth of the earthworm burrows. Darwin estimated
refer to what is called today humus-rich topsoil or the A rates of topsoil deposition in the range of 0.200.56 cm per
horizon (Figure 3) or mollic epipedon. It was his 1881 year, and the mean amount of soil brought upwards by the
book [2] that had the greatest impact on those who had often worms as 1740 t per ha per year. More recent studies in
regarded earthworms as pests that disfigured well-manicured Britain, France, Switzerland, and Germany have produced
Victorian lawns with their casts. They were thought to similar values for grass-dominated vegetation in a temperate
be useful only as fish bait or food for hens, but Darwin climate [13].
gave them a noble and useful character and even, more Earthworms are predominately saprophages and feed
controversially, considered that they had intelligence. chiefly on organic detritus, usually the decomposing leaves
Although the book was a great success at the time and and stems of plants together with smaller amounts of
was verified by many studies soon after its publication, it roots, seeds, algae, fungi, and testate Protozoa. They prefer
has become neglected in some areas of biology, especially materials rich in nitrogen and sugar, but low in polyphenols
soil science. A detailed review by Johnson [9] shows how [14]. Variable amounts of mineral soil can be ingested
biomechanical processes were largely ignored in models of together with organic material, and the mineral fraction
landscape evolution, and how soil science became dominated reflects that of the external medium. Darwin observed that
by chemical and hydrological processes. However, this review an astonishing number of half-decayed leaves were drawn
also demonstrates how more recent models of dynamic down by the worms into their burrows (Figure 2). Here
denudation incorporate bioturbation on equal terms with they were stored until they were suciently decomposed to
other major archaeogenic, geomorphogenic, and pedogenic be eaten. He thought that the mixture of partially digested
processes. Finally, it should be noted that although Darwins leaves and mineral soil in the faecal casts was responsible
book on earthworms became neglected by the earth sciences, for the characteristic dark colour of humus-rich topsoil
it has continued to be quoted in zoological texts [1012]. (Figure 3(a)). It is now known that the darkening is a much
slower process, involving primarily chemical reactions and
microbial activity [15]. However, the earlier processing of the
3. Earthworms as Living Ploughs: material in the earthworm gut may facilitate this process.
Darwins Major Conclusions Darwin was also the first scientist to state that earth-
worms improved the quality of soil by improving soil texture.
As there are already some lengthy reviews of the scientific Earthworm activity facilitates the physical comminution of
findings in Darwins book on earthworms (e.g., [10, 13]), organic particles, the amelioration of soil pH, the enhance-
only the more important conclusions are summarised here. ment of microbial activity, and the mixing of soil from
Darwin was probably the first scientist to examine a soil dierent strata in the profile. They promote the formation
profile and suggest factors responsible for the structure of of organomineral complexes and, by delivering faecal casts
the various layers (Figures 2 and 3). This vertical soil section at the surface, they bring organo-mineral crumbs from the
with a depth of about 13 cm was taken in October 1837 from deeper parts of the profile to the surface. Earthworms also
a field near the family home of Darwins uncle, the famous facilitate the transport of certain elements to the soil surface
English potter, Josiah Wedgewood. The field had been so that their faecal casts have concentrations of calcium,
drained, ploughed, harrowed, and covered extensively with sodium, potassium, magnesium, available phosphorus, and
burnt marl and cinders 15 years earlier. Darwin observed that molybdenum that are higher than in the surrounding soil.
this layer (Figure 3(c)) was now well below the surface and Therefore, earthworms not only improve the soil texture but
concluded that this was due to the actions of earthworms, also enrich the soil [3, 9, 10, 15].
a process described as bioturbation [3]. He was the first Darwin suggested that earthworms may change the
naturalist to point out the importance of earthworms in the chemical composition of materials that pass through their
formation of the layer of humus-rich topsoil that covers the gut. However, there is still little evidence that they can
land surface in every moderately humid country of the Earth. accelerate the alteration of parent materials or the breakdown
Darwin first recognised this importance of earthworms of larger soil particles [11]. Some work with the large
in soil formation (pedogenesis) by them acting as agents of Octodrilus sp. in the Romanian Carpathians suggests that
physical and chemical decomposition (weathering of rocks), these worms are able to aect the clay mineralogy and the
by promoting humus formation, and by improving soil formation of illite in their habitat, a process that usually
4 Applied and Environmental Soil Science
(a)
(b)
(c)
Figure 3: Cross section of the vegetable mould in a field, drained and reclaimed fifteen years previously. (a) Vegetable mould, without stones,
(b) Mould with fragments of burnt marl, coal-cinders and quartz pebbles, (c) Subsoil of black, peaty sand with quartz pebbles (adapted from
Darwin 1881 [2]).
takes many years [16]. If other earthworms are able to to sounds, also to odours with a selective sense of smell,
do this, then it is an important finding because sorption and to light, preferring darkness or very low irradiation,
of radiocaesium on illitic-type clay minerals served to except when they were mating. He also concluded that
reduce the amount of radiocaesium entering terrestrial and they had favourite foods. Darwin observed that earthworms
freshwater food chains after the Chernobyl accident of 26 plug the mouth of their burrows with leaves, leaf stalks,
April 1986 [17]. Most of the radiocaesium became fixed in or twigs and considered that an intelligent animal would
the interlayers between the platelets of the illite minerals. draw such irregular-shaped objects into a cylindrical hole by
Thus, when the Chernobyl plume passed over Northwest their narrowest part (Figure 2). Therefore, he placed around
England and it rained, the eects of the radiocaesium fallout the burrow entrance leaves of various native and foreign
varied considerably among lakes in the area and fish in plants and triangular pieces of paper of various sizes. In
the lakes [1821]. In lakes with illitic minerals in their the majority of trials, these objects were drawn into the
catchment, levels of radiocaesium decreased rapidly in the burrows by or near their narrow apex. The only exception
water, sediments, and fish, presumably because most of the was pine needles that were drawn in, by, or near their base.
radiocaesium was trapped in the catchment. In contrast, He concluded that worms, although standing low in the scale
levels remained high in the water, sediments, and fish of lakes of organisation, possess some degree of intelligence instead
surrounded by acid moorland. of a mere blind instinctive impulse [2, page 312].
The most controversial section of Darwins book dealt Before considering this conclusion further, it is useful to
with earthworm behaviour and if they could be described compare earthworms with their cousins, the leeches. Both
as intelligent. This section was chiefly responsible for the belong to the phylum Annelida and both are hermaphrodite
popularity of the book. The poor worms were subjected to with some segments near the middle of the body modified in
various tests, including response to touch and vibrations, mature animals to form a clitellum that secretes a cocoon for
strong breath and odours, a wide range of foods (e.g., fat, the eggs (see Figure 4). Hence, they are regarded as subclasses
raw meat, onions, starch, beads, paper, leaves of various Oligochaeta and Hirudinea of the class Clitellata [11, 22].
plants), and light and temperature gradients. He found Unlike earthworms, leeches are active predators [2225].
that they were sensitive to touch and vibrations but not Some species suck the blood of their prey whilst other species
Applied and Environmental Soil Science 5
(a)
Lumbricus terrestris
Cl
(b)
L. castaneus
1 cm
Figure 4: Photograph of two German earthworm species that inhabit grasslands, but occupy dierent ecological niches. Lumbricus terrestris
(a), a burrowing (anecic) species, and L. castaneus (b), an epigeic earthworm. The swollen clitellum (Cl) of the sexually mature L. castaneus
is indicated.
suck in their whole prey or devour pieces of moribund or (November/December 1881). We will quote here from some
dead animals. They have fewer segments than earthworms of these articles in order to document the immediate impact
and a more compact, muscular, body with anterior and of Darwins little earthworm book.
posterior suckers. Leeches are good swimmers but also travel In the journal The Academy, London, it was pointed out
by looping, using their suckers. Their sense organs are well that Mr. Darwins powers of work are inexhaustible, and not
developed so that they can detect movements of potential less remarkable than his genius. Here is another delightful
prey and chemicals released by injured prey. Most species book from his pen, . . . One of the charms of the present
have more than two pairs of eyes that can detect changes in work is, that it is extremely easy to read . . . it will delight
light intensity and direction. The medicinal leech can also everyone, every page being full of interest. In the Sunday
detect the warmest parts of its mammalian prey where it Review we read that Mr. Darwins little volume on the habits
sucks its blood meal [26]. With such a range of senses, it and instincts of earth-worms is no less marked than the
is not surprising that leeches have a well-developed brain earlier or more elaborate eorts of his genius by freshness of
consisting of a fusion of ganglia in the anterior segments observation, unfailing power of interpreting and correlating
of the body. Leeches can therefore react rapidly to a wide facts, and logical vigor in generalizing upon them. . . . All
range of stimuli but it would be wrong to regard them as lovers of nature will unite in thanking Mr. Darwin for the
intelligent; their behaviour is instinctive [23, 24]. Leeches new and interesting light he has thrown upon a subject so
can be regarded as worms with character. The so-called long overlooked, yet so full of interest and instruction, as the
brain in earthworms is much smaller than that of leeches, structure and the labors of the earth-worm.
which is not surprising in an animal that is adapted to a In the New York Graphic, a similar, very positive evalua-
subterranean life and is usually nocturnal. There are no tion was published: The result of the authors observations
definite eyes, but light-sensitive cells occur on the dorsal is the production of proof that the small and apparently
surface, especially at the anterior and posterior ends of the insignificant earth-worm is the cause of mighty changes in
body, the regions most frequently exposed to light [11]. As the surface of the earth, seeing that each of them, on the
noted above, they must have sense organs that are sensitive average, passes about twenty ounces of earth through its
to chemicals, changes in temperature, and especially touch body every year, which earth it brings often from a depth of
and vibration transmitted through solid objects. Like leeches, eight or ten feet below the surface to deposit it on the mould
their behaviour is instinctive and it is wrong to describe them at the top, thus doing the work of a plow. What the result of
as intelligent animals. this must be will be evident when it is known that an average
of 30,000 such plows are at work in every acre of common
arable land, and the worms must, therefore, work over about
4. Darwin and the Humble Earthworms: ten tons of earth per acre every year.
The Immediate Impact of His Book The review published in the Brooklyn Times emphasized
the novelty of Darwins observations and conclusions: Dar-
Darwins last monograph was published in October 1881 [2]. win confers upon the despised and humble earth-worm an
This book was distributed one year later in the United States interest it never possessed before, and introduces it as a factor
of America via the publisher D. Appleton and Company, New of, perhaps, unsuspected importance in agriculture. Portions
York. The US-company advertised this last publication of the of his book read almost like a romance, for there is much
famous British naturalist, using a selection of sentences from in his revelations of surprising strangeness and novelty. So
book reviews that were published during the previous year much is seen that might be patent of the dullest eye that it
6 Applied and Environmental Soil Science
seems remarkable that so little should have been known of well-known, dramatic mass destructions of earthworms
earth-worms before. after the submergence of their burrows were not mentioned
In the New York World, it was pointed out that Darwins by Darwin [2]. Representative specimens of two common
book is Curious and interesting throughout. Finally, in the earthworm species that were captured after a heavy rainfall
Boston Adviser, the role earthworms that have played over in Germany (L. terrestris and L. castaneus) are depicted in
thousands of years are described in the following words: Figure 4.
Respecting worms as among the most useful portions of As summarized above, Darwin [2] analyzed the
animate nature, Dr. Darwin relates, in this remarkable book, behaviour of earthworms with reference to their sensory
their structure and habits, the part they have played in the capacities, the construction of their burrows, nutrition, and
burial of ancient buildings and the denudation of the land, their supposed intelligence in burying of leaves. However,
in the disintegration of rocks, the preparation of soil for the he only briefly mentioned the reproductive biology of these
growth of plants, and in the natural history of the world. terrestrial oligochaetes.
These statements on Darwins last publication and his Four decades later, a detailed description of the repro-
general conclusions concerning soil biology and so forth. ductive biology of the common species L. terrestris was
document that the little book on a subject of small published by Grove (1925) [31]. Oligochaetes (earthworms)
importance had a large, immediate impact (Figure 1). The and hirudineans (leeches) (class Clitellata) are simultaneous
monograph sold so well that on 5 November 1881, less (or protandrous) hermaphrodites with reciprocal insemina-
than four weeks after the book became available, a clerk tion [23, 24]. In other words, in contrast to gonochorists,
of the British publisher John Murray (London) wrote to hermaphrodites function as males and as females. The
Darwin: We have now sold 3500 worms !!! [13]. Only five mating process of L. terrestris, as described by Grove [31] and
months later, on 19 April 1882, Charles Darwin died. In the supplemented by more recent studies [32, 33], is depicted
following years, his worm book was translated into several in Figure 5. During these nocturnal episodes, which last
foreign languages, but this monograph never became so well from one to 3 hours, the partners remain anchored in their
known as his work on the species problem published in 1859 home burrow with their tail end, which permits a rapid
[27, 28]. retreat in case of an attack of a predator. During copulation,
both worms establish a contact to the clitellar region of the
partner (see Figure 4). Thereafter, both earthworms bend
5. Biodiversity and Reproductive Behaviour of their anterior segments away from the partners body, which
European Earthworms results in an s-like position. During this tight body contact,
both partners exchange sperm and hence function as males.
In his most famous book On the Origin of Species [27], After reciprocal insemination is finished, the worms separate
Charles Darwin (1859) did not define what species are and from each other, a mechanical process that can cause severe
how they can be distinguished from varieties [29]. Decades body damage due to the partners sharp copulatory bristles
later, Theodosius Dobzhansky (19001975) and Ernst Mayr (setae).
(19042005), two of the architects of the synthetic theory According to Michiels et al. [33], the lunar cycle aects
of biological evolution of the 1950s, introduced the biological mating activity, since the relatively high copulation frequency
species concept that defines species as populations of during dark nights (once every 7 to 11 days) is very low
interbreeding organisms that are reproductively isolated during the full moon. Moreover, the authors have discovered
from other such groups [30]. Darwins relaxed opinion that sometimes smaller individuals are pulled out of their
concerning species definitions may have been the reason burrows by the larger partner after a tug-of-war that ends
why he did not identify the species of earthworms he a mating episode. As pointed out by Nuutinen and Butt [32],
was investigating [28]. It is likely that Darwin (1881) [2] L. terrestris is the only earthworm species for which mating
studied the most abundant burrowing (anecic) earthworms on the soil surface has been documented. In general, the
of Britain, Lumbricus terrestris (widespread), L. friendi (rare), mating process in L. terrestris (Figure 5) is reminiscent to
Aporrectodea longa, and A. nocturna (both widespread) [11, that of aquatic leeches of the genus Erpobdella and that of
15, 29]. However, it is well known that in southern English the European land leech Xerobdella lecomtei [24, 25]. Several
grasslands, 8 to 10 earthworm species occur [29]. Hence, days after copulation, the earthworms act as females and
more than the four taxa listed above may have contributed to produce lemon-shaped capsules (cocoons) that contain 5 to
the physical soil engineering or bioturbation described 8 fertilized eggs via their clitellum, a process that resembles
by Darwin [2]. that of worm-leeches of the genus Erpobdella [23, 24].
The common earthworm L. terrestris lives solitarily in
vertical, aerated burrows that are 1 to 2 m deep. The 6. The Discovery of the Giant Endemic
oligochaetes forage and mate on the surface at night Earthworm Lumbricus badensis
(Figure 2). After heavy rainfall and inundation of the soil,
the oxygen-dependent (aerobic) invertebrates escape from In contrast to his son Francis, who supported his father in his
their anoxic burrows and creep over the moist soil. During researches on the movements of plants, as well as the earth-
these forced excursions, most of the free-living earthworms worm studies described here, and later became a professional
are eaten by predators (birds, etc.) or die as a result of intense plant physiologist, the geologist/biologist Charles Darwin
radiation and heat caused by the reemerging sun. These never visited Germany. The older Darwin would have been
Applied and Environmental Soil Science 7
(a) (e)
(b) (f)
(c) (g)
(d) (h)
Figure 5: Precopulatory behaviour and mating in the common earthworm (Lumbricus terrestris), observed during dark summer nights with
special equipment. Both partners remain anchored in their burrows (distance of the holes ca. 7 to 8 cm) (a) and evaluate each other in
an extensive courtship process (b), (c), (d). Copulation occurs via the reciprocal attachment of the clitella (see Figure 4) and results in the
exchange of sperm (e), (f), (g). After 1 to 3 hours the worms separate and retreat into their burrows (h) (adapted from [32]).
pleased to study the geology and biology (fauna, flora) of ca. 0.6 cm) (Figure 4) and does not cooccur with L. badensis,
the Black Forest (Schwarzwald), a wooded mountain range adult Black Forest-worms (Figure 6) are up to 34 cm long
in southwest Germany (Federal State Baden-Wurttemberg) with diameters of 1.2 to 1.6 cm (body mass: 25 to 40 g).
that consists of a cover of sandstone on top of a core of When fully extended, adult L. badensis individuals can reach
gneiss. During the Wurm glaciation, which ended ca. 10 000 a length of up to 60 cm [35] and hence are on average as large
years ago, the Black Forest was covered with glaciers. The as the common limbless burrowing reptile Anguis fragilis.
six highest mountains are the Feldberg (1493 m), Herzo- This vertebrate is also known under the name slow worm
genhorn (1415 m), Belchen (1414 m), Spieshorn (1349 m), and has been confused with Lumbricus badensis. In Figure 7,
Schauinsland (1248 m), and the Kandel (1241 m above sea an adult L. badensis that was isolated from its burrow and
level). The dense forests consist mostly of pines (Pinus an A. fragilis of average length are juxtaposed. Both animals
sylvestris) and Norway spruce (Picea abies), which are grown were collected in the same habitat. The enormous body size
in many places as commercial monocultures. In addition, of the giant Black Forest earthworm becomes apparent [35].
beech (Fagus sylvaticus) forests form integral parts of the In forests with large litter layers, the usually deep-digging
lower regions of this unique landscape in Southern Germany. (anecic) species L. terrestris can live epigeic, without the
More than a century ago, the German annelid specialist construction of a burrow [37]. Darwin [2] would have been
W. Michaelsen investigated the soil of the southern part of surprised to hear that one of his common worms has, in
the Black Forest, but no common earthworms (L. terrestris) certain European habitats, adapted to such an alternative
were found in this habitat. However, he discovered a single way of life. Detailed studies have shown that the Black
individual of an unidentifiable earthworm that he later Forest earthworm (Figures 6 and 7) displays a switch from
described as L. papillosus (Syn. fiendi) var. badensis [34]. an epigeic to an anecic (burrowing) way of life during its
Hence, Michaelsen interpreted his giant earthworm from the ontogeny. This aspect of the life cycle of L. badensis is
Federal State Baden-Wurttemberg as a local (geographic) described in the next section.
variety of the common Atlantic-Mediterranean taxon L.
friendi. Later, it was discovered that this large earthworm
(Figure 6) represents a separate biospecies that is not closely 7. Biogeography, Evolutionary Origin,
related to the widespread L. terrestris but is a sister taxon of L. and Ecology of Lumbricus badensis
friendi [35], a relatively small species (length ca. 12 cm) that
Darwin [2] may have studied in Great Britain [10, 13, 29]. After decades of research it is now definitively clear that the
In contrast to the common earthworm (L. terrestris), giant earthworm L. badensis is a neoendemic species that
which can reach a body length of 15 cm (diameter at rest inhabits exclusively the acid soils in a relatively restricted
8 Applied and Environmental Soil Science
2 cm
Figure 6: Photograph of a giant Black Forest earthworm (adult individual of Lumbricus badensis) in its natural habitat. Note that the worm
is anchored with its anterior body part in its burrow (adapted from [36]).
(b)
Anguis fragilis
Cl
(a)
Lumbricus badensis
2 cm
Figure 7: Photographs of adult individuals of the giant earthworm (Lumbricus badensis) (a) and a limbless reptile (Anguis fragilis), the slow
worm (b), collected in the same habitat in the Black Forest (Schauinsland, Southern Germany, ca. 1200 m above sea level). Note that the
worm and the reptile are about the same size. The heads of both animals point to the right side. Cl=Clitellum.
area of the Black Forest, a region where no other Lumbricus- a new, reproductively isolated biospecies. Due to the large
species occur [36, 37, 39]. Detailed biogeographic studies dierence in body size and hence the dimension of the
on the occurrence and habitats of the sister taxa L. friendi corresponding clitellum, no copulations are possible between
(length ca. 12 cm) and L. badensis (length up to 34 cm) extant L. friendi and L. badensis. Zoogeographic studies
revealed that, after the end of the last ice age (ca. 10 000 along the narrow regions in Southwest Germany, where
years ago) founder populations of the smaller and more both species co-occur, have never found hybrids [35, 39].
widespread ancestor (a species closely related to extant L. It follows that Ernst Mayrs model of allopatric speciation
friendi), were separated via the river Rhine and hence became accounts for the evolutionary origin of the endemic Black
geographically isolated [37]. The young founder populations Forest-earthworm L. badensis [30, 40]. However, the ques-
of ancient L. friendi, which may have originated during tion why L. badensis evolved such an enormous body size
a time period between 8000 and 6000 years ago, rapidly within only a few thousand years is not yet answered. It is
occupied the new habitat in the Black Forest in regions from likely that these neoendemic earthworms rapidly adapted to
300 to 1400 m above sea level, where presumably no other the new habitat where predators were abundant and hence
competing earthworm species lived. As mentioned above, larger individuals in the variable founder populations had
the common species L. terrestris does not cooccor with L. a better change of survival, but more work is required to
badensis, possibly due to the high acid content of the soil further corroborate this hypothesis. As an alternative, it has
that the Black Forest worms inhabit. In this specific habitat, been postulated that specific environmental conditions, such
which represented a vacant ecological niche at that time, as the composition and structure of the soil, were factors
the geographically separated Atlantic earthworms established that caused the selection and survival of larger individuals
Applied and Environmental Soil Science 9
(a) (b)
(c)
Cocoon
1.5 cm
Figure 8: Schematic drawings of the burrows of juvenile (a) and adult (b) individuals of Lumbricus badensis. At depths of 40 to 150 cm below
the soil surface, along burrows of adult L. badensis individuals, cocoon chambers with egg-capsules have been observed and documented (c).
This indicates that parental investment is part of the reproductive strategy in this endemic earthworm species (adapted from [37]).
over thousands of subsequent generations [35], but no adult earthworms, several cocoon chambers along the main
direct evidence supports this idea. It should be noted that, tube were found in the region at 40 to 150 cm below the
according to Wikelski [41], a number of hypotheses have soil surface (Figure 8(c)). As in semiaquatic leeches of the
been proposed to account for the evolution of body size in genera Hirudo and Haemopis [24, 25], the giant earthworm
animals. Unfortunately, no consensus has yet emerged as to constructs brood chambers for the next generation. Hence,
a general explanation for this phenomenon. parental investment has evolved as a survival strategy of the
Twenty five years ago, the burrows of juvenile and adult populations in this endemic Black Forest earthworm. It is
L. badensis were investigated in fir-beech forests located in not known whether such a sophisticated mode of parental
the southern part of the Black Forest about 1000 m above sea investment occurs in any other earthworm species.
level [35, 37]. After hatching from the cocoons, which are At any rate, Charles Darwin, who explicitly pointed out
deposited in chambers located 40 to 150 cm below the soil that his metaphorical struggle for life does not only mean
surface (Figure 8(c)), L. badensis-individuals are 5 to 7 cm the competition for limited resources but also includes the
long (body mass: 0.4 to 0.6 g). It should be noted that nothing care for young by adults, and hence nonselfish, cooperative
is known about the mating behaviour in this earthworm behaviour [43], would have been pleased if he had known
species. The juvenile worms crawl upwards until they reach that one European worm species had evolved such an
the soil surface. Most of the newly hatched individuals, which intelligent mode of reproduction. In addition, it is obvious
are found during the spring, build horizontal tubes with that the earthworm burrows are a striking example for niche
their casts, usually between the soil surface and pieces of construction, that is, the active modification of the habitat of
bark, and so forth. One to 2-year-old earthworms (body organisms with positive consequences for survival and mode
mass: 1.5 to 2.5 g) construct U-shaped burrows (Figure 8(a)) of reproduction [12, 44].
that are similar to those of adult L. terrestris (see Figure 2)
[42]. Older juveniles with body masses of more than 2.5 g 8. Conclusions
construct deep, V-shaped burrows (depth ca. 2.5 m) that are
indistinguishable from those of the adults. A characteristic In 1837, one year after his return from the voyage of the
feature of all of the L. badensis burrows investigated in the Beagle, Charles Darwin started his career as an independent
Black Forest is that the tube splits into several (2 to 6) scientist with observations and a subsequent speech on
outlets near the soil surface (Figure 8(b)). In the burrows of earthworms that was published in 1838 [4]. Almost 45 years
10 Applied and Environmental Soil Science
Figure 9: Cartoon by E. L. Sambourne, published in the Punch in 1882 with the sentence Man is but a worm. This parody of Charles
Darwins concepts on the origin of humanity has been corroborated by recent molecular data on the phylogenetic relationships of annelids
and vertebrates (adapted from [38]).
later, he ended his life with the publication of a little book of less than 10 000 years [35]. In his masterpiece On the
on worms [2]. This became so popular that a famous Origin of Species [27], Charles Darwin argued that speciation
cartoon connected ancient annelids, via intermediate forms, events are too slow to be observed (or reconstructed) within
with the human species, represented by Charles Darwin the lifetime of one human being. He would have been pleased
(Figure 9). It should be noted that Darwins monograph to read that, 150 years later, earthworm researchers have
rapidly modified the perception of earthworms by society. elucidated a rapid speciation event that occurred after the
Up to then, earthworms were considered by gardeners, end of the last Ice Age in a restricted area of the south western
agriculturists, and so forth, as soil pests that have to be part of Germany.
eliminatedDarwins work changed this belief forever and
finally led to the concept of bioturbation as well as the
discipline of soil biology [3, 10, 13]. References
It is likely that Charles Darwin [2] was referring to [1] N. Barlow, Ed., The Autobiography of Charles Darwin, Collins
the common species L. terrestris when he pointed out that St. Jamess Place, London, UK, 1858.
earthworm burrows are . . . not mere excavations, but may [2] C. Darwin, The Formation of Vegetable Mould, through the
rather be compared with tunnels lined with cement [2, page Actions of Worms, with Observations on Their Habits, John
112]. Hence, according to the British naturalist, earthworms Murray, London, UK, 1881.
actively construct their home according to their needs. This [3] F. J. R. Meysman, J. J. Middelburg, and C. H. R. Heip,
is one of the earliest examples for the concept of niche Bioturbation: a fresh look at Darwins last idea, Trends in
construction we could find in the scientific literature on the Ecology and Evolution, vol. 21, no. 12, pp. 688695, 2006.
evolution of macro-organisms on Earth [12, 44]. [4] C. Darwin, On the formation of mould, Proceedings of the
We conclude that Darwins monograph on the biology of Geological Society of London, vol. 2, pp. 574576, 1838.
[5] A. Desmond and J. Moore, Darwin, Penguin Books, London,
earthworms was not simply a curious little book of small
UK, 1992.
importance [1], but a significant work that is still cited [6] C. Darwin, On the formation of mould, Transactions of the
today in a variety of scientific disciplines [3, 28]. Finally, Geological Society of London, pp. 505509, 1840.
we want to point out that modern earthworm research, [7] C. Darwin, On the origin of mould, Gardeners Chronicle and
which originated with Darwin [2], yielded the insight that Agricultural Gazette, vol. 14, p. 218, 1844.
geographic separation of founder populations can result in [8] C. Darwin, The formation of mould by worms, Gardeners
the creation of new Lumbricus species within a time period Chronicle and Agricultural Gazette, vol. 20, p. 530, 1869.
Applied and Environmental Soil Science 11
[9] D. L. Johnson, Darwin would be proud: bioturbation, [27] C. Darwin, On the Origin of Species by Means of Natural
dynamic denudation, and the power of theory in science, Selection, or the Preservation of Favoured Races in the Struggle
Geoarchaeology, vol. 17, no. 1, pp. 740, 2002. for Life, John Murray, London, UK, 1859.
[10] G. G. Brown, C. Feller, E. Blanchart, P. Deleporte, and S. S. [28] S. Rose, Ed., The Richness of Life: The Essential Stephen Jay
Chernyanskii, With Darwin, earthworms turn intelligent and Gould, W. W. Norton, New York, NY, USA, 2007.
become human friends, Pedobiologia, vol. 47, no. 5-6, pp. [29] R. W. Sims and B. M. Gerard, Earthworms. Synopsis of the
924933, 2003. British Fauna No. 31, Linnaean Society, London, UK, 1985.
[11] C. A. Edwards and P. J. Bohlen, Biology and Ecology of [30] U. Kutschera and K. J. Niklas, The modern theory of biolog-
Earthworms, Chapman & Hall, London, UK, 1996. ical evolution: an expanded synthesis, Naturwissenschaften,
[12] D. H. Erwin, Macroevolution of ecosystem engineering, vol. 91, no. 6, pp. 255276, 2004.
niche construction and diversity, Trends in Ecology and [31] A. J. Grove, On the reproductive processes of the earthworm
Evolution, vol. 23, no. 6, pp. 304310, 2008. Lumbricus terrestris, Quarterly Journal of Microscopical Sci-
[13] C. Feller, G. G. Brown, E. Blanchart, P. Deleporte, and S. S. ences, vol. 69, pp. 245291, 1925.
Chernyanskii, Charles Darwin, earthworms and the natural [32] V. Nuutinen and K. R. Butt, The mating behaviour of the
sciences: various lessons from past to future, Agriculture, earthworm Lumbricus terrestris (Oligochaeta: Lumbricidae),
Ecosystems & Environment, vol. 99, no. 13, pp. 2949, 2003. Journal of Zoology, vol. 242, no. 4, pp. 783798, 1997.
[14] J. E. Satchell, Lumbricidae, in Soil Biology, A. Burgess and F. [33] N. K. Michiels, A. Hohner, and I. C. Vorndran, Precopulatory
Raw, Eds., pp. 259322, Academic Press, London, UK, 1967. mate assessment in relation to body size in the earthworm
[15] M. H. B. Hayes, Darwins vegetable mould and some Lumbricus terrestris: avoidance of dangerous liaisons? Behav-
modern concepts of humus structure and soil aggregation, ioral Ecology, vol. 12, no. 5, pp. 612618, 2001.
in Earthworm Ecology: From Darwin to Vermiculture, J. E. [34] W. Michaelsen, Zur Kenntnis der deutschen Lumbriciden-
Satchell, Ed., pp. 1933, Chapman & Hall, London, UK, 1983. fauna, Mitteilungen des Naturhistorischen Museums Hamburg,
[16] V. V. Pop, Earthworm biology and ecologya case study: the vol. 24, pp. 1191, 1907.
genus Octodrilus Omodeo, 1956 (Oligochaeta, Lumbricidae), [35] F. Lamparski, Der Einflu der Regenwurmart Lumbricus
from the Carpathians, in Earthworm Ecology, C. A. Edwards, badensis auf Waldboden im Sudschwarzwald, Freiburger
Ed., pp. 65100, St. Lucie Press, Boca Raton, Fla, USA, 1998. Bodenkundliche Abhandlungen, vol. 15, 1985.
[17] B. Jonsson, T. Forseth, and O. Ugedal, Chernobyl radioactiv- [36] K. Riexinger, Ein Regenwurm der Superlative, Der Sonntag
ity persists in fish, Nature, vol. 400, no. 6743, p. 417, 1999. in Freiburg, vol. 2, p. 3, 1999.
[18] J. T. Smith, S. V. Fesenko, B. J. Howard, et al., Temporal [37] A. Kobel-Lamparsky and F. Lamparsky, Burrow construc-
change in fallout 137 Cs in terrestrial and aquatic systems: tions during the development of Lumbricus badensis individu-
a whole ecosystem approach, Environmental Science and als, Biology and Fertility of Soils, vol. 3, pp. 125129, 1987.
Technology, vol. 33, no. 1, pp. 4954, 1999. [38] M. J. Telford, A single origin of the central nervous system?
[19] J. T. Smith, R. N. J. Comans, N. A. Beresford, S. M. Wright, B. Cell, vol. 129, no. 2, pp. 237239, 2007.
J. Howard, and W. C. Camplin, Pollution: Chernobyls legacy [39] G. Osche, Der Riesenregenwurm (Lumbricus badensis) des
in food and water, Nature, vol. 405, no. 6783, p. 141, 2000. Sudschwarzwaldes, Der Feldberg im Schwarzwald. Natur-
[20] J. M. Elliott, J. Hilton, E. Rigg, P. A. Tullett, D. J. Swift, and und Landschaftsschutzgebiete Baden-Wurttembergs, vol. 12, pp.
D. R. P. Leonard, Sources of variation in post-Chernobyl 394396, 1982.
radiocaesium in fish from two Cumbrian lakes (Northwest [40] U. Kutschera, Species concepts: leeches versus bacteria,
England), Journal of Applied Ecology, vol. 29, no. 1, pp. 108 Lauterbornia, vol. 52, pp. 171175, 2004.
119, 1992. [41] M. Wikelski, Evolution of body size in Galapagos marine
[21] J. M. Elliott, J. A. Elliott, and J. Hilton, Sources of variation iguanas, Proceedings of the Royal Society B, vol. 272, no. 1576,
in post-Chernobyl radiocaesium in brown trout, Salmo trutta pp. 19851993, 2005.
L., and Arctic charr, Salvelinus alpinus L., from six Cumbrian [42] A. C. Evans, A method of studying the burrowing activities
lakes (Northwest England), Annales de Limnologie, vol. 29, pp. of earthworms, Annals Magazine Natural History, vol. 14, pp.
7998, 1993. 643650, 1947.
[22] V. Rousset, F. Pleijel, G. W. Rouse, C. Erseus, and M. E. Siddall, [43] U. Kutschera, Struggle to translate Darwins view of concur-
A molecular phylogeny of annelids, Cladistics, vol. 23, no. 1, rency, Nature, vol. 458, no. 7241, p. 967, 2009.
pp. 4163, 2007. [44] O. Seehausen, Ecology: speciation aects ecosystems,
[23] J. M. Elliott and K. H. Mann, A key to the British freshwater Nature, vol. 458, no. 7242, pp. 11221123, 2009.
leeches with notes on their life cycles and ecology, Scientific
Publications of the Freshwater Biological Association, vol. 40, pp.
172, 1979.
[24] U. Kutschera and P. Wirtz, The evolution of parental care in
freshwater leeches, Theory in Biosciences, vol. 120, no. 2, pp.
115137, 2001.
[25] U. Kutschera, I. Pfeier, and E. Ebermann, The European
land leech: biology and DNA-based taxonomy of a rare species
that is threatened by climate warming, Naturwissenschaften,
vol. 94, no. 12, pp. 967974, 2007.
[26] J. M. Elliott, Population size, weight distribution and food
in a persistent population of the rare medicinal leech, Hirudo
medicinalis, Freshwater Biology, vol. 53, no. 8, pp. 15021512,
2008.
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 562816, 12 pages
doi:10.1155/2010/562816
Review Article
Basic Research Tools for Earthworm Ecology
Copyright 2010 K. R. Butt and N. Grigoropoulou. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
Earthworms are responsible for soil development, recycling organic matter and form a vital component within many food webs.
For these and other reasons earthworms are worthy of investigation. Many technologically-enhanced approaches have been used
within earthworm-focused research. These have their place, may be a development of existing practices or bring techniques from
other fields. Nevertheless, let us not overlook the fact that much can still be learned through utilisation of more basic approaches
which have been used for some time. New does not always equate to better. Information on community composition within an area
and specific population densities can be learned using simple collection techniques, and burrowing behaviour can be determined
from pits, resin-insertion or simple mesocosms. Life history studies can be achieved through maintenance of relatively simple
cultures. Behavioural observations can be undertaken by direct observation or with low cost webcam usage. Applied aspects
of earthworm research can also be achieved through use of simple techniques to enhance population development and even
population dynamics can be directly addressed with use of relatively inexpensive, eective marking techniques. This paper seeks
to demonstrate that good quality research in this sphere can result from appropriate application of relatively simple research tools.
1. Introduction [13]; or, for example, isotopic work, looking at the transfer
of radio-labelled elements through earthworm-linked food
There is no need to make a case for studying earthworms, as chains [14]. However, such relatively high-tech methods will
their role within the soil has been recognized for more than a not be the focus of this work, which seeks to generally
century [1]. Collectively, these organisms are able to pass vast avoid reliance upon potentially costly and high-maintenance
quantities of soil through their guts and by doing so bring equipment. This article actually aims at doing one thing; it
about the creation of an improved crumb structure which seeks to show that the use of low-technology methods is still
incorporates mineral and organic elements and can become able to gain insights into fundamental questions relating to
a seedbed for plant growth [2]. In addition, earthworms may earthworms. Much is still to be fully understood about this
aerate soils and increase water infiltration, hence reducing group, and although many advances have recently been made
soil erosion, by burrow creation [3]. On top of all this some using sophisticated, expensive equipment/techniques, there
species are more highly regarded as they are attributed with is still room for the under-resourced professional or educated
ecosystem engineering capabilities; that is, they are able to amateur to make a serious contribution. To demonstrate
directly influence the environment around themselves and this, the article focuses on the following: a description of
the availability of resources to other organisms [4]. simple collection techniques, which can assist in revealing
Many avenues of research are available and this article a great deal of earthworm community structure, followed
could very easily seek to review and critique some of the by investigation of a major earthworm activityburrowing
more advanced techniques currently in use within the sphere and then a close inspection of earthworm life history and
of earthworm ecology. These might include DNA-related behaviours. Each aspect will hopefully show that basic
work examining the genome of selected species [12]; ecotox- techniques exist within earthworm ecology that can reveal
icology, following the accumulation of, for example, heavy previously unknown information and assist in building a
metals in the tissues of earthworms on contaminated land more comprehensive picture of this important animal group.
2 Applied and Environmental Soil Science
Table 1: Recent British examples of earthworm density/biomass/community structure from sampling with the same techniques (digging
and application of a mustard vermifuge).
Earthworm Earthworm
Sampling Dominant
Location Habitat density (No biomass Earthworm species Reference
date species
m2 ) (gm2 )
Aughton Woods, Deciduous
Oct 2006 37 29.8 Ach; Dr; Lt; Oc Oc [5]
Lancs woodland
Aughton Woods,
Pasture Oct 2006 183 110.9 Ach; Ac; Al; Ar; Lr; Lt; Oc Ac [5]
Lancs
Meresands Wood,
Dry Heathland Oct 2001 167 75.0 Ach; Ac; Al; Ar; Et; Lc; Lr; Lt; Oc Ac [6]
Lancs
Wistmans Wood, Upland oak
May 1999 13 9.3 Le; Lr; Dr Dr [7]
Devon woodland
Down House, Kent Pasture March 2004 310 149.6 Ach; Al; Ar; Lr; Ot; Sm Ot [8]
Down House, Kent Kitchen Garden March 2004 715 261.0 Ach; Ac; Al; Ar Ach [8]
Isle of Rum, Upland
May 2000 9 3.0 Do; Dr; Lr Dr [9]
Scotland moorland
Malham Tarn,
Pasture May 1998 291 86.1 Ach; Ac; Al; Ar; Do; Lc; Lt; Oc Ach [10]
Yorkshire
Newton Rigg Farm Winter Barley April 2006 18 6.0 Ach; Al Al [11]
Conservation
Newton Rigg Farm April 2006 118 76.2 Ach; Ac; Al; Ar; Do; Lr; Oc: Sm Al [11]
Headland
Key: Ach: Allolobophora clorotica; Ac: Aporrectodea caliginosa; Al: Aporrectodea longa; Ar: Aporrectodea rosea; Do: Dendrobaena octaedra; Dr:
Dendrodrilus rubidus; Et: Eiseniella tetraedra; Lc: Lumbricus castaneus; Le: Lumbricus eiseni; Lr: Lumbricus rubellus; Lt: Lumbricus terrestris; Oc: Octolasion
cyaneum; Ot: Octolasion tyrtaeum; Sm: Satchellius mammalis.
Having determined which earthworms are present in a (i) Which species of earthworms are present within the
given habitat, if desired, it is then possible to experimentally community in the given habitat?
manipulate the earthworms themselves or resources, such as
(ii) At what densities (number m2 ) and biomasses
food, in the habitat. Several studies have used field enclosures
(gm2 ) are these animals present?
to investigate the eects of earthworms on soil properties
and plants [22, 23]. Such enclosures can be formed with (iii) What proves to be the most ecient method for
PVC walls, buried in slit trenches to a depth of up to 45 cm collection of given earthworm species?
and a height of 15 cm above the soil surface. These have
been shown to act as eective barriers to lateral earthworm (iv) Can populations be experimentally manipulated
movements. Results have suggested that both earthworm to test density-related hypotheses (using addi-
removal and addition of field-collected earthworms within tion/removal, fencing, and trapping)?
enclosures can be an eective and useful approach for assess-
ing the influence of earthworms on ecosystem processes (see 3. Burrowing and Burrow Morphology
Figure 1).
Associated with earthworm enclosures is a novel method As with unearthing which species are present, as previously
(tunnel trapping) that can be used to observe and record described, working out which species are active and at what
emigration of earthworms. Trap units can be combined with depths is not so simple. Again, it usually requires some
earthworm fencing in the field [24], or with mesocosms form of intervention as many earthworms are relatively small
in laboratory experiments allowing examination of emigra- and generally live below the surface of the soil. However,
tion rates, while manipulating biotic and abiotic factors some species do proclaim their presence by depositing their
(e.g., population density, community structure, predation, casts (faeces) on the soil surface. This is particularly true
resources availability, temperature, precipitation). of larger species which may be digging burrows and have
Tunnel traps can be prepared using 1 litre plastic pots relatively large amounts of earth to dispose of and others
with mounted needle-perforated lids. Holes (r = 6 mm) which are almost constantly head down and bottom up
drilled in these smaller capture pots just below the lid producing surface casts. In temperate soils a good example of
allow insertion of PVC tubing (10 mm ID, 5 cm long) to this is Aporrectodea longa (the black-headed or long worm).
connect to either earthworm fencing in field enclosures or When present at high densities, this species is capable of
larger soil-filled mesocosms. Surface migrating species can almost totally covering the grass surface of a pasture with
move from enclosures/mesocosms into traps via the tubing casts. It has been suggested that the amount of casting
that is aligned at the soil surface (Figure 2). Movement of could even be used as a proxy for the density of (known
captured individuals back into containers is prevented by casting) species present in an area [25]. Where the spread
filling capture pots with soil or other suitable medium to of A. longa was being followed, after introduction to an
half of their total volume. Providing acceptable conditions unpopulated site, casting activity was used to follow dispersal
(e.g., soil and food) in capture pots can allow earthworms of this species through the soil over many years [26, 27].
to survive for long periods therefore permitting relatively Another deep burrowing earthworm which provides signs of
infrequent examination. Tunnel traps have been successfully its presence on the soil surface is L. terrestris. This species
used in both field and laboratory experiments which aimed constructs middens and these structures are normally
to examine dispersal of the anecic L. terrestris as aected by engineered above the opening of the near vertical burrow
population density and resources availability [24]. used by this animal. Scientists have been aware of such
The types of simple investigation associated with earth- structures since Darwins day, but the precise function is
worm sampling should allow some of the following questions still uncertain. Middens consist of organic (e.g., leaf) and
to be answered. inorganic (e.g., pebble) materials gathered together by the
4 Applied and Environmental Soil Science
Table 2: Details of cocoons and hatchlings of Lumbricus terrestris (mean SD) produced under a number of adult manipulations in Evans
boxes, kept at 17 C in darkness (CTRL: no manipulation; CLtRm: earthworm removed and reintroduced; LtRp: earthworm removed and
replaced by another; LtRm: earthworm removedadapted from [34]).
Figure 5: Detail of a side burrow with L. terrestris cocoon encased in 4. Life History Studies
parental casting seen in an Evans box with one glass side removed
(to permit better photography). Many species have been well documented and much is
known of their life history, but for example, ask any
researcher to tell you what age an earthworm can live to, or
[35] has been used to determine burrow configurations in which life stage is responsible for dispersal and you may find
such cores. Whilst this may be a useful tool; it is one which that no simple answer is forthcoming (even for L. terrestris).
required access to hospital-grade equipment so it cannot Great scope exists for gathering fundamental information on
be considered basic. However soil cores can be utilised to aspects of the life histories of most earthworm species. In
study relatively simple ecosystems with earthworms as Britain, where earthworms are reasonably well documented
a component. These may allow examination of dierent and a synopsis of species has been available in a number
6 Applied and Environmental Soil Science
Figure 12: Two litre Earthworm Inoculation Units (EIUs) ready for
inoculation into an organically-enriched landfill cap in the south of
Figure 11: A pair of mating L. terrestris on the soil surface, revealed England.
and photographed after sun rise.
used and have positive attributes but equally have less attrac-
observations of mating behaviour, through mate selection, tive features (see Table 3). To assist the reintroduction pro-
to close scrutiny of copulatory interaction, has all been cess, information gathered on earthworm life histories and
examined. Great scope still exists in the area of earthworm requirements for culture have been coupled with further data
behaviour and some of the following questions could be relating to activities in the soil and interactions with other
addressed. earthworm species [34, 4043]. In this way a relatively simple
(i) Which species exhibit mass dispersal and which life technique, the Earthworm Inoculation Unit (EIU), was
stages are involved? devised [26] seeking to overcome the problems associated
with the existing techniques. Irreverently known as worms
(ii) How much leaf litter is removed or consumed by in bags this technique seeks to cultivate a starter culture
earthworms in given habitats? of adults under optimal conditions over a period of a few
months. After this time, population development within the
(iii) Can removal of organic matter into the soil be plastic-bound units means that all life stages, adults, cocoons,
harnessed for soil improvement? and hatchlings ought to be present. The EIUs can then be
transported to the desired inoculation site ready for intro-
(iv) Is L. terrestris the only species that mates on the soil duction (see Figure 12). Inoculation requires the contents of
surface? the EIUs to be inserted into an appropriately sized hole in the
soil, after the plastic envelope has been carefully removed.
(v) Do other earthworm species show mate choice?
The contents thereby retaining their original position
in the soil profile and providing a protective microenvi-
6. Field Manipulation of Populations ronment. Over the past two decades, results from both
(Assisting the Plough) agricultural and post-industrial settings have been positive
[26, 48]. Spread of earthworms over one site at Calvert site
Where soils require an input of earthworms, augmentation was completed within a decade and positive interactions were
can be brought about using the above information recorded with the presence of alder trees (Alnus glutinosa
collection, selection for activities, and even selection for which fix nitrogen) and earthworm density [27]. At one of
mass culture before field-release. Earthworms, because of the sites, further investigations developed the EIU technique
their activities in the soil, are, where appropriate, considered with addition of organic matter. This was a response to
as vital components of a healthy, fully functional system. use of manure as earthworm attractant traps to augment
Reviews of research have shown that, across the world and assessment of the numbers and species present on site [26].
in numerous habitats, the provision of earthworms to sites Addition of earthworms to sites where they are absent
where they were absent, assistance with recolonisation, or (for some reason) may be valuable and permit a number of
improvements to the type of conditions conducive to their questions to be addressed.
survival can bring about marked positive changes in soil
properties [56, 57]. (i) What factors brought about the removal of earth-
worms?
Should areas exist that are devoid of earthworms, for
known or unknown reasons, then one approach might (ii) What can be done to remedy the situation?
be to (re)introduce them to site. Numerous methods are
(iii) How can the success of the operation be measured (in
available to achieve this but most can be described simply
terms of earthworms and soils)?
as collection and broadcast using the type of collection
techniques previously mentioned or turf transfer, digging (iv) Can more be learned of earthworm populations from
up and translocating soil with grass attached. Both have been this type of work?
10 Applied and Environmental Soil Science
Table 3: Relative Merits of existing Earthworm Inoculation Techniques (adapted from [26]).
[12] S. R. Sturzenbaum, J. Andre, P. Kille, and A. J. Morgan, [27] K. R. Butt, C. N. Lowe, J. Frederickson, and A. J. Moat, The
Earthworm genomes, genes and proteins: the (re)discovery of development of sustainable earthworm populations at Calvert
Darwins worms, Proceedings of the Royal Society B, vol. 276, Landfill Site, UK, Land Degradation & Development, vol. 15,
no. 1658, pp. 789797, 2009. no. 1, pp. 2736, 2004.
[13] C. J. Langdon, A. J. Morgan, J. M. Charnock, K. T. Semple, [28] K. R. Butt and V. Nuutinen, The dawn of the dew worm,
and C. N. Lowe, As-resistance in laboratory-reared F1, F2 and Biologist, vol. 52, no. 4, pp. 218223, 2005.
F3 generation ospring of the earthworm Lumbricus rubellus [29] K. R. Butt and C. N. Lowe, Presence of earthworm species
inhabiting an As-contaminated mine soil, Environmental within and beneath Lumbricus terrestris (L.) middens, Euro-
Pollution, vol. 157, no. 11, pp. 31143119, 2009. pean Journal of Soil Biology, vol. 43, supplement 1, pp. S57
S60, 2007.
[14] M. J. I. Briones, R. Bol, D. Sleep, D. Allen, and L. Sampedro,
[30] M. J. Shipitalo and K. R. Butt, Occupancy and geometrical
Spatio-temporal variation of stable isotope ratios in earth-
properties of Lumbricus terrestris L. burrows aecting infiltra-
worms under grassland and maize cropping systems, Soil
tion, Pedobiologia, vol. 43, no. 6, pp. 782794, 1999.
Biology and Biochemistry, vol. 33, no. 12-13, pp. 16731682,
[31] V. Nuutinen and K. R. Butt, Interaction of Lumbricus
2001.
terrestris L. burrows with field subdrains, Pedobiologia, vol.
[15] ISO 23611-1, Soil qualitysampling of soil invertebrates 47, no. 5-6, pp. 578581, 2003.
part 1: hand-sorting and formalin extraction of earthworms, [32] V. Nuutinen and K. R. Butt, Worms from the cold: lumbricid
ISO 23611-1, 2006. life stages in boreal clay during frost, Soil Biology and
[16] E. Eichinger, A. Bruckner, and M. Stemmer, Earthworm Biochemistry, vol. 41, no. 7, pp. 15801582, 2009.
expulsion by formalin has severe and lasting side eects on soil [33] A. C. Evans, Method of studying the burrowing activity of
biota and plants, Ecotoxicology and Environmental Safety, vol. earthworms, Annual Magazine of Natural History, vol. 11, pp.
67, no. 2, pp. 260266, 2007. 643650, 1947.
[17] A. Gunn, The use of mustard to estimate earthworm [34] N. Grigoropoulou, K. R. Butt, and C. N. Lowe, Eects of
populations, Pedobiologia, vol. 36, no. 2, pp. 6567, 1992. adult Lumbricus terrestris on cocoons and hatchlings in Evans
[18] A. P. Lawrence and M. A. Bowers, A test of the hot mustard boxes, Pedobiologia, vol. 51, no. 5-6, pp. 343349, 2008.
extraction method of sampling earthworms, Soil Biology and [35] M. Joschko, O. Gra, P. C. Muller, et al., A non-destructive
Biochemistry, vol. 34, no. 4, pp. 549552, 2002. method for the morphological assessment of earthworm
burrow systems in three dimensions by X-ray computed
[19] E. R. Zaborski, Allyl isothiocyanate: an alternative chemical
tomography, Biology and Fertility of Soils, vol. 11, no. 2, pp.
expellant for sampling earthworms, Applied Soil Ecology, vol.
8892, 1991.
22, no. 1, pp. 8795, 2003.
[36] J. H. Lawton, The ecotron facility at silwood park: the value of
[20] C. Pelosi, M. Bertrand, Y. Capowiez, H. Boizard, and J. Roger- Big Bottle experiments, Ecology, vol. 77, no. 3, pp. 665669,
Estrade, Earthworm collection from agricultural fields: com- 1996.
parisons of selected expellants in presence/absence of hand- [37] S. Naeem, J. H. Lawton, L. J. Thompson, S. P. Lawler, and R.
sorting, European Journal of Soil Biology, vol. 45, no. 2, pp. M. Woodfin, Biotic diversity and ecosystem processes: using
176183, 2009. the Ecotron to study a complex relationship, Endeavour, vol.
[21] N. Eisenhauer, D. Straube, and S. Scheu, Eciency of two 19, no. 2, pp. 5863, 1995.
widespread non-destructive extraction methods under dry [38] L. Cernosvitov and A. C. Evans, Lumbricidae (Annelida). With
soil conditions for dierent ecological earthworm groups, a Key to the Common Species, Synopses of the British Fauna,
European Journal of Soil Biology, vol. 44, no. 1, pp. 141145, no. 6, The Linnean Society of London, London, UK, 1947.
2008. [39] R. W. Sims and B. M. Gerard, Earthworms. Notes for Identi-
[22] J. M. Blair, R. W. Parmelee, M. F. Allen, D. A. McCartney, fication of British Species, R. S. K. Barnes and J. H. Crothers,
and B. R. Stinner, Changes in soil N pools in response to Eds. Synopses of the British Fauna, no. 31, Linnean Society of
earthworm population manipulations in agroecosystems with London and the Estuarine and Coastal sciences Association,
dierent N sources, Soil Biology and Biochemistry, vol. 29, no. 1999.
3-4, pp. 361367, 1997. [40] C. N. Lowe and K. R. Butt, Culture techniques for soil
[23] S. L. Lachnicht, R. W. Parmelee, D. Mccartney, and M. dwelling earthworms: a review, Pedobiologia, vol. 49, no. 5,
Allen, Characteristics of macroporosity in a reduced tillage pp. 401413, 2005.
agroecosystem with manipulated earthworm populations: [41] K. R. Butt, Depth of cocoon deposition by three earthworm
implications for infiltration and nutrient transport, Soil species in mesocosms, European Journal of Soil Biology, vol.
Biology and Biochemistry, vol. 29, no. 3-4, pp. 493498, 1997. 38, no. 2, pp. 151153, 2002.
[42] K. R. Butt, J. Frederickson, and R. M. Morris, Eect
[24] N. Grigoropoulou and K. R. Butt, Field investigations of of earthworm density on the growth and reproduction of
Lumbricus terrestris spatial distribution and dispersal through Lumbricus terrestris L. (Oligochaeta: Lumbricidae) in culture,
monitoring of manipulated, enclosed plots, Soil Biology and Pedobiologia, vol. 38, no. 3, pp. 254261, 1994.
Biochemistry, vol. 42, no. 1, pp. 4047, 2010. [43] K. R. Butt, Interactions between selected earthworm species:
[25] A. C. Evans and W. J. Mc. L. Guild, Studies on the rela- a preliminary, laboratory-based study, Applied Soil Ecology,
tionships between earthworms and soil fertility. I. Biological vol. 9, no. 13, pp. 7579, 1998.
studies in the field, Annals of Applied Biology, vol. 34, no. 3, [44] K. R. Butt, The eects of temperature on the intensive
pp. 307330, 1947. production of Lumbricus terrestris L. (Oligochaeta: Lumbrici-
[26] K. R. Butt, J. Frederickson, and R. M. Morris, The Earth- dae), Pedobiologia, vol. 35, no. 4, pp. 257264, 1991.
worm Inoculation Unit technique: an integrated system for [45] K. R. Butt and C. N. Lowe, A viable technique for tagging
cultivation and soil-inoculation of earthworms, Soil Biology earthworms using visible implant elastomer, Applied Soil
and Biochemistry, vol. 29, no. 3-4, pp. 251257, 1997. Ecology, vol. 35, no. 2, pp. 454457, 2007.
12 Applied and Environmental Soil Science
Review Article
The Role of Earthworms in Tropics with
Emphasis on Indian Ecosystems
Copyright 2010 R. D. Kale and N. Karmegam. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
The paper highlights the research carried out by dierent scientists in India on aspects of earthworm population dynamics and
species diversity, associated with other soil fauna and microflora. It also deals with the importance of earthworm activity on
physicochemical properties of soil with reference to India and other tropical countries. Stress is laid on the earthworm plant
association and importance of the secretions of earthworms as plant growth stimulators. Moreover, the earthworm species reported
and being utilized for vermicomposting in India are discussed, since vermicomposting is the ultimate technology which renders
for the improvement of soil fertility status and plant growth. Earthworms serve as indicators of soil status such as the level of
contamination of pollutants: agrochemicals, heavy metals, toxic substances, and industrial euents; human-induced activities:
land-management practices and forest degradation. In all these fields there is lacuna with respect to contributions from India when
compared to the available information from other tropical countries. There is lot of scope in the field of research on earthworms
to unravel the importance of these major soil macrofauna from holistic ecological studies to the molecular level.
texture, pH, electrolyte concentration, and food source in the nature of leaf matter, chemical compounds in them serve as
given ecosystem. This clearly indicates the interdependency attractants or repellants (Tables 3 and 4). Ganihar [4] is of
of the environmental factors to the survival of earthworms; the view that in land reclamation sites, if earthworms have
when such conditions are created, they further contribute to to be introduced, it is essential to develop above ground
soil fertility through their activity. plant community. Litter from such plants when mixes with
soil, at dierent levels of decomposition, serves as feed
to developing earthworm population. The available carbon
3. Food Niches of Earthworms source encourages population growth of earthworms [6]. In
India, Lampito mauritii is the most widely distributed earth-
Degradation of leaf material commences from the time it worm in dierent agro-ecosystems [712]. This earthworm
detaches itself from the plant and drops to ground to add preferred decomposing grass of paddy (Oryza sativa) and
to litter. Earthworms are the major secondary decomposers finger millet (Eleucine coracana) to other leaf litter [5]. The
in the soil faunal community. They feed on decomposed grasses when developed in reclamation sites can form an
organic material at dierent levels of degradation. Lee [1] ideal base for establishment of Lampito mauritii to bring
has suggested that earthworms survive on microorganisms, about improvement in soil structure and finally chemical and
micro- and mesofauna associated with ingested dead tissue. biological activities. Food preference and sensitivity to other
According to him, earthworms that feed near the surface on edaphic factors determine the possibility of introduction of
decomposing litter and at the root zone on dead roots are earthworms for land reclamation.
the detritivores and those remain at subsurface and consume
large quantities of soil are geophagous earthworms.
Lavelle [2] has categorized geophagous earthworms 4. Earthworm Activity on Physicochemical
as polyhumic, oligohumic, and mesohumic based on the Properties of Soil
proportion of humus and soil in their feed. Through factorial
analysis, he has given the explanation that temperature dif- Earthworms are the major macrofauna in the soil commu-
ferences with latitude and litter characteristics like quantity nity. They are distributed at dierent depths in soil strata.
and decomposability determine the variations observed with The litter feeders, which are not burrowers, constitute a
reference to their distribution. The detritivorous epigeic very small number in tropical situations. The burrowing
earthworms form the major component of earthworm fauna endogeic earthworms live in horizontal and vertical burrows
in temperate regions and mesohumic endogeic earthworms constructed in soil strata. They make these burrows partly
are predominant in tropical forests. There is minimum by ingesting soil particles through their way and partly by
representation of mesohumic earthworms in temperate pushing the soil to the sides [13]. The ingested soil along with
regions. Oligohumic earthworms that feed on soil having organic matter passes through the gut and undigested matter
very low level of organic matter are abundant only in tropical is released at the opening of the burrow on soil surface or at
regions. the subsurface as castings. The subsurface castings contribute
Lavelle [2] considers polyhumic earthworms as more to soil profile [1].
stable fraction of earthworm community occupying dierent The burrows of earthworms, which run horizontally or
soil strata as topsoil feeders to species of rhizosphere in vertically depending on burrow forming ability of species,
tropical regions. Thus, tropical earthworms depend more on will determine the possible physical eects on soil charac-
soil mixed with dierent levels of humic substances rather teristics. In temperate regions where deep burrowing anecic
than surface litter. More stable environments like heavy earthworms are of common occurrence, it is opined that
rainfall areas (2000 to above 4000 mm rain/annum) in the infiltrations can bring about leaching of nutrients from soils
state of Karnataka, India, have greater diversity of earth- to ground water. The leachate volume may show an increase
worms than the dry areas (<600 to 900 mm rain/annum). of four to twelve folds due to their activity [14]. Introduction
The geophagous earthworms of mesohumic and polyhumic of Aporrectodea caliginosa into coniferous forest soils resulted
types are widely distributed in places receiving heavy rainfall in fifty fold increase in concentration of nitrate and cations
in this subtropical part of the country (Tables 1 and 2). in soil solution. But the amount that entered ground water
The acceptance level of various leaf litters shows positive or plant system remained undetermined [15]. One of the
correlation to nitrogen and carbohydrate contents and major contributions of burrowing activity of earthworms
negative correlation to polyphenol content [3]. Ganihar is in aecting soil porosity [16, 17]. The major impact on
[4] studied the litter feeding of Pontoscolex corethrurus in hydrology has been worked out with respect to activity of
a multiple-choice test. He found variations in degree of anecic earthworm Lumbricus terrestris [18]. Information is
acceptability of dierent litter that showed positive corre- lacking in India with respect to burrows of earthworms, their
lations to levels of organic carbon and nitrogen content. structure, and any variations observed depending on soil
The least preference for Eucalyptus camaldulensis and Acacia type. Influence of organic matter, agricultural practices on
auriculiformis was linked with high levels of polyphenols. earthworm population, and similarly the role of earthworms
It has been shown that Lampito mauritii exhibited similar in modifying the situations in cultivable lands are very
preference either for partially decomposed large pieces of leaf meager in a country having diversity and abundance of
material of dierent types or for powdered leaves mixed with the populations in dierent agro-ecosystems. Reddy et al.
agar base [5]. It could be inferred that apart from physical [19] reported the influence of various management practices
Applied and Environmental Soil Science 3
Table 1: Earthworm distribution in Southern Karnataka (India) in dierent agroclimatic zones including coastal plains, hilly regions, and
interior plains.
Population
Vertical
Sl. No. Species Moisture level (%) Soil type Food niche density
distribution (cm)
(no./100 m2 )
Curgeona Wet land-in waterlogged
1 Red loamy soil Up to 45 Mesohumic 64011,250
narayani soil
Dichogaster Red loamy, alluvial Mesohumic
2 2040 510 60250
anis and lateritic to polyhumic
3 D. bolaui 2040 60450
4 D. curgensis 2040 Red loamy Polyhumic 25200
5 D. modigliani 2040 Red sandy Mesohumic 1025
6 D. saliens 2040 Red sandy 65265
Drawida
7 >40 Red loamy 1020 Polyhumic 275930
ampullacea
Red loamy to sandy
8 D. barwelli >50 1030 275576
soil
D. barwelli
9 >50 Red loamy 120430
impertusa
Red loamy to sandy
10 D. calebi >50 1030 Polyhumic 801200
soil
11 D. ferina 4050 Red loamy 2030 Mesohumic 40340
12 D. ghatensis 4050 1020 4501350
13 D. kanarensis 4050 85400
14 D. lennora 4050 Red sandy soil 1530
15 D. modesta 4050 1030 4500
16 D. paradoxa >40 Red loamy to alluvial 1020 Polyhumic 17002500
D. pellucida
17 >40 Lateritic to Red loamy Mesohumic 4500
pallida
18 D. scandens >40 Red sandy loam 510 Polyhumic 10350
19 D. sulcata >40 Alluvial soil 1030 Polyhumic 65235
Glyphidrillus Sandy bed to Red
20 >40 2045 Oligohumic 1301600
annandalei loam
Gordiodrilus
21 >40 Red sandy loam 1040 Mesohumic 24200
elegans
Hoplochaetella
22 3040 Lateritic to alluvial 1030 Polyhumic 10430
kempi
23 H. suctoria 3040 Alluvial 1020 50240
Hoplochaetella
24 4050 Red loam 2040 4603330
sp.
25 Howascolex sp. 3040 Red loam 1030 1452500
Lampito
26 2030 Red sandy to lateritic 1030 Mesohumic 7202190
mauritii
27 Mallehula indica 3040 Red loam 1020 Mesohumic 180880
Megascolex
28 3040 Lateritic 510 Polyhumic 15330
filiciseta
29 M. insignis 3040 Alluvial 520 Polyhumic 65800
Red loam to sandy
30 M. lawsoni 3040 1030 Mesohumic 1201000
loam
31 M. konkanensis 3040 Lateritic to alluvial 2045 Mesohumic 203900
Metaphire
32 >40 Alluvial and Red loam 1040 Polyhumic 182140
houlleti
Octochaetona
33 3040 Red loam 1020 Polyhumic 150650
albida
34 O. beatrix 2030 Sandy loam 40335
35 O. rosea 3040 Alluvial 1020 Mesohumic 15120
36 P. excavatus >40 Organic layer 05 Detritivore 188000
37 Plutellus timidus 3040 Alluvial 1015 Mesohumic 60460
Polypheretima Sandy loam to Red
38 >40 3060 Mesohumic 1944000
elongata loam
Pontoscolex Sandy, alluvial, loamy, Mesohumic
39 3050 515 2507100
corethrurus lateritic to polyhumic
4 Applied and Environmental Soil Science
Table 2: Habitat preference of widely distributed earthworm species Lampito mauritii and Pontoscolex corethrurus at study sites.
Table 3: Disintegration of dierent leaf matters due to selective feeding by earthworm Lampito mauritii [5].
Leaf matter 1 2 3 4 5 6 7 8 9
Millet straw 70.00 50.00 55.00
Paddy straw 48.00 11.00 27.50 22.00 13.00 33.00
Cashew litter 38.00 24.00 39.00 22.50 2.60 67.00
Mango litter 48.00 30.00 50.00 30.70 28.60 6.30
Guava litter 44.00 14.00 83.00 25.00 23.00
Eucalyptus litter 32.00 10.00 61.00 31.00 24.40 11.60
Note: Col: 13 data for first month
(1) Percent loss of litter per month due to microbial degradation and feeding by earthworms.
(2) Percent microbial degradation per month.
(3) Rate of litter consumption (mg) for hundred earthworms per day.
Col: 46 data for second month
(4) Percent loss of litter per month due to microbial degradation and feeding by earthworms.
(5) Percent microbial degradation per month.
(6) Rate of litter consumption (mg) for hundred earthworms per day.
Col: 79 data for third month
(7) Percent loss of litter per month due to microbial degradation and feeding by earthworms.
(8) Percent microbial degradation per month.
(9) Rate of litter consumption (mg) for hundred earthworms per day.
The table also shows the acceleration of litter breakdown in presence of earthworms.
aecting density and surface cast production. The casts of and Megascolex insignis), Octochaetidae (Dichogaster bolaui,
the earthworm, Pontoscolex corethrurus, and the surrounding D. saliens, and Octochaetona thurstoni), Moniligastridae
soil in an undisturbed forest floor in Sirumalai Hills, Tamil (Drawida chlorina, D. paradoxa, and D. pellucida pallida),
Nadu (South India) showed that the percentage of moisture and Glossoscolecidae (Pontoscolex corethrurus) in the study
content, organic carbon, and total nitrogen in the worm that was carried out at dierent locations in Dindigul
casts were higher and significantly diered from the values District (South India). The fluctuations in populations of
obtained in the surrounding soil [20]. earthworms were observed during the monthly collections in
According to the recent report by Julka et al. [21], in course of three years in all the selected sites. In the survey
India, there are 590 species of earthworms with dierent carried out from 1997 to 1999, the predominant species
ecological preferences, but the functional role of the majority that were recorded as maximum number of earthworms/m2
of the species and their influence on the habitat are lacking. in sites 110 were D. pellucida pallida (Jan. 1998-70.44),
Recently Karmegam and Daniel [11] reported the correlation D. pellucida pallida (Dec. 1999-32.30), L. mauritii (Feb.
of soil and environmental parameters on the abundance of 1998-55.22), D. pellucida pallida (Dec. 1999-25.54), L.
ten dierent earthworm species belonging to four families, mauritii (Dec. 1997-66.78), L. mauritii (Nov. 1997-43.40), L.
namely, Megascolecidae (Lampito mauritii, L. kumiliensis, mauritii (Jan. 1999-44.60), P. corethrurus (Nov. 1997-58.34),
Applied and Environmental Soil Science 5
P. corethrurus (Dec. 1999-64.30), and P. corethrurus (Dec. Table 4: Artificial diet (1 : 8 by weight) of agar and dierent leaf
1998-107.60) [22]. litter powder on feeding of earthworm Lampito mauritii in relation
The biomass dynamics also showed wide fluctuation to C/N of diets [5].
among the species in relation to the months of collection Daily food
from dierent collection sites. The highest worm biomass Litter powder in C/N of
intake
was recorded during December to February and certain agar the feed
mg/day/adult
species were totally absent during certain periods of the Paddy straw 8.05 0.28 37
survey. The total biomass of dierent species recorded
Millet straw 7.07 1.23 45
in the monthly observation over a period of three years
(1997 to 1999) varied in various study sites. The highest Mango litter 8.67 1.27 19
biomass of the respective earthworm species as well as the Guava litter 3.25 0.79 45
month and year of its occurrence in the study sites 1 to Cashew litter 4.44 1.10 30
10 as recorded includes D. pellucida pallida (30.63 g/m2 Eucalyptus litter 1.62 0.59 42
during Feb. 1998), D. pellucida pallida (22.88 g/m2 during Agar only (control) 2.53 1.23 38
Jan. 1998), D. pellucida pallida (29.27 g/m2 during Dec. Number of observations = 3; Palatability depends on texture as well as
1999), D. pellucida pallida (20.20 g/m2 during Dec. 1999), D. chemical nature of the feed.
pellucida pallida (44.65 g/m2 during Dec. 1999), D. pellucida
pallida (22.38 g/m2 during Dec. 1999), D. pellucida pallida
(29.66 g/m2 during Jan. 1998), P. corethrurus (15.20 g/m2 study site for its variety of habitats to assess the earthworm
during Dec. 1998), D. bolaui (19.79 g/m2 during Jan. species diversity, density, and biomass. The population and
1999), and P. corethrurus (26.34 g/m2 during Dec. 1998), biomass dynamics of dierent earthworm species and their
respectively [22]. Among the earthworm species studied, percentage abundance in relation to physicochemical char-
L. kumiliensis has been reported for the first time in acteristics of the soil and the climatic factors were recorded
Sirumalai Hills of Tamil Nadu, India [23]. This is the only in selected sites. The correlation of earthworm population to
study to highlight the cyclic fluctuations in the earthworm physicochemical characteristics of the soil and the climatic
populations for a continuous period of three years and parameters was carried out to find out the possibility
variations in the species structure at dierent time intervals. of arriving at a suitable endemic earthworm species for
Still the information on the physicochemical changes in the vermicomposting operations in this part of the country.
soil with respect to species composition at given time is not Since the populations of earthworms are extremely variable
clear. A composite study on microbial association with the in size ranging from only a few individuals (sometimes
predominant earthworm species at a given time may provide totally absent) to more than 1000 /m2 , the assessment of
necessary information on its ecological role. the size distribution and structure of earthworm population
is dicult. The seasonal change, demography, and vertical
distribution of the populations make it more complicated,
5. Factors Influencing the Abundance of and hence, it is absolutely essential to follow a uniform
Earthworm Populations method of determining the number of earthworms in small
sample areas as it has been done in this study. The regular
The percentage abundance of dierent species of earthworms monthly survey carried out for three years (1997 to 1999)
in the 10 collection sites during the survey period (1997 showed the presence of ten species of earthworms, with four
1999) is shown in Figures 1 and 2. In most of the study species restricted only to the hilly region and six species to
sites, that is, 17, L. mauritii was the dominant species and it the plain, including the foothills (Table 6). This observation
showed its presence during the premonsoon, monsoon, and indicates that species such as L. kumiliensis, D. bolaui, D.
postmonsoon months. P. corethrurus showed its abundance saliens, and P. corethrurus are specific only to the hilly region
in the sites 810. Various parameters, that is, pH, electrical and they are not found in the foothills. Though L. kumiliensis
conductivity (EC), organic carbon (OC), nitrogen (N), and L. mauritii both belong to the same genus, Lampito, L.
atmospheric temperature (AT), soil temperature (ST), soil kumiliensis was found only in the hilly region and L. mauritii
moisture (SM), humidity (HUM), and rainfall (RF) observed in the plains. This observation indicates that the distribution
during the survey period (19971999) are given in Table 5 of dierent earthworm species is limited even though they
and in Figure 3. All the parameters showed fluctuations in are closely related. Such niche dierences for closely related
all the ten study sites. Here, for the convenience of statistical species have been reported by earlier workers in the field
analysis the parameters were categorized into two major [28, 29].
groups: (a) physicochemical parameters which included pH, The results of the percentage abundance of dierent
EC, OC, and N; and (b) climatic parameters which included species of earthworms showed that L. mauritii and P.
ST, SM, HUM, and RF. corethrurus were the most abundant in the study sites 1
In Tamil Nadu, India, very limited information is to 7 and 8 to 10, respectively. Formation of aggregation
available on the distribution pattern of earthworms. The data of species has been observed in sites 1 to 7; that is,
on earthworm distribution is available for the stations like wherever L. mauritii was found, it was in association with
Palni Hills [24], Madras [25], and Sirumalai Hills [11, 23, 26, D. chlorina and D. pellucida pallida. This sort of association
27]. Dindigul, a District in Tamil Nadu, was considered as of earthworm species sharing the same habitat is not
6 Applied and Environmental Soil Science
Site 1 Site 2
100 100
Abundance
Abundance
75 75
(%)
(%)
50 50
25 25
0 0
J F M A M J J A S O N D J F M A M J J A S ON D J F MA M J J A S O N D J F M A M J J A S O N D J F M A M J J A S ON D J F MA M J J A S O N D
1997 1998 1999 1997 1998 1999
Sampling occasion (months) Sampling occasion (months)
D. chlorina L. mauritii D. chlorina L. mauritii
D. paradoxa M. insignis D. pellucida pallida O. thurstoni
D. pellucida pallida
(a) (b)
Site 3 Site 4
100 100
Abundance
Abundance
75 75
(%)
(%)
50 50
25 25
0 0
J F M A M J J A S O N D J F M A M J J A S ON D J F MA M J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D
1997 1998 1999 1997 1998 1999
Sampling occasion (months) Sampling occasion (months)
D. chlorina L. mauritii D. chlorina
D. pellucida pallida O. thurstoni D. pellucida pallida
L. mauritii
(c) (d)
Site 5
100
Abundance
75
(%)
50
25
0
J F M A M J J A S O N D J F M A M J J A S ON D J F MA M J J A S O N D
1997 1998 1999
Sampling occasion (months)
D. chlorina M. insignis
D. pellucida pallida O. thurstoni
L. mauritii
(e)
uncommon [1, 30]. L. mauritii is the dominant species found Evans and Guild [38] have shown that nitrogen rich
almost all over India along with other earthworm species diets help in rapid growth of earthworms and facilitate more
such as Drawida modesta, Octochaetona pattoni, O. thurstoni, cocoon production than those with little nitrogen available.
Ramiella pachpaharensis, Polypheretima elongata, and Pon- Due to the influence of nitrogen content of the soil, the per-
toscolex corethrurus [8, 31], but Bano and Kale [32] reported centage contribution of nitrogen to earthworm population
that L. mauritii was not found in some forest areas and might have shown a very high degree of dependence in the
coastal Karnataka. The population densities of earthworms present study. Some of the reports from the country well
observed in the 10 collection sites ranged from 0 to 228 /m2 . support qualitative dependence of earthworm population on
Other authors observed population densities (earthworm soil nitrogen content [26, 27, 39, 40].
no./m2 ) of 53.5 in plain grass land, 73 in deciduous forest, Soil moisture plays a major role in the distribution and
543 in the fallow phases of shifting agriculture, and 58.2 occurrence of various earthworm species. The same has been
in the maize crop land [3336]. In rubber plantations of observed by other workers in their studies [25, 28, 29, 41,
Tripura (India) about 20 species of earthworms, namely, 42]. The abundance and species diversity are dependent
Eutyphoeus gigas, E. gammiei, E. comillahnus, E. assamensis, on climatic conditions, especially the occurrence of dry
E. festivas, Eutyphoeus sp., Dichogaster bolaui, D. anis, and/or cold periods, and regional variation in vegetation,
Lennogaster chittagongensis, Octochaetona beatrix, Metaphire soil texture, and nutrient content. The climatic parameters,
houlleti, Perionyx sp., Kanchuria sumerianus, Kanchuria sp.1, that is, soil temperature, soil moisture, humidity, and rainfall
Kanchuria sp.2, Drawida nepalensis, Drawida sp.1, Drawida show seasonal fluctuations (Table 6 and Figure 3). The
sp.2, Pontoscolex corethrurus, and Gordiodrilus elegans were highest rainfall was recorded during October-November and
distributed and it was observed that the largely dominating the earthworm population was also the highest at this period.
species were endogeics [37]. The soil moisture content corresponded with earthworm
Applied and Environmental Soil Science 7
Site 6 Site 7
100 100
Abundance
Abundance
75 75
(%)
(%)
50 50
25 25
0 0
J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D
1997 1998 1999 1997 1998 1999
Sampling occasion (months) Sampling occasion (months)
D. chlorina D. chlorina
D. pellucida pallida D. pellucida pallida
L. mauritii L. mauritii
(a) (b)
Site 8 Site 9
100 100
Abundance
Abundance
75 75
(%)
(%)
50 50
25 25
0 0
J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D
1997 1998 1999 1997 1998 1999
Sampling occasion (months) Sampling occasion (months)
D. saliens D. bolaui
L. kumiliensis L. kumiliensis
P. corethrurus P. corethrurus
(c) (d)
Site 10
100
Abundance
75
(%)
50
25
0
J F M A M J J A S O N D J F M A M J J A S O N D J F MAM J J A S O N D
1997 1998 1999
Sampling occasion (months)
D. saliens
L. kumiliensis
P. corethrurus
(e)
population. Total annual rainfall of 1130, 1284, and 959 mm are determined essentially by the moisture content of the
was recorded during 1997, 1998, and 1999 in the plains and soil [43]. The temperature and moisture are usually inversely
foothills of Sirumalai (study sites 17). The highest rainfall of related and higher surface temperature and dry soils are
304 and 357 mm was received during October and November limiting factors to earthworms than low and water logged
1997 in the above study sites. The highest rainfall months in soils [44]. The soil temperature plays an important role in the
Sirumalai Hills (study sites 810) were October to December. maintenance of earthworm population in an ecosystem and
The soil moisture content directly matched with the rainfall. available information also indicates the negative correlation
The soil moisture content ranged from 2.0 to 30.4 percent of soil temperature to earthworm population [11, 25, 40, 45].
in the study sites 710 during the three years of the study. In rubber plantations of Tripura (India), the earthworms
The humidity also showed fluctuations in both the plains experienced 25.9 C, 24.8%, 4.85, and 1.8% mean soil
and hilly region of the study area. Soil moisture can explain temperature, moisture, pH, and organic matter, respectively
the increase in earthworm population, since soils are moist [37]. Temperature largely aects activity of earthworms in
under a mulch cover because of the restricted evaporation. temperate regions. Tropical species can withstand higher
There are many indications, to show that the population of temperatures. L. mauritii is available throughout the year
endogeic earthworms is controlled mainly by soil moisture where the annual temperature is 30 2 C. Population of O.
[42]. serrata was active between 27 and 28 C. In tropical regions
The influence of climatic factors on the populations of the temperature fluctuations are minimal when compared to
earthworm is not uncommon. The populations of Millsonia temperate regions.
anomala are dependent on climatic conditions as well as Moisture is another limiting factor for earthworm dis-
vegetational patterns. Earthworm activity and populations tribution as water constitutes a major portion of the body
8 Applied and Environmental Soil Science
Table 5: Physicochemical and climatic characteristics (average) of the study sites 1 to 10 (19971999) (refer to Table 6 for study site
description) [22].
Study sites
Parameter observed
1 2 3 4 5 6 7 8 9 10
1997
pH 7.78 7.63 7.13 6.86 7.59 7.67 6.78 7.04 7.50 6.55
EC (dS/m) 0.34 0.20 0.38 0.11 0.21 0.18 0.32 0.14 0.27 0.39
OC (%) 1.42 2.29 4.44 2.75 1.47 2.94 3.42 3.05 4.20 7.99
TN (%) 0.41 0.35 0.23 0.23 0.25 0.40 0.42 0.31 0.22 0.40
ST ( C) 28.90 29.83 27.84 29.29 30.31 29.27 29.83 23.47 22.49 21.30
SM (%) 8.10 6.34 10.34 7.22 7.16 8.30 10.25 15.75 15.46 14.99
1998
pH 7.95 7.51 7.25 6.66 7.51 7.62 6.45 7.15 7.34 6.44
EC (dS/m) 0.36 0.22 0.38 0.13 0.25 0.16 0.33 0.18 0.31 0.39
OC (%) 1.74 2.19 4.24 2.79 1.43 2.35 4.25 3.19 4.22 8.48
TN (%) 0.44 0.34 0.24 0.27 0.27 0.41 0.41 0.27 0.27 0.38
ST ( C) 29.23 30.18 28.27 30.63 29.92 29.30 30.18 24.14 22.68 21.30
SM (%) 12.14 9.93 15.18 9.73 12.83 12.03 14.35 16.00 17.09 16.29
1999
pH 7.85 7.49 7.37 6.85 7.38 7.59 6.47 6.98 7.45 6.64
EC (dS/m) 0.35 0.23 0.34 0.14 0.24 0.17 0.35 0.16 0.26 0.39
OC (%) 1.40 2.45 4.34 2.90 1.36 3.02 4.05 3.45 4.37 9.99
TN (%) 0.46 0.37 0.27 0.26 0.26 0.43 0.41 0.31 0.28 0.39
ST ( C) 27.42 28.55 26.49 29.66 30.42 27.46 28.55 25.21 23.51 22.80
SM (%) 9.50 7.27 11.70 8.50 9.27 9.37 10.34 12.56 14.37 13.86
EC: Electrical conductivity; OC: Organic carbon; TN: total nitrogen; ST: Soil temperature; SM: Soil moisture.
weight of an earthworm. Soil moisture and population environment, which, in turn, is essential for the maintenance
estimates are positively correlated [35]. Water constitutes of their life process.
7590 percent of the body weight of earthworms. So Systematic correlation analysis results indicate that only
the prevention of water loss is a major factor for their about 80 percent of the population dependence can be
survival. They apparently lack a mechanism to maintain explained by these physicochemical and climatic parameters
constant internal water content, so that their water content and it is presumed that the remaining may depend on other
is influenced greatly by the water potential of the soil [46], environmental factors. The correlation analysis technique
which directly depends on the adequate availability of soil may be used to quantify and rationalize the eects of
moisture. physicochemical parameters on the earthworm population.
The seasonal dynamics in an annual cycle shows that However, no single factor is likely to be solely responsible
earthworm numbers and biomass were high in the rainy for the horizontal distribution of earthworms, but rather
season with a gradual decline in number in the winter the interaction of several of the factors provides suitable soil
season. Earthworms were completely absent during the conditions for the existence of earthworm populations [11].
second half of January and February, when soil temperature
was very low (4.96.2 C). Dash and Patra [7] and Kale and
Krishnamoorthy [8, 47] have recorded maximum number of 6. Earthworm Casts: Abundance, Structure,
earthworms and biomass in the rainy and late rainy period. and Properties
The relationship between earthworm activity and rainfall
was observed by Fragoso and Lavelle [48] and Joshi and Earthworms release cast at the opening of their burrows.
Aga [49]. The moisture requirements for dierent species Epigeic earthworms release the castings exclusively on soil
of earthworms from dierent regions can be quite dierent surface. Their castings may be granular or spindle like masses
[42]. The dependence of earthworm population on soil that may be 2 to 3 cm high heaps as in Eudrilus eugeniae
moisture is seen in the studies carried out for three years or Perionyx excavatus. There is no definite shape to the
as of the highest degree when compared with other climatic excreted matter to identify as castings of Eisenia fetida.
parameters. This is because of certain physiological activities Eisenia fetida releases fine, powdery, dark brown material as
of earthworms such as cutaneous respiration and excretion surface cast. Soil living endogeic earthworms that feed on
of nitrogenous ammonia and urea, which need a moist dierent quantities of organic matter along with soil particles
Applied and Environmental Soil Science 9
Table 6: Population density of earthworms in dierent habitats in Dindigul District, Tamil Nadu studied during 19971999 [22].
use part of their castings to strengthen their burrow walls and Amount of cast produced can serve as an index for
the rest is released as castings. Castings of these earthworms assessing earthworm activity. Immediately after rains, release
may be ovoid or irregularly shaped minute mounds. Though of surface casts will be at a maximum level. At this point of
the nature of cast released is characteristic of a species, time, majority of earthworms are found at 0 to 10 cm depth
this cannot be criterion for their identification [50]. If and very few of them are found at 20 to 30 cm depth (Kale
pellet-like castings are released by Pheretima posthuma, and Dinesh, 2005, unpublished). Surface cast production
Perionyx millardi releases thread-like castings. Thick and long has been quantified in dierent agro-ecosystems to relate it
winding columns of hollow mound of 5 cm long and 2.5 cm to their abundance [5153]. Influence of seasonal variation
wide casts are characteristic of Hoplochaetella khandalaensis. and land use pattern was observed with respect to cast
The biggest cast of Notoscolex birmanicus weighing 1.6 kg production in shifting agriculture [34]. Norgrove and Hauser
after drying for four months is reported from Burma [54] have recorded around 30 to 35 t/ha of cast production in
[50]. Polypheretima elongata and Pontoscolex corethrurus tropical silvicultural system. Reddy [55] has reported annual
excrete the ingested soil as sticky, thick lumps on soil production of 23.4 to 140.9 tonnes by Pheretima alexandri.
surface. According to Lavelle [56], cast production is rhythmic and
10 Applied and Environmental Soil Science
100 700
600 structure [1]. Aggregate stability may result from addition
80
500 of mucus secretion from earthworm gut and of associated
Rain fall
60 400 microorganisms in the gut. It may also be due to macerated
40 300 organic particles in the castings that encourage microbial
200 activity after its release from the gut [59]. According to Parle
20
100 [60], stability of casts is due to fungal succession that takes
0 0 place in the cast. Habibulla and Ismail [61] are of the opinion
J FM AM J J A S ON D J FM AM J J A S OND J F MAM J J A S ON D
1997 1998 1999 that soil texture, particle size, and porosity play an important
Sampling occasion (months) role in burrowing and surface cast production. As casting
Atm. temperature ( C) activity is restricted to wet seasons, not much of attention
Humidity (%) is paid to assess the quantum of cast produced and its
Rain fall (mm) influence on soil physical, chemical, and biological properties
(a) as is available from other parts of the world. It is essential
to know the physicochemical and biological variations that
Temperature and humidity
Sampling occasion (months) turned the soil into cement-like clods had been reported
[62]. Puttarudraiah and Sastry [63] had observed stunting
Atm. temperature ( C) of growth in root crops like carrot, radish, and beetroots due
Humidity (%)
to castings of Pontoscolex corethrurus in pot culture studies.
Rain fall (mm)
Castings of earthworms are the store house of nutrients
(b) for plants. The increased earthworm activity with increase
in availability of carbon and in turn a raise in available
Figure 3: Atmospheric temperature (mean SD), Humidity (mean
SD), and average rainfall of the study sites 17 (a) and 810 (b).
nitrogen and phosphorus in their castings was also reported
[6]. Earthworm activity has shown to improve the soil
aggregates and soil minerals that are more available to
Table 7: Earthworm cast production during early postmonsoon plants than from soil [54, 64]. It is clear from various
period (Nov. 2004) at dierent agro-ecosystems in Kuti village of studies that earthworm casts may have more important
Somavarpatna Taluk of Karnataka State (Kale and Dinesh 2004, role in plant nutrition and nutrient cycling than it was
unpublished). assumed previously [65, 66]. In India, very early reports are
Land uses Castings (Kg/Sq. M)
available on such observations on the chemical properties
of earthworm castings that can play a positive role in plant
Natural forest 11. 20 0.46
growth [57, 67, 68]. The chemical composition of casts,
Coee plantation 17. 2 0.53 which is widely studied, is of holonephric lumbricid earth-
Cardamom plantation 16. 80 1.00 worms. In subtropical country like India where majority
Paddy fields (after
13. 60 1.00
of earthworms are meronephric, their castings may show
harvest) higher level of available plant nutrients than surrounding
Acacia plantation 2.40 soil. Dash and Patra [7, 53] had reported higher levels of
Grassland 0.8 nitrogen in casts of Lampito mauritii than in surrounding
Due to dryness prevailing at the collection spots castings could be collected soil. Ganeshmurthy et al. [69] have found higher rate
only from single spots out of 6 and 8 monolith points. of mobilization of micronutrients in earthworm castings.
It requires further studies on meronephric Megascolecid
earthworms and their castings on available and exchangeable
it will be at maximum at early morning hours. In general forms of nutrients to assess their contribution to soil fertility.
cast production in tropical countries is restricted to wet Kale and Krishnamoorthy [70] had shown increased levels
seasons. Table 7 provides the information on earthworm of soluble calcium and carbonates in castings of Pontoscolex
cast production in dierent agro-ecosystems during onset of corethrurus. Soluble carbonates contribute to exchangeable
postmonsoon season in the state of Karnataka, India. base contents of castings (Table 8). The physicochemical
The physicochemical properties of casts depend on the properties like pH, EC, organic C, total N, available P, K,
habitat soil and species of earthworm [57]. Their aggregate Na, Ca, and Mg of casts did not dier in zero tillage land
stability depends on the available organic matter [58]. treated with mulch of residues of annuals or perennials
The stability of casts and stability of fragmented casts on [19]. The population dynamics of a peregrine earthworm,
Applied and Environmental Soil Science 11
Table 8: Calcium and carbonates in castings of Pontoscolex Table 9: Microbial population in neem cake enriched vermicom-
corethrurus compared with that of habitat soil [70]. post [80].
Pontoscolex corethrurus, in undisturbed soil of Sirumalai Hills thick spore coats. This suggests the selective fungal feeding by
clearly showed that the parameters like rainfall, humidity, earthworms.
soil moisture, and organic carbon influence the population Drillosphere is the focus for understanding earthworm
positively [26, 27]. It has also been reported that in rubber microbe interrelationship. This association is also associated
plantations of Tripura, a part of north-east India, Pontoscolex with land use and metabolizable carbon present in the soil.
corethrurus was the dominant species, representing 61.5% Metabolizable carbon has positive eect on both microor-
biomass and 72% density of the total earthworm population ganisms and earthworms [75]. Microbial activity will be at a
where it might be linked to individual tree species eect higher level in the drillosphere than in surrounding soil and
(Hevea brasiliensis) that favoured P. corethrurus over other other edaphic factors determine the microbial diversity in
species [37]. drillosphere [76]. According to Kretzschmar [77], interaction
of soil fauna and microflora determines soil dynamics. The
contribution of their activity for formation of humus is an
7. Earthworms and Microflora index for soil fertility. Bhatnagar [78] had expressed that at 20
to 40 cm depth in drillosphere zone there were 40% aerobic
Earthworm activity is closely associated with microbial N-fixers, 13% anaerobic N-fixers, and 16% of denitrifiers.
activity. Lavelle [2] is of the opinion that there may exist com- He attributed low C/N ratio in soils rich in earthworm
petition between microorganisms and earthworms for easily population because of stimulation of N-fixers in drillosphere.
digestible and energy rich substrates. Such competition may Drillosphere provides necessary substrate for growth and
depend on availability of nutrients in the medium. Contrary establishment of microorganisms.
to this, earthworms may derive benefit from microorganisms Recent developments in the country as well as at the
when they have to survive on materials rich in cellulose or global level are the application of detritivorous epigeic earth-
hemi cellulose. So there exists mutualistic relation between worms for organic manure/vermicompost production from
earthworms and microorganisms. Tiunov and Scheu [6] have biodegradable organic materials recovered from agricultural
shown that earthworms deprive easily available carbon to lands, agro-based industries, and municipal solid waste. This
microorganisms and availability of carbon increases eective field of study is closely associated with earthworm microbe
mobilization of N and P by earthworms. The complex interaction. The quality of the manure or vermicompost
interrelationship of earthworms and microorganisms is at depends on microorganisms associated with the process
the level of their digestive tract, castings, and burrow walls of decomposition. Bhat [79] had reported that the diet
[71]. This establishes the probable mutualism that exists formulation or the composition of organic matter used as
between earthworms and microorganisms. Joshi and Kelkar feed influences the microflora associated with earthworm
[68] demonstrated higher microbial activity in earthworm activity. Similar studies were made on enhanced N-fixers
castings and their role in mineralization of nitrogen. They activity on using 2% neem cake in the feed mix of earthworm
incubated known weights of groundnut cake in a pot Eudrilus eugeniae [80] (Table 9).
containing earthworm castings and other containing soil During winter months in Himalayan region, fungal
from the same place. The release of N from groundnut cake population was higher in vermicomposting system than
was at a higher level in pot containing castings than from one in the native soil [81]. Maintenance of temperature in
having soil as the medium. vermicomposting system at a favourable level for earthworm
Bhat et al. [72] were the pioneer contributors to report on activity might have been the reason for establishment
role of microorganisms in the gut of earthworms. Khambata of fungal population. Press mud, a by-product of sugar
and Bhat [73] had made a detailed investigation on intestinal industry, is often used as one of the substrates in vermicom-
microflora of Pheretima sp. They had isolated Pseudomonas, posting. Subjecting of this material to earthworm activity
Corenyform bacteria, Nocardia, Streptomyces, and Bacillus along with other organic matter has resulted in changes in
from the intestinal tract. There is no report of nitrosofying microbial populations [82]. Rajani et al. [83] have related
and nitrifying bacteria in their observations in the gut of the microbial density and enzyme activity as a measure
earthworms. Dash et al. [74] have reported about isolation to assess the eectiveness of process of vermicomposting.
of 16 fungi from dierent parts of the gut out of 19 found It is essential to make an in-depth study to understand
in their habitat. In the fresh castings of the same earthworms the mutualistic association between microflora and earth-
there were only seven fungi with antibiotic properties or with worms in mechanism of decomposition of organic matter.
12 Applied and Environmental Soil Science
An increase in actinomycetes population was observed in region of India showed the presence of earthworms to the
the gut region of earthworms. Some of the isolates from maximum level wherever the farmers followed integrated
gut region of earthworms have expressed growth stimulatory farming (100%) practice and this was followed by organically
eect when used in pot cultures of tomato and finger millet managed (70%) and conventional (18.9%) agro-ecosystems.
[84]. The earthworm abundance was directly related to the
The colony forming units (CFUs) of bacteria and fungi management practices and the values of ecological indices
in the casts of P. corethrurus significantly deviated from the like Shannon diversity (H ), species dominance (C), the
CFU found in adjacent soil. The correlation between the species richness (S), and evenness (E). This clearly illustrates
physicochemical parameters and microbial populations of the anthropogenic pressure on earthworm communities
the casts of P. corethrurus showed that the establishment of in arable lands [90]. Similar report from Ivory Coast is
microbial population requires optimum moisture, organic available on the impact of land-use changes and land-
carbon, and nitrogen content [20]. The vermicasts of P. use intensification on earthworm populations and diversity
ceylanensis showed 14 dierent fungal species belonging to in intermediate-disturbed systems [91]. Even though these
the genera, Aspergillus, Chaetomium, Cladosporium, Cun- studies suggest the use of earthworms as bioindicators of
ninghamella, Fusarium, Mucor, Penicillium, and Rhizopus. man-made changes, it necessitates more field and laboratory
Total nitrogen, phosphorus, potassium, calcium, copper, investigations to find out earthworm community structure,
iron, and zinc were higher in vermicasts than in control species interrelations, and the most ecient species to be
(substrate without earthworms) while organic carbon and used in biomonitoring of ecosystem degradation due to
C/N ratio were lower in vermicasts. The total organic carbon anthropogenic activities in the forest areas.
was 42.3% in the control whereas it was 35.2% in the Certain toxic substances in soil aect the behaviour
vermicasts of P. ceylanensis. The incubation of vermicasts and physiology of earthworms that can serve as biomon-
(45 days) showed significant correlation with that of the itoring tool for their systematic eect on soil organisms
increase in fungal population (r = 0.720; P < .05) and and other higher organisms. For example, the presence of
decrease in moisture content (r = 0.984; P < .001), tetra ethyl lead (TEL) in leaded gasoline and lead oxide
and the decrease in moisture content statistically had no has a significant eect on behaviour, morphology, and
eect on the total fungal population in the vermicasts of histopathology of earthworms. Absorption of TEL into the
P. ceylanensis [85]. The total microbial population, namely, tissues of earthworms produced severe eects, rupture of the
bacteria, fungi, and actinomycetes was found to be many- cuticle, extrusion of coelomic fluid, and inflexible metameric
fold higher than in the initial vermibed substrate and in segmentation. This led to desensitization of the posterior
substrate without earthworms (control). The initial count region and its fragmentation [92].
of bacteria, fungi, and actinomycetes in the control was The ecient potential of earthworms in bioaccumula-
123.42 CFU 107 g1 , 159.64 CFU 103 g1 , and 86.90 CFU tion of heavy metals in their tissues serves as ecological
104 g1 whereas in castings (vermicompost) of P. ceylanensis indicator of soil contaminants. As per the recent report
the reported microbial populations were 268.62, 223.39, from India, the level of DTPA extractable metals in casts
and 141.09 [86]. These observations clearly indicate the of earthworms, Metaphire posthuma (endogeic) and Lampito
importance of microorganisms associated with earthworms mauritii (anecic) collected from cultivated land, urban gar-
in creating suitable environment for the standing crops as den and sewage soils were higher than those of surrounding
well as for vermicomposting of dierent organic wastes. soil. The concentration of Zn, Fe, Pb, and Mn in earthworm
It is still at the infancy to draw any inference regarding casts was higher in sewage soil followed by cultivated
earthworm, microbe, and plant association. land and urban garden, respectively. There exists a close
Studies are also in progress to assess the inhibitory eects relationship between metal concentration in earthworm
of the principles present in the body wall, gut extract, tissues and surrounding soils. The study also revealed the
and of coelomic fluid on some selected plant and animal presence of species-specificity in metal accumulation in
pathogens. The studies are at preliminary stages and it will earthworms. Higher level of metal concentrating in the
require some more time to draw any conclusions based tissues was found in endogeic M. posthuma than in tissues
on the available data. Such interdisciplinary applications of anecic L. mauritii. The dierence in burrowing patterns
of earthworm research help to understand the functional may influence the patterns of bioaccumulations of metals
complexity of these organisms other than their contribution apart from other contributory factors. Further, more detailed
to management of organic biodegradable residues as the study is still required to elaborate the proposed hypothesis
major secondary detritivorous group. [93]. Analogous study conducted in Egypt also suggests
that the variation in heavy metal concentration in soil and
earthworms in dierent sites may be significant depending
8. Earthworms as Bioindicators on soil properties and pollution status [88]. Sizmur and
Hodson [94] evidently suggested that earthworms increase
Earthworms can also serve as indicators of several changes/ metal mobility and availability but more studies are required
factors associated with soil. Many studies clearly showed that to determine the precise mechanism for this. So, this field of
the earthworms are best indicators of heavy metals, toxic research with earthworm requires in depth research to under-
pollutants, and direct and indirect anthropogenic changes stand the functional role of earthworms as bioindicators and
in soil [8789]. A study conducted in northern semiarid bioconcentrators.
Applied and Environmental Soil Science 13
[16] C. A. Edwards and J. R. Lofty, Nitrogenous fertilizers and composting, Part B: Verms and Vermicomposting, M. C. Dash,
earthworm populations in agricultural soils, Soil Biology and B. K. Senapati, and P. C. Mishra, Eds., pp. 815, 1986.
Biochemistry, vol. 14, no. 5, pp. 515521, 1982. [32] K. Bano and R. D. Kale, Earthworm fauna of Southern
[17] D. P. Knight, P. W. Elliott, J. M. Anderson, and D. Scholefield, Karnataka, India, in Advances in Management and Conser-
The role of earthworms in managed, permanent pastures in vation of Soil Fauna, G. K. Veeresh, D. Rajagopal, and C. A.
Devon, England, Soil Biology and Biochemistry, vol. 24, no. 12, Virakthamath, Eds., pp. 627634, Oxford & IBH, New Delhi,
pp. 15111517, 1992. India, 1991.
[18] M. J. Shipitalo and K. R. Butt, Occupancy and geometrical [33] R. V. Krishnamoorthy, Competition and coexistence in
properties of Lumbricus terrestris L. burrows aecting infiltra- a tropical earthworm community in a farm garden near
tion, Pedobiologia, vol. 43, no. 6, pp. 782794, 1999. Bangalore, Journal of Soil Biology and Ecology, vol. 5, pp. 33
[19] M. V. Reddy, V. R. Reddy, P. Balashouri, et al., Responses 47, 1985.
of earthworm abundance and production of surface casts [34] T. Bhadauria and P. S. Ramakrishnan, Earthworm population
and their physico-chemical properties to soil management in dynamics and contribution to nutrient cycling during crop-
relation to those of an undisturbed area on a semi-arid tropical ping and fallow phases of shifting agriculture (jhum) in north-
alfisol, Soil Biology and Biochemistry, vol. 29, no. 3-4, pp. 617 east India, Journal of Applied Ecology, vol. 26, no. 2, pp. 505
620, 1997. 520, 1989.
[20] N. Karmegam and T. Daniel, Selected physico-chemical [35] S. A. Ismail, C. Ramakrishnan, and M. M. Anzar, Density
characteristics and microbial populations of the casts of the and diversity in relation to the distribution of earthworms in
earthworm, Pontoscolex corethrurus (Muller) and surrounding Madras, Proceedings of Indian Academy of Sciences, Animal
soil in an undisturbed forest floor in Sirumalai Hills, South Sciences, vol. 99, no. 1, pp. 7378, 1990.
India, Asian Journal of Microbiology, Biotechnology and Envi- [36] B. R. Kaushal, S. P. S. Bisht, and S. Kalia, Population dynam-
ronmental Sciences, vol. 2, pp. 231234, 2000. ics of the earthworm Amynthas alexandri (Megascolecidae:
[21] J. M. Julka, R. Paliwal, and P. Kathireswari, Biodiversity Annelida) in cultivated soils of the Kumaun Himalayas,
of Indian earthworms-an overview, in Proceedings of Indo- Applied Soil Ecology, vol. 2, no. 2, pp. 125130, 1995.
US Workshop on Vermitechnology in Human Welfare, C. A. [37] P. S. Chaudhuri, S. Nath, and R. Paliwal, Earthworm pop-
Edwards, R. Jayaraaj, and I. A. Jayraaj, Eds., pp. 3656, Rohini ulation of rubber plantations (Hevea brasiliensis) in Tripura,
Achagam, Coimbatore, India, 2009. India, Tropical Ecology, vol. 49, no. 2, pp. 225234, 2008.
[22] N. Karmegam, Studies on earthworms, vermiculture, vermicom- [38] A. V. Evans and W. J. Mc. L. Guild, Studies on the
posting and utilization of vermicompost for plant growth, Ph.D. relationships between earthworms and soil fertility. IV. On
thesis, Gandhigram Rural University, Gandhigram, Tamil the life cycles of some British Lumbricidae, Annals of Applied
Nadu, India, 2002. Biology, vol. 35, pp. 471484, 1948.
[39] B. K. Senapati and S. K. Sahu, Population, biomass and sec-
[23] N. Karmegam and T. Daniel, A first report on the occurrence
ondary production in earthworms, in Earthworm Resources
of a Megascolecid earthworm, Lampito kumiliensis (Annelida:
and Vermiculture, pp. 5778, Zoological Survey of India,
Oligochaeta) in Sirumalai Hills of Tamil Nadu, South India,
Calcutta, India, 1993.
Ecology, Environment and Conservation, vol. 7, pp. 115116,
[40] S. R. Ganihar, Earthworm distribution with special refer-
2001.
ence to physicochemical parameters, Proceedings of Indian
[24] B. G. M. Jamieson, Preliminary descriptions of Indian earth-
National Science Academy B, vol. 62, pp. 1118, 1996.
worms (Megascolecidae: Oligocaheta) from the Palni hills,
[41] G. Gonzalez, X. Zou, and S. Borges, Earthworm abundance
Bullettin du Museum National dHistoire Naturelle Section A,
and species composition in abandoned tropical croplands:
vol. 313, pp. 478502, 1977.
comparisons of tree plantations and secondary forests, Pedo-
[25] S. A. Ismail and V. A. Murthy, Distribution of earthworms biologia, vol. 40, no. 5, pp. 385391, 1996.
in Madras, Proceedings of Indian Academy of Sciences (Animal [42] K. Auerswald, S. Weigand, M. Kainz, and C. Philipp, Influ-
Science), vol. 94, pp. 557566, 1985. ence of soil properties on the population and activity of
[26] N. Karmegam and T. Daniel, Abundance and population den- geophagous earthworms after five years of bare fallow, Biology
sity of three species of earthworms (Annelida: Oligochaeta) and Fertility of Soils, vol. 23, no. 4, pp. 382387, 1996.
in foothills of Sirumalai (Eastern Ghats), South India, Indian [43] P. Lavelle, Earthworm activities and the soil system, Biology
Journal of Environment and Ecoplanning, vol. 3, pp. 461466, and Fertility of Soils, vol. 6, no. 3, pp. 237251, 1988.
2000. [44] S. Nordstrom and S. Rundgren, Environmental factors and
[27] N. Karmegam and T. Daniel, Population dynamics of a pere- Lumbricid associations in Southern Sweeden, Pedobiologia,
grine earthworm, Pontoscolex corethrurus in an undisturbed vol. 13, pp. 301326, 1974.
soil in Sirumalai Hills of Tamil Nadu, South India, Journal of [45] B. K. Senapati and M. C. Dash, Influence of soil temperature
Ecological Research and Bioconservation, vol. 1, pp. 914, 2000. and moisture on the reproductive activity of tropical earth-
[28] T. Bhadauria and P. S. Ramakrishnan, Population dynamics worms of Orissa, Journal of Soil Biology and Ecology, vol. 4,
of earthworms and their activity in forest ecosystems of north- pp. 1321, 1984.
east India, Journal of Tropical Ecology, vol. 7, no. 3, pp. 305 [46] A. Kretzschmar and C. Bruchou, Weight response to the soil
318, 1991. water potential of the earthworm Aporrectodea longa, Biology
[29] P. S. Chaudhuri and G. Bhattacharjee, Earthworm resources and Fertility of Soils, vol. 12, no. 3, pp. 209212, 1991.
of Tripura, Proceedings of National Academy of Sciences, India, [47] R. D. Kale and R. V. Krishnamoorthy, Distribution and
vol. 69, pp. 159170, 1999. abundance of earthworms in Bangalore, Proceedings of Indian
[30] C. A. Edwards and P. J. Bohlen, Biology and Ecology of Academy of Sciences, vol. 88, pp. 2325, 1978.
Earthworms, Chapman & Hall, London, UK, 1996. [48] C. Fragoso and P. Lavelle, The earthworm community of
[31] S. A. Ismail, Earthworm resources of Madras, in Proceedings a Mexican tropical rain forest (Chajul, Chiapas), in On
of National Seminar on Organic Waste Utilization and Vermi- Earthworms, A. M. Bonvincini Paglai and P. Omodeo, Eds.,
Applied and Environmental Soil Science 15
Selected Symposia and Monographs U.Z.I., pp. 281295, [67] J. G. Shrikande and A. N. Pathak, Earthworms and insects in
Modena, Mucchi, Italy, 1987. relation to soil fertility, Current Science, vol. 17, pp. 327328,
[49] N. Joshi and S. Aga, Diversity and distribution of earthworms 1948.
in a subtropical forest ecosystem in Uttarakhand, India, The [68] N. V. Joshi and B. V. Kelkar, Role of earthworms in soil
Natural History Journal of Chulalongkorn University, vol. 9, pp. fertility, Indian Journal of Agricultural Science, vol. 22, pp.
2125, 2009. 189196, 1952.
[50] V. B. Tembe and P. J. Dubash, The earthworms: a review, [69] A. N. Ganeshamurthy, K. M. Manjaiah, and A. S. Rao, Mobi-
Journal of Bombay Natural History Society, vol. 58, pp. 171 lization of nutrients in tropical soils through worm casting:
201, 1961. availability of micronutrients, Soil Biology and Biochemistry,
[51] S. K. Roy, Studies on the activities of earthworms, Proceed- vol. 30, no. 13, pp. 18391840, 1998.
ings of Zoological Society, Calcutta, vol. 10, pp. 8198, 1957. [70] R. D. Kale and R. V. Krishnamoorthy, The calcium content of
body tissues and castings of earthworm Pontoscolex corethru-
[52] G. E. Gates, Ecology of some earthworms with special
rus (Annelida-Oligochaeta), Pedobiologia, vol. 20, pp. 309
reference to seasonal activity, American Midland Naturalist,
315, 1980.
vol. 66, pp. 6186, 1961.
[71] C. A. Edwards and N. Q. Arancon, Interactions among
[53] M. C. Dash and V. C. Patra, Worm cast production and nitro-
organic matter, earthworms and microorganisms in pro-
gen contribution to soil by a tropical earthworm population
moting plant growth, in Soil Organic Matter in Sustainable
from a grassland site from Orissa, India, Revue d Ecologie Et
Agriculture, pp. 327376, 2004.
de Biologie du Sol, vol. 16, pp. 7983, 1979.
[72] J. V. Bhat, S. R. Khambata, G. B. Maya, C. A. Sastry, R. V. Iyer,
[54] L. Norgrove and S. Hauser, Eect of earthworm surface casts and V. Iyer, Eect of earthworms on the microflora of the
upon maize growth, Pedobiologia, vol. 43, no. 6, pp. 720723, soil, Indian Journal of Agricultural Science, vol. 30, no. 2, pp.
1999. 106114, 1960.
[55] M. V. Reddy, Annual cast production by the Megascolecid [73] S. R. Khambata and J. V. Bhat, A contribution to the study
earthworm, Pheretima alexandri (Beddard), Comparative of the intestinal microflora of Indian earthworms, Archives of
Physiology and Ecology, vol. 8, pp. 8486, 1983. Microbiology, vol. 28, no. 1, pp. 6980, 1957.
[56] P. Lavelle, Les vers de terre de la savane de Lamto. Analyse [74] M. C. Dash, P. C. Mishra, and N. Behara, Fungal feeding by a
dun Ecosysteme tropical humide: LA Savanede Lamto (Cote tropical earthworm, Tropical Ecology, vol. 20, pp. 912, 1979.
dIvoire), Bullettin De Liaison des chercheurs de Lamto, vol. 5, [75] T. C. Dlamini, R. J. Haynes, and R. van Antwerpen, Exotic
pp. 133136, 1974. earthworm species dominant in soils on sugarcane estates
[57] S. D. Nijhawan and J. S. Kanwar, Physicochemical properties in the Eshowe area of the north coast of Kwazulu-Natal,
of earthworm castings and their eect on the productivity of in Proceedings of Annual Congress of South African Sugar
the soil, Indian Journal of Agricultural Sciences, vol. 22, pp. Technologists Association, vol. 75, pp. 217221, 2001.
357373, 1952. [76] G. G. Brown, I. Barois, and P. Lavelle, Regulation of
[58] A. K. Dutt, Earthworms and soil aggregation, Journal of soil organic matter dynamics and microbial activity in the
American Society for Agronomy, vol. 48, p. 407, 1948. drilosphere and the role of interactions with other edaphic
[59] R. J. Swaby, The influence of earthworm on soil aggregation, functional domains, European Journal of Soil Biology, vol. 36,
Journal of Soil Science, vol. 1, pp. 195197, 1950. no. 3-4, pp. 177198, 2000.
[60] J. N. Parle, A microbiological study of earthworm casts, [77] A. Kretzschmar, Importance of the interaction of soil fauna
Journal of General Microbiology, vol. 31, pp. 1322, 1963. and microflora for formation of humus and development of
organic substance, Berichte uber Landwirtschaft son der heft,
[61] A. M. Habibullah and S. A. Ismail, Preference to soil fractions
vol. 206, pp. 117126, 1992.
and the eect of soil compaction on the casting and burrowing
[78] T. Bhatnagar, Lombriciens et humification: un aspect nou-
behaviour of the earthworm Lampito mauritii, Journal of Soil
veau de lincorporation microbienne dazote induite par les
Biology and Ecology, vol. 5, pp. 2632, 1985.
vers de terre, in Biodegradation et Humification, pp. 169182,
[62] G. W. Agarwal, K. S. K. Rao, and L. S. Negi, Influence of
Pierron, Satreguemines, France, 1975.
certain species of earthworms on the structure of some hill
[79] J. V. Bhat, Suitability of experimentation diets for earthworm
soils, Current Science, vol. 27, p. 213, 1958.
culture, Current Science, vol. 43, pp. 266268, 1974.
[63] M. Puttarudraiah and K. S. S. Sastry, A preliminary study [80] R. D. Kale, K. Vinayaka, K. Bano, and D. J. Bagyaraj,
of earthworm damage to crop growth, Mysore Agriculture Suitability of neem cake as an additive in earthworm fed and
Journal, vol. 36, pp. 211, 1961. its influence on the establishment of microflora, Journal of
[64] P. M. Fraser, M. H. Beare, R. C. Butler, T. Harrison-Kirk, and Soil Biology and Ecology, vol. 6, pp. 98103, 1986.
J. E. Piercy, Interactions between earthworms (Aporrectodea [81] R. Nagar, N. Joshi, S. Dwivedi, and V. K. Khaddar, A
caliginosa), plants and crop residues for restoring properties physicochemical and micofloral profile of vermicompost in
of a degraded arable soil, Pedobiologia, vol. 47, no. 5-6, pp. Tarai region of Himalaya in winter season, Research on Crops,
870876, 2003. vol. 5, pp. 5154, 2004.
[65] M. A. Callaham Jr. and P. F. Hendrix, Impact of earthworms [82] K. Parthasarathi, L. S. Ranganathan, and J. Zeyer, Species
(Diplocardia: Megascolecidae) on cycling and uptake of specific predation of fungi by Lampito mauritii (Kinb) and
nitrogen in coastal plain forest soils from northwest Florida, Eudrilus eugeniae (Kinb) reared on press mud, in Session
USA, Applied Soil Ecology, vol. 9, no. 13, pp. 233239, 1998. 3. Earthworms and Vermicomposting, D. J. Bagyaraj, Ed., VII
[66] S. A. Materechera, O. T. Mandiringana, and K. Nyamapfene, National Symposium on Soil Biology and Ecology, Ab, p. 69,
Production and physico-chemical properties of surface casts 2001.
from microchaetid earthworms in central Eastern Cape, [83] B. S. Rajani, D. Radhakrishna, V. R. Ramakrishnaparama, R.
South African Journal of Plant and Soil, vol. 15, no. 4, pp. 151 D. Kale, and A. N. Balakrishna, Influence of vermicompost-
157, 1998. ing of urban solid wastes on microbial density and enzyme
16 Applied and Environmental Soil Science
Review Article
Role of Earthworms in Soil Fertility Maintenance through
the Production of Biogenic Structures
Copyright 2010 T. Bhadauria and K. G. Saxena. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
The soil biota benefits soil productivity and contributes to the sustainable function of all ecosystems. The cycling of nutrients
is a critical function that is essential to life on earth. Earthworms (EWs) are a major component of soil fauna communities in
most ecosystems and comprise a large proportion of macrofauna biomass. Their activity is beneficial because it can enhance
soil nutrient cycling through the rapid incorporation of detritus into mineral soils. In addition to this mixing eect, mucus
production associated with water excretion in earthworm guts also enhances the activity of other beneficial soil microorganisms.
This is followed by the production of organic matter. So, in the short term, a more significant eect is the concentration of large
quantities of nutrients (N, P, K, and Ca) that are easily assimilable by plants in fresh cast depositions. In addition, earthworms seem
to accelerate the mineralization as well as the turnover of soil organic matter. Earthworms are known also to increase nitrogen
mineralization, through direct and indirect eects on the microbial community. The increased transfer of organic C and N into
soil aggregates indicates the potential for earthworms to facilitate soil organic matter stabilization and accumulation in agricultural
systems, and that their influence depends greatly on dierences in land management practices. This paper summarises information
on published data on the described subjects.
Table 1: Some properties of casts of Pheretima alaxandri and their underlying soils with and without litter cover [10].
Table 2: Eect of land conversion and management practices on changes in functional catagories of earthworms in the Indo-Gangetic plains,
(SE, n = 10).
1.1. Functional Significance of Earthworms. The eects of physical properties and SOM dynamics. Besides they aect
EWs on soil biological processes and fertility level dier in some important soil ecological processes within their func-
ecological categories [12]. Anecic species build permanent tional domain [21, 22] where they concentrate nutrients and
burrows into the deep mineral layers of the soil; they drag resources that are further exploited by soil microorganism
organic matter from the soil surface into their burrows for communities [23, 24]. The eect of EWs on the dynamics
food. Endogeic species live exclusively and build extensive of organic matter varies depending on the time and space
nonpermanent burrows in the upper mineral layer of scales considered [25]. The activity of endogeic EWs in
soil, mainly ingested mineral soil matter, and are known the humid tropical environment accelerates initial SOM
as ecological engineers, or ecosystem engineers. They turnover through indirect eects on soil C as determinants
produce physical structures through which they can modify of microbial activity. Due to selective foraging of organic
the availability or accessibility of a resource for other particles, gut contents are often enriched in organic matter,
organisms [13]. Epigeic species live on the soil surface, nutrients, and water compared with bulk soil and can foster
form no permanent burrows, and mainly ingest litter and high levels of microbial activity [26, 27]. They have been
humus, as well as on decaying organic matter, and do not reported to enhance mineralization by first fragmenting
mix organic and inorganic matter [14]. In the majority of SOM and then mixing it together with mineral particles
habitats and ecosystems (Table 2), it is usually a combination and microorganisms, and thereby creating new surfaces of
of these ecological categories which together or individually contact between SOM and microorganisms [28]. In the short
are responsible for maintaining the fertility of soils [1517]. term, a more significant eect is the concentration of large
quantities of nutrients (N, P, K, and Ca) that are easily
assimilable by plants in fresh cast depositions [18]. Most of
1.2. Role of Earthworms in Nutrient Availability to Soil. EWs these nutrients are derived from earthworm urine and mucus
influence the supply of nutrients through their tissues but [29]. In highly leached soils of humid tropics, earthworm
largely through their burrowing activities; they produce activity is beneficial because of rapid incorporation of the
aggregates and pores (i.e., biostructures) in the soil and/or on detritus into the soils [30]. In addition to this mixing
the soil surface, thus aecting its physical properties, nutrient eect, mucus production associated with water excretion
cycling, and plant growth [19, 20]. The biogenic structures in the earthworm gut is known to enhance the activity of
constitute assemblages of organo-mineral aggregates. Their microorganisms [31]. This is followed by the production of
stability and the concentration of organic matter impact soil organic matter. So fresh casts show high nutrient contents
Applied and Environmental Soil Science 3
Table 3: Variation in nutrient concentration of earthworm casts and noningested soils during cropping under shifting agriculture in North
East India (SE, n = 5) [18].
5-year-cycle 15-year-cycle
Soil Worm cast Soil Worm cast
Organic Carbon (%) 2 (0.1) 2.5 (.13) 3.2 (.17) 4.5 (.23)
Total Nitrogen (%) 0.22 (0.01) 0.29 (.17) 0.4 (.03) 0.6 (.04)
Available Phosphorus (mg/100 g) 0.9 (0.03) 1.4 (.09) 2.0 (.06) 2.8 (.15)
Potassium (meq/100 g) 0.5 (0.02) 0.54 (.04) 1.2 (.05) 2.0 (.09)
Calcium (meq/100 g) 0.9 (0.01) 1.2 (.08) 1.5 (.04) 2.5 (.13)
Magnesium (meq/100 g) 1.2 (0.05) 1.8 (.09) 3.1 (.17) 4.0 (.34)
Table 4: Variation in nutrient concentration of earthworm casts and non ingested soils in abandoned agricultural fallows in North East
India (SE, n = 5) [18].
(Table 3). The chemical characteristics of casts dier from large macroaggregates leading to a possible long-term stabi-
those of noningested soil [32] and are rich in plant available lization of soil C [51] (Table 5). It has also been reported that
nutrients. Upon cast deposition, microbial products, in EWs increase the incorporation of cover crop-derived C into
addition to earthworm mucilages, bind soil particles and macroaggregates, and more important, into microaggregates
contribute to the formation of highly stable aggregates [33, formed within macroaggregates. The increased transfer of
34]. Although EWs may speed up the initial breakdown organic C and N into soil aggregates indicates the potential
of organic residues [35, 36], several studies have indicated for EWs to facilitate SOM stabilization and accumulation in
that they may also stabilize SOM through its incorporation agricultural systems [52].
and protection in their casts [3740]. Over longer periods EWs are known also to increase nitrogen mineraliza-
of time, this enhanced microbial activity decreases when tion, through direct and indirect eects on the microbial
the casts dry, and aggregation is then reported to physically community (Table 6). Our studies on the role of EWs in
protect SOM against mineralization. Thus C mineralization the nitrogen cycling during the cropping phase of shifting
rate decreases and mineralization of SOM from casts may agriculture in North East India showed (Table 7) that the
be blocked for several months [37, 41]. It might become total soil nitrogen made available for plants through the
accessible again for the microflora once these are degraded activity of EWs was higher than the total input of nitrogen to
into small fragments [4244]. In addition EWs seem to the soil through the addition of slashed vegetation, inorganic
accelerate the mineralization as well as the turnover of and organic manure, recycled crop residues, and weeds [54].
SOM [45]. Furthermore, studies have also indicated that An important role of EWs is the dramatic increase in soil pH
organic matter in the casts, once stabilized, can maintain this as observed through our studies in shifting agroecosystem
stabilization for many years [46, 47]. Nevertheless, chemical in North East India, in a sedentary terrace agroecosystem in
mechanisms may also contribute to the stabilization since central Himalayas, and in intensive agroecosystem in Indo-
evidence shows that the casts are held together by strong Gangetic plains. This increases microbial activity and N
interactions between mineral soil particles and SOM that fixation in the soil, so that nitrogen in the worm cast may
is enriched in bacterial polysaccharides and fungal hyphae be due at least in part to this rather than to concentration
[48, 49]. Earthworm casts are enriched in organic C and N, by gain worms. Nitrogen mineralization by microflora is also
exceeding the C and N contents of the non ingested soil by a quite intense in the earthworm gut and continues for several
factor of 1.5, and 1.3, respectively (Table 4). This enrichment hours in fresh casts [55, 56], respectively, by incorporating
appears in all particle-size fractions, not restricted to certain organic matter into the soil and or by grazing the bacterial
organic compound dynamics of a cultivated soil [50]. These community. EWs have been found to either enhance or
results clearly indicate the direct involvement of EWs in decrease bacterial biomass [5759], and to stimulate bacte-
providing protection of soil C in microaggregates within rial activity [60, 61]. The influence of EWs on N cycling,
4 Applied and Environmental Soil Science
Table 5: C and N contents and C : N ratio in particle-size organic fractions in control soil and cast of Pontoscolex corethrurus (SE) [53].
Table 6: Total and mineral nitrogen content in soil and fresh casts from earthworms incubated in dierent soil types (Barois et al., 1992
[53]).
Table 7: Nitrogen input/output budget during the cropping phase under 5- and 15-year Jhum cycle, (SE, n = 5) [54].
[15] T. Bhadauria, P. S. Ramakrishnan, and K. N. Srivastava, [29] I. Barois and P. Lavelle, Changes in respiration rate and
Population dynamics of earthworms during crop rotation some physicochemical properties of a tropical soil dur-
under rainfed agriculture in central Himalayas, India, Applied ing transit through Pontoscolex corethrurus (glossoscolecidae,
Soil Ecology, vol. 6, no. 3, pp. 205215, 1997. oligochaeta), Soil Biology & Biochemistry, vol. 18, no. 5, pp.
[16] B. Sinha, T. Bhadauria, P. S. Ramakrishnan, K. G. Saxena, 539541, 1986.
and R. K. Maikhuri, Impact of landscape modification on [30] T. Bhadauria and P. S. Ramakrishnan, Population dynamics
earthworm diversity and abundance in the Hariyali sacred of earthworms and their activity in forest ecosystems of north-
landscape, Garhwal Himalaya, Pedobiologia, vol. 47, no. 4, pp. east India, Journal of Tropical Ecology, vol. 7, no. 3, pp. 305
357370, 2003. 318, 1991.
[17] T. Bhadauria and K. G. Saxena, Influence of land scape [31] I. Barois, Interactions entre les Vers de terre (Oligochaeta)
modification on earthworm biodiversity in the Garhwal region tropicaux geophages et la microflore pour lexploitation de la
of Central Himalayas, in Proceedings of Indo US Workshop matiere organique des sols, Ph.D. thesis, University of Paris,
on Vermitechnology in Human Welfare(IndoUS Science and Paris, France, 1987.
Technology Forum), June 2007, C. A. Edwards, R. Jeyaraaj, and [32] E. Blanchart, P. Lavelle, E. Braudeau, Y. Le Bissonnais, and
I. Jayaraaj, Eds., pp. 8095, Coimbatoor, Tamil Nadu, India, C. Valentin, Regulation of soil structure by geophagous
2009. earthworm activities in humid savannas of Cote dIvoire, Soil
[18] T. Bhadauria and P. S. Ramakrishnan, Earthworm population Biology & Biochemistry, vol. 29, no. 3-4, pp. 431439, 1997.
dynamics and contribution to nutrient cycling during crop- [33] M. J. Shipitalo and R. Protz, Chemistry and micromorphol-
ping and fallow phases of shifting agriculture (jhum) in north- ogy of aggregation in earthworm casts, Geoderma, vol. 45, no.
east India, Journal of Applied Ecology, vol. 26, no. 2, pp. 505 3-4, pp. 357374, 1989.
520, 1989. [34] R. D. Kale, Earthworms; Cinderella of Organic Farming, Prism
[19] R. Lal, Soil conservation and biodiversity, in The Biodiversity Books Pvt, Bangalore, India, 1998.
of Microorganisms and Invertebrates: Its Role in Sustainable [35] P. Lavelle, Earthworm activities and the soil system, Biology
Agriculture, D. L. Hawksworth, Ed., pp. 89103, CAB Inter- and Fertility of Soils, vol. 6, no. 3, pp. 237251, 1988.
national, Wallingford, UK, 1999. [36] J. Six, E. T. Elliott, K. Paustian, and J. W. Doran, Aggregation
[20] S. Scheu, Eects of earthworms on plant growth: patterns and and soil organic matter accumulation in cultivated and native
perspectives, Pedobiologia, vol. 47, no. 5-6, pp. 846856, 2003. grassland soils, Soil Science Society of America Journal, vol. 62,
[21] S. Coq, B. G. Barthes, R. Oliver, B. Rabary, and E. Blanchart, no. 5, pp. 13671377, 1998.
Earthworm activity aects soil aggregation and organic [37] A. Martin, Short- and long-term eects of the endogeic
matter dynamics according to the quality and localization earthworm Millsonia anomala (Omodeo) (Megascolecid,
of crop residuesan experimental study (Madagascar), Soil Oligochta) of tropical savannas, on soil organic matter,
Biology & Biochemistry, vol. 39, no. 8, pp. 21192128, 2007. Biology and Fertility of Soils, vol. 11, no. 3, pp. 234238, 1991.
[22] P. Lavelle, Faunal activities and soil processes: adaptive [38] G. Guggenberger, R. J. Thomas, and W. Zech, Soil organic
strategies that determine ecosystem function, Advances in matter within earthworm casts of an anecic-endogeic tropical
Ecological Research, vol. 27, pp. 93132, 1997. pasture community, Colombia, Applied Soil Ecology, vol. 3,
[23] S. Scheu, Microbial activity and nutrient dynamics in no. 3, pp. 263274, 1996.
earthworm casts (Lumbricidae), Biology and Fertility of Soils, [39] H. Bossuyt, J. Six, and P. F. Hendrix, Protection of soil carbon
vol. 5, no. 3, pp. 230234, 1987. by microaggregates within earthworm casts, Soil Biology &
[24] J. C. Y. Marinissen and P. C. De Ruiter, Contribution Biochemistry, vol. 37, no. 2, pp. 251258, 2005.
of earthworms to carbon and nitrogen cycling in agro- [40] M. M. Pulleman, J. Six, A. Uyl, J. C. Y. Marinissen, and A.
ecosystems, Agriculture, Ecosystems and Environment, vol. 47, G. Jongmans, Earthworms and management aect organic
no. 1, pp. 5974, 1993. matter incorporation and microaggregate formation in agri-
[25] P. Mora, E. Miambi, J. J. Jimenez, T. Decaens, and C. Rouland, cultural soils, Applied Soil Ecology, vol. 29, no. 1, pp. 115,
Functional complement of biogenic structures produced by 2005.
earthworms, termites and ants in the neotropical savannas, [41] P. Lavelle and A. Martin, Small-scale and large-scale eects of
Soil Biology & Biochemistry, vol. 37, no. 6, pp. 10431048, endogeic earthworms on soil organic matter dynamics in soils
2005. of the humid tropics, Soil Biology & Biochemistry, vol. 24, no.
[26] R. J. Haynes and P. M. Fraser, A comparison of aggregate 12, pp. 14911498, 1992.
stability and biological activity in earthworm casts and [42] E. Blanchart, P. Lavelle, E. Braudeau, Y. Le Bissonnais, and
uningested soil as aected by amendment with wheat or C. Valentin, Regulation of soil structure by geophagous
Lucerne straw, European Journal of Soil Science, vol. 49, no. earthworm activities in humid savannas of Cote dIvoire, Soil
4, pp. 629636, 1998. Biology & Biochemistry, vol. 29, no. 3-4, pp. 431439, 1997.
[27] R. D. Kale, Significant contribution with Vermiculture, [43] T. Decaens, Degradation dynamics of surface earthworm
in Proceedings of the DST and DBT Sponsored National casts in grasslands of the eastern plains, of Colombia, Biology
Seminar Cum Workshop on Conservation and Inventerization and Fertility of Soils, vol. 32, no. 2, pp. 149156, 2000.
of Soil Biota, Kathireswari and R. D. Kale, Eds., pp. 12, [44] H. Bossuyt, J. Six, and P. F. Hendrix, Protection of soil carbon
Tiruchengode, Tamil Nadu, India, 2008. by microaggregates within earthworm casts, Soil Biology &
[28] R. W. Parmelee, P. J. Bohlen, and J. M. Blair, Earthworms and Biochemistry, vol. 37, no. 2, pp. 251258, 2005.
nutrient cycling processes: integrating across the ecological [45] C. A. Edwards and P. J. Bohlen, The Role of Earthworms in
hierarchy, in Earthworm Ecology, C. Edwards, Ed., pp. 179 Organic matter and nutrient cycles, in Biology and Ecology of
211, St. Lucie Press, Boca Raton, Fla, USA, 1998. Earthworms, pp. 155180, Chapman and Hall, NY, USA, 1996.
Applied and Environmental Soil Science 7
[46] M. McInerney and T. Bolger, Decomposition of Quercus [60] O. Daniel and J. M. Anderson, Microbial biomass and activity
petraea litter: influence of burial, comminution and earth- in contrasting soil materials after passage through the gut of
worms, Soil Biology & Biochemistry, vol. 32, no. 14, pp. 1989 the earthworm Lumbricus rubellus Homeister, Soil Biology
2000, 2000. & Biochemistry, vol. 24, no. 5, pp. 465470, 1992.
[47] L. Mariani, J. J. Jimenez, N. Asakawa, R. J. Thomas, and T. [61] V. Wolters and R. G. Joergensen, Microbial carbon turnover
Decaens, What happens to earthworm casts in the soil? A in beech forest soils worked by Aporrectodea caliginosa (Savi-
field study of carbon and nitrogen dynamics in Neotropical gny) (Oligochaeta:Lumbricidae), Soil Biology & Biochemistry,
savannahs, Soil Biology & Biochemistry, vol. 39, no. 3, pp. 757 vol. 24, no. 2, pp. 171177, 1992.
767, 2007. [62] M. B. Postma-Blaauw, J. Bloem, J. H. Faber, J. W. van
[48] G. S. Bhandari, N. S. Ranghawa, and M. S. Maskina, On the Groenigen, R. G. M. de Goede, and L. Brussaard, Earthworm
polysaccharide content of earthworm casts, Current Science, species composition aects the soil bacterial community and
vol. 36, pp. 519520, 1967. net nitrogen mineralization, Pedobiologia, vol. 50, no. 3, pp.
[49] K. H. Domsch and H.-J. Banse, Mykologische untersuchun- 243256, 2006.
gen an regenwurmexkrementen, Soil Biology & Biochemistry, [63] G. G. Brown, B. Pashanasi, C. Villenave, et al., Eects of
vol. 4, no. 1, pp. 3138, 1972. earthworms on plant production in the tropics, in Earth-
[50] T. Desjardins, F. Charpentier, B. Pashanasi, A. Pando-Bahuon, worm Management in Tropical Agro Ecosystems, P. Lavelle, L.
P. Lavelle, and A. Mariotti, Eects of earthworm inoculation Brussaard, and P. Hendrix, Eds., pp. 87147, CABI Publishing,
on soil organic matter dynamics of a cultivated ultisol, Wallinford, UK, 1999.
Pedobiologia, vol. 47, no. 5-6, pp. 835841, 2003. [64] S. J. Fonte, A. Y. Y. Kong, C. van Kessel, P. F. Hendrix, and J.
[51] X. Zhang, J. Wang, H. Xie, J. Wang, and W. Zech, Comparison Six, Influence of earthworm activity on aggregate-associated
of organic compounds in the particle-size fractions of earth- carbon and nitrogen dynamics diers with agroecosystem
worm casts and surrounding soil in humid Laos, Applied Soil management, Soil Biology & Biochemistry, vol. 39, no. 5, pp.
Ecology, vol. 23, no. 2, pp. 147153, 2003. 10141022, 2007.
[52] S. J. Fonte, A. Y. Y. Kong, C. van Kessel, P. F. Hendrix, and J. [65] G. G. Brown, P. F. Hendrix, and M. H. Beare, Earthworms
Six, Influence of earthworm activity on aggregate-associated (Lumbricus rubellus) and the fate of 15 N in surface-applied
carbon and nitrogen dynamics diers with agroecosystem sorghum residues, Soil Biology & Biochemistry, vol. 30, no. 13,
management, Soil Biology & Biochemistry, vol. 39, no. 5, pp. pp. 17011705, 1998.
10141022, 2007. [66] G. G. Brown, C. A. Edwards, and L. Brussaard, How earth-
[53] I. Barois, P. Lavelle, and J. K. Kajondo, Adaptive strategies worms aect plant growth: burrowing into the mechanisms,
and short term eects of selected earthworm species, selection in Earthworm Ecology, C. A. Edwards, Ed., pp. 1349, CRC
of particles, in Conservation of Soil Fertility in Low-Input Press, Boca Raton, Fla, USA, 2nd edition, 2004.
Agricultural Systems of the Humid Tropics by Manipulating [67] J. Cortez and R. H. Hameed, Simultaneous eects of plants
Earthworm Communities, P. Lavelle, Ed., pp. 3567, IRD, and earthworms on mineralisation of 15 N-labelled organic
Bondy, France, 1992, Report of the CCE Project No.TS2.0292- compounds adsorbed onto soil size fractions, Biology and
F(EDB). Fertility of Soils, vol. 33, no. 3, pp. 218225, 2001.
[54] T. Bhadauria and P. S. Ramakrishnan, Role of earthworms [68] R. D. Kale, The need for an interdisciplinary approach
in nitrogen cycling during the cropping phase of shifting in understanding the importance of earthworms in India,
agriculture (Jhum) in north-east India, Biology and Fertility in Proceedings of Indo US Workshop on Vermitechnology in
of Soils, vol. 22, no. 4, pp. 350354, 1996. Human Welfare (IndoUS Science and Technology Forum),
[55] J. M. Blair, R. W. Parmelee, M. F. Allen, D. A. Mccartney, and B. June 2007, C. A. Edwards, R. Jeyaraaj, and I. Jayaraaj, Eds., p.
R. Stinner, Changes in soil N pools in response to earthworm 164, Coimbatoor, Tamil Nadu, India, 2009.
population manipulations in agroecosystems with dierent N
sources, Soil Biology & Biochemistry, vol. 29, no. 3-4, pp. 361
367, 1997.
[56] H. Bossuyta, J. Six, and P. F. Hendrix, Comparison of organic
compounds in the particle-size fractions of earthworm casts
and surrounding soil in humid Laos. Protection of soil carbon
by micro aggregates within earthworm casts, Soil Biology &
Biochemistry, vol. 37, pp. 251258, 2005.
[57] B. E. Ruz-Jerez, P. R. Ball, and R. W. Tillman, Laboratory
assessment of nutrient release from a pasture soil receiving
grass or clover residues, in the presence or absence of Lumbri-
cus rubellus or Eisenia foetida, Soil Biology & Biochemistry,
vol. 24, pp. 15291534, 1992.
[58] P. J. Bohlen and C. A. Edwards, Earthworm eects on N
dynamics and soil respiration in microcosms receiving organic
and inorganic nutrients, Soil Biology & Biochemistry, vol. 27,
no. 3, pp. 341348, 1995.
[59] J. Cortez, G. Billes, and M. B. Bouche, Eect of climate,
soil type and earthworm activity on nitrogen transfer from
a nitrogen-15-labelled decomposing material under field
conditions, Biology and Fertility of Soils, vol. 30, no. 4, pp.
318327, 2000.
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 526934, 6 pages
doi:10.1155/2010/526934
Research Article
Casting Activity of Scherotheca gigas in
No-Till Mediterranean Soils: Role in Organic Matter
Incorporation and Influence of Aridity
Copyright 2010 Paloma Bescansa et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
The behaviour of earthworms, their role in organic matter incorporation into the soil, and the influence of aridity in such processes
in arid and semiarid regions have scarcely been studied. In this study, physico-chemical analyses of the casts and the surrounding
no-till agricultural soils of three experimental sites representing an aridity gradient in Navarre (NW Spain) were done. The casts
were formed by the activity of the only anecic species, Scherotheca gigas (Duges, 1828), ubiquitous in no-till soils in this region. We
observed a significant depletion of clay and higher concentration of total organic C and labile C in the form of particulate organic
matter (POM) in the casts as compared to the surrounding soil, suggesting selective ingestion of soil by S. gigas. This, together with
the observation of increased concentration in POM with increasing aridity, suggests a major role of this species in the observed
progressive gains of organic C stocks in no-till soils in the region.
has a narrow geographical distribution worldwide [9]. In a reference evapotranspiration (ET0 ) increase in the same
study in the role of earthworms in soil aggregate formation, order.
S. gigas was cited by Bouche and Al-Addan [10] as one of the A direct seeder that opens a seed-furrow 30 to 50 mm
most abundant species in a dry grassland on calcareous soil. deep is used for barley seeding in fall in the studied NT plots
As for most earthworm species, soil moisture and at the three sites, using similar seeding doses (160 kg/ha)
temperature aect the activity of S. gigas. Field observations and fertilization treatments. Average barley yield decreases
led us to distinguish two periods of surface casting activity with increasing aridity (Table 1).
over the year [8], each interrupted by a period of inactivity
in January/February and June/September. As observed in
2.2. Sampling Methods. As already mentioned, earthworm
other semiarid areas [11], during the dry summer months
activity in the region is clearly seasonal, and coincides
the species undergo diapause and cannot be found at the soil
with the two rainfall peaks and mild temperatures observed
surface.
in spring and fall. Three field NT replicates (plots) were
The contribution of earthworms to organic matter incor-
sampled in November 2007 at each study site, in order to
poration into the soil can be studied by comparing surface
identify the earthworm species present in the soil. Two soil
casts and the surrounding soil. Properties of surface casts
blocks (0.20 by 0.20 by 0.20 m) were taken in each plot.
usually dier from those of the bulk soil, but contradictory
Earthworms were sampled by hand-sorting and counted
findings have been reported. Dierences are related to the
in the field. Individuals were fixed with ethanol-formalin,
type of soil [12] and/or to earthworm species [13]. Brown
and preserved in 10% formalin [20]. They were classified
et al. [14] have described in detail the role of earthworms
at the Department of Ecology and Animal Biology of the
in organic matter stabilization. These authors consider that
University of Vigo (Spain). Thirty to 50 individuals of S.
the inclusion of the active fractions of the soil organic
gigas were found per square meter at the three study sites.
matter (SOM) into earthworm casts can contribute to its
Considering the size and the ability of this species to dig deep
protection and stabilization when casts dry up, a process that
into the soil, these numbers are likely an underestimation
can happen within hours or days after its deposition. It has
of the actual abundance of S. gigas in the studied soils.
also been demonstrated that soil management can greatly
It was observed that S. gigas was the only anecic species
influence this process [1517].
found, which indicates that surface casts present in the three
The protection of SOM from biological degradation in
soils were created by individuals of this species. This also
surface casts [18, 19] has a special significance for soils with
illustrates the ubiquity of this species in NT soils in the
high mineralization rates and low contents in SOM, as is the
region, regardless of soil characteristics and agroclimatic
case for the soils of the Ebro Valley. In addition, soils rich
conditions.
in calcium carbonate also contribute to the persistence of
Simultaneously, four replicates of surface earthworm
casts over longer time periods and thus to long-time SOM
casts were collected at three random points in the NT plots at
protection.
each study site. Casts were air-dried, ground to pass through
The purpose of this study was to gain knowledge on the
a 2-mm sieve and stored for further analyses.
behavior of S. gigas in no-till carbonated Mediterranean soils
Soil (030 cm) was sampled using an Edelman-type
by studying its role in the incorporation and preservation of
auger. Disturbed subsamples were collected at four random
organic matter into the soil and the influence of aridity in
points per plot, and combined to obtain a composite sample
this process.
per plot, so that three field replicates were analyzed at each
site. Samples were air-dried and ground to pass through a
2-mm sieve.
2. Methodology
2.1. Study Sites. The study was conducted at three long- 2.3. Laboratory Analyses. Clay, total organic C content, and C
term experimental sites that include dierent soil man- in the form of particulate organic matter (C-POM [21]) were
agement treatments in the Ebro Valley in Navarre (NE, determined both in the casts and the bulk soil. Clay content
Spain). These sites were located in Pamplona (42 47 32 N; was determined by the pipette method [22], using a modified
1 37 54 W), Olite (42 27 33 N; 1 41 07 W), and San- Robinson pipette. Samples were chemically dispersed with a
tacara (42 23 44 N; 1 32 32 W). Only the plots under solution of 5% (NaPO3 )6 before analysis. Due to the elevated
no-till (NT) of each experimental site were chosen for carbonate content of the three soils (Table 1), wet oxidation
earthworms and soil sampling. This was done because greater was used to analyze total organic C [23].
earthworm activity has been observed in the area in NT Particulate organic matter is acknowledged to represent
plots [8]. The three sites contain carbonated soils which are the most labile fraction of organic matter in the soil, and
cropped to rainfed barley (Hordeum vulgare L.), but dier it is related to the formation of stable aggregates [24]. For
in some soil properties and, especially, in their agroclimatic this study, POM was isolated by dispersion and sieving of
characteristics (Table 1). They represent an aridity gradient 10 g of air-dried soil, as described by Marriott and Wander
because average rainfall is greater in Pamplona (Mediter- [25]. Briefly, samples were dispersed with 150 mL of 5%
ranean sub-humid type of climate) and decreases southward (NaPO3 )6 and the fraction >53 m (which includes the POM
to Olite (semiarid Mediterranean) and then Santacara (arid and sand-size mineral components of the soil) was collected
Mediterranean), while average annual temperatures and on a 53-m-opening polycarbonate mesh (Gilson Co. Inc.,
Applied and Environmental Soil Science 3
Columbus, OH) after 3 rinses with distilled water, and on an Oxisol occurred preferentially in the form of POM.
then oven-drying at 50 C. Samples were then ground to a They related this to the higher aggregate stability observed
powdery consistency before measuring their C content to in the casts in comparison to the surrounding soil. They
determine POM-C by wet oxidation [23]. further suggested that the mechanisms that protect organic
matter from decomposition during aggregate formation and
2.4. Statistics. Data are presented as standard error of the stabilization, as also described by Tisdall and Oades [30] and
mean for casts and soil characteristics. Data were analysed Six et al. [24], can be enhanced or facilitated by earthworm
using ANOVA (univariate linear model), and means were casting activity. Direct incorporation of POM into stable
compared among the three soils and between soil and casts microaggregates through earthworm transit in the soil has
at each study site using significant dierences. Post hoc also been described by Pulleman et al. [15] as an alternative
analysis was performed by Duncans multiple range test. pathway to the microbial-mediated one for the stabilization
Significant results are based on a probability level of P < .05. of POM by occlusion within microaggregates in undisturbed
All statistical analyses were performed using the SPSS 16.0 soils.
software [26]. Long-term stabilization of organic matter occluded
within aggregates inside earthworm casts is in fact possible
[31] and depends on the type of soil [32], earthworm species
3. Results and Discussion [33], the age of casts, the way they dry [3436], and the level
3.1. Role of S. gigas in the Incorporation of Organic Matter of disturbance to which casts are subjected [12]. A number
into the Soil. Lower clay contents were observed in the of studies have shown that the quantity of organic matter
S. gigas casts than the bulk soil in the three studied fields incorporated into the soil by earthworms also significantly
(Table 2). Our findings support thus the suggestion of aects the stability of casts. In the present study elevated clay
Schrader and Zhang [27] that selective particle ingestion and carbonates contents of the soils allow for overall high
by earthworms leading to increased clay contents in casts aggregate stability [8]. In Olite and Santacara, scarce rainfall
than in the surrounding soil [28] appears to be confined to and high average temperatures cause a rapid dehydration of
sandy soils, and/or might be more common in other smaller casts and, as a result, intact earthworm casts are observed
species of earthworms than the anecic S. gigas. An alternative several months after their formation at these two study sites.
explanation could be the existence of ultra-stable silt-size or In addition, NT techniques ensure low disruption of the
sand-size aggregates in the casts, which would resist chemical soil surface and protection against raindrops by the mulch.
dispersion. Considering the observed contribution of S. gigas to POM
Results from the analysis of the organic components of preservation within the casts, the contribution of this species
casts and bulk soils revealed that S. gigas casts contained to the stabilization of organic materials and the overall
more total organic C and POM than the soil (Table 2), as increase of organic C observed in NT soils in the region
has also been reported through other studies [14]. More [37, 38] is likely to be of importance.
interestingly, the percentage of C in the form of POM was
also greater within the casts than in the soil at the three 3.2. Influence of Aridity in the Behavior of S. gigas. Dierences
studied sites, suggesting a selective ingestion of the more related to the agroclimatic context of the three studied soils
edible fresh plant residues and labile organic materials by were found in the enrichment factor and composition of
S. gigas [14]. This finding is of special importance in the casts in relation to bulk soil (Table 3).
studied soils, which are naturally poor in organic matter, While in all the three sites casts contained less clays than
because POM entrapped within casts is likely to be more the bulk soil, the relative amount of clay found in the casts
protected against microbial activity than elsewhere in the of the more humid soil in Pamplona was significantly greater
soil [12]. Guggenberger et al. [29] reported that the incor- than in Olite and Santacara (Table 3). If we consider that the
poration of organic matter in the casts of anecic earthworms soil clay content was similar in Pamplona and Santacara and
4 Applied and Environmental Soil Science
Table 2: Content in clay, total organic C, and C in the form of POM (C-POM) in bulk soil samples and in Scherotheca gigas casts at the three
study sites. Values marked with are significantly dierent (P < .05) between soil and casts for each parameter and site. Values followed
by the same letter in the same row belong to the same Duncans homogeneous groups (P < .05) for each parameter among sites. Means
standard error (n = 3).
Table 3: Cast-to-soil ratios of clay, total organic C, and C in the form of POM (C-OPM) at the three study sites. Values followed by the same
letter in the same row belong to the same Duncans homogeneous groups (P < .05) for each parameter among sites. Means standard error
(n = 3).
greater in Olite (Table 2), this finding suggests that climate fresh stubble being the most significant available source of C
is a more important factor for this relative diminution in in this field.
the clay content of the casts than the soil texture itself. Not
much information is available on the influence of climate
on the burrowing and casting activity of any particular
4. Conclusions
earthworm species. In temperate areas, annual variations in By studying the composition of surface casts of S. gigas and
the casting activity of anecic species (Lumbricus terrestris) the surrounding soil under dierent agroclimatic conditions
have been described as related to rainfall and soil moisture in NT fields in the Ebro Valley, we found that this species
[39]. has an important role in the incorporation of organic matter,
In tropical semiarid areas, no earthworms are found and in particular of the most labile fractions, to the soil. The
during the dry seasons in soils that show earthworm activity casting activity of S. gigas seems thus related to the observed
during the rainy season [17]. progressive increments of organic C stocks in NT soils in the
Higher moisture in the soil in Pamplona than in the region. We also found a proportionally greater enrichment in
more aridic Olite and Santacara could be one reason for the labile organic particles in casts with increasing aridity, which
enhanced casting activity and thus for more intense remixing suggests that the importance of S. gigas in organic matter
of the casts with bulk soil. Lower concentration of carbonates stabilization under NT increases with aridity in the region.
in this soil (Table 1) probably also favored the formation of The relationship between climate, S. gigas casts texture, and
less cemented casts with less nondispersible sand- and silt- organic C content remains however incompletely understood
size aggregates within casts. Further research is needed in this and merits further research.
sense.
Regarding the incorporation of organic materials into Acknowledgments
the casts, it was observed that the enrichment factor in
total organic C in the casts compared to bulk soil was C. Gonzalez and M. Moriones are thanked for their technical
similar among the three studied soils, but a clear and laboratory assistance, and the Instituto Nacional de Investi-
significant trend towards higher enrichment ratios in POM gacion Agraria y Agroalimentaria (INIA, Spanish Agency) is
was observed with increasing aridity (Table 3). The role of acknowledged for funding this study in the framework of the
S. gigas in incorporation of POM was most significant in Research Call Accion: Sumideros Agroforestales de Efecto
the arid soils of Santacara, which had the lowest total SOC Invernadero of the National Program I+D+i (Project no.
and POM values as well as the lowest crop yield (Table 1), SUM 2006-00012-00-00). The authors are grateful also to
as compared to the other two sites. This more evident Professor M. J. Briones (University of Vigo, Spain) for her
preferential ingestion of POM in this soil probably is due to kind advice and for the classification of earthworms.
Applied and Environmental Soil Science 5
References management, Soil Biology and Biochemistry, vol. 39, no. 5, pp.
10141022, 2007.
[1] S. W. James, Systematics, biogeography and ecology of earth- [17] M. V. Reddy, V. R. Reddy, P. Balashouri, et al., Responses
worms from Eastern, Central, Southern and Southwestern of earthworm abundance and production of surface casts
USA, in Ecology and Biogeography of Earthworms in North and their physico-chemical properties to soil management in
America, P. E. Hendrix, Ed., pp. 2951, Lewis, Boca Raton, Fla, relation to those of an undisturbed area on a semi-arid tropical
USA, 1995. alfisol, Soil Biology and Biochemistry, vol. 29, no. 3-4, pp. 617
[2] J. P. Curry, Factors aecting the abundance of earthworms in 620, 1997.
soils, in Earthworm Ecology, C. A. Edwards, Ed., pp. 91113, [18] F. Binet and R. C. Le Bayon, Space-time dynamics in situ of
CRC Press LLC, Boca Raton, Fla, USA, 2nd edition, 2004. earthworm casts under temperate cultivated soils, Soil Biology
[3] D. J. Diaz-Cosin, D. Trigo, and R. Mascato, Earthworms of and Biochemistry, vol. 31, no. 1, pp. 8593, 1999.
the iberian peninsula. Species list and some biogeographical [19] J. K. Whalen, L. Sampedro, and T. Waheed, Quantifying
considerations, Soil Biology and Biochemistry, vol. 24, no. 12, surface and subsurface cast production by earthworms under
pp. 13511356, 1992. controlled laboratory conditions, Biology and Fertility of Soils,
[4] M. V. Reddy, Management of Tropical Agroecosystems and the vol. 39, no. 4, pp. 287291, 2004.
Beneficial Soil Biota, Science Publishers, Enfield, NH, USA, [20] G. H. Baker and K. E. Lee, Earthworms, in Soil Sampling
1999. and Methods of Analysis, M. R. Carter, Ed., pp. 359371, Lewis,
[5] C. A. Edwards and P. J. Bohlen, Biology and Ecology of Boca Raton, Fla, USA, 1993.
Earthworms, Chapman & Hall, London, UK, 3rd edition, 1996. [21] C. A. Cambardella and E. T. Elliot, Particulate soil organic-
[6] P. M. Mele and M. R. Carter, Impact of crop management fac- matter changes across a grassland cultivation sequence, Soil
tors in conservation tillage farming on earthworm density, age Science Society of America Journal, vol. 56, no. 3, pp. 777783,
structure and species abundance in south-eastern Australia, 1992.
Soil and Tillage Research, vol. 50, no. 1, pp. 110, 1999. [22] P. R. Day, Particle fractionation and particle-size analysis,
[7] M. J. I. Briones, P. Bescansa, M. J. Imaz, I. Virto, and in Methods of Soil Analysis, Part I, C. A. Black, Ed., ASA
A. Enrique, Eects of dierent tillage practices on soil Agronomy Series, no.12, pp. 545567, American Society of
properties and earthworm population, in Proceedings of the Agronomy, Madison, Wis, USA, 1965.
8th International Symposium on Earthworms Ecology, p. 169, [23] H. Tiessen and J. O. Moir, Total and organic carbon, in Soil
Krakow, Poland, September 2006. Sampling and Methods of Analysis, M. Carter, Ed., pp. 187200,
[8] I. Virto, M. J. Imaz, A. Enrique, W. Hoogmoed, and P. Lewis, Boca Raton, Fla, USA, 1993.
Bescansa, Burning crop residues under no-till in semi- [24] J. Six, H. Bossuyt, S. Degryze, and K. Denef, A history of
arid land, Northern Spain. Eects on soil organic matter, research on the link between (micro)aggregates, soil biota, and
aggregation, and earthworm populations, Australian Journal soil organic matter dynamics, Soil and Tillage Research, vol.
of Soil Research, vol. 45, no. 6, pp. 414421, 2007. 79, no. 1, pp. 731, 2004.
[9] E. Rota, Fauna Europaea: Lumbricidae, Lumbricinae, Fauna [25] E. E. Marriott and M. M. Wander, Total and labile soil organic
Europaea version 1.1, 2004, http://www.faunaeur.org/. matter in organic and conventional farming systems, Soil
[10] M. B. Bouche and F. Al-Addan, Earthworms, water infiltra- Science Society of America Journal, vol. 70, no. 3, pp. 950959,
tion and soil stability: some new assessments, Soil Biology and 2006.
Biochemistry, vol. 29, no. 3-4, pp. 441452, 1997. [26] SPSS Inc., Statistical software SPSS 16.0. Chicago, Ill, USA,
[11] M. V. Reddy, V. P. K. Kumar, V. R. Reddy, et al., Earthworm 2008.
biomass response to soil management in semi-arid tropical [27] S. Schrader and H. Zhang, Earthworm casting: stabilization
Alfisol agroecosystems, Biology and Fertility of Soils, vol. 19, or destabilization of soil structure? Soil Biology and Biochem-
no. 4, pp. 317321, 1995. istry, vol. 29, no. 3-4, pp. 469475, 1997.
[12] M. J. Shipitalo and R. Le Bayon, Quantifying the eects of [28] P. Lavelle, F. Charpentier, C. Villenave, et al., Eects of
earthworms on soil aggregation and porosity, in Earthworm earthworms on soil organic matter and nutrient dynamics at
Ecology, C. A. Edwards, Ed., pp. 183200, CRC Press LLC, a landscape scales over decades, in Earthworm Ecology, C. A.
Boca Raton, Fla, USA, 2nd edition, 2004. Edwards, Ed., pp. 145160, CRC Press LLC, Boca Raton, Fla,
[13] R. J. Haynes, P. M. Fraser, J. E. Piercy, and R. J. Tregurtha, USA, 2nd edition, 2004.
Casts of Aporrectodea caliginosa (Savigny) and Lumbricus [29] G. Guggenberger, R. J. Thomas, and W. Zech, Soil organic
rubellus (Homeister) dier in microbial activity, nutrient matter within earthworm casts of an anecic-endogeic tropical
availability and aggregate stability, Pedobiologia, vol. 47, no. pasture community, Colombia, Applied Soil Ecology, vol. 3,
5-6, pp. 882887, 2003. no. 3, pp. 263274, 1996.
[14] G. G. Brown, I. Barois, and P. Lavelle, Regulation of [30] J. M. Tisdall and J. M. Oades, Organic matter and water-
soil organic matter dynamics and microbial activity in the stable aggregates in soils, Journal of Soil Science, vol. 33, no.
drilosphere and the role of interactions with other edaphic 2, pp. 141163, 1982.
functional domains, European Journal of Soil Biology, vol. 36, [31] H. Bossuyt, J. Six, and P. F. Hendrix, Protection of soil carbon
no. 3, pp. 177198, 2000. by microaggregates within earthworm casts, Soil Biology and
[15] M. M. Pulleman, J. Six, A. Uyl, J. C. Y. Marinissen, and A. Biochemistry, vol. 37, no. 2, pp. 251258, 2005.
G. Jongmans, Earthworms and management aect organic [32] M. McInerney and T. Bolger, Temperature, wetting cycles
matter incorporation and microaggregate formation in agri- and soil texture eects on carbon and nitrogen dynamics in
cultural soils, Applied Soil Ecology, vol. 29, no. 1, pp. 115, stabilized earthworm casts, Soil Biology and Biochemistry, vol.
2005. 32, no. 3, pp. 335349, 2000.
[16] S. J. Fonte, A. Y. Y. Kong, C. van Kessel, P. F. Hendrix, and J. [33] H. Zhang and S. Schrader, Earthworm eects on selected
Six, Influence of earthworm activity on aggregate-associated physical and chemical properties of soil aggregates, Biology
carbon and nitrogen dynamics diers with agroecosystem and Fertility of Soils, vol. 15, no. 3, pp. 229234, 1993.
6 Applied and Environmental Soil Science
Review Article
Effect of Soil Physical State on the Earthworms in Hungary
Marta Birkas, Laszlo Bottlik, Attila Stingli, Csaba Gyuricza, and Marton Jolankai
Institute of Crop Production, Szent Istvan University, 2103 Godollo, Hungary
Copyright 2010 Marta Birkas et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Hungarian authors have long been discussing the role of earthworms in improving soil productivity. Earthworm counts in our
higher quality soils are similar to those found in soils where more attention is paid to earthworm activity. Negative impacts that
are independent of farmingsuch as sustained dry spells in the summeralso aect earthworm counts. Negative impacts that
definitely depend on farming include land use causing soil moisture loss, deep stubble treatment leaving the soil without cover,
and ploughing in the summer without subsequent pressing. The climate change is having both positive and negative impacts.
Weather patterns are causing losses but adopting climate mitigating tillage are generating benefits. In the trials results so far show
that tillage focusing on preserving soil moisture, structure, and organic materials, covering the surface in the critical months as
well as adequate soil loosening are fundamental pre-requisites for making the soil a favourable habitat for earthworms.
earthworm numbers under lathyrus grown for being used Table 1: Number of earthworms (pcs m2 ) in the top 20 cm layer
as green manure. He found soil under conserving tillage of a brown gleyic forest soil, under maize (Pyhra, 19982006, from
to be a good habitat for them, in contrast to ploughing [33]).
in the summer, creating definitely adverse conditions for Tillage variants 1998 2000 2002 2004 2006 Mean
earthworms. He noted that earthworms are hard hit both
Direct drilling 54 72 66 88 288 113.6
by summer drought and heat alike, finding a 15 C soil
temperature as being optimal for these organisms. Today Ridge till 27 32 42 28 72 40.2
they have been observed to have a broader range of tolerance Ploughing 10 12 31 16 56 25.0
in terms of temperature, but weeks of extremely high Years rainy dry rainy average average
temperatures will definitely reduce their activities. Other
authors also found, relatively early, the poor habitat value Table 2: Earthworms live weight (g m2 ) in the top 20 cm layer
of cloddy and dry soil after ploughing, for instance, Tischler of a brown gleyic forest soil, under maize (Pyhra, 19982006, from
[21]. Kemenesy [17, 18] noted that soils in their pristine [33]).
condition, that have never been disturbed, oer the best
Tillage variants 1998 2000 2002 2004 2006 Mean
habitat for earthworms. Some authors have reported [22
25] that the application of excessive amounts of chemicals Direct drilling 52.7 24.2 55.1 64.3 217.8 82.8
reduce the value of sites as habitat. In land under crops sown Ridge till 9.8 11.3 41.9 17.8 67.1 29.6
by direct seeding where crop protection is limited practically Ploughing 14.7 3.5 23.8 11.7 42.3 19.2
to the application of chemicals, authors still found higher Years rainy dry rainy average average
earthworm numbers [2628]. Accordingly, factors aecting
a sites value as a habitat can be assessed only by adopting
a complex approach. Wide-ranging tests were carried out natural habitats the earthworms that are longer than 5 mm
by Zicsi [29, 30] in Hungary to produce qualitative and can be picked out of the soil. In the experiments, counts
quantitative assessments of the earthworm populations in were taken every 10 days during the period concerned, in
various soil types. In the new publications the authors discuss six repetitions, from the soil down to depths of 2030 cm
earthworm counting for the most part as supplementary as appropriate, as a consequence a negligible number of
aspects instead of primary goals of experiments. Between earthworms were not included in the count. The findings
1996 and 1998 Gyuricza [31, 32] assessed earthworm activity of Laszlo [33] apply to settling brown gleyic forest soil
in tillage experiments set up in Chromic Luvisol and in Typic Pyhra, Austriain the case of three dierent types of tillage
Argiudoll between 1996 and 2006, along with Laszlo [33] or soil disturbance. Measurements were taken by Laszlo
between 1998 and 2006 also in long-term tillage experiments using the ISO 23611-1:2006 testing methodin mid-June
in brown gleyic forest soil. Birkas et al. [34, 35] used when the soil was well-shaded by maize (Table 1). Since the
earthworms as indicators of the soil state in their soil quality soil had a good supply of potassium, no potash was applied,
experiment set up in chernozem soils (Calcic Chernozem) and the P fertiliser dose was between 42 and 112 kg ha1
and at dierent sites under field conditions from 1994 according to the residual supply from the previous year, while
on. This study provides an overview of the findings of the quantity of N fertiliser wasalso according to the soil
experiments carried out during recent years. analysisbetween 92 and 154 kg ha1 [32], as was fit for
the soil concerned. Findings were processed with the aid of
nonparametric variance analysis.
2. Earthworm Activities in In 1998in a rainy yeartwo times more earthworms
Soils Cultivated in Different Ways (54) were found in soil under crop sown by direct drilling
than in soil after ridge till (27) and 5.4 times more than under
There are 40 dierent earthworm species [18, 25, 29] in conventional tillage (10). In a dry year (2000) the dierences
Hungary, the most commonly found species easily found in were greater, while in another rainy season (2002) they were
arable fields and in gardens. The most frequently encoun- smaller. In average years (2004 and 2006) the density of
tered species is called common earthworm (Lumbricus earthworms was significantly higher after direct seeding (88
terrestris), whose specimens dig deep vertical burrows in the and 288) than that counted after the other two types of
soil. Satchell [22] and Lee [23] note that the presence or tillage. The dierences also appeared in the five year average
the absence of earthworms is a rather good indicator of the figures as well. Significant dierences (7.9992 P < .05) were
quality of the soil, so they can be used as biological soil found between the types of tillage. The soil state modified by
indicators. This particular form of soil quality assessment is tillage also aected the live weight of earthworms (Table 2).
also applied by Hungarian scientists in tillage experiments. In a year of slightly more precipitation than the average
In comparison to other soil-borne organisms there is a as is favourable for earthwormsLaszlo [33] found five
definite relationship between the number of earthworms and times greater total of earthworm live weight (52.7) in soil
the state of the soil, and theISO 23611-1:2006testing under direct drilling than in soil under ridge till (9.8) and
methods are relatively simple [33]. Earthworms are collected three and a half times more than in soil under conventional
from underneath a known soil surface areafor example, a tillage (14.7). Earthworm populations were reduced by less
quadrant (0.25 m2 )after excavating and screening a certain precipitation in dryer years but dierences between their
volume of soil. Under Hungarys climatic conditions in populations in soils of dierent states remained significant.
Applied and Environmental Soil Science 3
Table 3: Earthworm burrow density (>2 mm burrows m2 ) in the chernozem, and meadow alluvial) with humus contents of
top 20 cm layer of a brown gleyic forest soil, under maize (Pyhra, 1.8%, 3.1% and 3.4%, respectively. Ten to fifteen, years ago
19982006, from [33]). farmers did not consider earthworms to be of particular
Tillage variants 1998 2000 2002 2004 2006 Mean
importance, therefore according to Birkas [34] the maximum
of 36 earthworms (per m2 ) in the chernozem soil is to be
Direct drilling 374 425 386 407 1372 592.8
considered to be very good. Incidentally, this was the soil
Ridge till 211 293 305 319 584 342.4 in which the largest numbers of earthworms were found
Ploughing 97 198 287 113 460 231.0 regardless of the soil states. According to the ranking based
Years rainy dry rainy average average on earthworm counts undisturbed and deeply loosened soil
state is the most favourable under a high (55%) cover. More
deeply loosened soil with medium (35%) coverage was the
In the rainy year 2002 ploughing had a notably positive 2nd in the rank, followed by shallower loosened layer and
impact, yet it was still as not as favourable as those treatments medium coverage. Ploughed soil came as the 5th in the
involving less soil disturbance. The dierence between the rank, despite the fact that ploughing put the largest amount
earthworm counts in 2006 between dierent tillage variants of plant residues in the soil (5 t ha1 ), but inverting in the
was also reflected in the weight of the earthworms. The same depth was not found to be advantageous. Ploughed
dierence between the live weights of earthworms in soils soil turned into a particularly disadvantageous habitat when
under dierent tillage variants was smaller than the dier- not even field residues were mixed into the soil. Birkas
ence between the numbers of earthworms counted. Laszlo [34] underlined that a compact tillage pan is not suitable
[33] found no significant dierence between tillage variants for earthworms at all (more deeply loosened state was
(5.6600 P > .05). It was also him who examined burrow favourable for maize, surface cover was not, but a compact
numbers (Table 3), finding that there were 1.73 times more state was disadvantageous). Tests showed the importance
earthworm burrows than under ridge till and 2.56 times of covering the soilfrom the aspect of the earthworm
more than in soil under conventional tillage. He found both habitattherefore this factor was also taken into account in
horizontal and vertical burrows. He found no significant other experiments.
dierences between tillage variants (5.4600 P > .05), but he
found a close relationship between earthworm density and
burrow density (R2 = 0.79). 4. The Importance of Surface Cover
Laszlo [33] underlined that in the given gleyic forest soil
In an experiment conducted by Birkas et al. [3841] the soil
earthworms favoured soil under direct drilling, that is, less
surface was covered as follows: ploughing 0%, loosening,
disturbed but adequately loosened soil in terms of the total
disking 25%, tillage with cultivator 35%, and direct seeding
porosity space. Their other requisites for life, that is, adequate
65%. These coverage ratios were kept up regardless of crops
moisture andeven in the dry year of 2000food were
(2002: mustard, 2003: wheat, rye, 2004: rye, pea, 2005:
continuously available for them in the soil.
wheat, mustard, 2006: wheat, phacelia, 2007: maize, and
2008: sunflower). The authors found earthworm counts
3. Importance of the Looseness of the Soil and increasing in parallel with increasing coverage ratios. On
of the Depth of the Loosened Layer the other hand, some increase was found in all types of
tillage during the first 5 years, thereafter earthworm counts
Earthworm burrows play an important roleas bio- dropped. The authors concluded that densely sown crops
poresin soils water, material, and gas transport heat eared cereals as main crops, followed by catch cropscreated
exchange processes [24, 31]. Horizontal burrows in the top more favourable conditions, while more wide row crops
soil layer enable primarily the soil aeration, while deep created slightly less favourable conditions as a consequence
vertical earthworm burrows enabling the seeping of water of the modest shading such plants provide. In order to
into the soil function as important gravitational pores, enable a more accurate evaluation the authors sought for
making it possible, for instance, for quick transport of a relationship between the depth of soil disturbance, soil
sudden downpours to deeper layers of the soil [33, 36, coverage and typical earthworm counts (Table 5).
37]. According to Laszlo [33] vertical earthworm burrows The authors found that increasing depththat is
mitigate erosion in sloping sites as run-o is reduced by favourable habitat at lower depths, is favourable in the
improved water absorption. Birkas [34] considered that a case of every mulch variant. Smaller numbers of earthworms
certain looseness of the soil is a prerequisite for the particular were found under bare surface, almost in all cases, than
soil loosening activity of earthworms. This was concluded under various percentages of coverage. The earthworm count
from findings of field experiments set up in the 1990s on under direct drilling was higher than in ploughed soils,
various soil typesbrown forest, chernozem, and meadow as found by many other authors [28, 32, 33]. If, however,
alluvialby three dierent clay content levels (Table 4). soils disturbed to greater depths were covered, even after
The earthworm count was an important factor in ploughing, they were found to be better than settled soils. In
addition to monitoring soil state changes in the experiments the case of coverage between 0% and 25%, between 0% and
whose results are summed up in Table 4. The three dierent 35%, and between 0% and 65%, an average of 28%, 43%,
clay content levels applied to three dierent soil types (forest, and 67%, respectively, were found in favour of the higher
4 Applied and Environmental Soil Science
Table 4: Relationship between the soil clay content, soil state, and earthworm count, under maize (19941999, June [34]).
Clay %, v/v
Rank of soil states based on
30 50 60 earthworm counts
Earthworm count per m2 (020 cm)
(1) Undisturbed soil, loosened to
26 36 28 a depth of 45 cm, covered to an
extent of 55%
(2) Soil loosened down to 40 cm,
25 34 26 covered up to 35% (plant residue
mixed in the soil: 3 t ha1 )
(3) Soil tilled with cultivator to a
depth of 1822 cm, under 35%
24 30 26
coverage (plant residue mixed in
the soil: 3 t ha1 )
(4) Soil tilled with cultivator to a
depth of 1618 cm, under 20%
21 26 23
coverage (plant residue mixed in
the soil: 3 t ha1 )
(5) Soil ploughed to a depth of
16 22 16 2225 cm (plant residue inverted
to the soil: 5 t ha1 )
(6) Undisturbed, uncovered,
16 20 9 settled soil (field residues
removed)
(7) Soil ploughed to a depth of
6 10 7 2225 cm (plant residues
removed)
0 0 0 (8) Plough pan and disk pan
1.786 1.908 1.216 LSD5%
Table 5: Eects of depth of soil disturbance and soil coverage on increased, except in soils under direct drilling. The authors
earthworm count (in loam soil of 19%22%, w/w soil moisture noted that the amount of field residue mixed in the soil
contents as an average of 6 repetitions). equalled, on an average and per year, 0.2 (only in the case of
direct drilling), 3.0, 3.7, and 4.3 t ha1 [41]. Eventually, the
Mulch %
Tillage depth (cm) Mean authors established a close relationship between the depth
0 25 35 65
of disturbance, the ratio of coverage, and the earthworm
05 14 18 20 21 18 counts. The tillage-mulch interaction was reliable at a P =
1620 24 24 27 31 26 1% level. They assumed that increased soil cover makes it
2025 22 31 32 39 31 possible to decrease tillage interventions by a reasonable
3035 25 34 41 47 37 measure. This was also confirmed by the study carried out
Mean 21 27 30 35 in their stubble trial [42].
LSD5% .
Between dierent tillage depths under identical mulch treatment: 3.44 5. The Importance of Soil Moisture
Between dierent tillage depths as an average of the mulch variants: 2.06
Between mulch variants under the identical depth treatments: 4.977
As has been described above, earthworms favour soils loos-
Between mulch variants as an average of depths: 4.146
Between two depth variants in the case of dierent mulch percentages: 4.670 ened to increased depths. Soil coverage is also an important
Tillage depth: P > .1%; Mulch %: P > .1%; Depth Mulch: P > 1%. habitat as covered soil is less exposed to the risk of damage by
heat or water stress and it also helps the soil keep its moisture
content.
In their experiment Birkas et al. [40, 41] were seeking
coverage rates. Deeper disturbance increased earthworm to identify the relationship between soil moisture and
counts by 44%, 72%, and 105%in the order presented earthworm count. The data have been presented merely as an
in the left-hand-side column in Table 5, respectively, illustration, without supplementing them by a mathematical
creating better habitats accordingly. It should also be noted evaluation. The optimum moisture range for tillage of
that along with the increasing depth the amount of food chernozem soil that is moderately prone to compacting
for earthworms (that is, the mass of field residue) also near the town of Hatvanis between 19%, w/w and 25%,
Applied and Environmental Soil Science 5
number (m2 )
50
Earthworm
found that during the period between 2003 and 2008 the
40
shortage of water varied between 5% and 25%, but it was 30
characteristically aected by tillage variants (Figure 1). The 20
shortage of water had the smallest impact on ploughed soil, 10
followed by direct drilling, while the greatest shortage of 0
deficit (%)
water was found in soil after disking. In the average of six 10
water
successive years the earthworm number was the smallest in 20
disked soil (35), hardly more (36) in ploughed soil. The 30
number of earthworms in soil under direct drilling was 40
on an average, slightly more in soil loosened to a depth of 2003 D 2006 A
40 cm (43), while the highest (48) count was found in soil 2004 D 2007 D/A
loosened with cultivator to a depth of 20 cm. The authors 2005 R 2008 R
found [38, 40] that in the case of water shortage not heavily Figure 1: Coherence between water deficit of soil and earthworm
restricting cropping, earthworm activity, and so forth, other number (Hatvan, 20022008). Legend: A: average season, D: dry, R:
factorsfor example, soil cover and the required looseness rainy, D/A: dry and average in one season, L: loosening 40 cm, P:
will have increased impacts. ploughing 30 cm, C: cultivator use 20 cm, D: disk tillage 16 cm, and
Accordingly, supplementary studies were carried out in DD: direct drilling.
the experiment site, involving soils of 8 dierent depths of
the loosened layer and three dierent levels of soil moisture
content. In any given soil an 11%, w/w soil moisture content 60
qualifies as dry, while 22%, w/w and 28%, w/w qualify as
humid and wet, respectively. The findings are presented in 50
Figure 2.
Earthworm number (m2 )
60
50 surface press [45] were likely to have reduced earthworm
40 activity for quite some time. Moreover, the same mistakes
30 were repeatedly made in the same fields [45, 46]. The
20 climate change has had both negative and positive impacts
10 in Hungary. Extreme weather patterns are causing losses but
0 the recognition of the necessity and the application of climate
(Rye, pea)
(Maize)
(Mustard)
(Sunflower)
phacelia)
mustard)
(Wheat,
(Wheat,
(Wheat,
damage mitigating tillage have been found to have favourable
2007
2003
rye)
2006
2005
2004
2002
2008
impacts on soils as well [41]. During recent years in soils
under conservation tillage, under 15%25% mulch coverage
Aggregate (0.2510 mm) even after sowing, 68 earthworms were found under every
Dust (<0.25 mm) plant grown in wide rows, after harvest. It should also be
Clod (>10 mm) mentioned that no earthworms at all were found in soils
of damaged structure. Accordingly, the solutionincluding
Figure 3: The trend of crumb forming in the average of 6 tillage increased earthworm activityis oered by preserving the
variants, under dierent crops (Hatvan, 20022008, From Birkas
quality of the soil and mitigating the damage to be caused
et al. [41]).
by climate conditions [46]. Results achieved so far show
that soil moisture, structure, and organic material conserving
tillage, covering the soil surface during the critical summer
90 months and maintaining adequate looseness are essential
prerequisites for making the soil a suitable habitat for
80 earthworms as well.
70
8. Conclusions
y = 0.0049x2 0.6494x + 58.764
60
R2 = 0.5775 Earthworms have been duly appreciated in technical lit-
y = 0.0144x2 0.9168x + 27.631 erature in Hungary but precious little research has been
50
R2 = 0.5217 focused on them. In tillage experiments supplementary
types of evaluations have been produced concerning the
40
relationships between earthworm count, depth of loosened
layer, soil moisture, and soil surface cover. The authors
30
found that earthworm-friendly tillage results in loosening
and crumb forming, it creates minimised soil surface and is
20
0 10 20 30 40 50
characterised by mulch cover on the soil. The depth of the
Depth of loosen layer
layer loosened by tillage should be around 3040 cm and it
may even be shallower (even as shallow as 20 cm) if there is
Aggregate (%) no compact tillage pan underneath the tilled layer.
Earthworm number
Soil moisture content that makes the soil workable is
Figure 4: Relationships between the depth of the loosened layer
also favourable for earthworms. Soil surface coverage may
(n = 7), crumb forming (n = 21), and earthworm counts (n = increase in importance in the future, during the warm
28) in soils of favourable soil moisture contents (1922%, w/w). and hot summer months. An at least 35% soil coverage
(Hatvan, 20022008). is necessary, but the optimum is as high as 45%. Field
residues mixed into the soil serve as food for earthworms
therefore shortage of that is just as disadvantageous as a
large, inadequately distributed mass. Climate damage mit-
basis of the photos and site descriptions the earthworms igating tillage produces habitats favourable for earthworms
counted probably fall in the anecic and the endogenic as well.
groups. Earthworm counts in well-tended soils in Hungary
are similar to those measured in West European countries Acknowledgments
and in the USA.
The amount of the application of fertilisers and chem- This paper presents results of research programmes sup-
icals never reached the levels prevailing in countries with ported by NTTIJM08, CRO-33/2007, and HR-43/2008, and
advanced agriculture sectors. By examining soils under sugar our thanks are also to the Experimental and Training Farm
beets Birkas [44] found that in the case of reasonable of Hatvan, Mezohegyesi Menesbirtok Zrt; Belvardgyulai Mg.
application of chemicals the quality of tillage and mulch Zrt; Agroszen Kft. Szentgal, Rona Kft. Hodmezovasarhely.
Applied and Environmental Soil Science 7
Research Article
The Effect of Earthworm (Lumbricus terrestris L.) Population
Density and Soil Water Content Interactions on Nitrous Oxide
Emissions from Agricultural Soils
Copyright 2010 Andrew K. Evers et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Earthworms may have an influence on the production of N2 O, a greenhouse gas, as a result of the ideal environment contained
in their gut and casts for denitrifier bacteria. The objective of this study was to determine the relationship between earthworm
(Lumbricus terrestris L.) population density, soil water content and N2 O emissions in a controlled greenhouse experiment based
on population densities (90 to 270 individuals m2 ) found at the Guelph Agroforestry Research Station (GARS) from 1997 to 1998.
An experiment conducted at considerably higher than normal densities of earthworms revealed a significant relationship between
earthworm density, soil water content and N2 O emissions, with mean emissions increasing to 43.5 g ha1 day1 at 30 earthworms
0.0333 m2 at 35% soil water content. However, a second experiment, based on the density of earthworms at GARS, found no
significant dierence in N2 O emissions (5.49 to 6.99 g ha1 day1 ) aa a result of density and 31% soil water content.
monoculture. A TBI system is defined as an approach to However, these values were tripled in order to ensure the
land use that incorporates trees into farming systems and detection of N2 O for the purpose of finding optimal soil
allows for the production of trees and crops or livestock water content and also to represent an earthworm invasion
from the same piece of land in order to obtain economic, where populations could initially be very high and decline
ecological, environmental and cultural benefits [12]. These over time [15]. These values were 30, 20, and 10 earthworms
systems incorporate leaf litter and increase soil water content, per 4 kg of soil or 0.033 m, for the high, medium, and low
which could encourage higher earthworm populations com- treatments, respectively, and a control with no earthworms.
pared to sole cropping systems. In turn, this could increase L. terrestris were purchased from Kingsway Sports (Guelph,
the overall volume of the earthworm gut, thereby facilitating Ontario, Canada). Earthworms were counted and weighed
denitrification and higher N2 O emissions from a TBI system. prior to being added to the mesocosms.
Price and Gordon [11] also speculated that the reason Prior to adding the earthworms, each mesocosm was
earthworm densities were higher in the intercropped system fertilized with urea (46-0-0, N-P-K), which represented
compared to the conventional monoculture was because the N fertilizer requirement for corn planted at GARS
earthworms move to an area with a lower soil temperature, (215 kg ha1 ). Deionized water was applied to each meso-
which in turn are areas that also have higher soil water cosm for one week prior to adding the earthworms in
content. order to achieve the desired gravimetric soil water content
Currently, very little information exists on the influence for each treatment. A small hole in the bottom of each
that earthworm density has on N2 O emissions from agricul- mesocosm allowed for proper drainage. During the course of
tural soils, and specifically those potentially associated with a the experiment, soil water content was maintained by weight.
TBI system. The objective of this study was to investigate the The mesocosms were weighed every day for the entire course
relationship, if any, between N2 O flux, earthworm density, of the experiment and deionized water was added to bring
and gravimetric soil water content, taking into account the each mesocosm to the desired water content.
earthworm densities calculated by Price [13] in the TBI and The mesocosms were placed in a greenhouse with a
monoculture systems located at GARS and using the most constant air temperature of 20 C and monitored light
common earthworm species found in GARS, the common conditions of 16/8 hr cycles. Soil temperature was monitored
nightcrawler (Lumbricus terrestris L). It was hypothesized using Priva soil temperature sensors (Priva North America
that N2 O flux would be higher as earthworm density and soil Inc., Vineland Station, Ontario, Canada) to ensure a constant
water content increased. soil temperature of approximately 20 C. N2 O sampling
technique and calculations will be explained in the following
section.
2. Materials and Methods A second experiment was conducted from February
2009 to March 2009 in the Science Complex Phytotron at
2.1. Study Design. The first experiment was conducted in the University of Guelph. Experiment 2 was a completely
the Science Complex Phytotron at the University of Guelph, random design with four replications for a total of 16
Guelph, Ontario, Canada. The purpose of the first experi- experimental units. A control with no earthworms and
ment was to determine the optimal soil water content for earthworm densities of 9 (high), 6 (medium), and 3 (low)
earthworm activity resulting in the highest N2 O emissions. earthworms per mesocosm were used for a total of four
The experiment was a two factorial, completely random treatments. The high, medium, and low density treatments
design with four replications for a total of 64 experimental were calculated based on actual densities found by Price [13]
units. The first factor was earthworm density (see below) and at GARS representing an earthworm density adjacent to the
the second factor was gravimetric soil water content (15%, tree row, 3 m from the tree row, and 6 m from the tree row in
25%, 35%, and 45%). a TBI system, respectively; a control with no earthworms was
Soil was collected from GARS and homogenized using a also included.
2 mm sieve. The soil is sandy loam in texture with an average Optimal gravimetric soil water content was determined
pH of 7.2 [14]. A leaf litter mixture composed of silver maple in Experiment 1 and was found to be 31%. This soil water
(Acer saccharinum L.) and poplar (Populus spp.) leaves was content treatment was held constant for all four earthworm
also collected from GARS, dried at 60 C for one week, and density treatments over the duration of the experiment.
mixed into the homogenized soil to achieve a soil organic Methods for soil preparation, maintaining gravimetric soil
matter content of approximately 3%. Four kilograms of the water content, and monitoring temperature were the same as
soil and leaf litter mixture was then put into each of the 5 L in Experiment 1.
polypropylene mesocosms, equipped with an airtight lid and
rubber septum for sampling. The lids were only placed on the
mesocosms at the time of N2 O sampling. The surface area of 2.2. Sampling Procedure. At the time of N2 O sampling, the
each mesocosm was 0.033 m2 . airtight lid was placed onto each mesocosm and a 30 mL air
Earthworm density was calculated based on data col- sample using a 26-gauge needle and syringe was taken at
lected in the spring of 1997 from GARS by Price [13]. The t = 0, 30, and 60 min to calculate N2 O flux over an hour.
three earthworm densities included high, medium, and low Air samples were deposited into 12 mL Exetainers (Labco
earthworm densities, representing populations found 0 m, Limited, United Kingdom) and analyzed using a SRI Model
3 m, and 6 m from the tree row in a TBI system, respectively. 8610C Gas Chromatograph (Torrance, California, USA) at
Applied and Environmental Soil Science 3
Environment Canada (Burlington, Ontario, Canada). N2 O the mesocosms, which created negative flux values [17].
samples were taken once a week for four weeks beginning at Therefore, a value of 100 was added to all flux values in order
10:00 AM. to complete statistical analyses and maintain positive values
A soil sample was taken from each mesocosm, both since the statistical program could only read positive values.
before the addition of earthworms and after the last week of The final flux values following analysis were then subtracted
sampling. This was done to measure the initial and the final by 100 to present actual flux values in the following sections.
nitrate (NO3 ), ammonium (NH4 + ), and total inorganic N
(TIN) concentrations to determine if there was a change over
2.4. Statistical Analysis. All statistical tests were conducted
the course of the experiment. Soil samples were stored in the
using SAS v.9.1 (SAS Institute, Cary, NC, USA) at an error
freezer until analysis. N content was measured following a
rate of = 0.05. An analysis of variance (ANOVA) using
2N KCl extraction [16], and samples were run through an
repeated measures in the PROC MIXED function was used
Astoria 2-311 Analyzer (Astoria-Pacific Inc., Oregon, USA).
to compare the eects of earthworm density and N2 O flux
Measurements of soil inorganic and organic carbon (C)
according to soil water content treatment to determine the
were also done for initial and final C content using a Leco
variance in initial and final earthworm biomass between
C determinator (Leco Corporation, St Joseph, MI, U.S.A.).
moisture treatments, as well as mortality rates between
However, results for soil N and C are not reported here and
moisture treatments in Experiments 1 and 2. A response
are part of a larger study.
surface design using the PROC RSREG function [18] was
applied to data from Experiment 1 to determine the optimal
2.3. N2 O Flux Calculation. N2 O flux was calculated using range levels of earthworm density and soil water content
the ideal gas law; the molar volume of N2 O at 0 C and 1 for the production of N2 O over ranges for these parameters
atm is 44.0128 L/mol. The N2 O flux was adjusted for air that were not part of the original experimental design. The
temperature and pressure using the following formula: optimal soil water content found through the RSREG was
[(273.16 K+T C)] then applied to Experiment 2.
Flux adjustment = 44.0128 L mol1
273.16 K
(1013.2 hPa) 3. Results
,
P hPa 3.1. N2 O Emissions. The earthworm density and soil water
(1)
content interaction on N2 O emissions was significant (P =
where T is the air temperature and P is the air pressure on the .0457). Mean N2 O emissions ranged from 0.54 g ha1 day1
day of sampling. These values were taken into consideration from the 15% moisture and no earthworm density treatment
because a temperature greater than 0 C increases molar to 43.5 g ha1 day1 from the 35% moisture and high earth-
volume and, air pressure that is greater than atmospheric worm density treatment as illustrated in Figure 1. Patterns
decreases molar volume. did exist in emissions, where N2 O emissions were highest at
The volume of the mesocosm was then converted to mol the high density across all moisture treatments and lowest
of air and multiplied by the slope of the flux determined by in the mesocosms with no earthworms across all moisture
hourly measurement. This value was then used to calculate treatments. The extent of emissions across all of the moisture
the flux in mol m2 s1 : treatments was high > medium > low > control. Emissions
due to moisture were 35% > 25% > 45% > 15% across
S nmol mol1 s1 (M mol) all earthworm densities except when earthworm density = 0,
Flux mol m2 s 1
= , (2) where emissions were 35% > 25% > 45% = 15%. Emissions
X m2 were only significant at the high density and 25% and 35%
where S represents the slope of the line (N2 O concentration soil water content treatments, as well as the medium density
at each measurement interval over one hour), M is the molar and 35% soil water content treatment compared to the rest
volume of the air in the mesocosm, and X represents the area of the treatments.
of the mesocosm. This value was then converted into kg of Over the course of the experiment, N2 O emissions only
N2 O ha1 day1 : increased at 45% soil water content, where emissions were
highest in the last week of sampling compared to the first
Flux g ha1 day(1) = Fmol m2 s1 1.0 109 mol week at all density treatments (Figure 2). At 15% and 25%
soil water content, emissions peaked at week three and
1
week two, respectively, and declined by week four. In the
44.0128 L mol 10000 m2
25% moisture treatment, emissions had a significant peak at
(86400 s) 1000 g , 56.6 g ha1 day1 at high density in week two compared to
(3) 1.5 g ha1 day1 , 3.2 g ha1 day1 , and 3.6 g ha1 day1 in the
control, low, and medium densities, respectively. An outlier
where F is the flux calculated from (2). did exist in the 25% moisture and high density treatment
Some of the flux values were negative as a result of a sink during week two, but when left in, it did not significantly
of N2 O being created rather than the N2 O being emitted change the result. However, it may explain the peak in
through the soil surface during the extraction period from emissions during week two at the high density treatment.
4 Applied and Environmental Soil Science
a
50 g (%) Low Medium High
40 15 2.0 a 11.0 a 15.6 a
a 25 2.0 a 2.5 a 5.0 a
30 ab a 35 0.0 a 8.5 a 18.3 a
ab
a
45 0.0 a 6.0 a 10.0 a
20
a SE 0.6 0.6 1.0
a a
10 a a P value .1994 .2139 .0571
a a
a a Within columns, means followed by the same letter are not significantly
0 dierent according to Tukey-Kramer means adjustment (0.05).
0 10 20 30
Low, medium, and high refer to densities of earthworms per 0.033 m2 : 10,
Earthworm density (earthworms per 0.033 m2 )
20, and 30, respectively.
15% soil moisture 35% soil moisture
25% soil moisture 45% soil moisture
occurred at 35% soil water content. The largest increase
Figure 1: The relationship between N2 O emissions, earthworm
in biomass in the medium density treatment occurred at
density per 0.033 m2 , and gravimetric soil water content (P =
.0457, SE = 4.07, 5.29, 6.10, and 4.52 for 15%, 25%, 35%, and
35% soil water content where the final earthworm biomass
45%, resp.). Bars with same letter indicate no significant dierence was significantly higher than the initial biomass. Earthworm
between treatments at P = .05 according to Tukey-Kramer means biomass declined in the 15% soil water content treatment
adjustment. due to a mortality rate of 11%; however, this decline was
not significant. The highest increase in earthworm biomass
over the course of the experiment occurred at 25% soil water
content in the high density treatment; however, this increase
N2 O emissions declined over the course of the experiment
was not significant. There was also a decline in earthworm
in all densities at 35% moisture except in the high density
biomass over the course of the experiment in the 15% and
treatment where emissions were the highest in week two at
35% soil water content treatment due to high mortality rates
69.6 g ha1 day1 .
in the high density treatment; however this decline was not
A response surface regression indicated that the lowest
significant.
N2 O emissions would occur at soil water content of 15%
and an earthworm density of 13 earthworms per 0.033 m2 ,
whereas the highest emissions would occur at a soil water 3.3. N2 O Emission at 31% Gravimetric Soil Water Content.
content of approximately 31% and an earthworm den- Based on the gravimetric soil water content of 31% found
sity of 30 individuals per 0.033 m2 as seen in Figure 3. in the response surface in Experiment 1, there was no
The lowest and highest emissions correspond to 1.7 significant dierence in N2 O flux across all earthworm
and 22.3 g ha1 day1 , respectively. These numbers represent densities (P = .8085). Mean N2 O flux over the duration of
emissions within the treatment range of the experiment. the experiment was 6.99, 5.49, 6.36, and 5.63 g ha1 day1
Emissions at soil water content or earthworm density outside for the control, low, medium, and high earthworm densities,
of the treatment range can be determined using the equation respectively. There was also no significant dierence in mean
found in the caption for Figure 3. N2 O flux according to the week by density interaction (P =
0.7611, SE = 2.37 for the control, SE = 2.05 for low,
3.2. Earthworm Mortality and Biomass. Mortality rates were medium, and high earthworm density). However, at all
not significantly dierent between moisture treatments earthworm densities, N2 O flux peaked at week two and then
within the density treatments (Table 1). There was very declined below week one levels at week three.
little mortality in the low-density treatment across all soil
moisture treatments. Mean mortality rates in the medium 3.4. Earthworm Mortality and Biomass at 31% Soil Water
density treatment ranged from 3% to 11%, the highest Content. Earthworm survival was 100% in the low and
mortality rate occurring in the 15% moisture treatment and medium density treatments and 95% in the high density
the lowest in the 25% moisture treatment. Mean mortality treatment. Initial and final earthworm biomass was signif-
in the high-density treatment ranged from 5% to 18%, the icantly dierent across all earthworm densities. Earthworm
highest mortality rate occurring in the 35% soil moisture biomass in the low density treatment increased from 12.6 g
treatment and the lowest occurring in the 25% moisture at the start of the experiment to 27.1 g at the end (P =
treatment. .0007) as seen in Table 3. In the medium density treatment
The dierence in the initial and final earthworm biomass the initial earthworm biomass was 28.6 g and increased to
was significant according to soil water content across all 44.4 g by the end of the experiment (P = .0003). In the high
earthworm density treatments as seen in Table 2. The largest density treatment, earthworm biomass increased from 36.9 g
increase in biomass in the low density treatment also to 74.2 g by the completion of the experiment (P = .0001).
Applied and Environmental Soil Science 5
60
60
50
40
30
20 20
10
0
0
1 2 3 4 1 2 3
(week) (week)
(a) (b)
80 14
12
60 10
8
40
6
4
20
2
0 0
2
20 4
1 2 3 1 2 3 4
(week) (week)
Figure 2: N2 O flux over the entire course of the experiment according to the control, low, medium, and high earthworm density at (a) 15%
(P = .1398), (b) 25% (P = .3912), (c) 35% (P = .2451), and (d) 45% (P = .0685) gravimetric soil water content.
Table 3: Mean initial and final biomass in the low, medium, and
high earthworm densities at 31% gravimetric soil moisture content.
25
20 Initial 12.6 a 28.6 a 36.9 a
15 Final 27.1 b 44.4 b 74.2 b
1
N2 O flux (g ha
10
SE 1.94 1.94 1.94
5
0 P value .0007 .0003 .0001
5
Within columns, means followed by the same letter are not significantly
10 dierent according to Tukey-Kramer means adjustment (0.05).
Low, medium, and high refer to densities of earthworms per 0.033 m2 : 3, 6,
50
45 and 9, respectively.
40
35
So
35
30
il
30
m
25
oi
25 20
stu
ty
20 15 ensi
re
15 5 hwo
Eart
)
0
10 5 been the reason for the drastic decline in emissions in the
high density treatment at 35% soil water content and lower
mortality in the medium (9%) and low (0%). Another reason
25 5 for the decline in emissions after week two could be due
20 0 to the ability of high earthworm populations to speed up
15 5 residue decomposition [19]. Organic matter is more palat-
10 10
able to earthworms at higher soil water content; therefore,
Figure 3: A response surface regression showing the relationship ingestion of organic matter is enhanced. Organic matter
between N2 O flux (kg ha1 day1 ), gravimetric soil water content turnover could have been enhanced at the 35% moisture and
(%), and earthworm density (number of earthworms 0.033 m2 ). high density combination by week two resulting in a decrease
Equation of the line is 36.7186 (0.36143 D) + (3.1095 M) + in preingested organic matter and a decline in earthworm
(0.0174 D D)+(0.00810 M D) (0.0518 M M) (R2 = 0.17, activity.
P .0001), where D is earthworm density and M is gravimetric soil The gravimetric soil water content treatments of 15%,
water content. 25%, 35%, and 45% are approximately equivalent to a water-
filled pore space (WFPS) of 30%, 55%, 75%, and 100%. It
is generally accepted that denitrification rates are optimal
Table 2: Mean initial and final earthworm biomass in the low, between a WFPS between 60% and 100%, where N2 O is
medium and high earthworm densities according to g (%) the primary product between 60% and 90% [21]. Above
treatment. 90% N is the dominant product [21], which could be the
Density Treatment Biomass (g)
reason for lower N2 O flux measurements in the 45% soil
water content, where the WFPS was 100%. The highest N2 O
g (%) Low Medium High
flux occurred at 35% soil water content or 75% WFPS,
15 Initial 40.88 a 86.97 a 130.55 abc which is within the range of optimal denitirification rates.
15 Final 50.92 a 83.85 a 121.48 abc Furthermore, nitrification rates are highest between 45%
25 Initial 43.08 a 86.97 a 125.85 abc and 75% [21]. The product of nitrification is NO3 , a
25 Final 52.19 a 101.95 b 150.85 c primary input for denitrification. This means that in the
35 Initial 47.20 a 103.60 b 145.63 ac 35% soil water content treatment, both nitrification and
35 Final 89.94 b 123.30 c 144.50 ac denitrification were optimal, which may have contributed to
45 Initial 33.28 c 70.29 a 103.90 b the significantly higher N2 O flux compared to the 15% and
45 Final 55.59 a 75.60 a 117.10 ab 45% soil water content treatments.
N2 O emissions could be lower at dryer soil water contents
SE 2.69 4.02 5.54
as a result of earthworm diapause or aestivation. In this
P value <.0001 .0420 .0323
an increase in the ingestion of organic matter compared of an increase in the microbial biomass pool and subsequent
to dryer soils. Leaf litter is more palatable to earthworms increase in respiration causing lower O2 levels in the soil.
when wetted, and as a result ingestion is increased. This Groman et al. [28] found that in areas with the presence
could explain higher emissions in the 25% and 35% moisture of earthworms, microbial biomass was significantly higher
treatments compared to 15% soil water content, as well as in the mineral soil compared to areas without the presence
the decrease in earthworm biomass in the medium and high of earthworms. In turn, Fisk et al. [29] discovered that
densities at 15% soil water content. Earthworms would ingest this increase in microbial biomass due to the presence of
higher carbon substrates at these moisture contents, which earthworms increased respiration rates by 20% compared to
would in turn provide energy for denitrifying bacteria found areas without earthworms. Therefore, O2 levels will decline
in the earthworm gut and increase N2 O production. providing a more ideal environment for denitrification to
Earthworm surface casting also increases in wetter soils, occur and subsequent gaseous N losses. However, even
which provides another ideal environment for denitrifi- though microbial biomass may increase with earthworm
cation. Earthworm casts contain higher populations of presence, a subsequent increase in mineralization and nitri-
denitrifying bacteria compared to mineral soils due to higher fication rates may not occur. Bohlen et al. [30] and Groman
amounts of carbon substrates, and as a result, higher N2 O et al. [28] found that mineralization and nitrification rates in
emissions are produced [23]. Elliot et al. [24] found that the soil did not dier significantly in plots with and without
denitrification was higher in earthworm casts than surround- earthworms. They speculated that earthworms facilitated
ing mineral soil. Denitrification rates from earthworm casts a C-sink in the soil and subsequently created an N-sink,
ranged between 0.20.9 g N g1 during the fall compared preventing the increase in N mineralization and nitrification
to 0.050.3 g N g1 from the soil within the same time rates in the soil. This could mean that the majority of the
period. This indicates that a portion of the emissions from N2 O released from the mesocosms was attributed to the
this experiment could be due to increased surface casting in presence of earthworms and earthworm gut, rather than
the 25% and 35% moisture treatments at the high density denitrification occurring in the surrounding soil, since NO3
treatments. concentrations may have been low due to low nitrification
Trends in N2 O emissions according to earthworm density rates.
did occur. The high, medium, and low density treatments In Experiment 2, N2 O emissions were not significantly
represent 9.1 105 , 6.1 105 ,and 3.0 105 earthworms ha1 , dierent across earthworm population densities; however,
respectively. Emissions consistently increased as earthworm the results were consistent to what was found in Experiment
density increased in all moisture treatments. However, 1. N2 O flux in Experiment 2 across all earthworm densities
emissions were only significantly higher at the medium (0, 3, 6, and 9) was in the same range as emissions
and high densities in the 25% and 35% soil water con- in Experiment 1 between the control and low density
tent treatments (Figure 1). Frederickson and Howell [25] earthworm treatments (0 and 10). This was expected since
found no relationship between earthworm density and N2 O the earthworm densities used in Experiment 2 were within
emissions in large-scale vermicomposting beds. However, the range of the control and low density treatments in
in a subsequent laboratory experiment, emissions were Experiment 1, and there were no significant dierences in
correlated with earthworm density at five earthworm density emissions between the control and low density treatments
treatments (R2 = 0.76). in Experiment 1. No significant dierences in N2 O flux
The reason for this may be a result of an increase in occurred even with significant dierences in initial and final
the ingestion of organic matter and, with that, denitrifier biomass between density treatments. This shows that even
bacteria at higher earthworm densities; therefore, denitri- with an increase of approximately 3.0 105 earthworms
fication may occur at faster rates than in soils with lower ha1 from zero earthworms, there would be no significant
earthworm densities. Denitrification occurs at higher rates corresponding change in emissions between a TBI and sole
in the earthworm gut due to the anoxic environment and cropping system, like the systems found at GARS. This could
sucient supply of carbon for denitrifier bacteria compared be a result of other compounding factors such as soil water
to soil homogenates [6, 26, 27]. An increase in earthworm content, soil temperature, residual soil N and C, and land
density results in an increase in this ideal environment management practices, which could all mask the earthworm
of earthworms for denitrifier bacteria and therefore, could eect on denitrification.
increase emissions. The number of denitrifier bacteria is The same general trend of N2 O emissions occurred
also higher in the earthworm gut and surface castings over time as in the 35% soil water content treatment in
than outside soil homogenates [8]. These authors calculated Experiment 1, where emissions hit a peak at week 2 and
that there were 256-fold more denitrifier bacteria in the declined at week 3 to levels the same or lower than at week
earthworm gut of L. rubellus than in the surrounding soil 1. This cannot be explained by earthworm mortality since
where the earthworms were found. This indicates that an earthworm mortality was insignificant or did not occur in
increase in earthworm density also increases the number Experiment 2 compared to Experiment 1. However, since soil
of denitrifier bacteria in the gut of the earthworms facil- water content of 31% was found to be optimal for earthworm
itating higher N2 O emissions as could be the case in this activity, this may have sped up organic matter decomposition
study. [18] between weeks 1 and 2 leaving the less palatable lignin
Another reason why N2 O emissions were highest at the compounds, thereby slowing earthworm activity between
high density earthworm treatments could have been a result weeks 2 and 3.
8 Applied and Environmental Soil Science
Review Article
Can We Predict How Earthworm Effects on Plant Growth Vary
with Soil Properties?
Copyright 2010 Kam-Rigne Laossi et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Earthworms are usually assumed to enhance plant growth through dierent mechanisms which are now clearly identified. It
is however dicult to determine their relative importance, and to predict a priori the strength and direction of the eects of
a given earthworm species on a given plant. Soil properties are likely to be very influential in determining plant responses to
earthworm activities. They are likely to change the relative strength of the various mechanisms involved in plant-earthworm
interactions. In this paper, we review the dierent rationales used to explain changes in earthworm eect due to soil type. Then, we
systematically discuss the eect of main soil characteristics (soil texture, OM, and nutrient contents) on the dierent mechanisms
allowing earthworm to influence plant growth. Finally, we identify the main shortcomings in our knowledge and point out the new
experimental and meta-analytical approaches that need to be developed. An example of such a meta-analysis is given and means
to go further are suggested. The result highlights a strong positive eect size in sandy soil and a weakly negative eect in clayey soil.
plant growth. (2) If earthworms are able to alleviate limiting through several mechanisms, but here again the outcome
factor for plant growth, their impacts are expected to be weak is dicult to be predicted. First, plant growth regulators
in soils where the factor is not limiting. According to this are though to be released by bacteria [24] and may be
rationale, the main mechanism through which earthworms dierently available depending on the levels of microbial
aect plants should depend on soil type and in some soils activity in the soil. Sandy soils and soil with low organic
earthworms might have no detectable or negative eect on matter contents usually have lower microbial biomasses and
plant growth. low potential for plant growth regulator production [25].
Thus, in such soils, earthworm eects via production of plant
growth regulator could lead to weak eects on plant growth.
2. How Soil Properties Should Modulate Second, soil texture and soil organic matter could also aect
Earthworm Effects on Plant Growth? the short-term availability of the produced phytohormones.
For instance, clays and organic matter are known to adsorb
Below, we go through the dierent mechanisms listed above organic molecules [26] and could reduce plant growth
and try to determine how soil properties should modulate regulator availability to plants and weaken earthworm eect
their eect on plant growth. on plant growth.
(1) Earthworm activities usually have a positive impact (4) Earthworms are known to alleviate the negative eect
on the mineralization of soil organic matter [8]. This eect is of some parasites on plant growth by reducing strongly
assumed to be a consequence of plant litter fragmentation their density [27], ingesting and killing some pathogens in
and incorporation into the soil, as well as of the selective their intestine, or producing unfavourable conditions in cast
stimulation of microbial activity [9, 10]. Hence earthworms material or tunnel lining [28]. This kind of mechanism
may enhance the release of nutrients that become available to may be influential for plant growth, especially in soil
plants and thus increase plant growth when they allow higher properties (such as moisture and temperature) that allow
nutrient uptake than nutrient leaching [11, 12]. Anecic and the development of abundant parasite populations. We can
endogeic earthworms have dierent feeding habits and aect thus expect more parasites and greater negative eect of
dierently soil organic matter composition and distribution earthworms on them in a clayey soil.
[13]. Anecic earthworms feed on plant litter at the soil (5) Similarly, earthworms can increase plant growth
surface and tend to live in semipermanent vertical burrows through the stimulation of symbionts or the increase in
while endogeic earthworms are active within the soil profile the contact between plants and symbionts [29]. Besides, if
where they feed on soil organic matter [14]. This can lead symbionts such as mycorrhizae provide nutrients to plants,
to dierent eect on plant growth [1517] which could also symbiont-mediated earthworm eect (as their eect through
vary with soil properties such as organic matter and nutrient mineralization) on plants should be more marked in poor
contents [18]. However, this rationale only holds if nutrients soils than in rich soils where mineral resources are already
are limiting plant growth, that is, in soils where nutrients available.
are poorly available. In contrast, in nutrient-rich soils, plants
are less limited by the availability of mineral nutrients and Taken together, these elements show that earthworm
earthworm-mediated mineralization should have less or no eects on plants vary with soil type but that it is dicult
influence on plant growth [2]. Water is between the factors to predict the direction and the intensity of these variations.
that limit plant growth and earthworms have been found to To make relevant predictions, we need to develop studies
increase drought stress in plants [19]. This eect should be comparing in the same experiment earthworm eects on
stronger in sandy soil which retains less water than in a clayey plants under dierent soil conditions. It is also necessary to
one. set up meta-analyses using data of previous earthworms
(2) Earthworms aect plant growth through modifica- plants studies. We provide below an example of what could
tions of soil structure. They tend to increase soil porosity be done through computing the eect size of earthworms on
and the stability of organomineral aggregates by creating plant growth using meta-analysis with the data of the studies
burrows and organomineral casts at dierent places within listed in Table 1.
the soil profile [20, 21]. This eect is assumed to enhance
plant growth in most situations [2] although opposite eects 3. How Can We Go Further?
have also been reported [22]. It is dicult to predict how soil
texture will modulate these eects. In clayey soils, earthworm To determine how earthworms eects on plant growth
might lead to very stable structures which could in turn change with soil properties a first approach would be to
strongly influence plant growth. This influence could be compare earthworm-induced eects in dierent soils but in
positive if the casts produced by earthworms do not lead to the same experimental conditions (same plant and earth-
soil compaction [22], or negative with a physical protection worm species, same watering protocol, same greenhouse,
of organic matter that impedes the release of mineral etc.). Such experiments have been so far very scarce (but
nutrients. In sandy soils, structures created by earthworms see [57]). To help predicting earthworm eects on plant
are more fragile [23] but more mineral nutrients can be growth in dierent soil types one could also use the all-
released since the soil organic matter is less protected. minus-one tests proposed by Brown et al. [2]. In such
(3) Earthworm eects on plant growth via the release of experiments, only one factor such as mineral nutrition
plant growth regulators may be modulated by soil properties [4] or a root parasite [27] is limiting plant growth so
Applied and Environmental Soil Science 3
Table 1: References included in the survey of C and N contents in soil and the soil texture used in earthworm eects on plant growth.
Table 1: Continued.
References Soil classification Soil texture N total Clay Sand C Total
Stephens and Davoren
Calcic Natrixeralf Calcic soil ? ? ? ?
1997
Thompson et al. 1993 ? Loam soil ? ? ? ?
Dystric brunisols,
Welke and Parkinson 21.63%
grey-brown Sandy loam soil 0.1%1.07% ? ?
2003 43.73%
luvisols
Loamy sandy
Wurst et al. 2008 ? 0.13% ? ? 2.1%
mineral soil
Wurst et al. 2005 Cambisol Loam soil 0.087% ? ? 1.58%
Wurst et al. 2003 ? Loam soil 0.087% ? ? 1.58%
Zaller and Arnone 1999 Rendzina Calcareous soil ? ? ? ?
This result supports the assertion of Brown et al. [2] [4] M. Blouin, S. Barot, and P. Lavelle, Earthworms (Millso-
that positive eects of earthworms on plant growth are more nia anomala, Megascolecidae) do not increase rice growth
pronounced in sandy soils (generally nutrient-poor soils) through enhanced nitrogen mineralization, Soil Biology and
that in clayey soils (generally nutrient-rich soil). However, as Biochemistry, vol. 38, no. 8, pp. 20632068, 2006.
showed in Table 1 most studies used sandy soils while only [5] B. M. Doube, P. M. L. Williams, and P. J. Willmott, The influ-
ence of two species of earthworm (Aporrectodea trapezoides
few studies have used clayey ones. We thus need to release this
and Aporrectoedea rosea) on the growth of wheat, barley and
bias by developing more studies for clayey soil. Nevertheless,
faba beans in three soil types in the greenhouse, Soil Biology
our meta-analysis is the first formal test of the influence of and Biochemistry, vol. 29, no. 3-4, pp. 503509, 1997.
soil properties on earthworm eect on plant growth. [6] S. Wurst and T. H. Jones, Indirect eects of earthworms
(Aporrectodea caliginosa) on an above-ground tritrophic inter-
action, Pedobiologia, vol. 47, no. 1, pp. 9197, 2003.
5. Conclusion [7] K.-R. Laossi, A. Ginot, D. C. Noguera, M. Blouin, and S.
Although the majority of authors provided detailed data on Barot, Earthworm eects on plant growth do not necessarily
decrease with soil fertility, Plant and Soil, vol. 328, no. 1-2, pp.
soil characteristics, this basic information was not available
109118, 2010.
in all studies in earthworm impacts on plant production
[8] P. J. Bohlen, D. M. Pelletier, P. M. Groman, T. J. Fahey, and M.
(Table 1). Further studies should pay attention to providing C. Fisk, Influence of earthworm invasion on redistribution
a standardized description of soil characteristics, which and retention of soil carbon and nitrogen in northern
would thus be available for meta-analyses on earthworms temperate forests, Ecosystems, vol. 7, no. 1, pp. 1327, 2004.
plants studies. For example, data on soil texture (sand [9] P. J. Bohlen, C. A. Edwards, Q. Zhang, R. W. Parmelee,
and clay percentage), total C, total N content, NH4 + , and and M. Allen, Indirect eects of earthworms on microbial
NO3 should be systematically published. Because such assimilation of labile carbon, Applied Soil Ecology, vol. 20, no.
information, is not always given (see Table 1), we have only 3, pp. 255261, 2002.
compared the eect of wide texture classes on earthworm [10] A. Martin, A. Mariotti, J. Balesdent, and P. Lavelle, Soil
eect. Finally, we have shown that these texture classes organic matter assimilation by a geophagous tropical earth-
only explain 11% of the variations in eect sizes. This is worm based on 13 C measurements, Ecology, vol. 73, no. 1,
pp. 118128, 1992.
probably due to a variety of other factors that we have
[11] J. Domnguez, P. J. Bohlen, and R. W. Parmelee, Earthworms
not taken into account: soil properties mentioned above increase nitrogen leaching to greater soil depths in row crop
but also earthworm species (or its functional group) and agroecosystems, Ecosystems, vol. 7, no. 6, pp. 672685, 2004.
plant species (or its functional group), and so forth [2, [12] P. Jouquet, F. Bernard-Reversat, N. Bottinelli, et al., Influence
3]. Gathering more studies on earthworm eects on plant of changes in land use and earthworm activities on carbon
growth and documenting for each of these studies all these and nitrogen dynamics in a steepland ecosystem in Northern
factors would allow disentangling, through a unique meta- Vietnam, Biology and Fertility of Soils, vol. 44, no. 1, pp. 69
analysis statistical model, the respective eect of all these 77, 2007.
factors on earthworm-induced eect on plant growth, as well [13] M. B. Bouche, Strategies lombriciennes, in Soil Organisms
as interactions between these factors. This kind of general as Components of Ecosystems, U. Lohm and T. Persson, Eds.,
and systematic approach is required to derive general results Ecological Bulletins 25, pp. 122132, Stockholm, Sweden,
on soil ecology and to develop the theoretical background 1977.
[14] P. Lavelle, I. Barois, E. Blanchart, et al., Earthworms as a
needed to base soil ecology on solid bases [33].
resource in tropical agroesosystems, Nature and Resources,
Taken together, while a given earthworm species could vol. 34, pp. 2640, 1998.
have positive eects in a soil, it could have negative eects [15] K.-R. Laossi, D.-C. Noguera, and S. Barot, Earthworm-
in another soil. To restore soil fertility or to enhance the mediated maternal eects on seed germination and seedling
sustainability of crop production [14], the right earthworm growth in three annual plants, Soil Biology and Biochemistry,
species has indeed to be chosen according to soil properties vol. 42, no. 2, pp. 319323, 2010.
and crop type. Developing applications based on the use of [16] K.-R. Laossi, Eet des vers de terre sur les plantes : du
earthworms would thus also require implementing the gen- fonctionnement individuel a la structure des communautes
eral meta-analysis (as suggested above) and the subsequent vegetales, Ph.D. thesis, Universite Pierre et Marie Curie, Paris,
development of a general and comprehensive framework on France, 2009.
earthworm-induced eect on plant growth that is so far [17] K.-R. Laossi, D. C. Noguera, J. Mathieu, M. Blouin, and S.
Barot, Eects of an endogeic and an anecic earthworm on
missing.
the competition between four annual plants and their relative
fecundity, Soil Biology and Biochemistry, vol. 41, no. 8, pp.
References 16681673, 2009.
[18] P. Jouquet, J. Dauber, J. Lagerlof, P. Lavelle, and M. Lepage,
[1] C. A. Edwards, Ed., Earthworm Ecology, CRC Press, Boca Soil invertebrates as ecosystem engineers: intended and
Raton, Fla, USA, 2004. accidental eects on soil and feedback loops, Applied Soil
[2] G. G. Brown, C. A. Edwards, and L. Brussaard, How earth- Ecology, vol. 32, no. 2, pp. 153164, 2006.
worms eect plant growth: burrowing into the mechanisms, [19] M. Blouin, P. Lavelle, and D. Laray, Drought stress in
in Earthworm Ecology, C. A. Edwards, Ed., pp. 1349, 2004. rice (Oryza sativa L.) is enhanced in the presence of the
[3] S. Scheu, Eects of earthworms on plant growth: patterns and compacting earthworm Millsonia anomala, Environmental
perspectives, Pedobiologia, vol. 47, no. 5-6, pp. 846856, 2003. and Experimental Botany, vol. 60, no. 3, pp. 352359, 2007.
6 Applied and Environmental Soil Science
Research Article
Earthworms and Plant Residues Modify Nematodes in Tropical
Cropping Soils (Madagascar): A Mesocosm Experiment
Cecile Villenave,1 Bodo Rabary,2 Emilie Kichenin,1 Djibril Djigal,3 and Eric Blanchart1
1 Institut de Recherche pour le Developpement (IRD), UMR 210 Eco&Sols (INRA, IRD, SupAgro), 2 place Viala,
34060 Montpellier cedex 1, France
2 Centre National de Recherche Appliquee au Developpement Rural (FOFIFA), URP SCRID, BP 230, Antsirabe 110, Madagascar
3 Institut de Recherche pour le Developpement (IRD), UMR 210 Eco&Sols (INRA, IRD, SupAgro), LEMSAT (IRD, ISRA),
Copyright 2010 Cecile Villenave et al. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Free-living nematodes present several characteristics that have led to their use as bioindicators of soil quality. Analyzing the
structure of nematofauna is a pertinent way to understand soil biological processes. Earthworms play an important role in soil
biological functioning and organic matter dynamics. Their eects on soil nematofauna have seldom been studied. We studied
the eect of the tropical endogeic earthworm, Pontoscolex corethrurus, on nematode community structure in a 5-month field
mesocosm experiment conducted in Madagascar. Ten dierent treatments with or without earthworms and with or without
organic residues (rice, soybean) were compared. Organic residues were applied on the soil surface or mixed with the soil. The
abundance of nematodes (bacterial and fungal feeders) was higher in presence of P. corethrurus than in their absence. The type of
plant residues as well as their localisation had significant eects on the abundance and composition of soil nematodes. The analysis
of nematode community structure showed that earthworm activity led to an overall activation of the microbial compartment
without specific stimulation of the bacterial or fungal compartment.
1. Introduction dierent levels of the soil food web and present variable
tolerance toward stress, nematofauna provide information
Soil organisms play a leading role in decomposition and about OM decomposition pathways and soil pollution status
mineralization of organic matter (OM) [1]. They are [3, 57]. Nematodes interact with other soil organisms
involved in processes that aect carbon (C) sequestration including earthworms, which also play an important role
as well as in the modification of soil physical structure in soil biological functioning and OM dynamics [8, 9].
and chemical properties. They also interact with other soil Until now, studies on interactions between nematodes and
fauna and these interactions result in complex food webs earthworms have focused on the contribution of earthworm
[2]. Nematodes are small organisms (ca. 1 mm long at the burrowing and casting activity to nematofauna abundance,
adult stage) abundant in soil (several million m2 soil), composition, and activity [1014]. These studies were mainly
they present a high species diversity (about 11,000 species conducted in temperate regions or under specific conditions
have already been described). Nematodes live in the film such as vermicomposting. Results show that interactions
of water between soil particles and present various feeding between nematodes and earthworms are site and species
behaviours. During the last twenty years, many studies have specific.
been conducted on these microfaunal organisms because In Madagascar, like in other tropical countries, alter-
they can be an ecient tool to assess soil quality and soil native cropping systems are being developed in order to
biological functioning [24]. Because they are present at decrease soil erosion and environmental impacts and to
2 Applied and Environmental Soil Science
increase crop productivity or sustainability. No-tillage sys- 2.2. Experimental Design. Ten dierent treatments were
tems with living or dead (mulch) cover plants have beneficial tested: five treatments inoculated with earthworms and five
eects both on environment and crop biomass [15]. In without earthworms. Among the five treatments (with or
Madagascar, it has been shown that these cropping systems without earthworms), two received soybean residues, two
increase the carbon sequestration in soil and decrease soil others rice residues, and one did not receive any residue.
erosion [15]. Moreover, they increase the density, activity, When residues were applied, they were placed either on
and diversity of soil fauna and especially earthworms and soil the soil surface or buried. Each treatment was replicated
microorganisms [16]. five times, which led to a total of fifty mesocosms in the
This study was part of a larger project aimed at field experiment. In each bucket with earthworms (E+),
determining the consequences of earthworm activity for six adult or subadult earthworms of the species Pontoscolex
soil aggregation, OM dynamics, and soil biological activity corethrurus Muller 1856 (Glossoscoloscidae), sampled near
in no-tillage systems in Madagascar [16]. In the present the study site, were inoculated in January 2005. This endogeic
experiment, we focused on the interaction between the trop- geophagous earthworm is a tropical peregrine earthworm
ical endogeic peregrine earthworm P. corethrurus, and soil [22] abundant in the study area, feeding and living in the
nematofauna. This earthworm was chosen to be inoculated soil. Soybean (Glycine max L.) and rice (Oryza sativa L.)
in the experiment because it was dominant in the study area, residues were added at the same amounts as those measured
feeding and living within the soil although. It is an invasive in cropped fields in local no-tillage systems, that is, 293 g m2
earthworm, originated from South America. (18.3 g per bucket) for soybean residues and 365 g m2
The abundance and diversity of soil organisms, including (14.6 g per bucket) for rice residues. Soybean residues were
nematodes, depend on cropping practices [17]. Indeed, mostly composed of woody twigs with a C/N ranging
OM amendments like manure generally have a positive between 16 and 23 while rice residues were mainly composed
eect on microbial biomass and consequently on nematode of straw with a C/N ranging between 45 and 64 [23, 24].
density [18, 19]. The quality of the organic resource applied Residues were cut into 2-3 cm long pieces. Mesocosms were
(particularly the carbon to nitrogen ratio (C/N), lignin, randomly located in the experimental plot. Buckets were
phenolic compounds, and cellulose content) influences the watered during the experiment by natural rainfalls.
trophic structure of the nematofauna [3]. OM incorporation
by tillage can also lead to modifications in the nematode
2.3. Analysis. After 5 months in the field, mesocosms were
density [20, 21].
removed, and their content was separated into a 010 and
In this study, we tested the interaction between earth-
a 1020 cm soil layer. The soil was roughly disaggregated to
worms and nematofauna under applications of dierent
check that earthworms were still alive. The earthworms were
organic matter (rice residues or soybean residues) brought
all alive, and since they were mostly present in the 1020 cm
as mulch or buried in the soil.
layer, all analyses were performed in this layer.
Nematodes were extracted from an average of 93 g of
humidified, and homogenized soil (min. 90 g, max. 95 g)
2. Materials and Methods using the Cobb method. It consists of mixing the soil with
a large volume of water allowing a brief time for heavy
2.1. Study Site. The study was conducted in Madagascar
particles to settle, and then pouring the mixture through
in the region of Antsirabe (19 52 S; 47 04 E) at an altitude
several sieves of a mesh size from 500 m to 50 m to
of 1500 m above sea level. Mean annual temperature is
retain large debris or nematodes; the second step is used to
16 C and mean annual rainfall 1300 mm. The climate is
further clean up the sample (48 hours on a 40 m sieve)
subtropical humid with hot and humid summers (Oct-Apr)
[25]. Nematodes were counted under a binocular microscope
and cold and dry winters (May-Sep). The soil at the sampling
and fixed at 65 C with 4% formalin and subsequently
site is highly desaturated red ferrallitic (andic dystrustept),
mounted for mass-slide identification (5 cm 7.5 cm slides).
with 62% clay mainly as 1 : 1 minerals, but presents andic
An average of 175 nematodes was identified on each slide.
characteristics. In the upper 10 cm of soil, carbon content
Nematodes were identified to family or genus level and
was 45.6 g kg1 dry soil, bulk density was 0.76 g cm3 , pHH2 O
assigned to seven trophic groups according to Yeates et al.
was 5.7, the C/N ratio was 14.8, and exchangeable cation
[26]: bacterial-feeders, fungal-feeders, entomopathogenics,
capacity was 17.3 cmol kg1 dry soil [15].
plant-feeders, root hair-feeders, omnivores, and predators.
The experiment was conducted in field mesocosms on
Microbivorous nematode taxa were also allocated to c-p
a 100 m2 plot and lasted 5 months (from January 2005 to
groups following T. Bongers and H. Bongers [5]. Colonizers
June 2005, during the wet season) (see [16] for more details).
(c) and persisters (p) are the two extremes on a scale from 1
Fifty plastic buckets (20 cm deep) with a diameter of 25 cm
to 5, respectively. The c-p value takes into account nematode
were filled with 8 kg of soil previously sieved at 2 mm and
ecological characteristics, that is, their demography and their
homogenised, and were then introduced into the soil so
life-history strategies [5].
that surface level was similar inside and outside the buckets.
Before the buckets were filled with soil, their bottoms were
drilled (8 holes 1 cm diameter) and covered with a mosquito 2.4. Statistical Analysis. Dierences in taxa and trophic
net so that water could flow but earthworms could not group densities were assessed by ANOVA (Xlstat 2006
escape. Addinsoft) after log(n + 1) transformation of the data.
Applied and Environmental Soil Science 3
A two-way ANOVA was first performed on the 50 samples dierences for the fungal-feeders, which were more abun-
to test the eects of the addition of earthworms and dant in the treatments with residues, whatever the residue
residues. The 10 samples that did not receive any residues quality, than in the treatments without residues. Among the
were excluded before performing a three-way ANOVA to bacterial-feeders, one group (Panagrolaimidae) was more
test not only the eects of the addition of earthworms abundant in presence of soybean residues than in absence
and the quality of the residue applied, but also the eect of residues, whereas several groups (Rhabditidae, Alaimus
of the location of the residues. A nonparametric multi- and Amphidelus) were more abundant when rice residues
dimensional scaling analysis (MDS) was performed using were added. The abundances of Acrobeles and Cervidellus
Primer software (PRIMER-E ltd) to compare the structure of were reduced due to rice and soybean residues, respectively.
the nematofauna between treatments. Statistical significant Among the fungal-feeders, Aphelenchus density was signif-
dierences in community composition between treatments icantly higher with soybean residues, whereas Ditylenchus
were assessed by analysis of similarities: ANOSIM (which density was higher with rice and soybean residues.
uses permutation/randomisation methods on the similarity Nematode density was significantly higher in the meso-
matrix). cosms with buried residues than with mulched ones
(Table 1). Moreover, bacterial-feeders density was signifi-
cantly higher in the buried residue treatments with sig-
3. Results nificant increases in Rhabditidae, Acrobeloides, Plectidae,
In our experiment, 31 nematode taxa were identified. Rhabdolaimus, and Amphidelus without any interactions,
Bacterial-feeders represented 74.9% of total nematofauna whereas density of Panagrolaimidae, Prismatolaimidae, and
including 12 taxa (Table 1). Fungal-feeders (5 taxa) rep- Rhabdolaimus was increased with an interaction between
resented 13.7% of nematode abundance. An entomopath- earthworms and localization and Cervidellus, Prismatolaimi-
ogenic nematode (Steinernema) was present in some samples dae, and Alaimidae with an interaction between residues and
and represented 0.3% of the total density. Plant-feeders localization.
represented 6.1% of total density; 9 genera were identi- A fungal-feeder group, Tylencholaimoidea, was signifi-
fed (Pratylenchus, Paratylenchus, Aorolaimus, Rotylenchus, cantly more abundant in the treatments with buried residues
Helicotylenchus, Tylenchorhynchus, Meloidogyne, Paratri- than with mulched ones with no interaction with the others
chodorus, Xiphinema). Root hair-feeders (only members treatments (earthworms and residue), whereas Ditylenchus
of the Tylenchidae family) represented 3.9% of the total showed a significant eect of localisation of residues but
nematode abundance, whereas omnivores and predators also an interaction between residue and localization. Ento-
(mainly diverse Dorylaimoidea, Aporcellaimellus, Disco- mopathogenics and root hair-feeders were also significantly
laimus) together represented 1.2%. The ANOVA results on more abundant in the treatments with buried residues (with
abundance of the dierent taxa are summarized in Table 1. no interaction).
There was only one statistically significant interaction in the
2-way ANOVA between earthworm and addition of residues; 3.3. Eect of Addition of Earthworms and Residue on the
there were more interactions in the 3-way ANOVA between Structure of the Nematofauna. There was no significant
the three factors (earthworm, addition of residues, location dierence in the structure of the nematofauna (abundance of
of residues) (Table 1). the 31 taxa) between treatments with earthworms and treat-
ments without earthworms (similarity analysis: ANOSIM,
3.1. Eect of Earthworms on the Density of the Dierent Nema- P < .15). In contrast, there was a significant dierence in
tode Taxa. Total nematode density was significantly higher in nematofauna structure between treatments with rice residues
the treatments with P. corethrurus than in the non-inoculated and treatments with soybean residues (ANOSIM, P < .05)
treatments (Table 1). The density of fungal-feeders was (Figure 1). The outlier is a replicate of the treatment with
significantly higher in the presence of earthworms. Three earthworm, with rice residue addition, mulched residue
nematode taxa were significantly more abundant in inoc- where an unexplained proliferation of Aphelenchoididae
ulated treatments: two bacterial-feeders, Acrobeloides and occurred.
Prismatolaimidae, and one fungal-feeder, Aphelenchus. For There was no significant dierence in the structure of the
the fungal-feeders, all taxa showed an increasing trend in nematofauna between treatments without residues and the
the presence of earthworms (statistically significant only for two treatments with residues (soybean or rice) (ANOSIM,
Aphelenchus whereas, for bacterial feeders none of the taxa P > .05). Moreover, mixing the residues with soil led to a
other than Acrobeloides and Prismatolaimidae showed any significantly dierent structure of the community than that
sign of response). None of the taxa were significantly reduced measured in treatments without residues or with residues
in numbers due to the presence of the earthworms. placed on the soil surface (ANOSIM, P < .05).
Earthworm Residues
No With rice With
c-p Earthworm No earthworm Interaction Buried Mulched Interaction anova3
residue residue soybean
anova2 residue residue
addition addition residue
ER E R EL RL ER L
Nematodes trophic groups
Bacterial-feeders
Monhysteridae 1 20 25 4 33 21 28 26
Panagrolaimidae 1 2054 2587 1203 b 2123 ab 3075 a 4127 1071
Rhabditidae 1 944 652 60 b 1451 a 514 b 1370 595
Acrobeles 2 147 291 383 a 104 b 252 c 230 126
Acrobeloides a 2 7001 2840 4162 3054 7166 6513 3707
Cervidellus 2 196 229 236 a 267 a 147 b 330 84
Drilocephalobus 2 592 613 598 ab 388 b 818 a 608 598
Plectidae 2 24 34 14 50 17 52 15
Prismatolaimidae 3 628 427 491 475 599 672 402
Rhabdolaimus 3 345 322 292 346 343 484 205
Alaimus 4 447 481 173 b 549 a 525 ab 697 377
Amphidelus 4 41 30 12 b 71 a 12 b 52 31
Total 12 439 8531 7628 8911 13 489 15 163 7237
[-.7pt] Fungal-feeders
Aphelenchoididae 2 1108z 297 135 1317z 372 567 1121z
Aphelenchus 2 1133 793 750 b 798 b 1235 a 991 1042
Ditylenehus 2 286 139 16 b 141 a 382 a 473 50
Diphterophoridae 3 44 27 33 41 31 29 43
Tylencholaimoidea 4 46 34 13 29 64 80 13
Total 2617 1289 946 b 2326 a 2084 a 2140 2270
Entomopathogenic 235 175 338 235 110 268 77
Plant-feeders 1000 722 983 912 749 602 1059
Root hair-feeders 547 553 564 617 476 845 247
Omnivores and predators 155 189 140 200 160 203 158
Applied and Environmental Soil Science
this experiment, there were more twigs in the soybean following earthworm inoculation in field experimental situ-
treatment than in the rice treatment, thus explaining the ations, in Earthworm Management in Tropical Agroecosystems,
development of fungi which are able to digest complex P. Lavelle, L. Brussaard, and P. Hendrix, Eds., pp. 173197,
compounds like lignin [31, 37, 38]. When correcting the Cabi, New York, NY, USA, 1999.
value of Aphelenchoididae in the treatment mulch residue, [10] M. Aira, F. Monroy, and J. Domnguez, Eects of two
omitting the outlier replicate, we found that fungal-feeding species of earthworms (Allolobophora spp.) on soil systems:
a microfaunal and biochemical analysis, Pedobiologia, vol. 47,
nematodes (Ditylenchus and Tylencholaimoidea) were sig-
no. 5-6, pp. 877881, 2003.
nificantly more abundant with buried residues than with
[11] M. Aira, F. Monroy, J. Domnguez, and S. Mato, How
mulched residues. earthworm density aects microbial biomas and activity in pig
manure, European Journal of Soil Biology, vol. 38, no. 1, pp. 7
5. Conclusion 10, 2002.
[12] R. Hyvonen, S. Andersson, M. Clarholm, and T. Persson,
Our results showed that the earthworm P. corethrurus Eects of lumbricids and enchytraeids on nematodes in
had a positive eect on total nematode densities mainly limed and unlimed coniferous mor humus, Biology and
Fertility of Soils, vol. 17, no. 3, pp. 201205, 1994.
by increasing the density of dominant bacterial-feeding
[13] K. Ilieva-Makulec and G. Makulec, Eect of the earthworm
(Acrobeloides) and fungal-feeding (Aphelenchus) nematodes.
Lumbricus rubellus on the nematode community in a peat
The structure of the nematode community indicated that the meadow soil, European Journal of Soil Biology, vol. 38, no. 1,
decomposition of soybean residues was more fungal-based pp. 5962, 2002.
than that of the rice residues. Changes in the composition of [14] A. V. Tiunov, M. Bonkowski, M. Bonkowski, J. A. Tiunov, and
the nematode fauna were greater when organic matter was S. Scheu, Microflora, protozoa and nematoda in Lumbricus
buried in the soil than when it was left on the surface. Buried terrestris burrow walls: a laboratory experiment, Pedobiolo-
residues were responsible for the development of bacterial- gia, vol. 45, no. 1, pp. 4660, 2001.
feeder nematode populations, reflecting a stimulation of the [15] T. M. Razafimbelo, Stockage et protection du carbone
bacterial compartment. dans un sol ferrallitique sous systemes en semis direct avec
couverture vegetale des hautes terres malgaches, Montpellier,
2005.
Acknowledgment [16] S. Coq, B. G. Barthes, R. Oliver, B. Rabary, and E. Blanchart,
Earthworm activity aects soil aggregation and organic
This study was conducted in the project Nemageco-Icones matter dynamics according to the quality and localization
0575C0042 funded by the French Environment and Energy of crop residuesan experimental study (Madagascar), Soil
Development Agency (ADEME). Biology and Biochemistry, vol. 39, no. 8, pp. 21192128, 2007.
[17] G. D. Bending, M. K. Turner, and J. E. Jones, Interactions
between crop residue and soil organic matter quality and
References the functional diversity of soil microbial communities, Soil
Biology and Biochemistry, vol. 34, no. 8, pp. 10731082, 2002.
[1] P. Lavelle and A. Spain, Soil Ecology, Kluwer Academic
[18] C. Villenave, T. Bongers, K. Ekschmitt, P. Fernandes, and R.
Publishers, Dordrecht, The Netherlands, 2001.
Oliver, Changes in nematode communities after manuring in
[2] H. Ferris, T. Bongers, and R. G. M. de Goede, A framework for
millet fields in Senegal, Nematology, vol. 5, no. 3, pp. 351358,
soil food web diagnostics: extension of the nematode faunal
2003.
analysis concept, Applied Soil Ecology, vol. 18, no. 1, pp. 13
29, 2001. [19] C. Villenave, K. Ekschmitt, S. Nazaret, and T. Bongers,
[3] T. Bongers and H. Ferris, Nematode community structure Interactions between nematodes and microbial communities
as a bioindicator in environmental monitoring, Trends in in a tropical soil following manipulation of the soil food web,
Ecology and Evolution, vol. 14, no. 6, pp. 224228, 1999. Soil Biology & Biochemistry, vol. 36, no. 12, pp. 20332043,
[4] K. Ritz and D. L. Trudgill, Utility of nematode community 2004.
analysis as an integrated measure of the functional state of [20] D. W. Freckman, Bacterivorous nematodes and organic-
soils: perspectives and challenges: discussion paper, Plant and matter decomposition, Agriculture, Ecosystems and Environ-
Soil, vol. 212, no. 1, pp. 111, 1999. ment, vol. 24, no. 13, pp. 195217, 1988.
[5] T. Bongers and M. Bongers, Functional diversity of nema- [21] R. Lenz and G. Eisenbeis, The vertical distribution of
todes, Applied Soil Ecology, vol. 10, no. 3, pp. 239251, 1998. decomposition activity and of litter-colonizing nematodes in
[6] D. W. Freckman and E. P. Caswell, The ecology of nematodes soils under dierent tillage, Pedobiologia, vol. 42, no. 3, pp.
in agroecosystems, Annual Review of Phytopathology, vol. 23, 193204, 1998.
pp. 275296, 1985. [22] C. Fragoso, G. G. Brown, J. C. Patron, et al., Agricultural
[7] G. W. Yeates and T. Bongers, Nematode diversity in agroe- intensification, soil biodiversity and agroecosystem function
cosystems, Agriculture, Ecosystems and Environment, vol. 74, in the tropics: the role of earthworms, Applied Soil Ecology,
no. 13, pp. 113135, 1999. vol. 6, no. 1, pp. 1735, 1997.
[8] T. Desjardins, F. Charpentier, B. Pashanasi, A. Pando-Bahuon, [23] S. Abiven, S. Recous, V. Reyes, and R. Oliver, Mineralisation
P. Lavelle, and A. Mariotti, Eects of earthworm inoculation of C and N from root, stem and leaf residues in soil and role
on soil organic matter dynamics of a cultivated ultisol, of their biochemical quality, Biology and Fertility of Soils, vol.
Pedobiologia, vol. 47, no. 5-6, pp. 835841, 2003. 42, no. 2, pp. 119128, 2005.
[9] C. Villenave, F. Charpentier, P. Lavelle, et al., Eects of [24] J. T. Gilmour, A. Mauromoustakos, P. M. Gale, and R. J.
earthworms on soil organic matter and nutrient dynamics Norman, Kinetics of crop residue decomposition: variability
Applied and Environmental Soil Science 7
Review Article
Effects of Pesticides on the Growth and Reproduction of
Earthworm: A Review
Copyright 2010 S. Yasmin and D. DSouza. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Scientific literature addressing the influence of pesticides on the growth and reproduction of earthworm is reviewed. Earthworms
are considered as important bioindicators of chemical toxicity in the soil ecosystem. Studies on this aspect are important because
earthworms are the common prey of many terrestrial vertebrate species such as birds and small mammals, and thus they play a key
role in the biomagnification process of several soil pollutants. Majority of the studies have used mortality as an endpoint rather
than subtler endpoints such as reproductive output. It is now emphasized that, whereas higher concentrations of a pollutant can
easily be assessed with the acute (mortality) test, contaminated soils with lower (sublethal) pollutant concentrations require more
sensitive test methods such as reproduction test in their risk assessment.
may be produced. According to Riepert et al. [25] the earthworm weight in the laboratory when applied at 10
acute earthworm test is part of the basic test set, but the normal rate. Weight loss appears to be a valuable indicator
earthworm reproduction test is considered ecologically more of physiological stress, related to the degree of intoxication
relevant. Therefore, growth and reproduction have been and time of exposure [22, 38]. Coiling, another symptom
recommended as useful sub lethal criteria [26, 27]. This seen in 100% of the Parathion treated worms, is related
article reviews in short the available scientific literature on with weight loss and is regarded as the consequence of
the eects of pesticides on the key biological processes, that alteration in muscular function elicited by organophosphoric
is growth and reproduction of earthworms. pesticides which may explain the diculties for locomotion
of the intoxicated worms and their relative inability to feed
themselves [3].
2. Sublethal Toxicity Testing Method Negative impact of pesticides on earthworm growth
has been reported by various researchers. Xiao et al. [39]
The earthworm reproduction test with Eisenia fetida/Eisenia
suggested that growth can be regarded as sensitive param-
andrei aims to assess the impact of soil contaminants
eters to evaluate the toxicity of acetochlor on earthworms.
on sublethal parameters in earthworms. Endpoints include
Helling et al. [36] tested in laboratory the eect of copper
reproductive parameters (cocoon production per adult per
oxychloride, while Yasmin and DSouza [40] investigated
week, juveniles hatching per adult per week and cocoon
the impact of carbendazim, glyphosate and dimethoate on
viability) and weight change of adults. During the test, adult
Eisenia fetida and found a significant reduction in the
mature worms are exposed to dierent concentrations of
earthworm growth in a dose-dependent manner. According
a substance (pollutant) in a standard test soil; when field
to Van Gestel et al. [27] parathion aects the growth of
soils are used, homogenised and air-dried soil samples are
Eisenia andrei. Booth et al. [41] studied the eect of two
sieved and added to the test chamber and brought to a
organophosphates, chlorpyrifos and diazinon, while Mosleh
given moisture content. Ten acclimatized individuals are
et al. [42] investigated the toxicity of aldicarb, cypermethrin,
added to each vessel containing 500 g dry weight of the
profenofos, chlorfluazuron, atrazine, and metalaxyl in the
selected soil. Growth eects and mortality are determined
earthworm Aporrectodea caliginosa and observed a reduction
after four weeks and eects on reproduction are assessed
in growth rate in all pesticide-treated worms. Mosleh et
after eight weeks of exposure. The assay has been used
al. [43, 44] studied the eects of endosulfan and aldicarb
to measure the eects of a wide range of chemicals such
on Lumbricus terrestris and have suggested growth rate as
as metals [28] and pesticides [29]. In addition use of a
important biomarkers for contamination by endosulfan and
suitable control soil is essential. This test is standardized
aldicarb. Zhou et al. [45] assessed and found chlorpyrifos had
at the international level, being recognized and promoted
adverse eect on growth in earthworm exposed to 5 mg/kg
by international organizations (OECDOrganization of
chlorpyrifos after eight weeks. Some studies have shown that
Economical Cooperation and Development, and ISO
growth of earthworms appeared to be more severely aected
International Organization of Standardization), aiming to
at juvenile stage than at adult stage [46, 47].
elaborate international guidelines on environment quality
assessment.
4. Effects on Reproduction
3. Effects on Growth
Numerous reproductive parameters have been studied in
A number of studies have been conducted on the stan- earthworms exposed to various xenobiotics: cocoon and
dard worm Eisenia fetida/andrei. Some of the responses hatchling production, viability of the worms produced [18,
of earthworms to sublethal concentrations of pesticides is 20, 4854], and sexual maturation [50]. Cocoon production
shown in Table 1. Zhou et al. [30] have reported that was found to be the most sensitive parameter for paraquat,
the weight of the earthworms was a more sensitive index fentin, benomyl, phenmedipham, carbaryl, copper oxychlo-
compared to the mortality in indicating toxic eects of ace- ride, dieldrin [36, 5557], while cocoon hatchability was
tochlor and methamidophos. Espinoza-Navarro and Bustos- most sensitive for pentachlorophenol, parathion and carben-
Obregon [31] treated Eisenia fetida with organophosphate dazim, copper oxychloride [36, 55, 56]. Bustos-Obregon and
insecticide malathion and Bustos-Obregon and Goicochea Goicochea [3] explored the eect of exposure to commercial
[3] explored the eect of exposure to commercial parathion parathion on the reproductive parameters such as sperm and
on Eisenia fetida; both observed decrease in the body weight cocoon production and genotoxicity on male germ cells of
of treated worms . Weight loss has also been reported for Eisenia fetida and reported that alterations in reproductive
organochlorine pesticides intoxication [18, 32, 33] and for parameters were conspicuous in regard to the number of
the eects of fungicides and herbicides in Eisenia fetida and sperm, cocoons, and worms born. Numbers of juveniles per
Lumbricus terrestris [3436]. Choo and Baker [37] found cocoon can be regarded as sensitive parameters to evaluate
endosulfan did significantly reduce the weight of juvenile the toxicity of acetochlor on earthworms as reported by
Aporrectodea trapezoides within 5 weeks when applied to soil Xiao et al. [39]. Choo and Baker [37] also found that
at normal application rate in both the field and laboratory cocoon production in Aporrectodea trapezoides was inhibited
while fenamiphos did so at normal application rate in by endosulfan and fenamiphos at normal application rates
the field only. Both fenamiphos and methiocarb reduced and methiocarb at 10 normal rate.
Table 1: Laboratory experiments on responses of earthworm to sublethal concentrations of pesticides.
Pesticide Concentration of pesticide/exposure Test conditions Species Responses Reference
Substrate = Dried, ground,
finely sieved cattle manure
8.92, 15.92, 39.47, 108.72, 346.85 mg
Copper oxychloride pH = 7.1 0.26.1 0.3 Eisenia fetida (Freshly Earthworm growth and cocoon
Cu/ kg substrate [36]
(pure) Moisture = hatched earthworms) production were significantly reduced
56 days
77.6 0.778.8 1.1
Temp = 25 C
Soil like substrate
80.150, 300, 600 mg/kg soil pH = 6.5, Significant reduction in body weight
Malathion (pure) Eisenia fetida (Adults) [31]
1, 5, 15, 30 days decreased spermatic viability
Applied and Environmental Soil Science
Temp = 21-22 C,
Moisture = 50%,
OECD artificial soil At higher concentrations of acetochlor
5, 10, 20, 40 and 80 mg/kg soil
pH = 6.5, (2080 mg/kg growth and numbers of
Acetochlor 7, 15, 30, 45 and 60 days (growth) Eisenia fetida (Adults) [39]
Moisture = 50% juveniles per cocoon were aected
28 days (reproduction)
Temp = 20 1 C significantly
OECD artificial soil
5, 20, 40, 60, 80 mg/kg soil pH = 6.0 0.5. Adverse impact on growth and
Chlorpyrifos (pure) Eisenia fetida (Adults) [45]
4 and 8 weeks Moisture = 50% reproduction
Temp = 20 C
OECD artificial soil
Significant reduction in cocoon
5, 10, 20, 40, 60 mg/kg soil pH = 6.0 0.5,
Cypermethrin (pure) Eisenia fetida (Juveniles) production [47]
4 and 8 weeks Moisture = 50%
Juveniles more sensitive than adults
Temp = 20 C
OECD artificial soil
Temp = 20 2 C
Toxicity of benomyl was lower in
pH = 6.1
0.32, 1.0, 3.2, 10, 32 mg/kg soil tropical than temperate artificial soils [24]
Benomyl (pure) Moisture = 56% Eisenia fetida (Adults)
56 days No reproduction in tropical natural soil
LUFA 2.2
due to low pH
pH = 6.1
Temp = 20 2 C
Moisture = 50%
Tropical artificial soil
Temp = 28 2 C
pH = 6.6
Moisture = 47%
Tropical natural soil, Brazil
pH = 3.9
Temp = 28 2 C
Moisture = 40%
3
4
Table 1: Continued.
Pesticide Concentration of pesticide/exposure Test conditions Species Responses Reference
OECD artificial soil
Moisture = 50%
Chlorpyrifos (pure) 1, 3, 10, 30, 100, 300, 900 mg/kg soil Toxicity of chlorpyrifos and carbofuran
Temp = 20 2C
Carbofuran (pure) 0.5, 1, 2, 4, 8, 16, 32 mg/kg soil on growth and reproduction in artificial [48]
pH = 6 Eisenia Andrei (Adults)
carbendazim, 0.1, 0.3, 1, 3, 10, 30, 90 mg/kg soil soil was higher at 26 C. in the natural
LUFA 2.2 soil
formulated as Derosal 28 days, 56 days soil
Moisture = 50%
(AgrEvo, 360 g/L) carbendazim toxicity was lower at 26 C
Temp= 20 2C
in both the soil types
pH = 5.96.1
OECD artificial soil
Moisture = 50%
Temp = 26 2 C
pH = 6
Natural soil
Moisture = 45%
Temp = 26 2 C
pH = 6.2
0, 25, 50, 100, 150, 200, 250, 500 mg/kg
Horse manure, sand and
soil
Carbaryl (pure) deionized water Inhibition of growth and cocoon
0, 25, 50, 100, 150, 200, 250, 500 mg/kg Eisenia fetida (Juveniles) [49]
Dieldrin (pure) Moisture = 75 5% production
soil
Temp = 25 C
4, 6, 8 weeks
Paraquat (pure),
Parathion (pure)
Fentin (pure)
20, 45, 100, 200, 450, 1000 mg/kg soil
Benomyl (pure)
10, 18, 32, 56, 100, 180 mg/kg soil OECD artificial soil
Pentachlorophenol
0.32, 1, 3.2, 10, 32 mg/kg soil pH = 6.07.3, Reduction in growth rate
(pure)
0.1, 0.32, 1,3.2 mg/kg soil Temp = 20 5 C Eisenia Andrei (Adults) reduction in number of juveniles [27]
Carbendazim
5, 10, 20, 40, 60 mg/kg soil Moisture = 35% produced per worm
(formulated as Derosal
0.6, 1.92, 6 mg/kg soil
60%)
1.62, 5.18, 16.2, 51.8, 162 mg/kg soil
Phenmedipham
(formulated as Betanal
16.2%)
Growth was retarded even at
Washed cow manure
10, 30, 50, 100 mg/kg agricultural doze of 5 kg/ha
Dieldrin (pure) Moisture = 60% Eisenia fetida (Juveniles) [50]
Every 15 days, 90 days Clitellum development retarded,
Temp = 20 C
influencing reproduction
Diazinon (formulated
Natural soil
as Basudin 600 EW), Significant eect on growth of juveniles
High = 60 mg/kg; Low = 12 mg/kg pH = 6.57, Aporrectodea caliginosa
Chlorpyrifos and adults [46]
High = 28 mg/kg; Low = 4 mg/kg Temp = 20 C (Adults and juveniles)
(formulated as Lorsban cocoon production significantly reduced
Moisture = 2025%
40 EC)
Applied and Environmental Soil Science
Table 1: Continued.
Pesticide Concentration of pesticide/exposure Test conditions Species Responses Reference
Endosulfan formulated
Loss in weight
as END 35 (endosulfan Dierent concentrations used; Natural soil
Reduction in the growth rate
concentration of LC10 and LC25 for aldicarb; LC10, Temp = 14 1 C, Lumbricus terrestris
Aldicarb was more toxic than [44]
350 g/L) LC25, and LC50 for endosulfan R.H = 7090% (Adults)
endosulfan
Aldicarb formulated as 2,7 and 15 days pH = 8.16
Temik 10 G
Aldicarb (formulated
as aldicarb; granular
mix, 10% active
Applied and Environmental Soil Science
ingredient)
Cypermethrin
(formulated as
Cypermethrin
emulsifiable
concentrate 5%)
Artificial soil Reduction in growth rate
Profenofos (formulated
Dierent concentrations used Temp = 23 1 C Aporrectodea caliginosa chlorfluazuron, atrazine, and metalaxyl
as Curacron, 50% EC) [42]
1, 2, 3, and 4 weeks R.H = 7090% (Adults) caused the highest reduction in worm
Chlorfluazuron
growth rate.
(formulated as Atabron
emulsifiable
concentrate 50%)
Atrazine (formulated
as Gesaprim, 80%
WP)
Metalaxyl Mn-Zn
(formulated as
Ridomil, 72% WP)
Toxicity decreased in the order of
carbofuran > chlorpyrifos > mancozeb
Chlorpyrifos (pure) for both the pure compounds and the
Chlorpyrifos formulations
formulated as Judo 40 1, 3, 10, 30, 100, 300 and 900 mg/kg soil OECD artificial soil Chlorpyrifos, carbofuran and mancozeb
EC 0.5, 1, 2, 4, 8, 16 and 32 mg/kg soil Moisture = 50% Perionyx excavates are more toxic to P. excavatus than to
[51]
Carbofuran (pure) 1, 3, 10, 30, 100, 300, 900 and Temp = 26 2 C (Adults) the standard test species E. andrei at
Carbofuran formulated 1200 mg/kg soil pH = 6.56.8 temperatures representative of tropical
as Curater (3% a.i.G) conditions
Mancozeb (pure) Formulated compounds depressed
earthworm reproduction more than the
pure compounds.
5
6 Applied and Environmental Soil Science
Espinoza-Navarro and Bustos-Obregon [31] treated Eise- thus aecting its life cycle. Further, the eects of a pesticide
nia fetida with organophosphate insecticide malathion and can dier strongly when tested under tropical and temperate
found that malathion decreased the spermatic viability in conditions [24]. This may be because the physicochemical
spermatheca, altering the cell proliferation and modifying variables aecting the biotic processes as well as the fate of
the DNA structure of spermatogonia. Sperm count also pesticides in the tropics are dierent from those in temperate
seems to be a very sensitive marker [42, 50], malathion could regions [60, 61]. The high temperature and humidity, found
aect the sperm count, but in addition, its metabolites could in the tropics, seem to favor degradation and volatilization
aect sperm quality [58]. of the chemical in the soil [62, 63]. On the other hand,
Several scientists have reported that pesticides influence humid and warmer conditions might enhance the toxicity
the reproduction (cocoon production, a reduced mean and of some pesticides by increasing the penetration through the
maximum number of hatchlings per cocoon, and a longer skin of animals, and these might be taken up more quickly by
incubation time) of worms in a dose-dependent manner, tropical biota [64].
with greater impact at higher concentration of chemical Furthermore, information on the side eects of pesticides
[35, 40, 41, 56]. Gupta and Saxena [56] studied the eects in the tropics is scarce [65] and a risk assessment based
of carbaryl, an N-methyl carbamate insecticide, on the on temperate data could be less appropriate for tropical
reproductive profiles of the earthworm, Metaphire posthuma conditions. Some of the studies have been conducted in this
and found sperm head abnormalities even at the lowest test direction, for example, Garcia [66] attempted to compare
concentration of 0.125 mg/kg. Wavy head abnormalities were the toxicity of selected pesticides on dierent strains of
observed at 0.125 mg/kg carbaryl, whereas at 0.25 mg/kg and Eisenia fetida in temperate and tropical conditions, whereas,
0.5 mg/kg, the sperm heads became amorphous and the head Helling et al. [36], Rombke et al. [24], and Garcia et al. [67]
nucleus was turned into granules deposited within the wavy applied standardized protocols to determine pesticide eects
head. to soil invertebrates under tropical conditions. De Silva et al.
Xiao et al. [39] showed that acetochlor had no long- [48] found that sublethal eects (reproduction and growth)
term eect on the reproduction of Eisenia fetida at field varied inconsistently with temperature and soil types. All
dose (510 mg/kg1 ). At higher concentrations, acetochlor these researchers suggested that toxicity of pesticides in
(2080 mg/kg) revealed sublethal toxicity to Eisenia fetida. tropics cannot be predicted from data generated under
Zhou et al. [45] assessed and found chlorpyrifos had temperate conditions, even within the same species [48].
adverse eect on fecundity in earthworm exposed to 5 mg/kg Furthermore, it is suggested that tropical risk assessment may
chlorpyrifos after eight weeks. According to Zhou et al. [47] be more realistic when conducted on ecologically relevant
reproduction of earthworms appeared to be more severely earthworm species, rather than standard Eisenia sp [51]. De
aected by cypermethrin at juvenile stage than at adult stage. Silva [68] suggests that Eisenia being temperate compost
Application of 20 mg/kg, cypermethrin caused significant worms is less ecologically relevant and Perionyx excavatus
toxic eects in reproduction of worms. may be used as standard test species for tropical soils.
Coiling, seen in the parathion treated worms, interferes An important aim in earthworm ecotoxicology is to be
with the reproduction too since worms find their partner less able to predict the eects of harmful chemicals in the field
easily and copulation is abnormal in terms of mating posture. on the basis of laboratory experiments. Holmstrup [69]
Ejection of sperm seems also to be hindered and therefore estimated the in situ cocoon production in grassland of
a large number of spermatozoa are found in intoxicated two earthworm species, Aporrectodea longa and Aporrectodea
worms in spite of a clear eect on sperm production under rosea, in relation to application dose of benomyl. The results
parathion treatment as discussed by Bustos-Obregon and obtained in this field study were compared with results from
Goicochea [3]. According to Espinoza-Navarro and Bustos- laboratory reproduction tests with other earthworm species.
Obregon [58] malathion also has a direct cytotoxic eect There was good agreement between eects of benomyl on
causing coiling of the tail, with increase of metachromasia reproduction in the laboratory and in the field. These results
of the chromatin of the spermatozoa and altering the sperm therefore suggest that standardized laboratory tests provide
count a reasonable prediction of the eect in the field. However,
according to Van Gestel [55], results of field studies on the
earthworm toxicity of pesticides are in agreement with those
5. Confounding Variables of laboratory studies when a homogeneous distribution
of the pesticide dosage over the top 2.5-cm soil layer is
The results of earthworm ecotoxicological tests may be chosen as a starting point. In field situations, earthworm
confounded with dierent properties of soils such as organic exposure is strongly dependent on the degree of deposition
matter, water holding capacity, pH, cation exchange capacity, of pesticides on the soil surface, on the behavior of the
Carbon/Nitrogen ratio, and clay content and its interaction pesticide in the soil, and on the vertical distribution of
with chemical substances and dierent species of earthworm earthworms in the soil. The soil ecosystem is very complex,
chosen as test species [23]. Soil pH may aect the survival where interaction occurs between abiotic and biotic factors.
of adults and thus production of juveniles [23, 59]. Low Therefore, extrapolation of eects of pesticides observed
reproduction of earthworm was seen in finely sieved soil as in laboratory studies to eects in the field studies may
compared to sandy soil [23] indicating that porosity of soil be impeded by various environmental variables (especially
may influence earthworm mobility and gaseous exchange, the soil characteristics and weather conditions) influencing
Applied and Environmental Soil Science 7
exposure of earthworms to chemical [15]. Neuhauser and to an organophosphate pesticide, Environmental Toxicology
Callahan [49] suggested that more consideration should be and Chemistry, vol. 18, no. 2, pp. 237240, 1999.
given to evaluation of sublethal eects under field conditions. [6] S. A. Reinecke and A. J. Reinecke, Lysosomal response of
Ecotoxicological studies on soil fauna in laboratories usually earthworm coelomocytes induced by longterm experimental
involve single or a few species. For proper environmental risk exposure to heavy metals, Pedobiologia, vol. 43, no. 6, pp. 585
assessment, three tiered studies should be conducted [70], 593, 1999.
that is (1) basic laboratory tests (mainly acute); (2) extended [7] M. C. Sandoval, M. Veiga, J. Hinton, and B. Klein, Review
laboratory tests (mainly chronic); (3) tests using microcosms of biological indicators for metal mining euents: a proposed
(model ecosystem tests) or even field tests. Although, the protocol using earthworms, in Proceedings of the 25th Annual
highest tier is most important for an ecotoxicological risk British Columbia Reclamation Symposium, pp. 6779, 2001.
assessment, it is rarely performed due to its high complexity, [8] K. A. Lord, G. G. Briggs, M. C. Neale, and R. Manlove, Uptake
costs and time needed [71]. De Silva [68] also indicates of pesticides from water and soil by earthworms, Pesticide
Science, vol. 11, no. 4, pp. 401408, 1980.
that linking of laboratory data to field may be possible and
successful, but more research is required (especially w.r.t [9] J. C. Sanchez-Hernandez, Earthworm biomarkers in ecologi-
tropical conditions) on this aspect to state conclusively [15, cal risk assessment, Reviews of Environmental Contamination
and Toxicology, vol. 188, pp. 85126, 2006.
55, 69, 72, 73].
In conclusion, growth and reproductive parameters of [10] ISO, Soil qualityeects of pollutants on earthworms (Eise-
nia fetida)part 1: determination of acute toxicity using arti-
earthworms exposed to agropesticides seem to be useful
ficial soil substrate, ISO 11268-1, International Organization
bioindicators of soil pollution. Such studies are simple to for Standardization, Geneva, Switzerland, 1993.
do and do not require great technical expertise. However,
[11] ISO, Soil qualityeects of pollutants on earthworms (Eise-
the studies conducted so far have focused on a few species
nia fetida)part 2: determination of eects on reproduction,
of earthworms. Additional studies with dierent species ISO 11268-2, International Organization for Standardization,
of earthworm, including dierent endpoints, temperature Geneva, Switzerland, 1998.
regimes and soil types, are required. Research should be [12] OECD, Guideline for testing of chemicals, no. 207, Earth-
extended to ecologically relevant species of earthworms, worm Acute Toxicity Test. Organization for Economic Co-
as stated earlier [51], and also to other soil fauna to get Operation and Development, Paris, France, 1984.
a comprehensive knowledge on the malfunction in the [13] OECD, Guideline for testing of chemicals, no. 222, Earth-
soil biological processes due to pesticide pollution. All of worm Reproduction Test (Eisenia fetida/andrei). Organization
the above-mentioned studies indicate negative impact of for Economic Co-Operation and Development, Paris, France,
pesticides on earthworm growth and reproduction. Some 2004.
studies also indicate that microorganisms in the soil help [14] W. C. Ma and J. Bodt, Dierences in toxicity of the insecticide
degrade the chemicals [74, 75]. So, there is a need to acquire chlorpyrifos to six species of earthworms (Oligochaeta, Lum-
more knowledge on the chemical nature, mode of action, bricidae) in standardized soil tests, Bulletin of Environmental
and means of degradation of pesticides in soil, so that harm Contamination and Toxicology, vol. 50, no. 6, pp. 864870,
caused to soil fauna as well as to organisms higher up in the 1993.
food chain can be minimized. [15] H. Kula, Comparison of laboratory and field testing for
the assessment of pesticide side eects on earthworms, Acta
Zoologica Fennica, vol. 196, pp. 338341, 1995.
Acknowledgments
[16] D. G. Fitzgerald, K. A. Warner, R. P. Lanno, and D. G. Dixon,
We are grateful to P.M.C.S. De Silva and J. Rombke for Assessing the eects of modifying factors on pentachlorophe-
providing full texts of several references that helped us nol toxicity to earthworms: applications of body residues,
Environmental Toxicology and Chemistry, vol. 15, no. 12, pp.
immensely in preparing this manuscript.
22992304, 1996.
[17] D. E. Bayer and C. L. Foy, Action and fate of adjuvants
References in soils, in Adjuvants for Herbicides, pp. 8492, WSSA,
Champaign, Ill, USA, 1982.
[1] M. D. Culy and E. C. Berry, Toxicity of soil-applied granular
insecticides to earthworm populations in cornfields, Down to [18] C. A. M. Van Gestel and W. A. Van Dis, The influence of
Earth, vol. 50, pp. 2025, 1995. soil characteristics on the toxicity of four chemicals to the
[2] J. Sorour and O. Larink, Toxic eects of benomyl on earthworm Eisenia fetida andrei (Oligochaeta), Biology and
the ultrastructure during spermatogenesis of the earthworm Fertility of Soils, vol. 6, no. 3, pp. 262265, 1988.
Eisenia fetida, Ecotoxicology and Environmental Safety, vol. 50, [19] C. A. M. Van Gestel, W. A. Van Dis, E. M. Van Breemen, and P.
no. 3, pp. 180188, 2001. M. Sparenburg, Development of a standardized reproduction
[3] E. Bustos-Obregon and R. I. Goicochea, Pesticide soil toxicity test with the earthworm species Eisenia fetida andrei
contamination mainly aects earthworm male reproductive using copper, pentachlorophenol, and 2,4-dichloroaniline,
parameters, Asian Journal of Andrology, vol. 4, no. 3, pp. 195 Ecotoxicology and Environmental Safety, vol. 18, no. 3, pp. 305
199, 2002. 312, 1989.
[4] A. Beeby, What do sentinels stand for? Environmental [20] P. Y. Robidoux, J. Hawari, S. Thiboutot, G. Ampleman, and
Pollution, vol. 112, no. 2, pp. 285298, 2001. G. I. Sunahara, Acute toxicity of 2,4,6-trinitrotoluene in
[5] G. DellOmo, A. Turk, and R. F. Shore, Secondary poisoning earthworm (Eisenia andrei), Ecotoxicology and Environmental
in the common shrew (Sorex araneus) fed earthworms exposed Safety, vol. 44, no. 3, pp. 311321, 1999.
8 Applied and Environmental Soil Science
[21] F. Moriarty, Ecotoxicology: The Study of Pollutants in Ecosys- [38] C. A. M. Van Gestel, J. Zaal, E. M. Dirven-Van Breemen, and
tems, Academic Press, London, UK, 1983. R. Baerselman, Comparison of two test methods for deter-
[22] G. K. Frampton, S. Jansch, J. J. Scott-Fordsmand, J. Rombke, mining the eects of pesticides on earthworm reproduction,
and P. J. Van den Brink, Eects of pesticides on soil Acta Zoologica Fennica, vol. 196, pp. 278283, 1995.
invertebrates in laboratory studies: a review and analysis using [39] N. Xiao, B. Jing, F. Ge, and X. Liu, The fate of herbicide
species sensitivity distributions, Environmental Toxicology acetochlor and its toxicity to Eisenia fetida under laboratory
and Chemistry, vol. 25, no. 9, pp. 24802489, 2006. conditions, Chemosphere, vol. 62, no. 8, pp. 13661373, 2006.
[23] M. J. B. Amorim, J. Rombke, and A. M. V. M. Soares, [40] S. Yasmin and D. DSouza, Eect of pesticides on the repro-
Avoidance behaviour of Enchytraeus albidus: eects of Beno- ductive output of Eisenia fetida, Bulletin of Environmental
myl, Carbendazim, phenmedipham and dierent soil types, Contamination and Toxicology, vol. 79, no. 5, pp. 529532,
Chemosphere, vol. 59, no. 4, pp. 501510, 2005. 2007.
[24] J. Rombke, M. V. Garcia, and A. Scheczyk, Eects of the [41] L. H. Booth, V. J. Heppelthwaite, and K. OHalloran, Growth,
fungicide benomyl on earthworms in laboratory tests under development and fecundity of the earthworm Aporrectodea
tropical and temperate conditions, Archives of Environmental caliginosa after exposure to two organophosphates, New
Contamination and Toxicology, vol. 53, no. 4, pp. 590598, Zealand Plant Protection, vol. 53, pp. 221225, 2000.
2007. [42] Y. Y. Mosleh, S. M. M. Ismail, M. T. Ahmed, and Y. M. Ahmed,
[25] F. Riepert, J. Rombke, and T. Moser, Ecotoxicological Charac- Comparative toxicity and biochemical responses of certain
terization of Waste, Springer, New York, NY, USA, 2009. pesticides to the mature earthworm Aporrectodea caliginosa
[26] M.G. Paoletti, The role of earthworms for assessment of under laboratory conditions, Environmental Toxicology, vol.
sustainability and as bioindicators, Agriculture, Ecosystems 18, no. 5, pp. 338346, 2003.
and Environment, vol. 74, no. 13, pp. 137155, 1999. [43] Y. Y. Mosleh, S. Paris-Palacios, M. Couderchet, and G. Vernet,
[27] C. A. M. Van Gestel, E. M. Dirven-Van Breemen, R. Baersel- Biological eects of two insecticides on earthworms (Lumbri-
man, et al., Comparison of sublethal and lethal criteria for cus terrestris L.) under laboratory conditions, Mededelingen
nine dierent chemicals in standardized toxicity tests using the Rijksuniversiteit te Gent. Fakulteit van de Landbouwkundige en
earthworm Eisenia andrei, Ecotoxicology and Environmental Toegepaste Biologische Wetenschappen, vol. 67, no. 2, pp. 5968,
Safety, vol. 23, no. 2, pp. 206220, 1992. 2002.
[28] K. Lock and C. R. Janssen, Cadmium toxicity for terrestrial [44] Y. Y. Mosleh, S. Paris-Palacios, M. Couderchet, and G. Vernet,
invertebrates: taking soil parameters aecting bioavailability Acute and sublethal eects of two insecticides on earthworms
into account, Ecotoxicology, vol. 10, no. 5, pp. 315322, 2001. (Lumbricus terrestris L.) under laboratory conditions, Envi-
[29] H. Kula and O. Larink, Development and standardization ronmental Toxicology, vol. 18, no. 1, pp. 18, 2003.
of test methods for the prediction of sublethal eects of [45] S.-P. Zhou, C.-Q. Duan, H. Fu, Y.-H. Chen, X.-H. Wang, and
chemicals on earthworms, Soil Biology and Biochemistry, vol. Z.-F. Yu, Toxicity assessment for chlorpyrifos-contaminated
29, no. 3-4, pp. 635639, 1997. soil with three dierent earthworm test methods, Journal of
[30] Q.-X. Zhou, Q.-R. Zhang, and J.-D. Liang, Toxic eects Environmental Sciences, vol. 19, no. 7, pp. 854858, 2007.
of acetochlor and methamidophos on earthworm Eisenia [46] L. H. Booth and K. OHalloran, A comparison of biomarker
fetida in phaiozem, northeast China, Journal of Environmental responses in the earthworm Aporrectodea caliginosa to the
Sciences, vol. 18, no. 4, pp. 741745, 2006. organophosphorus insecticides diazinon and chlorpyrifos,
[31] O. Espinoza-Navarro and E. Bustos-Obregon, Eect of Environmental Toxicology and Chemistry, vol. 20, no. 11, pp.
malathion on the male reproductive organs of earthworms, 24942502, 2001.
Eisenia foetida, Asian Journal of Andrology, vol. 7, no. 1, pp. [47] S. Zhou, C. Duan, X. Wang, W. H. G. Michelle, Z. Yu, and
97101, 2005. H. Fu, Assessing cypermethrin-contaminated soil with three
[32] M. Cikutovic, Pathologies in earthworm: sub lethal biomarkers dierent earthworm test methods, Journal of Environmental
of xenobiotic toxicity, dissertation, University of North Texas, Sciences, vol. 20, no. 11, pp. 13811385, 2008.
1991. [48] P. M. C. S. De Silva, A. Pathiratne, and C. A. M. van Gestel,
[33] E. Martikainen, Toxicity of dimethoate to some soil animal Influence of temperature and soil type on the toxicity of three
species in dierent soil types, Ecotoxicology and Environmen- pesticides to Eisenia andrei, Chemosphere, vol. 76, no. 10, pp.
tal Safety, vol. 33, no. 2, pp. 128136, 1996. 14101415, 2009.
[34] A. Haque and W. Ebing, Toxicity determination of pesticides [49] E. F. Neuhauser and C. A. Callahan, Growth and repro-
to earthworms in the soil substrate, Journal of Plant Diseases duction of the earthworm Eisenia fetida exposed to sublethal
and Protection, vol. 90, no. 4, pp. 395408, 1983. concentrations of organic chemicals, Soil Biology and Bio-
[35] J. A. Addison and S. B. Holmes, Comparison of forest chemistry, vol. 22, no. 2, pp. 175179, 1990.
soil microcosm and acute toxicity studies for determining [50] J. M. Venter and A. J. Reinecke, Dieldrin and growth and
eects of fenitrothion on earthworms, Ecotoxicology and development of the earthworm, Eisenia fetida (oligochaeta),
Environmental Safety, vol. 30, no. 2, pp. 127133, 1995. Bulletin of Environmental Contamination and Toxicology, vol.
[36] B. Helling, S. A. Reinecke, and A. J. Reinecke, Eects 35, no. 5, pp. 652659, 1985.
of the fungicide copper oxychloride on the growth and [51] P. M. C. S. De Silva, A. Pathiratne, and C. A. M. van Gestel,
reproduction of Eisenia fetida (Oligochaeta), Ecotoxicology Toxicity of chlorpyrifos, carbofuran, mancozeb and their
and Environmental Safety, vol. 46, no. 1, pp. 108116, 2000. formulations to the tropical earthworm Perionyx excavatus,
[37] L. P. D. Choo and G. H. Baker, Influence of four commonly Applied Soil Ecology, vol. 44, no. 1, pp. 5660, 2010.
used pesticides on the survival, growth, and reproduction [52] P. Y. Robidoux, C. Svendsen, J. Caumartin, et al., Chronic
of the earthworm Aporrectodea trapezoides (Lumbricidae), toxicity of energetic compounds in soil determined using the
Australian Journal of Agricultural Research, vol. 49, no. 8, pp. earthworm (Eisenia andrei) reproduction test, Environmental
12971303, 1998. Toxicology and Chemistry, vol. 19, no. 7, pp. 17641773, 2000.
Applied and Environmental Soil Science 9
[53] S. A. Reinecke, M. W. Prinsloo, and A. J. Reinecke, Resistance earthworms in laboratory tests performed under temperate
of Eisenia fetida (Oligochaeta) to cadmium after long-term and tropical conditions, Environmental Pollution, vol. 153, no.
exposure, Ecotoxicology and Environmental Safety, vol. 42, no. 2, pp. 450456, 2008.
1, pp. 7580, 1999. [68] P. M. C. S. De Silva, Pesticide eects on earthworms: a tropical
[54] M. S. Maboeta, A. J. Reinecke, and S. A. Reinecke, Eects of perspective, Ph.D. thesis, Department of Ecological Science,
low levels of lead on growth and reproduction of the Asian VU University, Amsterdam, The Netherlands, 2009.
earthworm Perionyx excavatus (Oligochaeta), Ecotoxicology [69] M. Holmstrup, Field assessment of toxic eects on reproduc-
and Environmental Safety, vol. 44, no. 3, pp. 236240, 1999. tion in the earthworms Aporrectodea longa and Aporrectodea
[55] C. A. M. Van Gestel, Validation of earthworm toxicity rosea, Environmental Toxicology and Chemistry, vol. 19, no. 7,
tests by comparison with field studies: a review of benomyl, pp. 17811787, 2000.
carbendazim, carbofuran, and carbaryl, Ecotoxicology and [70] J. Rombke, C. Bauer, and A. Marschner, Hazard assessment
Environmental Safety, vol. 23, no. 2, pp. 221236, 1992. of chemicals in soilproposed ecotoxicological test strategy,
[56] S. K. Gupta and P. N. Saxena, Carbaryl-induced behavioural Environmental Science and Pollution Research, vol. 3, no. 2, pp.
and reproductive abnormalities in the earthworm Metaphire 7882, 1996.
posthuma: a sensitive model, Alternatives to Laboratory Ani- [71] J. Rombke and J. Notenboom, Ecotoxicological approaches
mals, vol. 31, no. 6, pp. 587593, 2003. in the field, in Environmental Analysis of Contaminated Sites,
[57] M. A. Cikutovic, L. C. Fitzpatrick, B. J. Venables, and A. J. G. I. Sunahara, A. Y. Renoux, C. Thellen, C. L. Gaudet, and A.
Goven, Sperm count in earthworms (Lumbricus terrestris) as Pilon, Eds., pp. 181195, John Wiley & Sons, Chichester, UK,
a biomarker for environmental toxicology: eects of cadmium 2002.
and chlordane, Environmental Pollution, vol. 81, no. 2, pp. [72] F. Heimbach, Correlation between data from laboratory
123125, 1993. and field tests for investigating the toxicity of pesticides to
[58] O. Espinoza-Navarro and E. Bustos-Obregon, Sublethal earthworms, Soil Biology and Biochemistry, vol. 24, no. 12, pp.
doses of malathion alter male reproductive parameters of 17491753, 1992.
Eisenia fetida, International Journal of Morphology, vol. 22, no. [73] S. Jansch, G. K. Frampton, J. Rombke, P. J. Van den Brink,
4, pp. 297302, 2004. and J. J. Scott-Fordsmand, Eects of pesticides on soil
[59] M. J. Amorim, J. P. Sousa, A. J. A. Nogueira, and A. M. V. M. invertebrates in model ecosystem and field studies: a review
Soares, Comparison of chronic toxicity of Lindane (-HCH) and comparison with laboratory toxicity data, Environmental
to Enchytraeus albidus in two soil types: the influence of soil Toxicology and Chemistry, vol. 25, no. 9, pp. 24902501, 2006.
pH, Pedobiologia, vol. 43, no. 6, pp. 635640, 1999. [74] A. R. Abdullah, C. M. Bajet, M. A. Matin, D. D. Nhan,
[60] V. Laabs, W. Amelung, A. Pinto, and W. Zech, Fate of and A. H. Sulaiman, Ecotoxicology of pesticides in the
pesticides in tropical soils of Brazil under field conditions, tropical paddy field ecosystem, Environmental Toxicology and
Journal of Environmental Quality, vol. 31, no. 1, pp. 256268, Chemistry, vol. 16, no. 1, pp. 5970, 1997.
2002. [75] B. K. Singh, A. Walker, J. A. W. Morgan, and D. J. Wright,
[61] L. C. Paraba, A. L. Cerdeira, E. F. Da Silva, J. S. Martins, Eects of soil pH on the biodegradation of chlorpyrifos and
and H. L. Da Costa Coutinho, Evaluation of soil temperature isolation of a chlorpyrifos-degrading bacterium, Applied and
eect on herbicide leaching potential into groundwater in the Environmental Microbiology, vol. 69, no. 9, pp. 51985206,
Brazilian Cerrado, Chemosphere, vol. 53, no. 9, pp. 1087 2003.
1095, 2003.
[62] W. Klein, Mobility of environmental chemicals, including
abiotic degradation, in Ecotoxicology and Climate. SCOPE 38,
P. Bordeau, J. A. Haines, W. Klein, and C. R. Krishna Murti,
Eds., pp. 6578, John Wiley & Sons, Chichester, UK, 1989.
[63] P. Bourdeau, J. A. Haines, W. Klein, and C. R. Krishnamurti,
Ecotoxicology and climate, in SCOPE 38 IPCS Joint Sym-
posia 9, p. 392, John Wiley & Sons, Chichester, UK, 1989.
[64] P. N. Viswanathan and C. R. Krishnamurti, Eects of
temperature and humidity on ecotoxicology of chemicals, in
Ecotoxicology and Climate with Special Reference to Hot and
Cold Climates, P. Bourdeau, J. A. Haines, W. Klein, and C. R.
Krishanamurti, Eds., pp. 139154, John Wiley & Sons, New
York, NY, USA, 1989.
[65] P. J. Van den Brink, S. N. Sureshkumar, M. A. Daam, et al.,
Environmental and human risk of pesticide use in Thailand
and Sri Lanka. Results of a preliminary risk assessment,
Alterra Report 789. MAMAS Report Series No. 3/2003,
Research Institute for the Green World, Wageningen Alterra,
The Netherlands, 2003.
[66] M. V. B. Garcia, Eects of Pesticides on Soil Fauna: Development
of Ecotoxicological Test Methods for Tropical Regions, vol. 19
of Ecology and Development Series, University of Bonn, Bonn,
Germany, 2004.
[67] M. Garcia, J. Rombke, M. T. de Brito, and A. Scheczyk,
Eects of three pesticides on the avoidance behavior of
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 850758, 4 pages
doi:10.1155/2010/850758
Research Article
Effect of Butachlor Herbicide on Earthworm
Eisenia fetida Its Histological Perspicuity
Copyright 2010 M. Gobi and P. Gunasekaran. This is an open access article distributed under the Creative Commons
Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is
properly cited.
With the advent of the Green Revolution, there has been a quantum leap in the use of synthetic herbicides and pesticides
throughout the world to sustain high yielding crop varieties. Continuous use of these synthetic chemicals leads to loss of soil
fertility and soil organisms. To explore the eect of exposure to commercial herbicide (Butachlor) on the life history parameters
(biomass, clitellum development, and cocoon production) and the histological changes in the earthworm Eisenia fetida over 60
days, the dried cow dung was contaminated with 0.2575 mg kg1 , 0.5150 mg kg1 , and 2.5750 mg kg1 of butachlor based on the
LC50 value, and a control was maintained. The mean earthworm biomass was found to be decreased with increasing herbicide
concentration. Similarly, cocoon production was also reduced by the increasing herbicide concentration. A possible explanation is
an increased demand for energy, needed for the regulation and detoxification of herbicide. All earthworms in the exposed group
were found to have glandular cell enlargement and to be vacuolated.
Table 1: Influence of dierent concentrations of herbicide on the growth of E. fetida over 60 days.
number 207 [7]. Dierent amounts of test substances had hours to remove all the soil from their gut. After removing
been mixed homogenously. The selected earthworm species the gut contents, earthworms were narcotized and cut into
for toxicity test were exposed to dierent concentrations of pieces and transferred to Zenkars fixative for 12 hours
herbicides (equivalent to 100 g dry weight) by amendment and washed with running tap water for 1224 hours. The
method for 96 hours. Each concentration level was tested worm samples were mounted weekly and stained with Iron
where five replicates in lieu of level was tested with five repli- Haemtoxylin stain for histological observation.
cates. Finneys [8] probit method using graphical analysis
was followed to calculate the LC50 value. In this study, the
LC50 value was 0.515 mg kg1 dry weight of medium.
3. Results and Discussion
3.1. Influence of Herbicide on the Growth of E. fetida. The
2.3. Sublethal Toxicity Test. The substrate used was urine- worms gained weight up to the last day of the experiment (see
free cattle manure that was sun dried, ground and sieved Table 1). The earthworm (15th day) in the control group had
to a particle size of 5001000 m. Butachlor was diluted in a mean biomass of 0.094 0.0026 g and those in the exposure
solvent and mixed into the substrate to give moisture content group 0.3534 0.0278 g in 0.2575 mg kg1 , 0.3626 0.0404 g
of 75%. Prepared substrate was left for 24 hours to evaporate in 0.5150 mg kg1 , and 0.342 0.0203 g in 2.5750 mg kg1 .
the excess solvents mixed in test chemicals. One group served On the termination of experiment, earthworms (60 days
as control, and three groups were exposed to a concentra- old) in the control group had mean biomass of 0.365
tion of 0.2575 mg kg1 , 0.5150 mg kg1 , and 2.5750 mg kg1 , 0.0194 g. But in the exposure group it was 0.3534 0.0278 g
respectively. Three replicates of each concentration, each in 0.2575 mg kg1 , 0.3626 0.0404 g in 0.5150 mg kg1 ,
vessel containing ten animals, were set up, and ten-day-old and 0.342 0.0203 g in 2.5750 mg kg1 ; the dierence was
earthworms were inoculated. Biomass was determined over significant at P < .001 levels. Further, Tukey test confirms
60 days by removing the worms from substrate, washing the significant deference between days and treatments. At the
them with distilled water and drying them on paper towels. end of experiment there was no dierence between the mean
They were then weighed fortnightly in a preweighed water- biomass of control group and the exposure group.
filled boats. This was done to prevent the worms from drying
out and dying. 3.2. Influence of Herbicide on the Clitellum Development of
E. fetida. The rate at which the worms attained maturity
2.4. Clitellum Development and Cocoon Production. Worms diered in E. fetida exposed to dierent concentrations of
were observed closely every two days starting from four butachlor. The percentage of mature specimens (expressed
weeks after they hatched. Worms were classified as juve- in terms of clitellate specimens) is shown in Figure 1. All
nile, preclitellate, and clitellate using the rather subjective specimens of E. fetida started developing clitellum from
criterium clitellum and absence, partial development of the 29th day and on 33rd day clitellum development com-
clitellum, and the presence of a fully developed clitellum. pleted. The percentage of clitellum development decreased
The culture medium of troughs was thoroughly searched for with increasing concentration of butachlor. The maximum
cocoons every second day, starting from 35th day. Cocoons clitellum development was observed in control on 30th
were transferred to multicell containers to be incubated in day (40%), 43.3% for 0.2575 mg kg1 at 29th day, 33.3%
distilled water. The containers were kept in the dark place and for 0.5150 mg kg1 , and 26.6% for 2.5750 mg kg1 con-
the water contents were replaced weekly to prevent bacterial centration. Analysis of Variance (ANOVA) shows that the
growth. percentage of clitellum development of E. fetida diered
significantly at (P < .01) in between days and it was not
2.5. Histological Study. After completion of life cycle, earth- significant between treatment.
worms from each concentration were taken and washed with
distilled water after which 50 mL jars were filled with 30 mL 3.3. Influence of Herbicide on the Cocoon Production of E.
of 1.5% agar gel prepared with deionized water. After getting fetida. The mean number of E. fetidas cocoon production
cooled and solidified, this gel in the jars was taken out in dierent concentrations of butachlor is listed in Table 2.
and cut into small pieces. The earthworms were transferred The maximum number of cocoons laid by control worm
separately into jars containing agar pieces and kept for 96 was 79.66 2.603 on the 65th day. The worms exposed
Applied and Environmental Soil Science 3
100 Ch
90
80
Clitellum development %
70
V
60
50 IVS
40 L
30
20
Figure 2: Cross section of earthworm E. fetida normal intestine and
10 chloragogen tissue at control. L: Lumen; V: Villi; Ch: chloragogen
0 tissue; IVS: Inter villious space.
29th 30th 31st 32nd 33rd
Days
CD
2.575 mg/Kg 0.257 mg/Kg
0.515 mg/Kg Control
L FV
Figure 1: Percentage of clitellum development in E. fetida after
exposure to dierent concentrations of herbicide.
3.4. Histopathological Changes on the Earthworm E. fetida. and vas deferens. The size of chloragogen tissue was redu-
The intestine in control worm of E. fetida (Figure 2) ced. However, 0.2575 mg kg1 concentration (Figure 5) also
consists of normal epithelial layer, the intermediate layer of shows the fused villous growth in the epithelial layer. There
longitudinal and circular muscle and blood vessels, and the was no intervillous space between villi. In contrast, the
other chloragogenous layer. Figure 3 revealed the histological pyknotic nuclei were found in many cells and cavitation was
changes of E. fetida at 2.5750 mg kg1 concentration. The seen in chloragogen tissue layer.
epithelial layer structure was grossly destroyed; fused and
extra villous growth was pertained. Cell debris originated 4. Discussion
due to necrotic cell rupture and was found disseminated.
Pyknotic nuclei had expressed. The chloragogen tissue was The biomass results of E. fetida revealed that earthworms
completely devastated with weak reserve inclusion. had no inhibitory eect on the biomass. This result on
In 0.5150 mg kg1 concentration (Figure 4), the epithe- growth was contradictory to that of Muthukaruppan et al.
lial layer of villi was fused. A distinct cavitation was deve- [9] who exposed Perionyx sansibaricus to the same herbicide
loped and pyknotic nuclei were observed in epithelial layer. butchlor and found that there was significant biomass
The vaculoation could be seen inside the testis, testis sac, dierence. This is due to species sensitivity of earthworm.
4 Applied and Environmental Soil Science
References
Ch CD [1] C. A. Edwards and P. J. Bohlen, Biology and Ecology of
Earthworms, Chapman and Hall, London, UK, 1996.
[2] R. L. Rudd, Pesticides and the Living Landscape, Faber and
Faber, London, UK, 1964.
[3] K. R. Bunyan, M. J. Van Den Heuvel, P. I. Stanley, and E. N.
Wright, An intensive field trail and a multi-site surveillance
exercise on the use of aldicarb to investigate methods for the
assessment of possible environmental hazards present by new
Figure 5: Cross section of earthworm E. fetida showing intestine pesticides, Agro Ecosystems, vol. 7, pp. 239262, 1981.
and chloragogen tissue at 2.5750 mg kg1 concentration of herbi- [4] A. M. M. Abdul Rida and M. B. Bouche, Heavy metal linkages
cide. Va: Vacuoles. with mineral, organic and living soil compartments, Soil
Biology and Biochemistry, vol. 29, no. 3-4, pp. 649655, 1997.
[5] A. P. Gilman and A. Vardanis, Carbofuran: comparative
toxicity and metabolism in the worms Lumbricus terrestris and
The maturation rate could not, therefore, be considered
Eisenia fetida, Journal of Agricultural and Food Chemistry, vol.
as a sensitive parameter to evaluate the eect of herbicide 22, no. 4, pp. 625628, 1974.
butachlor on this species. [6] J. Stenersen, A. Gilman, and A. Vardanis, Carbofuran:
In the present study, earthworm E. fetida produced its toxicity to and metabolism by earthworm (Lumbricus
cocoons which showed decreasing trend when the concen- terrestris), Journal of Agricultural and Food Chemistry, vol. 22,
trations of butachlor were increased. Similarly [10] observed no. 2, pp. 342347, 1974.
that the fungicide copper oxychloride reduced cocoon pro- [7] OECD, Test no. 207: earthworm, acute toxicity tests, in
duction with increased concentration of fungicide in Eisenia OECD Guideline for the Testing of Chemicals, OECD, Paris,
fetida. The present study confirms that the ability to resist a France, 1984.
toxicant physiologically may be expensive interms of energy [8] D. J. Finney, Statistical Methods in Biological Assay, Grin
and other resources. This could involve a diminution of the Press, London, UK, 1971.
ability to invest in other processes; for example, the energy [9] G. Muthukaruppan, S. Janardhanan, and G. S. Vijayalak-
shmi, Sublethal toxicity of the herbicide butachlor on the
available for reproduction is reduced. In the present study,
earthworm Perionyx sansibaricus and its histological changes,
epithelial tissue of earthworm E. fetida, exposed to butachlor, Journal of Soils and Sediments, vol. 5, no. 2, pp. 8286, 2005.
was severely aected. The present study confirms to the [10] B. Helling, S. A. Reinecke, and A. J. Reinecke, Eects
findings [11] that extreme nuclear swelling resulting in more of the fungicide copper oxychloride on the growth and
than 2-fold volume increase of the average minimum could reproduction of Eisenia fetida (Oligochaeta), Ecotoxicology
yet be observed only on the eect of sublethal paraquat and Environmental Safety, vol. 46, no. 1, pp. 108116, 2000.
toxication. [11] E. fischer and L. Molnar, Environmental aspects of the
chloragogenous tissue of earthworms, Soil Biology and Bio-
chemistry, vol. 24, no. 12, pp. 17231727, 1992.
5. Conclusion
Earthworms are useful as test organisms to assess the toxi-
city of herbicidal contaminated soils, because of their sen-
sitive changes occurred in biomass and cocoon production,
and histological changes in tissues. The results clearly indi-
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 294258, 13 pages
doi:10.1155/2010/294258
Review Article
Earthworm Protease
Copyright 2010 Rong Pan et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The alimentary tract of earthworm secretes a group of proteases with a relative wide substrate specificity. In 1983, six isozymes
were isolated from earthworm with fibrinolytic activities and called fibriniolytic enzymes. So far, more isozymes have been found
from dierent earthworm species such as Lumbricus rubellus and Eisenia fetida. For convenience, the proteases are named on the
basis of the earthworm species and the protein function, for instance, Eisenia fetida protease (Ef P). The proteases have the abilities
not only to hydrolyze fibrin and other protein, but also activate proenzymes such as plasminogen and prothrombin. In the light of
recent studies, eight of the Ef Ps contain oligosaccharides chains which are thought to support the enzyme structure. Interestingly,
Ef P-II has a broader substrate specificity presenting alkaline trypsin, chymotrypsin and elastase activities, but Ef P-III-1 has a
stricter specificity. The protein crystal structures show the characteristics in their specificities. Earthworm proteases have been
applied in several areas such as clinical treatment of clotting diseases, anti-tumor study, environmental protection and nutritional
production. The current clinical utilizations and some potential new applications of the earthworm protease will be discussed in
this paper.
2.1. Isozymes from Lumbricus rubellus. Six proteases (LrP- both antithrombotic and fibrinolytic activities during oral
I-0, LrP-I-1, LrP-I-2, LrP-II, LrP-III-1, and LrP-III-2) of administration.
fibrinolytic enzymes were isolated from L. rubellus [3, 4, 23]. Although several groups of isozymes have been studied
The molecular masses of the isozymes measured by ion- in the species above, the total number is still not clear. The
spray mass spectrometry are 23,013; 24,196; 24,220; 24,664; molecular weights of the proteases are in a relative narrow
29,667; and 29,662, respectively. They are single peptide range (2035 kDa) and they have activities in a wide pH
chains having more asparagine and aspartic acid residues but scope.
less lysine. They have a wide functional acidic range (pH 1.0
11.0) and do not inactivate until 60 C. The enzyme activity
(LrP-II and LrP-III-1) is maximally exhibited around pH 9.0 3. Localization of the Protease in an Earthworm
at 50 C [24].
Ef Ps are expressed and synthesized in the epithelial cells and
In 2005, Nakajima and colleagues purified an enzyme
mainly localized in the crop and gizzard, particularly in the
that catalyzes the hydrolysis of triacylglycerol [25]. The N-
anterior alimentary regions (Figures 1 and 2) [30]. In these
terminal amino acid sequence and the catalytic function of
regions, the proteases maybe contribute to digest protein and
the purified enzyme were identical to those of LrP-II. The
peptide in food.
isozyme might act on the hydrolysis of triacylglycerol as well
as the protein decomposition.
4. Activity Assays
2.2. Isozymes from Eisenia fetida. In 1988, Zhou and cowork-
ers [22] separated at least seven components with fibrinolytic There are three methods to measure the activity of the
activity from earthworm E. fetida. They are stable at pH 5.0 isozymes: fibrin plate, chromophoric procedure, and light
9.0 and denaturated below pH 2.6. After that, a plasminogen scattering (Table 2). Initially, fibrinolytic activity is measured
activator (e-PA) with two subunits was separated from E. by both plasminogen-rich and plasminogen-free fibrin plates
fetida [10], similar to the results reported previously [6]. This [31, 32]. Individual earthworm is cut into pieces and placed
enzyme is considered a serine protease and its molecule mass on a plasminogen-rich fibrin plate. The fibrinolytic activity is
is 45,000 Da. The two constituting subunits (26,000 Da and determined by measuring the diameter of the plaque. Later,
18,000 Da) with dierent fibrinolytic activities are bound an assay using chromophoric substrate has been developed
by hydrophobic interaction. Wu and colleagues isolated [24]. When the chromophoric substrate Chromozym TH
eight fibrinolytic enzymes (Ef P-0-1, Ef P-0-2, Ef P-I-1, Ef P- reacts with the proteases, the absorbance at 405 nm will
I-2, Ef P-II-1, Ef P-II-2, Ef P-III-1, and Ef P-III-2) through a increase. The linear section from 15 to 30 seconds is
stepwise-purification procedure in 2007 [26]. They are all used to calculate the activity of the protease. The unit is
glycoproteins (Table 1). Two of them (Ef P-0-2 and Ef P-II- defined as the specific activity required converting 1 M
2) are new isozymes and the other six in their primary substrate/minutes/mg of enzyme.
structures are similar to those purified by Mihara and Another method records the changes of the scattering
coworkers. intensity during the conversion of fibrinogen to fibrin
In 2008, another serine protease was purified from the [33]. Changes of the scattering intensity of the thrombin-
coelomic fluid of the earthworm E. fetida [27]. It has fibrin colloid follow a sigmoid curve with a relaxation
strong antiviral activities against cucumber mosaic virus and phase and the maximum at 480 nm. The intercept at the
tomato mosaic virus. The protease (27,000 Da) is the most maximum slope is directly proportional to the concentration
active at pH 9.5 and 4050 C. of thrombin when fibrinogen is at a constant concentration.
Thus, the intercept is employed to calculate the thrombin
2.3. Isozymes from Lumbricus bimastus. Three proteins have activity. The earthworm protease blocks the increase in the
been isolated from the extraction of earthworm L. bimastus light scattering intensity, because the enzyme hydrolyzes
by Xu and coworkers [28]. The apparent molecular masses both fibrinogen and fibrin. The amount of the protease is
of the proteins are about 30,000, 29,000, and 28,000 Da inversely proportional to the intensity.
exhibited on SDS-PAGE, respectively. The fragment encodes
a 242-amino-acid protein called PV242 .
5. Substrates of the Earthworm Protease
2.4. Isozymes from Eisenia andrei. Lee and colleagues have The earthworm protease shows dierent activities in the
isolated a protease fraction (SPP-501) from the earth- presence of dierent substrates. LrP-I (Ef P-I) is considered
worm E. andrei [29]. The antithrombotic activity has a chymotrypsin-like protease [4]. Ef P-II is capable of
been investigated in a thrombosis model. SPP-501 shows recognizing the six substrates N--benzoyl-L-Arginine ethyl
Applied and Environmental Soil Science 3
Gizzard
Crop Clitellum Intestine
1 2 3 4 5 6 7 8 9
(a)
120
1
2
80
8
RA (%)
9 3
7 40
4
6
0
5
0 2 4 6 8 10
Sections
(b) (c)
Figure 1: Localization and total relative activity of the earthworm segments: (a) nine pieces of the earthworm E. fetida (b) fibrin plate assay
(c) enzymic activity of each segment (see [30]).
ester (BAEE), N-acetyl-L-tyrosine ethyl ester (ATEE), Chro- various substrates, which may make for their living in a vile
mozym TH (Ch-TH, Car-Val-Gly-Arg-4-NA), Chromozym environment.
TRY (Ch-TRY, Tos-Gly-Pro-Arg-4-NA), Chromozym U
(Ch-U, Ben--Ala-Gly-Arg-4-NA), and Chromozy ELA (Ch- 6. Inhibitors of the Earthworm Protease
ELA, Suc-Ala-Ala-Ala- pNA ) and gives relative Km values as
follows: [KmTH ] < [KmU ] < [KmELA ] < [KmBAEE ] < [KmTRY ] The activity of the earthworm protease is inhibited by several
< [KmATEE ]. This sequence indicates that Ef P-II acts as inhibitors [4, 9, 23, 35, 36]. Diisopropyl fluorophosphate
a strong thrombin-like, moderate elastase-like, and weak (DFP) completely inhibits the activity of all the isozymes
chymotrypsin-like serine protease. On the other hand, Ef P- (pH 7.2) at room temperature. LrP-I-0, LrP-I-1, and LrP-I-2
III-1 reacts with neither Ch-ELA nor ATEE, but reacts are partially inhibited while LrP-III-1 and LrP-II are strongly
with BAEE, Ch-TRY, Ch-U, and Ch-TH, giving relative Km inhibited by SBTI and aprotinin. However, the activity
values as follows: [KmBAEE ] < [KmTRY ] < [KmU ] < [KmTH ], of the protease is not significantly aected by tosyl-lysyl-
characteristic of a trypsin-like protease. Note that the Km chloromethylketose, Tosyl-phenylalanyl chloromethylketose,
values for these substrates are approximately of the same elastatinal, -amino caproic acid, EDTA, or various metal
order of magnitude (105 M), suggesting a higher substrate ions [23]. The specificity of substrates and inhibitors gives
specificity for Ef P-III-1 than that for Ef P-II [34]. The the evidence that the isozymes are alkaline serine-like
earthworm proteases have the abilities to degrade and digest proteases.
4 Applied and Environmental Soil Science
(a1) (b1)
(a2) (b2)
(a3) (b3)
Figure 2: In situ localization of Ef P-II and Ef P-III-1 in the intestine of Eisenia fetida (a) segment 2 as shown in Figure 1. Anti-Ef P-II (panel
a2) or anti-Ef P-III-1 (panel a3) as primary antibodies was added, without adding the primary antibodies as control (panel a1). (b) Segment
5 (see [30]).
2 -Macroglobulin (2 M), at a high concentration enzyme mole by mole equivalently and the interaction may
(approx. 2.0 M) in blood plasma, is an important endoge- undergo a chelate irreversible inhibition.
nous inhibitor with the ability to inhibit all four classes of
(cysteine, serine, aspartate, and metallo) proteases [37, 38].
The fibrinolytic activity of LrP-III-1 decreased to 65% when 7. Protein Structural Features
incubated with 2 M, while it decreases to 30% in the plasma
under the same conditions [39]. After LrP-III-1 goes into 7.1. Primary Structure. As shown in Table 3, the N-terminal
blood, the enzyme may be firstly inhibited by 2 M because sequences of the isozymes from L. rubellus and E. fetida have
the kinetics of inactivation of LrP-III-1 with 2 M is similar been analyzed [26]. The sequences of the isozymes from
to that of the initial phase with plasma. 2 M binds to the L. rubellus and E. fetida have a lot of identical residues.
Applied and Environmental Soil Science 5
The N-terminal sequences of LrP-III-1 and LrP-III-2 are of the substrate and induced fit of the S1 pocket are achieved.
identical, and so are those of LrP-I-1 and LrP-I-2; Ef P-0- Compared with the stable active site of Ef P-III-1, that of Ef P-
1 and Ef P-0-2; Ef P-I-1 and Ef P-I-2; Ef P-II-1 and Ef P-II-2; II (EFEa) is more flexible, resulting in a broader substrate
Ef P -III-1and Ef P -III-2, respectively. As shown in Figure 3, specificity [13].
so far, they all are thought to belong to the serine protease
family, which could be further divided into three groups
according to the following sequences: earthworm protease- 8. Fibrinolytic Mechanism and Cleavage Sites
1 (Ef P-0), earthworm protease-2 (Ef P-I, EFEa, and Ef P-II), The earthworm proteases have relatively broad substrate
and earthworm protease-3 (Ef P-III-1, EFEb, LrP-III-1, and specificities, such as trypsin (cleaving the carboxylic sites of
LrP-III-2), as shown in the phylogenetic tree. Arg and Lys) and chymotrypsin (cleaving the carboxylic sites
The glycan chains play a role in the stability, the spatial of Phe, Trp, Tyr, and Leu) [34, 58]. Furthermore, Ef P-III-
conformation, and the antigenicity of the protein. Recent 1 specifically recognizes the carboxylic sites of arginine and
studies show that the earthworm proteases are glycosylated lysine. The protease cleaves the chain of fibrinogen at R252 -
[26]. The result of staining on the native-SDS gel with G253 , R19 -V20 , and K429 -V430 , respectively. According to the
Schi s reagent shows that the eight isozymes isolated from densities of the protein bands on the SDS-PAGE, hydrolysis
Eisenia fetida by Wu and colleagues are all glycoproteins. In of chain is the fastest, and hydrolysis of chain is faster
addition, the contents of sugar have been determined with than that of chain. This indicates that Ef P-III-1 possesses
sodium metaperiodate and glycoprotein-test reagent, shown strong -fibrinogenase, moderate -fibrinogenase, and weak
in Table 4. The proteases have dierent glycan contents and -fibrinogenase activities. Ef P-III-1 activates plasminogen
the oligosaccharides are composed of mannose residues. cleaving at R557 -I558 . This cleavage site is also recognized
by tPA. Besides, Ef P-III-1 has Xa-like function. Ef P-III-1
7.2. Secondary Structure. The secondary structures of LrP- recognized peptidyl bonds at R3 -A4 , R158 -S159 , R274 -T275 ,
III-1 [40], LrP-III-2 [41], EFEa [42], EFE-b [43], Ef P-0 R396 -N397 , and R287 -T288 . Ef P-III-1 cleaves prothrombin at
[44], Ef P-I [45], Ef P-II [46], and Ef P-III-1 [47] are predicted R274 -T275 , thereby releasing the intermediates fragment 1.2
on the basis of their primary structures. The proteins have and prethrombin-2. As mentioned above, Ef P-III-1 cleaves at
distinct predicted secondary structures, for example, -sheet, R287 -T288 and releases an -thrombin-like product with a 13-
-helix, turn, and coil, as shown in Table 5. The sequence residue deletion at the N-terminus of a chain. Similar to the
of Ef P-II (EFEa) is highly similar to some related serine preference for residue N397 by thrombin, which produces the
proteases with known structures [4854] or other earthworm -thrombin-like fragments [59], Ef P-III-1 cleaves at residue
serine proteases [55] (Table 6). R396 . That is to say, Ef P-III-1 has the ability to hydrolyze
fibrinogen and to activate plasminogen and prothrombin,
7.3. Tertiary Structure. The catalytic characterization of the playing a part not only in fibrinogenolysis but also in
earthworm protease is influenced directly by their tertiary fibrogenesis. Based on this, the roles of Ef P-III-1 in proco-
structures. The crystal structural study shows that Ef P-III- agulation and anticoagulation can be summarized as follows
1 (EFE-b) is a trypsin-like protease with two chains (an N- (Figure 5). The function in both activating prothrombin and
terminal, pyroglutamated light chain and an N-glycosylated catalyzing fibrinogenolysis suggests that Ef P-III-1 plays a role
heavy chain) [56]. The structural features (Figure 4) proba- in the balance between procoagulation and anticoagulation.
bly endow Ef P-III-1 with high level of stability in resistance
to heat, organic solvents, and proteases [57]. 9. Oral Administration
Ef P-II is not only a chymotrypsin-like serine protease
but also has an essential S1 pocket of elastase (Figure 4). The Usually the macromolecules cannot permeate the biological
S1 specificity pocket is preferable for elastase-specific small membranes. In particular, protein can be degraded by
hydrophobic substrate, while its accommodation of long pepsin, trypsinase, and chymotrypsin. The gastric juice
and/or bulky substrate is also feasible if enhanced binding has a low pH value and denatures the ordinary proteins.
6 Applied and Environmental Soil Science
20 40 60 80
Ef P-0
Ef P-I
Ef P-II
EFEa
Ef P-III-1
EFEb
LrP-III-1
LrP-III-2
Ef P-0
Ef P-I
Ef P-II
EFEa
Ef P-III-1
EFEb
LrP-III-1
LrP-III-2
Ef P-0
Ef P-I
Ef P-II
EFEa
Ef P-III-1
EFEb
LrP-III-1
LrP-III-2
260
Ef P-0
Ef P-I
Ef P-II
EFEa
Ef P-III-1
EFEb
LrP-III-1
LrP-III-2
EFEa
Ef P-II
Ef P-I
Ef P-0
Ef P-III-1
EFEb
LrP-III-2
LrP-III-1
491.9
450 400 350 300 250 200 150 100 50 0
Amino Acid Substitutions (100)
Figure 3: Multiple sequence alignment of some earthworm proteases. The amino acid sequences were from GenBank and PDB (see [4047]).
Applied and Environmental Soil Science 7
Table 6: Comparison of homologous sequences with some serine play a role in the process of the membrane transportation
proteases. of biological macromolecules.
Proteases Identity (%)
Pocine pancreatic elastase (PPE) 36 10. Clinical Application and Medical Research
Human leukocyte elastase (HLE) 28
Trypsin 35 10.1. The Earthworm Protease as a Fibrinolytic Agent. The
Chymotrypsin 34 formation of thrombus in the blood causes many devastating
U(t)-PA, Plasmin 32 diseases such as stroke and myocardial infarction. Several
enzymes have been used as the thrombolytic agents includ-
F-III-1(2) 35
ing urokinase (UK), streptokinase, recombinant tissue-type
Earthworm chymotrypsinogen 31
plasminogen activator, staphylokinase, and recombinant
Lugworm chymotrypsinogen 44 prourokinase [63, 64]. These agents are administered via
See Tang et al. [13]. intravenous injection generally. Some of them are eective,
but they also have some limitations such as fast clearance,
lack of resistance to reocclusion, bleeding complications, and
other adverse eects [63].
Whereas, some therapeutic proteins with specific prop- The earthworm protease functions in the fibrinolysis
erties can be absorbed with the intact and active form and plasminogen activation, distinct from those enzymes
before being degraded in the alimentary tract, such as - (UK, tissue-type plasminogen activator, etc.) [6567]. There-
lactoglobulin, hepatitis-B surface antigen, bromelain, and fore they have been used to treat the thrombosis. The
epoxy--carotenes [60]. proteases during orally experiments both in animals and
Furthermore, the earthworm protease could also be clinics show significant fibrinolytic ecacy. A distinct
transported into blood through intestinal epithelium and amelioration is observed in the treatment of blood high-
perform its biological functions in the blood [61]. The in viscosity syndrome and thrombocytosis [68]. In addition,
vitro experimental data show that 15% intact LrP-III-1 is the proteases are stable during a long-term storage at
absorbed through intestinal epithelium. About 10% full- room temperature [69], in the form of oral capsule.
size enzyme is transported through the peritoneum after the Earthworm is easily raised, which renders the isozymes
intraperitoneal injection in the rat. The maximum activity in into a relatively inexpensive thrombolytic agent. So far, the
blood is detected around 60 minutes after the injection. earthworm proteases have been used as an orally admin-
The N-terminal sequences of LrP-III-1 and LrP-III-2 are istered fibrinolytic agent to prevent and treat clotting dis-
similar to protein transduction domain [62]. The sequences eases, such as myocardial infarction and cerebral thrombus
are rich in hydrophobic amino acid residues, which may [70].
8 Applied and Environmental Soil Science
4 4
3 3
2 C 2 C
A A
(a)
(b)
Figure 4: Superposition of EFE-b with EFE-a and trypsin. (a) Stereoview of the superposition of EFE-b with EFE-a is illustrated as follows:
EFE-b is represented by green and EFE-a by light goldenrod yellow. The glycan is represented by a ball-and-stick model (carbon atoms,
green). Some loops in which EFE-b greatly diers from EFE-a are indicated: loop A (3441); loop C (97103); loop 2 (217225); loop 3
(169174); loop 4 (201208). (b) Stereoview of the superposition of EFE-b with trypsin is illustrated as follows: EFE-b is represented by
green and trypsin (Protein Data Bank, accession number, 1PPE) by orange. The glycan is represented by a ball-and-stick model (carbon
atoms, green) (see [56]).
of G-90 on the fibrinolysis rate is related to not only infarction in rats. Decreasing of the ICa-L and [Ca2+ ]i in
its concentration, but also to histological type where the ventricular myocytes is the possible mechanism.
malignant tumors invade. The blood with the fibrin clots The study has been conducted with 10 patients who had
derived from the dogs with cardiopathies and the dogs with coronary artery disease and stable angina. Stress technetium-
malignant tumors was examined for the time of coagulation 99 m sestamibi myocardial perfusion imaging has been
and fibrinolysis by adding dierent substances including G- performed before and at the end of the treatment period.
90. The clotting time in the presence of G-90 shows dogs with As a result, the angina symptom is ameliorated in 6 out of
malignant tumors > healthy dogs > dogs with cardiopathies 10 patients. No adverse reaction such as major or minor
[14]. bleeding has been observed. That is to say, oral LrP improves
Recently, a glycosylated component is separated from regional myocardial perfusion in patients with stable angina
the earthworm E. fetida by Xie and coworkers [76], which [83]. In this research, some expectable results have been
has relations with apoptosis of tumor cells. It is highly achieved on patients with coronary artery disease and stable
homologous to LrP-I-1 and LrP-I-2. It is identified to be a angina. It is in favor of better application of earthworm
plasmin and also a plasminogen activator. From the results of proteases.
the phase-contrast microscopy observation of apoptotic cells The mechanism of the anti-ischemia function of LrP
and the localization of fluorescent antibodies in cell nucleus, in brain has been also studied. The results show that the
the antitumor activity is observed. anti-ischemic activity of LrP was due to its antiplatelet
The earthworm protease possesses obvious anti-tumor activity by elevating cAMP level and attenuating the calcium
activity in the hepatoma cells. The proliferation of the release from calcium stores, the antithrombosis action due
hepatoma cell treated with the proteases is inhabited in to inhibiting of ICAM-1 expression, and the antiapoptotic
proportion to the concentration of the proteases. The eect due to the activation of JAK1/STAT1 pathway [84].
growth of tumor xenograft in nude mice is significantly
suppressed after being fed with the earthworm protease for
four weeks. At the same time, it has been found that the 11. Problems and Potential Solutions of
earthworm protease can induce apoptosis of hepatoma cells the Earthworm Protease as a Medicine
and downregulated the expression of matrix metal protease-
2. As described above [77], the earthworm protease is a Though the earthworm protease has good pharmaceutical
potential candidate for treating some kind of tumors. eect in clinic application, some limitations still exist as
a clinical fibrinolytic agent. It hydrolyzes not only the
fibrinogen and fibrin but also some other proteins in vivo.
10.3. Assistant to Implantation. After an artificial organ is
Besides, the half-life of the earthworm protease is short in
introduced into a living body, small thrombus is usually
circulation. An ideal fibrinolytic medicine should meet the
formed on the surface of the graft. Many approaches have
qualifications such as strong fibrinolytic activity, specificity
been tried to improve the blood compatibility to biomaterial.
on fibrinogen and fibrin, low immunogenicity, long half-life
However, the results, so far, are not satisfactory. In 1994,
in vivo, low reocclusion rate, and reasonable cost [85]. In
LrP was immobilized on the surface of polyurethane using
order to increase the bioavailability and strengthen the drug
maleic anhydride methylvinyl ether copolymer as an enzyme
action, dierent methods are under trials.
carrier [78]. So the LrP-immobilized polyurethane surface
has highly antithrombogenic activity and can reduce surface-
induced thrombus. LrP-immobilized surface may minimize
11.1. Drug Delivery. Recently, some other ways of drug
platelet adhesion and activation by preventing fibrinogen
delivery have been studied. In Chengs research, a water-
from adsorption or by altering the conformation of adsorbed
soluble earthworm protease was used in the delivery of the
fibrinogen at an early stage of blood contact.
water-in-oil (w/o) microemulsions. The w/o microemulsion
LrP has been immobilized in a Korean-type total artificial
comprises of Labrafac CC, Labrasol, Plurol Oleique CC
heart valve by photoreaction, and polyallylamine is used as
497, and saline (54/18/18/10% w/w). The characters of
a photoreactive linker [7981]. The proteolytic activity on
conductivity, viscosity, particle size, and in vitro mem-
the azocasein of the treated valves is three times higher than
brane permeability have been studied. The intraduodenal
that of untreated valves. The LrP-treated polyurethane valve
bioavailability of the microemulsion group was 208 folds
leads to decreasing thrombus formation in vivo and their
higher than that of control group. Meanwhile, no tissue
biocompatibility is, therefore, greater than that of untreated
damage of the intestinal mucosa has been found after oral
valve. This method may be developed and may be useful in
multiple-dose administration of the protease microemulsion
clinical application.
to rats. Therefore, the w/o microemulsion is a promising oral
delivery system for hydrophilic bioactivity macromolecules
10.4. Anti-Ischemia. Recently, the eect of the earthworm [86].
protease against myocardial ischemia [82] has been investi- Besides, the eect of some absorption enhancers on the
gated on a rat model with acute myocardial infarction. Mean- intestinal absorption of the earthworm protease has been
while the L-type calcium current (ICa-L) and intracellular studied including chitosan, sodium deoxycholate, Na2 EDTA,
calcium concentration ([Ca2+ ]i) have been measured. The sodium dedocyl sulfate, sodium caprylate, poloxamer, and
results indicate that it has protective actions on myocardial HP-beta-CD. The enzyme can be transported into blood
10 Applied and Environmental Soil Science
and kept its biological activity across intestinal endothe- in the production of amino acids from elastin, hemoglobin,
lial membrane after administration via duodenum site, casein, and collagen. Thus, the proteases are useful in the field
whereas with lower bioavailability. Some of the absorption of waste treatment of nondegradable proteins.
enhancers have eects on intestinal absorption in vitro
and in situ experiments [87]. So the safety enhancer with 12.2. Hydrolyzation of Ester. The earthworm proteases exhib-
few side eects is a good choice for drug manufacturing ited ester-hydrolyzing ability as well as the proteolytic activity
enterprise. [69]. The earthworm proteases could be used as a biocatalyst
for unmasking of the unnecessary acetyl moiety from the
11.2. Parental Routes of Administration. The oral administra- building blocks in organic synthesis. For example, the prepa-
tion of the earthworm proteases has a relatively slow absorp- ration of vinyl p-coumarate from the acetyl p-coumarate
tion process; hence, it is unsuitable to treat the emergency vinyl ester in ethanol is enabled using isozymes LrP-III-1,
thrombus such as acute myocardial infarction, acute cerebral LrP-III-2, and LrP-II. Polylactate film was decomposed to
thrombosis, peripheral limbs arteriovenous thrombus. and some extent by the enzyme.
other acute diseases involved in thrombosis. Therefore the
injection agent is another choice. In order to fulfill the 12.3. Nutrition for the Microorganisms. The production of
goal, first, we should analyze all primary structures of the the autolysate is considered to be caused mainly by the action
isozymes and identify essential groups and then search the of the earthworms own proteases without the involvement of
relationship between structure and function that are related microbial degradation [69]. Growth of the microorganisms
to the preparation of injection agent. Second, the antigenic in the medium with the autolysate in place of polypepton
features of the isozymes should be investigated [88]. Third, and in the original medium without changes in the other
the structure of the earthworm proteases molecule should ingredients has been compared. The growth of bakers yeast
be optimized and modified chemically, so that the domains in the medium containing the same amount of earthworm
or groups leading to hostile responses could be removed or autolysate as would have been used for polypepton is
blocked. Finally the method of cloning and expressing of the substantially better than that in the medium containing
recombinant earthworm proteases should be established to polypepton. E. coli XL1-blue as well as Bacillus coagulans IFO
investigate the possibility of an injection agent produced by 12583 and B. stearothermophilus DSM 297 could grow in the
gene engineering. media containing the autolysate as well as in those containing
polypepton [69].
11.3. Chemically Modified Structure. In order to enhance the
ecacy and tolerability of thrombolytic agents, we should 13. Conclusion
improve the specificity of the enzyme on fibrin to decrease
the side eects and enhance the resistance to plasminogen Earthworm proteases are getting more significant in our
activator inhibitor to elongate the half-life. daily life nowadays. It is applicable in both experiment
Chemical modification has been used to stabilize the and production, such as medical usage, environmental
native structure of the earthworm protease and decrease the protection, and nutritional production. In the near future,
antigenicity during administration. The stabilization of the more products based on the earthworm protease will reach
protease is managed by chemical modification of the enzyme the market.
with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and
phenylglyoxal to protect the activity from the autolytic Acknowledgments
inactivation. Stabilization is also possible under acidic con-
ditions, in which the stability of the enzyme was rather The authors are grateful to Wen-Rui Chang for kindly
low, by immobilization with folded sheet mesoporous mate- providing his X-ray crystal structural figures of EFEa and
rial [89]. The strongest fibrinolytic protease LrP-III-2 has EFEb. The authors also thank Yuan Zhou for her useful
been modified chemically with fragmented human serum advice for this paper. This work was in part supported by
albumin (MW, 10,00030,000) [90]. The modified enzyme NSFC (30870544).
lost the antigenicity of the native enzyme. The enzyme is
a nonhemorrhagic protein and does not induce platelet References
aggregation. The enzyme kept potent proteolytic activity
for fibrin and fibrinogen than that of human plasmin. The [1] L. Fredericq, La digestion des matieres albuminoides chez
enzyme easily solubilizes actual fibrin clots (thrombi) of quelques invertebres, Archives de Zoologie Experimentale et
whole blood induced by thrombin in a rats vena cava. Generale, vol. 7, p. 391, 1878.
[2] D. Keilin, On the pharyngeal or salivary gland of the
earthworm, Quarterly Journal of Microscopical Science, vol. 65,
12. Other Potential Utilizations pp. 3361, 1920.
[3] H. Mihara, H. Sumi, and K. Akazawa, Fibrinolytic enzyme
12.1. Degradation of Proteins in Waste. The proteolytic extracted from the earthworm, Thrombosis and Haemostasis,
activity, except for the fibrinolytic activity, of the earthworm vol. 50, p. 258, 1983.
protease has been studied using various protein substrates. [4] H. Mihara, H. Sumi, T. Yoneta, et al., A novel fibrinolytic
Both LrP-III-2 and LrP-II are more eective than trypsin enzyme extracted from the earthworm, Lumbricus rubellus,
Applied and Environmental Soil Science 11
Japanese Journal of Physiology, vol. 41, no. 3, pp. 461472, [20] J. E. Satchell, Lumbricidae, in Soil Biology, A. Burges and F.
1991. Raw, Eds., pp. 259322, Academic Press, New York, NY, USA,
[5] P. Wu and R. Fan, An eective and rapid thromblytic agent 1967.
e-TPA, Acta Biophysica Sinica, vol. 87, 1986. [21] Y. Lu, R. Jin, Y. Wu, and X. Mang, The purification and char-
[6] J. S. Yang and B. G. Ru, Purification and characterization acterization of fibinolytic enzymes from Amynthas dancatala,
of an SDS-activated fibrinolytic enzyme from Eisenia fetida, Chinese Journal of Biochemistry & Molecular Biology, vol. 4, pp.
Comparative Biochemistry and Physiology Part B, vol. 118, no. 166172, 1988.
3, pp. 623631, 1997. [22] Y. C. Zhou, H. Zhu, and Y. C. Chen, The isolation and
[7] J. S. Yang, L. Y. Li, and B. G. Ru, Degradation of N-acetyl- purification of earthworm fibrinolytic protease from Eisenia
L-tyrosine ethyl ester (ATEE) by a plasminogen activator fetida, Acta Biochimica et Biophysica Sinica, vol. 20, pp. 35
from Eisenia fetida (e-PA), Chinese Journal of Biochemistry & 42, 1988.
Molecular Biology, vol. 14, pp. 417421, 1998. [23] N. Nakajima, H. Mihara, and H. Sumi, Characterization
[8] J. S. Yang, L. Y. Li, and B. G. Ru, Degradation of benzoyl- of potent fibrinolytic enzymes in earthworm, Lumbricus
L-arginine ethyl ester (BAEE) by a plasminogen activator rubellus, Bioscience, Biotechnology & Biochemistry, vol. 57, no.
from Eisenia fetida (e-PA), Chinese Journal of Biochemistry & 10, pp. 17261730, 1993.
Molecular Biology, vol. 14, pp. 412416, 1998. [24] J. Zhou, R. Fan, C. Wu, and R.-Q. He, Assay of lumbrokinase
[9] J. S. Yang, L. Y. Li, and B. G. Ru, Characterization of a with a chromophoric substrate, Protein and Peptide Letters,
plasminogen activator from Eisenia fetida, Chinese Journal of vol. 4, no. 6, pp. 409414, 1997.
Biochemistry & Molecular Biology, vol. 14, pp. 164169, 1998. [25] N. Nakajima, M. Sugimoto, S. Tsuboi, H. Tsuji, and K.
[10] J. S. Yang, L. Y. Li, and B. G. Ru, Purification of a plasminogen Ishihara, An isozyme of earthworm serine proteases acts
activator from Eisenia fetida, Chinese Journal of Biochemistry on hydrolysis of triacylglycerol, Bioscience, Biotechnology &
& Molecular Biology, vol. 14, pp. 156163, 1998. Biochemistry, vol. 69, no. 10, pp. 20092011, 2005.
[11] J. S. Yang, Y. Q. Guo, and B. G. Ru, The enzymology [26] J. X. Wu, X. Y. Zhao, R. Pan, and R. Q. He, Glycosylated
properties and the CD spectra of the active centers of the small trypsin-like proteases from earthworm Eisenia fetida, Inter-
subunit of a plasminogen activator from Eisenia fetida (e-PA), national Journal of Biological Macromolecules, vol. 40, pp. 399
Chinese Journal of Biochemistry & Molecular Biology, vol. 14, 406, 2007.
pp. 721725, 1998.
[27] M. Ueda, K. Noda, M. Nakazawa, et al., A novel anti-plant
[12] Y. Tang, J. Zhang, L. Gui, et al., Crystallization and pre-
viral protein from coelomic fluid of the earthworm Eisenia
liminary X-ray analysis of earthworm fibrinolytic enzyme
foetida: purification, characterization and its identification as a
component A from Eisenia fetida, Acta Crystallographica D,
serine protease, Comparative Biochemistry and Physiology Part
vol. 56, no. 12, pp. 16591661, 2000.
B, vol. 151, no. 4, pp. 381385, 2008.
[13] Y. Tang, D. Liang, T. Jiang, J. Zhang, L. Gui, and W.
[28] Y. Xu, G. Liang, Z. Sun, et al., Cloning and expression of the
Chang, Crystal structure of earthworm fibrinolytic enzyme
novel gene-PV242 of earthworm fibrinolytic enzyme, Progress
component A: revealing the structural determinants of its dual
in Biochemistry and Biophysics, vol. 29, pp. 610614, 2002.
fibrinolytic activity, Journal of Molecular Biology, vol. 321, no.
[29] C. K. Lee, J. S. Shin, B. S. Kim, I. H. Cho, Y. S. Kim, and E. B.
1, pp. 5768, 2002.
Lee, Antithrombotic eects by oral administration of novel
[14] M. Popovic, T. M. Hrzenjak, T. Babic, J. Kos, and M. Grdisa,
proteinase fraction from earthworm Eisenia andrei on venous
Eect of earthworm (G-90) extracton formation and lysis of
thrombosis model in rats, Archives of Pharmacal Research, vol.
clots originated from venous blood of dogs with cardiopathies
30, pp. 475480, 2007.
and with malignant tumors, Pathology and Oncology Research,
vol. 7, no. 3, pp. 197202, 2001. [30] J. Zhao, R. Xiao, J. He, et al., In situ localization and
[15] M. Popovic, T. M. Hrzenjak, M. Grdisa, and S. Vukovic, substrate specificity of earthworm protease-II and protease-
Adhesins of immunoglobulin-like superfamily from earth- III-1 from Eisenia fetida, International Journal of Biological
worm Eisenia fetida, General Pharmacology, vol. 30, pp. 795 Macromolecules, vol. 40, no. 2, pp. 6775, 2007.
780, 1998. [31] H. Sumi, N. Nakajima, and H. Mihara, A very stable and
[16] T. M. Hrzenjak, M. Popovic, and L. Tiska-Rudman, Fib- potent fibrinolytic enzyme found in earthworm Lumbricus
rinolytic activity of earthworms extract (G-90) on lysis of rubellus autolysate, Comparative Biochemistry and Physiology
fibrin clots originated from the venous blood of patients with Part B, vol. 106, pp. 763766, 1993.
malignant tumors, Pathology & Oncology Research, vol. 4, no. [32] A. Tage and M. Sten, The fibrin plate method for estimating
3, pp. 206211, 1998. fibrinolytic activity, Archives of Biochemistry and Biophysics,
[17] T. M. Hrzenjak, M. Popovic, T. Bozic, M. Grdisa, D. Kobre- vol. 40, no. 2, pp. 346351, 1952.
hel, and L. Tiska-Rudman, Fibrinolytic and anticoagulative [33] J. Zhou, K. Jiang, R. He, and Y. Han, Assays of therombin,
activities from the earthworm Eisenia foetida, Comparative hirudin and lumbrokinase with light scattering in the solution
Biochemistry and Physiology Part B, vol. 119, no. 4, pp. 825 of fibirinogen, Acta Biophysica Sinica, vol. 14, pp. 531535,
832, 1998. 1997.
[18] T. Hrzenjak, M. Hrzenjak, V. Kasuba, P. Efenberger- [34] J. Zhao, R. Pan, J. He, Y. Liu, D. F. Li, and R. Q. He,
Marinculic, and S. Levanat, A new source of biologically Eisenia fetida protease-III-1 functions in both fibrinolysis and
active compounds-earthworm tissue (Eisenia foetida, Lumbri- fibrogenesis, Journal of Biomedicine and Biotechnology, vol.
cus rubelus), Comparative Biochemistry and Physiology Part A, 2007, Article ID 97654, 10 pages, 2007.
vol. 102, no. 3, pp. 441447, 1992. [35] S. Mao, Z. Yan, and S. Chen, Purification and kinetic char-
[19] M. Grdisa, M. Popovic, and T. Hrzenjak, Glycolipoprotein acteristics of fibrinolytic enzymes from earthworm, Journal of
extract (G-90) from earthworm Eisenia foetida exerts some Wenzhou Medical College, vol. 30, pp. 277278, 2000.
antioxidative activity, Comparative Biochemistry and Physiol- [36] J. Zhao, L. Li, C. Wu, and R.-Q. He, Hydrolysis of fibrinogen
ogy Part A, vol. 128, no. 4, pp. 821825, 2001. and plasminogen by immobilized earthworm fibrinolytic
12 Applied and Environmental Soil Science
enzyme II from Eisenia fetida, International Journal of fetida, Acta Crystallographica D, vol. 60, no. 5, pp. 933935,
Biological Macromolecules, vol. 32, pp. 165171, 2003. 2004.
[37] A. J. Barret and P. M. Starkey, The interaction of 2- [58] N. Nakajima, M. Sugimoto, K. Ishihara, K. Nakamura, and
Macroglobulln with proteinases, Biochemical Journal, vol. H. Hamada, Further characterization of earthworm serine
133, pp. 709724, 1973. proteases: cleavage specificity against peptide substrates and
[38] P. E. H. Jensen and L. Sottrup-Je, Primary structure of human on autolysis, Bioscience, Biotechnology and Biochemistry, vol.
2-Macroglobulin, Journal of Biological Chemistry, vol. 261, 63, no. 11, pp. 20312033, 1999.
pp. 1586315869, 1986. [59] E. Bovill, R. Tracy, T. Hayes, R. Jenny, F. Bhushan, and
[39] C. Wu, L. Li, J. Zhao, Q. Fan, W. X. Tian, and R. Q. K. Mann, Evidence that meizothrombin is an intermediate
He, Eect of 2M on earthworm fibrinolytic enzyme III-1 product in the clotting of whole blood, Arteriosclerosis,
from Lumbricus rubellus, International Journal of Biological Thrombosis, and Vascular Biology, vol. 15, no. 6, pp. 754758,
Macromolecules, vol. 31, pp. 7177, 2002. 1995.
[40] GenBank database, accession number, BAB40768.1. [60] A. B. Barua, Intestinal absorption of epoxy--carotenes by
[41] GenBank database, accession number, BAB40767.1. humans, Biochemical Journal, vol. 339, no. 2, pp. 359362,
[42] GenBank database, accession number, AAM73677.1. 1999.
[43] Protein Data Bank, accession number, 1YM0A. [61] Q. Fan, C. Wu, L. Li, et al., Some features of intestinal
[44] GenBank database, accession number, ABG68022. absorption of intact fibrinolytic enzyme III-1 from Lumbricus
[45] GenBank database, accession number, ABD76397. rubellus, Biochimica et Biophysica Acta, vol. 1526, no. 3, pp.
[46] GenBank database, accession number, ABG68023. 286292, 2001.
[47] GenBank database, accession number, ABB19359. [62] M. Green and P. M. Loewenstein, Autonomous functional
[48] L. H. Takahashi, R. Radhakrishnan, R. E. Rosenfield Jr., E. F. domains of chemically synthesized human immunodeficiency
Meyer Jr., and D. A. Trainor, Crystal structure of the covalent virus tat trans-activator protein, Cell, vol. 55, no. 6, pp. 1179
complex formed by a peptidyl..,..-difluoro-..-keto amide 1188, 1988.
with porcine pancreatic elastase at 1.78.ANG. resolution, [63] M. Verstraete, Third-generation thrombolytic drugs, Amer-
Journal of the American Chemical Society, vol. 111, pp. 3368 ican Journal of Medicine, vol. 109, no. 1, pp. 5258, 2000.
3374, 1989. [64] J. Zhao and D. Li, Research progress on anticoagulant protein
[49] A.-Z. Wei, I. Mayra, and W. Bode, The refined 2.3 A crystal molucular, Microbiology, vol. 29, pp. 102107, 2002.
structure of human leukocyte elastase in a complex with [65] S. Kasai, H. Arimura, M. Nishida, and T. Suyama, Proteolytic
a valine chloromethyl ketone inhibitor, Federation of the cleavage of single-chain pro-urokinase induces conforma-
Societies of Biochemistry and Molecular Biology Letter, vol. 234, tional change which follows activation of the zymogen and
no. 2, pp. 367373, 1988. reduction of its high anity for fibrin, Journal of Biological
[50] M. Marquart, J. Walter, J. Deisenhofer, W. Bode, and R. Huber, Chemistry, vol. 260, pp. 1236712376, 1985.
The geometry of the reactive site and of the peptide groups in [66] E. L. Madison, G. S. Coombs, and D. R. Corey, Substrate
trypsin, trypsinogen and its complexes with inhibitors, Acta specificity of tissue type plasminogen activator, Journal of
Crystallographica B, vol. 39, pp. 480490, 1983. Biological Chemistry, vol. 270, no. 13, pp. 75587562, 1995.
[51] A. Mac Sweeney, G. Birrane, M. A. Walsh, T. OConnell, J. [67] J. S. Kim, J. K. Kang, H. C. Chang, et al., The thrombolytic
P. G. Malthouse, and T. M. Higgins, Crystal structure of eect of lumbrokinase is not as potent as urokinase in a rabbit
deta-chymotrypsin bound to a peptidyl chloromethyl ketone cerebral embolism model, Journal of Korean Medical Science,
inhibitor, Acta Crystallographica D, vol. 56, pp. 280286, vol. 8, no. 2, pp. 117120, 1993.
2000. [68] Y. Cong, Y. Liu, and J. C. Chen, Advance in lumbrokinase,
[52] G. Spraggon, C. Phillips, U. K. Nowak, et al., The crystal Chinese Journal of Biochemical Pharmaceutics, vol. 21, pp. 159
structure of the catalytic domain of human urokinase-type 162, 2000.
plasminogen activator, Structure, vol. 3, no. 7, pp. 681691, [69] N. Nakajima, M. Sugimoto, and K. Ishihara, Stable earth-
1995. worm serine proteases: application of the protease function
[53] L. Doriano, B. Margit, H. Robert, et al., The 2.3 A crystal and usefulness of the earthworm autolysate, Journal of
structure of the catalytic domain of recombinant two-chain Bioscience and Bioengineering, vol. 90, no. 2, pp. 174179,
human t-type plasminogen activator, Journal of Molecular 2000.
Biology, vol. 258, pp. 117135, 1996. [70] L. Jin, H. Jin, G. Zhang, and G. Xu, Changes in coagulation
[54] X. Wang, X. Lin, A. L. Jerey, J. Tang, and X. C. Zhang, and tissue plasminogen activator after the treatment of
Crystal structure of the catalytic domain of human plasmin cerebral infarction with lumbrokinase, Clinical Hemorheology
complexed with streptokinase, Science, vol. 281, no. 5383, pp. and Microcirculation, vol. 23, no. 24, pp. 213218, 2000.
16621668, 1998. [71] F. Zhang and K. W. Wang, The inhibition of hep-2 cells
[55] M. Sugimoto and N. Nakajima, Molecular cloning, sequenc- using earthworm extract (912), Journal of the Fourth Military
ing, and expression of cDNA encoding serine protease with Medical University, vol. 8, p. 224, 1987.
fibrinolytic activity from earthworm, Bioscience, Biotechnol- [72] X. Zeng, B. Zhang, X. Mai, et al., The eects of extraction
ogy and Biochemistry, vol. 65, no. 7, pp. 15751580, 2001. from earthworm on various tumour cells in vitro, Journal of
[56] F. Wang, C. Wang, M. Li, et al., Crystal structure of earth- Shanxi Medical University, vol. 18, pp. 8183, 1995.
worm fibrinolytic enzyme component B: a novel, glycosylated [73] K. Wang, S. Zhang, Y. Li, Q. Tian, and G. Zhi, Antltumori-
two-chained trypsin, Journal of Molecular Biology, vol. 348, genic eect of an extract of rarthworm on S (180) and H (22)
no. 3, pp. 671685, 2005. cells in mice, Journal of the Fourth Military Medical University,
[57] F. Wang, C. Wang, M. Li, L. Gui, J. Zhang, and W. Chang, vol. 7, pp. 8588, 1986.
Crystallization and preliminary crystallographic analysis of [74] W. Zhang, L. Li, and H. Mao, The clinical observation of
earthworm fibrinolytic enzyme component B from Eisenia lymphoma and lung cancer treated with chemical drugs and
Applied and Environmental Soil Science 13
912, Chinese Journal of Clinical Oncology, vol. 18, pp. 181 fibrinolytic enzyme with human serum albumin fragment
182, 1991. and characterization of the protease as a therapeutic enzyme,
[75] S.-Z. Zhang, Q. Tian, K.-W. Wang, and D.-M. Xu, Radio Bioscience, Biotechnology and Biochemistry, vol. 60, no. 2, pp.
enhancement eect of radiotherapy combined with earth- 293300, 1996.
worm capsule in the treatment of esophagus and lung
carcinoma, Journal of the Fourth Military Medical University,
vol. 13, pp. 165168, 1992.
[76] J. B. Xie, Z. Q. Guo, N. Weng, H. T. Wang, G. Q. Jiang, and
B. G. Ru, Purification, identification and partial characteriza-
tion of an apoptosis-related serine protease from earthworm,
Progress in Biochemistry and Biophysics, vol. 30, no. 3, pp. 453
460, 2003.
[77] H. Chen, S. Takahashi, M. Imamura, et al., Earthworm
fibrinolytic enzyme: anti-tumor activity on human hepatoma
cells in vitro and in vivo, Chinese Medical Journal, vol. 120,
no. 10, pp. 898904, 2007.
[78] G. H. Ryu, S. Park, M. Kim, D. K. Han, Y. H. Kim, and
B. Min, Antithrombogenicity of lumbrokinase-immobilized
polyurethane, Journal of Biomedical Materials Research, vol.
28, no. 9, pp. 10691077, 1994.
[79] Y. Park, E. Ryu, H. Kim, et al., Characterization of antithrom-
botic activity of lumbrokinase-immobilized polyurethane
valves in the total artificial heart, Artificial Organs, vol. 23, no.
2, pp. 210214, 1999.
[80] G. H. Ryu, D. K. Han, S. Park, M. Kim, Y. H. Kim, and B.
Min, Surface characteristics and properties of lumbrokinase-
immobilized polyurethane, Journal of Biomedical Materials
Research, vol. 29, pp. 403409, 1995.
[81] G. H. Ryu, S. Park, D. K. Han, Y. H. Kim, and B. Min,
Antithrombotic activity of a lumbrokinase immobilized
polyurethane surface, Asaio Journal, vol. 39, no. 3, pp. 314
318, 1993.
[82] H. L. Sun, J. D. Jiao, Z. W. Pan, D. L. Dong, and B. F. Yang, The
cardioprotective eect and mechanism of lumbrokinase, Yao
Xue Xue Bao, vol. 41, no. 3, pp. 247251, 2006.
[83] M. Kasim, A. A. Kiat, M. S. Rohman, Y. Hanifah, and H. Kiat,
Improved myocardial perfusion in stable angina pectoris by
oral lumbrokinase: a pilot study, Journal of Alternative and
Complementary Medicine, vol. 15, no. 5, pp. 539544, 2009.
[84] H. Ji, L. Wang, H. Bi, et al., Mechanisms of lumbrokinase
in protection of cerebral ischemia, European Journal of
Pharmacology, vol. 590, pp. 281289, 2008.
[85] D. Collen, On the regulation and control of fibrinolysis,
Thrombosis and Haemostasis, vol. 43, no. 2, pp. 7789, 1980.
[86] M. B. Cheng, J. C. Wang, Y. H. Li, et al., Characterization
of water-in-oil microemulsion for oral delivery of earthworm
fibrinolytic enzyme, Journal of Controlled Release, vol. 129, no.
1, pp. 4148, 2008.
[87] Y. H. Li, M. Zhang, J. C. Wang, S. Zhang, J. R. Liu, and
Q. Zhang, Eects of absorption enhancers on intestinal
absorption of lumbrokinase, Yao Xue Xue Bao, vol. 41, pp.
939944, 2006.
[88] X. Y. Zhao, T. Y. Jing, X. Y. Jiang, M. X. Duan, and C. X.
Zheng, Antigenicity of components constituting earthworm
fibrinolytic enzyme, Chinese Journal of Biochemistry & Molec-
ular Biology, vol. 18, pp. 209212, 2002.
[89] N. Nakajima, K. Ishihara, M. Sugimoto, T. Nakahara, and
H. Tsuji, Further stabilization of earthworm serine protease
by chemical modification and immobilization, Bioscience,
Biotechnology and Biochemistry, vol. 66, no. 12, pp. 27392742,
2002.
[90] N. Nakajima, K. Ishihara, M. Sugimoto, H. Sumi, K. Mikuni,
and H. Hamada, Chemical modification of earthworm
Hindawi Publishing Corporation
Applied and Environmental Soil Science
Volume 2010, Article ID 726946, 7 pages
doi:10.1155/2010/726946
Review Article
Heavy Metal-Induced Oxidative DNA Damage in
Earthworms: A Review
Copyright 2010 T. Hirano and K. Tamae. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Earthworms can be used as a bio-indicator of metal contamination in soil, Earlier reports claimed the bioaccumulation of
heavy metals in earthworm tissues, while the metal-induced mutagenicity reared in contaminated soils for long duration. But
we examined the metal-induced mutagenicity in earthworms reared in metal containing culture beddings. In this experiment we
observed the generation of 8-oxoguanine (8-oxo-Gua) in earthworms exposed to cadmium and nickel in soil. 8-oxo-Gua is a major
premutagenic form of oxidative DNA damage that induces GC-to-TA point mutations, leading to carcinogenesis.
O O O H
ROD N N
N HN
HN ( OH) HN
OH O
H2 N N H2 N N
N N N H2 N
N
Guanine 8-hydroxyguanine 7, 8-dihydro-8-oxoguanine
(8-OH-Gua) (8-oxo-Gua)
Figure 1: Structure of 8-oxo-Gua. 8-Oxo-Gua is formed by the hydroxylation of guanine at the C-8 position.
common feature of human cancers. In this context, the most extensively studied, because it can be quantitated with
studies of 8-oxo-Gua, which is an oxidized guanine, have high sensitivity by high-performance liquid chromatography
significant implications for understanding the mechanisms coupled with electrochemical detection (HPLC-ECD), and
of mutation-associated diseases, especially cancer [10]. 8- it is quite easily measured in laboratories [5, 11]. 8-oxo-
oxo-Gua is a mutagenic lesion formed spontaneously in Gua and 8-oxoadenine (8-oxo-Ade) have been well studied
the genomic DNA of aerobic organisms (Figure 1) and in mutagenic oxidized DNA products, and their frequencies
by the actions of exogenous factors, such as ionizing of generation in mammalian DNA and their degrees of
radiation, chemical pollutants, heavy metals, food, and mutagenicity are similar [1215].
bacteria. Although 8-oxo-Gua is not necessarily the most Since 8-oxo-Gua was discovered and reported in 1984
abundant form of oxidative DNA damage, it has been the [16], this form of DNA damage and its repair systems
Applied and Environmental Soil Science 3
70 70 70 70 70 70
Metal concentration
60 60 60
Cd concentration
60 60
Ni concentration
60
50 50 50 50 50 50
40 40 40 40 40 40
30 30 30 30 30 30
20 20 20 20 20 20
10 10 10 10 10 10
0 0 0 0 0 0
S1 200 S1 200 Cd 10
S2 10 S2 10 S1
S3 S3 S2 Ni 10
0 0 S3
S4 S4 S4 NT
CdCl2 3 weeks NiCl2 3 weeks 3 months
(a) (b) (c)
Figure 3: Heavy metal accumulation in E. fetida. Each data point represents the mean of three individuals. Heavy metal concentrations were
measured by atomic absorption spectrometry, and are expressed as g per body weight. (Data are modified by Nakashima et al. [18]).
AC AC AC AC
1 Week
2 Weeks
AC AC AC
AC
3 Weeks
1 Week
SV
with skim milk as a food source until heavy metal exposure. evidence, because almost all of the specimens showed posi-
Three to six individuals were kept in a 600 mL glass container tive signals in the gut epithelial layers and the dierence in the
containing 50 g of soil with/without heavy metal. They were signal strength was too small to conclude that Cd exposure
exposed to 10 or 200 g heavy metal/g soil for 1, 2, and 3 increased 8-oxo-Gua accumulation in the organs. On the
weeks or to 10 g heavy metal/g soil for 3 months (Figure 2). other hand, the positive signals in the seminal vesicles were
As a result, we detected a high level of Cd accumulation in clearly detected only in E. fetida treated with 10 g of Cd for
E. fetida (Figures 3(a) and 3(c)). On the other hand, no Ni 3 months (Figure 4(h)). The seminal vesicles are considered
accumulation was observed (Figures 3(b) and 3(c)). as metallothionein-(MT-)poor organs. Therefore, it seems
In addition, we observed positive staining of 8-oxo-Gua reasonable to speculate that a lower level of MT expression
in the gut epithelial layers in almost all samples (Figures is involved in Cd-induced DNA damage accumulation.
4(a)4(f)). The metal absorption routes include the digestive
system and the surface wall [45, 46], but the main route is 6. Conclusions
the digestive system. Since gut epithelial layers are frequently
exposed to ROS, 8-oxo-Gua accumulation was constantly In our recent study, we observed a high level of Cd accumula-
detected. Although the 200 g Cd-exposed E. fetida showed tion and no Ni accumulation in E. fetida, accompanied with
relatively stronger signals (P1+++ in Table 2) at 2 weeks in an increase in 8-OH-dG accumulation in the organs of Cd-
comparison to the others, this did not seem to be significant exposed E. fetida. Based on these results, it is reasonable to
Applied and Environmental Soil Science 5
[17] K. C. Cheng, D. S. Cahill, H. Kasai, S. Nishimura, and L. [31] Y. Xue, X. Gu, X. Wang, et al., The hydroxyl radical generation
A. Loeb, 8-hydroxyguanine, an abundant form of oxidative and oxidative stress for the earthworm Eisenia fetida exposed
DNA damage, causes G T and A C substitutions, to tetrabromobisphenol A, Ecotoxicology, vol. 18, no. 6, pp.
Journal of Biological Chemistry, vol. 267, no. 1, pp. 166172, 693699, 2009.
1992. [32] R. B. Misra, K. Lal, M. Farooq, and R. K. Hans, Eect of
[18] T. Nakashima, T. Okada, J. Asahi, et al., 8-hydroxydeo- solar UV radiation on earthworm (Metaphire posthuma),
xyguanosine generated in the earthworm Eisenia fetida grown Ecotoxicology and Environmental Safety, vol. 62, no. 3, pp. 391
in metal-containing soil, Mutation Research, vol. 654, no. 2, 396, 2005.
pp. 138144, 2008. [33] F. Brulle, G. Mitta, C. Cocquerelle, et al., Cloning and
[19] M. Vidovic, A. Sadibasic, S. Cupic, and M. Lausevic, Cd real-time PCR testing of 14 potential biomarkers in Eisenia
and Zn in atmospheric deposit, soil, wheat, and milk, fetida following cadmium exposure, Environmental Science
Environmental Research, vol. 97, no. 1, pp. 2631, 2005. and Technology, vol. 40, no. 8, pp. 28442850, 2006.
[20] T. Hirano, Y. Yamaguchi, and H. Kasai, Inhibition of 8- [34] A. J. Reinecke and S. A. Reinecke, Earthworm as test
hydroxyguanine repair in testes after administration of cad- organisms in ecotoxicological assessment of toxicant impacts
mium chloride to GSH-depleted rats, Toxicology and Applied on ecosystems, in Earthworm Ecology, C. A. Edwards, Ed., pp.
Pharmacology, vol. 147, no. 1, pp. 914, 1997. 299320, CRC Press LLC, Boca Baton, Fla, USA, 2004.
[21] N. Mei, N. Kunugita, T. Hirano, and H. Kasai, Acute arsenite- [35] N. T. T. M. Steenbergen, F. Iaccino, M. De Winkel, L. Reijnders,
induced 8-hydroxyguanine is associated with inhibition of and W. J. G. M. Peijnenburg, Development of a biotic ligand
repair activity in cultured human cells, Biochemical and model and a regression model predicting acute copper toxicity
Biophysical Research Communications, vol. 297, no. 4, pp. 924 to the earthworm Aporrectodea caliginosa, Environmental
930, 2002. Science and Technology, vol. 39, no. 15, pp. 56945702, 2005.
[22] C.-K. Youn, S.-H. Kim, D. Y. Lee, et al., Cadmium down- [36] M. G. Burgos, C. Winters, S. R. Sturzenbaum, P. F. Randerson,
regulates human OGG1 through suppression of Sp1 activity, P. Kille, and A. J. Morgan, Cu and Cd eects on the earth-
Journal of Biological Chemistry, vol. 280, no. 26, pp. 25185 worm Lumbricus rubellus in the laboratory: multivariate sta-
25195, 2005. tistical analysis of relationships between exposure, biomarkers,
and ecologically relevant parameters, Environmental Science
[23] K. Bialkowski, A. Bialkowska, and K. S. Kasprzak, Cad-
and Technology, vol. 39, no. 6, pp. 17571763, 2005.
mium(II), unlike nickel(II), inhibits 8-oxo-dGTPase activity
[37] R. Huang, B. Wen, Z. Pei, X.-Q. Shan, S. Zhang, and P. N.
and increases 8-oxo-dG level in DNA of the rat testis, a target
Williams, Accumulation, subcellular distribution and toxicity
organ for cadmium(II) carcinogenesis, Carcinogenesis, vol.
of copper in earthworm (Eisenia fetida) in the presence of
20, no. 8, pp. 16211624, 1999.
ciprofloxacin, Environmental Science and Technology, vol. 43,
[24] T. Hirano, K. Kawai, Y. Ootsuyama, and H. Kasai, Frag- no. 10, pp. 36883693, 2009.
mentation of the DNA repair enzyme, OGG1, in mouse
[38] J. Andre, J. Charnock, S. R. Sturzenbaum, P. Kille, A. John
nonparenchymal liver cells by arsenic compounds, Genes and
Morgan, and M. E. Hodson, Accumulated metal speciation
Environment, vol. 28, pp. 6267, 2006.
in earthworm populations with multigenerational exposure
[25] K. P. Singh, R. Kumari, C. Pevey, D. Jackson, and J. W. to metalliferous soils: cell fractionation and high-energy
DuMond, Long duration exposure to cadmium leads to synchrotron analyses, Environmental Science and Technology,
increased cell survival, decreased DNA repair capacity, and vol. 43, no. 17, pp. 68226829, 2009.
genomic instability in mouse testicular Leydig cells, Cancer [39] Z. S. Zhang, D. M. Zheng, Q. C. Wang, and X. G. Lv, Bioac-
Letters, vol. 279, no. 1, pp. 8492, 2009. cumulation of total and methyl mercury in three earthworm
[26] N. J. Hodges and J. K. Chipman, Down-regulation of the species (drawida sp., allolobophora sp., and Limnodrilus sp.),
DNA-repair endonuclease 8-oxo-guanine DNA glycosylase 1 Bulletin of Environmental Contamination and Toxicology, vol.
(hOGG1) by sodium dichromate in cultured human A549 83, no. 6, pp. 937942, 2009.
lung carcinoma cells, Carcinogenesis, vol. 23, no. 1, pp. 5560, [40] IARC, Chromium, Nickel, Welding, vol. 49 of IARC Mono-
2002. graphs, IARC, Lyon, France, 1990.
[27] A. J. Lee, N. J. Hodges, and J. K. Chipman, Interindividual [41] IARC, Beryllium, Cadmium, Mercury and Exposures in the
variability in response to sodium dichromate-induced oxida- Glass Manufacturing Industry, vol. 58 of IARC Monographs,
tive DNA damage: role of the Ser326 Cys polymorphism in the IARC, Lyon, France, 1993.
DNA-repair protein of 8-oxo-7,8-dihydro-2 -deoxyguanosine [42] H. Dally and A. Hartwig, Induction and repair inhibition
DNA glycosylase 1, Cancer Epidemiology Biomarkers and of oxidative DNA damage by nickel(II) and cadmium(II) in
Prevention, vol. 14, no. 2, pp. 497505, 2005. mammalian cells, Carcinogenesis, vol. 18, no. 5, pp. 1021
[28] V. Sava, D. Mosquera, S. Song, F. Cardozo-Pelaez, and J. R. 1026, 1997.
Sanchez-Ramos, Eects of melanin and manganese on DNA [43] H. Merzenich, A. Hartwig, W. Ahrens, et al., Biomonitoring
damage and repair in PC12-derived neurons, Free Radical on carcinogenic metals and oxidative DNA damage in a
Biology and Medicine, vol. 36, no. 9, pp. 11441154, 2004. cross-sectional study, Cancer Epidemiology Biomarkers and
[29] C. M. Bolin, R. Basha, D. Cox, et al., Exposure to lead (Pb) Prevention, vol. 10, no. 5, pp. 515522, 2001.
and the developmental origin of oxidative DNA damage in the [44] J. G. Hengstler, U. Bolm-Audor, A. Faldum, et al., Occu-
aging brain, The FASEB Journal, vol. 20, no. 6, pp. 788790, pational exposure to heavy metals: DNA damage induction
2006. and DNA repair inhibition prove co-exposures to cadmium,
[30] R. J. Potts, R. D. Watkin, and B. A. Hart, Cadmium exposure cobalt and lead as more dangerous than hitherto expected,
down-regulates 8-oxoguanine DNA glycosylase expression in Carcinogenesis, vol. 24, no. 1, pp. 6373, 2003.
rat lung and alveolar epithelial cells, Toxicology, vol. 184, no. [45] J. K. Saxe, C. A. Impellitteri, W. J. Peijnenburg, and H. E.
2-3, pp. 189202, 2003. Allen, Novel model describing trace metal concentrations
Applied and Environmental Soil Science 7
Research Article
Nutrient Status of Vermicompost of Urban Green Waste Processed
by Three Earthworm SpeciesEisenia fetida, Eudrilus eugeniae,
and Perionyx excavatus
Copyright 2010 S. Pattnaik and M. V. Reddy. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Major nutrient status of vermicompost of vegetable market waste (MW) and floral waste (FW) processed by three species of
earthworms namely, Eudrilus eugeniae, Eisenia fetida, and Perionyx excavatus and its simple compost were assessed across dierent
periods in relation to their respective initiative substrates. Their physical parameterstemperature, moisture, pH, and electrical
conductivitywere also recorded. The nutrientsnitrogen, phosphorus, potassium, calcium, and magnesiumincreased in the
vermicompost and compost while the organic carbon, C/N and C/P ratios decreased as the composting process progressed from
0 to 15, 30, 45, and 60 days. The nutrient statuses of vermicomposts of all earthworm species produced from both the wastes
were more than that of the compost and that of their respective substrates. Moreover, the vermicompost produced by E. eugeniae
possessed higher nutrient contents than that of E. fetida, P. excavatus, and compost. The MW showed higher nutrient contents
than the FW. Thus, vermicomposting is the paramount approach of nutrient recovery of urban green waste.
Table 1: Growth parameters of three earthworm species during the process of vermicomposting of MW and FW.
of vermicomposting [913]. The main aim of the present P. pterocarpum (Family-Fabaceae and Subfamily Caesalpin-
investigation was to know the extent to which vermicom- ioideae), a widely appreciated shade tree and a reclamation
posting and the normal composting of urban green waste plant with dense spreading crown, and planted along the
may be combined in order to maximize the potentials roadsides in the Pondicherry University campus. These
of both the processes. Earlier, Graziano and Casalicchio wastes were characterized by segregating and discarding the
[14] have proposed a combination of aerobic composting nonbiodegradable fraction, and the biodegradable compo-
and vermicomposting to enhance the value of the final nent was used for the experiment. Five samples of each waste
products. Frederickson and Knight [15] have showed that were taken for experimentation and analyses.
vermiculture and anaerobic systems can be combined to
enhance organic matter stabilisation. The benefits of a 2.2. Sample ProcessingPre-Composting. The collected MW
combined system to process urban green waste could include and FW were air dried separately spreading over a polythene
eective sanitization and pathogen control due to an initial sheet for 48 hours. The air dried samples were pre-
brief period of thermophilic composting, enhanced rates composted for three weeks before putting into vermicom-
of stabilization, plus the production of earthworms and posting and composting process. Pre-composting is the pre
vermicompost [16]. Stabilization of green waste such as yard processed and pretreated practice of raw waste. The waste
waste and vegetable waste through the process of composting materials, in the pre-composting process were decomposed
and vermicomposting has been carried out earlier [1618]. aerobically by the active role of bacteria due to which
The present investigation attempted mainly to evaluate the temperature raised up to 60 C. As such a high temperature
nutrient status of dierent vermicomposts produced by the was lethal for earthworm survival, the thermal stabilization
three earthworm species and that of compost of urban MW was done prior to introduction of earthworms into the
and FW in relation to the respective initial substrates, and substrate. When the temperature of the pre-composted
also to obtain empirical information on the growth and substrate diminished to 25 C, adult earthworms with well-
productivity of the three species of earthworms cultured in defined clitella belonging to the three species namely, E.
the two substrates. eugeniae, E. fetida, and P. excavatus were introduced on the
pre-composted material filled in each set of earthen pots
(The earthworms were collected from a local vermiculture
2. Materials and Methods unit at Lake Estate of Auorbindo Ashram, Puducherry,
India).
2.1. Methods of Waste Collection. The MW and FW samples
each weighing about 125 kg were collected separately in 2.3. Experimental Design. In each pot five kg of the substrate
random manner. The MW, both fresh and decomposed, was mixed with cow dung in 3 : 1 ratio were taken for vermicom-
collected from the main vegetable market of Puducherry, posting and composting. A total of four sets of earthen pots
which comprised of dierent leftover putrefied vegetables each set comprising six replicates was taken for each waste,
such as cabbage, tomato, potato, onion, carrot, turnip, of which three sets were used for vermicomposting with each
brinjal, and leafy vegetables; the FW was obtained from the set using one species of earthworm and the forth set was used
Applied and Environmental Soil Science 3
for normal composting that is, without using any earthworm. individual weight gained by each of the three species was
Three species of earthworms, each of fifty adult individuals, 200.0, 261.2, and 525.8% in MW and 265.7, 432.8, and
were introduced on the top of the pre-composted substrate 906.4% in FW respectively, at the end of the experiment
in each of the three sets of pots keeping aside the fourth (Table 1). The net individual weight gain and total biomass
set for composting without earthworms. All the pots were gain were higher in P. excavatus than that of E. fetida, and
covered on the top by jute cloth cover and wire mesh to E. Eugeniae. The total biomass gain was found 1456.6 and
prevent and protect the earthworms from the predators 2171.4% by E. eugeniae, 2095.2 and 3465.1% by E. fetida,
centipedes, moles, and shrews. Small holes were drilled at and 4303.9 and 7272.3% by P. excavatus in MW and FW
the bottom of each pot which was filled with small stones respectively, at the end of the vermicomposting process.
up to a height of 5 cm for air circulation and good drainage. Cocoon production rate was higher in P. excavatus than that
The processes of vermicomposting and composting were of E. eugeniae and E. fetida. The number of worms produced
carried out for a period of 60 days. The temperature and per cocoon was 28.9 and 71.0% higher in E. fetida than
moisture content were maintained by sprinkling adequate that of E. eugeniae and P. excavatus, respectively, while the
quantity of water at frequent intervals. The harvesting of number of cocoons collected at the end of the experiment
vermicompost and compost, and total earthworm biomass, was more in P. excavatus by 245.6% than that of E. eugeniae
individual body weight, total numbers of juveniles, adults, and 286.3% than that of E. fetida in MW; and by 186.8%
and cocoons were carried out, and the mortality rates of the and 194.6% than that of E. eugeniae and E. fetida in FW,
three earthworm species were calculated after 60 days, at the respectively. The number of juveniles collected was 83.3%
end of the experiment. higher in P. excavatus than that of E. eugeniae and 50.5% than
that of E. fetida in MW, whereas the increase was 74.2% in E.
2.4. Physico-Chemical Analyses. The homogenized sub- eugeniae and 30.6% in E. fetida. Adult earthworm number
samples of each substrate material and their respective was higher in P. excavatus than that of E eugeniae, and E.
compost and vermicompost samples (on the basis of 100 g fetida by 35.8 and 15.8% in MW, and 16.8 and 9.4% in
dry weight) were collected undestructively at 0 (i.e., sub- FW, respectively. The production of cocoons, juveniles, and
strate), 15, 30, 45, and 60 days from each replicate pot adults of all the three species was higher in FW than that of
and compound samples were made, which were processed MW, which indicated the former waste material as a better
for analyses of organic carbon (OC) and major nutrients substrate for the earthworms. The mortality rate of the P.
total nitrogen (N), available phosphorus (P), exchangeable excavatus was 900% higher than that of E eugeniae and 400%
potassium (K), calcium (Ca), and magnesium (Mg). The higher than that of E. fetida grown in MW, while it was higher
temperature ( C), moisture (%), pH, and electrical conduc- by 1100 and 650% than E eugeniae and E. fetida grown in FW,
tivity (EC) were recorded for the substrate and during the respectively.
vermicomposting and composting processes. Temperature The mean individual length and live weight, mean
was noted daily using a thermometer, and moisture content growth rate of an individual (mg/day), individual and total
was measured gravimetrically. The pH and EC of samples biomass gain, reproduction rate (cocoon worm1 day1 ),
were recorded by a digital pH meter and conductivity fecundity rate (worm cocoon 1 day1), total cocoon, juve-
meter, respectively. The OC of the samples was measured niles and adult numbers, and mortality rate in the present
by Walkey-Black method [19]; the N was estimated by the study varied across dierent treatments. The worms when
Kjeldahl method [20], and the P and K contents of the introduced into wastes showed an increased growth rate
samples were analyzed by calorimetric method [21] and and reproduction activities [1]. The increase in body weight
flame photometric method [22], respectively. The Ca and of all three earthworm species was noted in both the
Mg contents of the samples were also analyzed using atomic substrates during vermicomposting process, which could
absorption spectrophotometer (GBC make) [20]. The C : N be due to the substrate quality or could be related to
ratio was calculated from the measured values of C and N. fluctuating environmental conditions [2325]. The readily
available nutrients in MW and FW enhanced the feeding
activity of the worms, showing their increase in biomass
2.5. Statistical Analysis. Two-way analysis of variance [1]. Interestingly, cocoon production rate was higher in
(ANOVA) was computed using SPSS (version No. 10) to P. excavatus, whereas the number of worms per cocoon
test the level of significance of dierence between the was higher in E. fetida compared to other species. The
vermicomposts produced by the three species earthworms indigenous species, P. excavates, exhibited better growth and
and compost samples with respect to nutrient parameters. reproduction performance compared to the other two exotic
species [26]. The higher numbers of cocoons, juveniles,
3. Result and Discussion and adults collected from the vermicompost processed by
P. excavatus, were probably because its indigenous nature
3.1. Growth and Productivity of Earthworms. The growth being acclimatized to the abiotic environmental conditions
parameters of three earthworm species cultured in MW and extremely well compared to other species. The dierence in
FW showed that the length increased by 23.3% in E. eugeniae, worm mortality among the three species could be related
43.7% in E. fetida, and 85.0% in P. excavatus grown in MW, to the species-specific composting behavior or to specific
while it increased by 29.3% in E. eugeniae, 53.7% in E. fetida, tolerance nature of earthworm according to the changing
and 122.5% in P. excavatus grown in FW, whereas the net microenvironmental conditions in composting subsystem
4 Applied and Environmental Soil Science
Table 2: Weight and other dierent physical parameters of the substratesMW and FWand their respective compost and vermicompost
of three earthworm species (Mean sd; n = 3).
[1]. Moreover, the growth rate dierence between the three by 19.1 and 15.8% in the vermicompost processed by E.
species was probably due to the species-specific growth pat- eugeniae, by 18.8 and 11.7% in that of E. fetida, by 18.1
terns or could be related to the feed quality and preferences and 11.3% in that of P. excavates, and by 17.1 and 9.8%
by individual species of earthworm [1]. in compost than that of initial substrate of MW and FW,
respectively. The moisture content of vermicompost of E.
3.2. Waste Stabilization. The reduction in bulk dry mass of eugeniae varied by 17.0 and 75.6%, by 16.1 and 72.4% in
both the substratesMW and FW, the range of temperature, that of E. fetida, by 14.9 and 69.5% in that of P. excavates,
moisture content, pH, EC of the substrate, compost and and by 13.2 and 66.1% in the compost than that of initial
vermicompost presented in Table 2. depicted that higher MW and FW, respectively. The pH ranged from 6.31 to
mass reduction of MW was recorded in the vermicompost 7.37 and increased by 12.8, 12.2, 10.1, and 8.9% than that
processed by E. eugeniae (75%), followed by that of E. of MW; and 7.7, 6.4, 2.1 and 0.7% than that of FW, in
fetida (63%), and P. excavatus (50%) compared to that of vermicompost of E. eugeniae, E. fetida, P. excavatus, and
compost (26%), whereas the mass reduction was higher 83% compost, respectively. The EC of vermicompost ranged
in vermicompost produced by E. eugeniae, 67% by that of E. from 152.2 to 3354.4 mhos/cm and increased EC noted in
fetida, 56% in that of P. excavates, and 30% in sole compost vermicompost processed by E. eugeniae, E. fetida, P. excavatus
than that of FW. The marked stabilization of both the and in compost was 577.0, 448.3, 300.2, and 261.1% more
substrates due to vermicomposting process was higher in the than that of MW, and was 249.9, 206.4, 173.1, and 138.8%
vermicompost processed by E. eugeniae compared to that of more than that of FW, respectively, at the end of composting
other two and the compost. The FW and its vermicomposts process. Temperature, moisture content, and EC were more
and composts were found to be more stabilized than that of and pH was less in MW compared to that of FW.
MW.
The pre-composting because of its thermophilic nature 3.4. Temperature. At the start of the experiment, the temper-
prior to vermicomposting helped in mass reduction and ature of the substrate was high and then decreased gradually
pathogen reduction [27]. It was found that the bulk (dry) as the composting process progressed. The heat released by
mass reduction and stabilization of both the wastes during the oxidative action of intensive microbial activity on the
present study through vermicomposting process were signif- organic matter resulted in the rise in temperature during
icant [2, 27]; the vermicomposting may also be known as the first mesophilic phase of composting process [33]. The
vermistabilization [28]. The cow dung used as the inoculant temperature of the following thermophilic phase rose up
in the vermicomposting process enhanced the quality of above 40 C reaching about 60 C when most of the organic
feeding resource attracting the earthworms and accelerated matter was degraded with the help of thermophilic bacteria
the breakdown of wastes resulting in the reduction of C : N and fungi, consequently depleting most of the oxygen.
ratio by increasing certain nutrients [1, 2931]. The thermophilic phase was followed by cooling phase,
when compost maturation stage occurred and compost
3.3. Physical State of MW and FW during Vermicompost- temperature dropped to that of the ambient [34]. Then,
ing and Composting Processes. The physical characteristics the decreasing trend of temperature with the progress of
recorded during the period of this study presented in Table 2 composting process occurred, which was probably due to
were conducive for vermicomposting process [6, 32]. The the decreased bacterial activity. It may also be attributable to
temperature ranged from 22.3 to 29.8 C and was lower regular sprinkling of water.
Applied and Environmental Soil Science 5
90
2.4
80
70
60
1.6
OC (%)
50
N (%)
40
30
0.8
20
10
0 0
Ee-15
Ee-30
Ee-45
Ee-60
Ee-15
Ee-30
Ee-45
Ee-60
Pe-15
Pe-30
Pe-45
Pe-60
Pe-15
Pe-30
Pe-45
Pe-60
I.S
I.S
I.S
I.S
I.S
I.S
I.S
I.S
C-15
C-30
C-45
C-60
C-15
C-30
C-45
C-60
Ef-15
Ef-30
Ef-45
Ef-60
Ef-15
Ef-30
Ef-45
Ef-60
Treatments across dierent intervals Treatments across dierent intervals
FW FW
MW MW
(a) (b)
1.4
1.2 1.2
1 1
0.8 0.8
P (%)
0.6 0.6
K (%)
0.4 0.4
0.2 0.2
0 0
Ee-15
Ee-30
Ee-45
Ee-60
Ee-15
Ee-30
Ee-45
Ee-60
Pe-15
Pe-30
Pe-45
Pe-60
Pe-15
Pe-30
Pe-45
Pe-60
I.S
I.S
I.S
I.S
I.S
I.S
I.S
I.S
C-15
C-30
C-45
C-60
C-15
C-30
C-45
C-60
Ef-15
Ef-30
Ef-45
Ef-60
Ef-15
Ef-30
Ef-45
Ef-60
0.2
Figure 1: Major nutrientsOC, N, P, K (%) of vermicompost (VC) of three dierent species of earthwormsEudrilus eugeniae (Ee) at 15
days (Ee-15), 30 days (Ee-30), 45 days (Ee-45), and 60 days (Ee-60); Eisenia fetida (Ef) at 15 days (Ef-15), 30 days (Ef-30), 45 days (Ef-45),
and 60 days (Ef-60); Perionyx excavatus (Pe) at 15 days (Pe-15), 30 days (Pe-30), 45 days (Pe-45), and 60 days (Pe-60); and Compost (C) at
15 days (C-15), 30 days (C-30), 45 days (C-45), and 60 days (C-60) produced from FW and MW. (a) OC, (b) N, (c) P, (d) K.
3.5. Moisture Content. Moisture content ranged from 50 higher rate of degradation of waste by earthworms. Relatively
70% [35]. Edwards and Bater [36] reported that optimum highest moisture content of vermicompost produced by E.
moisture content for growth of earthwormsE. fetida, eugeniae followed by that of E. fetida and P. excavatus implied
E. eugeniae and P. excavatuswas 85% in organic waste greater palatability of the substrate by the species.
management. The rate of mineralization and decomposition
becomes faster with the optimum moisture content [37]. 3.6. pH. It was neutral being around 7 and increased
According to Liang et al. [38], the moisture content of gradually from substrate to compost to vermicompost [35,
6070% was proved having maximal microbial activity, 39]. The near-neutral pH of vermicompost may be attributed
while 50% moisture content was the minimal requirement by the secretion of NH+4 ions that reduce the pool of H+
for rapid rise in microbial activity. Vermicompost samples ions [40] and the activity of calciferous glands in earthworms
during the present study showed higher moisture content containing carbonic anhydrase that catalyzes the fixation of
than the compost and substrate, which may be due to CO2 as CaCO3 , thereby preventing the fall in pH [9]. The
their high absorption capacity, and may also be because increased trend of pH in the vermicompost and compost
of assimilation rate by microbial population indicating the samples is in consistence with the findings of Tripathi and
6 Applied and Environmental Soil Science
Table 3: ANOVA of dierent nutrients of vermicomposts produced by three species of earthworms and compost (Treatments) of Market
Waste across dierent time intervals.
Source of Variation SS df MS F
OC
Time Intervals 648.6706 3 216.2235 83.74185
Treatments 923.0771 3 307.6924 119.1671
Error 23.23823 9 2.582025
N
Time Intervals 0.431569 3 0.143856 38.0167
Treatments 1.881169 3 0.627056 165.7113
Error 0.034056 9 0.003784
C/N Ratio
Time Intervals 2834.197 3 944.7322 36.40393
Treatments 301.5306 3 100.5102 3.87302
Error 233.5624 9 25.95138
P
Time Intervals 0.286919 3 0.09564 418.6049
Treatments 0.568369 3 0.189456 829.231
Error 0.002056 9 0.000228
C/P Ratio
Time Intervals 6752.972 3 2250.991 39.35673
Treatments 225.6022 3 75.20074 1.314823
Error 514.751 9 57.19456
K
Time Intervals 0.32795 3 0.109317 141.5612
Treatments 0.2005 3 0.066833 86.54676
Error 0.00695 9 0.000772
Ca
Time Intervals 28.18897 3 9.396323 2027.679
Treatments 8.064019 3 2.688006 580.0583
Error 0.041706 9 0.004634
Mg
Time Intervals 0.30515 3 0.101717 1220.6
Treatments 0.3242 3 0.108067 1296.8
Error 0.00075 9 8.33E-05
Level of significance: P < .001
Bhardwaj [41] and Loh et al. [42], which was due to is, in the form of cations in the vermicompost and compost
higher mineralization, whereas the present findings are in [44, 46].
contradiction to the findings of Suthar and Singh [1], Haimi
and Huhta [40] and Ndegwa et al. [43] who reported lower
3.8. Nutrients in MW and FW and Their Vermicompost and
pH. The increased pH during the process was probably
Compost. It was found that the N was 0.45% in MW and
due to the degradation of short-chained fatty acids and
0.17% in FW; P was 0.25% in MW and 0.11% in FW; K
ammonification of organic N [4446]. Fares et al. [47] found
was 0.18% in MW and 0.02% in FW, Ca was 0.62% in MW
the increased pH at the end of the composting process, which
and 0.07% in FW; Mg was 0.17% in MW and 0.04% in FW,
was attributed to progressive utilization of organic acids and
while the content of OC was 79.6% in MW and 42.9% in FW
increase in mineral constituents of waste.
(Figures 1 and 2).
The present study revealed that all vermicomposts
3.7. EC. The increased EC during the period of the compost- prepared from their respective organic wastes possessed
ing and vermicomposting processes is in consistence with considerably higher levels of major nutrientsN, P, K, Ca,
that of earlier workers [48, 49], which was probably due to and Mg compared to that of the substrates [31, 50]. The
the degradation of organic matter releasing minerals such as increase in the nutrients and decrease in OC, C/N ratio
exchangeable Ca, Mg, K, and P in the available forms, that and C/P ratios in the vermicompost, are in consistence
Applied and Environmental Soil Science 7
7 1.2
6
1
5
0.8
4
Ca (%)
Mg (%)
0.6
3
0.4
2
1 0.2
0 0
Ee-15
Ee-30
Ee-45
Ee-60
Ee-15
Ee-30
Ee-45
Ee-60
Pe-15
Pe-30
Pe-45
Pe-60
Pe-15
Pe-30
Pe-45
Pe-60
I.S
I.S
I.S
I.S
I.S
I.S
I.S
I.S
C-15
C-30
C-45
C-60
C-15
C-30
C-45
C-60
Ef-15
Ef-30
Ef-45
Ef-60
Ef-15
Ef-30
Ef-45
Ef-60
Treatments across dierent intervals Treatments across dierent intervals
FW FW
MW MW
(a) (b)
300 450
400
250
350
200 300
C/N ratio
C/P ratio
250
150
200
100 150
100
50
50
0 0
Ee-15
Ee-30
Ee-45
Ee-60
Ee-15
Ee-30
Ee-45
Ee-60
Pe-15
Pe-30
Pe-45
Pe-60
Pe-15
Pe-30
Pe-45
Pe-60
I.S
I.S
I.S
I.S
I.S
I.S
I.S
I.S
C-15
C-30
C-45
C-60
C-15
C-30
C-45
C-60
Ef-15
Ef-30
Ef-45
Ef-60
Ef-15
Ef-30
Ef-45
Ef-60
Figure 2: Major nutrientsCa and Mg (%), C/N ratio and C/P ratio of vermicompost (VC) of three dierent species of earthworms
Eudrilus eugeniae (Ee) at 15 days (Ee-15), 30 days (Ee-30), 45 days (Ee-45), and 60 days (Ee-60); Eisenia fetida (Ef) at 15 days (Ef-15), 30
days (Ef-30), 45 days (Ef-45), and 60 days (Ef-60); Perionyx excavatus (Pe) at 15 days (Pe-15), 30 days (Pe-30), 45 days (Pe-45), and 60 days
(Pe-60); and Compost (C) at 15 days (C-15), 30 days (C-30), 45 days (C-45), and 60 days (C-60) produced from FW and MW. (a) Ca, (b)
Mg, (c) C/N ratio, (d) C/P ratio.
with the findings of earlier investigators [25, 26]. Moreover, in all the three vermicomposts and in the sole compost
comparing the nutrient contents of vermicompost with that as the composting process progressed from 15 days to 60
of compost, vermicompost possessed significantly higher days. Interestingly, the C/N ratio (Figure 2(c)) and C/P
concentrations of nutrients than that of compost (P < .05), ratio (Figure 2(d)) in all the samples of vermicomposts and
which was probably due to the coupled eect of earthworm compost declined at the end of the experiment (i.e., after 60
activity as well as a shorter thermophilic phase [51, 52], days of processing). The nutrient contents showed significant
making the plant-availability of most the nutrients higher temporal variation in vermicompost and compost of both
in vermicomposting than that of composting process [3, 53, the substrates, that is, MW (Table 3) and FW (Table 4) (P <
54]. .001).
The vermicompost of MW produced by E. eugeniae
3.9. Temporal Variation in Nutrients. In the present study showed 177.8, 224.0, 166.7, 296.7, and 264.7% increase after
the percentage of OC decreased (Figure 1(a)) and that 15 days of processing and 317.8, 372.0, 427.8, 887.1, and
of N increased (Figure 1(b)), while the percentage of 476.5% increase after 60 days of processing in N, P, K,
P (Figure 1(c)) and K (Figure 1(d)), and that of Ca Ca, and Mg compared to that of the substrate, respectively,
(Figure 2(a)) and Mg (Figure 2(b)) also increased gradually whereas it decreased by 35.9 and 52.8% after 15 and 60 days,
8 Applied and Environmental Soil Science
Table 4: ANOVA of dierent nutrients of vermicomposts produced by three species of earthworms and compost (Treatments) of Floral
Waste across dierent time intervals.
Source of Variation SS df MS F
OC
Time Intervals 76.11592 3 25.37197 28.39579
Treatments 426.3413 3 142.1138 159.0508
Error 8.041606 9 0.893512
N
Time Intervals 0.151425 3 0.050475 118.7647
Treatments 0.649525 3 0.216508 509.4314
Error 0.003825 9 0.000425
C/N Ratio
Time Intervals 1629.242 3 543.0806 67.49946
Treatments 103.9289 3 34.64297 4.305774
Error 72.41133 9 8.045703
P
Time Intervals 0.130719 3 0.043573 78.33333
Treatments 0.127569 3 0.042523 76.44569
Error 0.005006 9 0.000556
C/P Ratio
Time Intervals 4035.872 3 1345.291 636.1514
Treatments 295.7819 3 98.59395 46.6224
Error 19.0326 9 2.114733
K
Time Intervals 0.062619 3 0.020873 81.45528
Treatments 0.072769 3 0.024256 94.65854
Error 0.002306 9 0.000256
Ca
Time Intervals 2.90885 3 0.969617 23.82676
Treatments 3.5505 3 1.1835 29.08259
Error 0.36625 9 0.040694
Mg
Time Intervals 0.1621 3 0.054033 35.62637
Treatments 0.31855 3 0.106183 70.01099
Error 0.01365 9 0.001517
Level of significance: P < .001
respectively in OC; whereas that of E. fetida increased by 91.1, was respectively 80.2, 74.2, 71.9, and 70.4% at 15 days of
128.0, 127.8, 161.3, and 188.2%; and 173.3, 284.0, 338.9, processing and 90.0, 91.7, 91.2, and 92.2% at 60 days of
716.1, and 394.1% while decreased by 41.2% and 68.1% after processing in the vermicompost produced by E. eugeniae, E.
15 and 60 days of processing, respectively. The N, P, K, Ca, fetida, P. excavatus, and in sole compost compared to that of
and Mg contents in vermicompost produced by P. excavatus the substrate.
increased by 51.1, 76.0, 83.3, 50.0 and 100.0%, respectively The vermicompost of FW produced by E. eugeniae
and the OC decreased by 50.5%, at 15 days of processing; increased by 317.6, 254.5, 750.0, 1057.1, and 700.0% after
whereas the increase was 137.8, 212.0, 283.3, 648.4 and 15 days of processing and 482.3, 545.4, 1800.0, 3285.7, and
323.5% and the decrease was 73.1% at 60 days of processing, 1525.0% after 60 days of processing in N, P, K, Ca, and Mg,
respectively. In compost, the increase was relatively less and respectively compared to the substrate, whereas it decreased
was 2.2, 36.0, 38.9, 4.8, and 35.3% and 80.0, 168.0, 216.7, by 35.7 and 52.6% after 15 and 60 days, respectively in OC,
572.6, and 264.7% in N, P, K, Ca, and Mg, respectively and while that of E. fetida increased by 200.0, 190.9, 500.0, 814.3
its decrease in OC was 59.7, and 79.1% compared to that and 575.0% and 376.5, 400.0, 1350.0, 2728.6, and 1300%;
of substrate after 15 and 60 days of composting process, while decreased by 44.3 and 60.9% after 15 and 60 days of
respectively. The C/N ratio reduction was 76.9, 69.2, 67.3, processing, respectively. The N, P, K, Ca, and Mg contents in
and 60.6% after 15 days of processing and 88.7, 88.4, 88.7, vermicompost produced by P. excavatus increased by 129.4,
and 88.4% after 60 days while the C/P ratio reduction 145.4, 250.0, 285.7, and 200.0%, respectively, and the OC
Applied and Environmental Soil Science 9
decreased by 55.2% at 15 days of processing, whereas the Sangwan et al. [61], in contrast to the present findings,
increase was 282.3, 345.4, 1000.0, 1785.7, and 950.0% and reported decrease in potassium content in the vermicompost
the decrease was 68.5% at 60 days of processing, respectively. produced by E. fetida compared to that of the substrate.
In compost, there was less increase and was 23.5, 72.7, 50.0, Khwairakpam and Bhargava [58] compared the vermicom-
28.6, and 75.0% and 141.2, 254.5, 650.0, 742.8, and 475.0% post of sewage sludge processed by these three earthworm
in N, P, K, Ca, and Mg, respectively, and its decrease in OC species in order to report the suitability of worm species
was 73.4, and 79.9% after 15 and 60 days, respectively of for composting. Reddy and Okhura [5] have assessed the
composting process compared to that of substrate. The C/N vermicomposts produced by dierent earthworm species
ratio reduction was 84.6, 81.4, 80.5 and 78.5% after 15 days Perionyx excavatus, Octohaetona phillotti, and Octonachaeta
of processing and 91.9, 91.8, 91.7, and 91.7% after 60 days rosea using the rice straw as substrate and found that
while the C/P ratio reduction was respectively 81.9, 80.8, vermicompost produced P. excavatus possessed possessed
81.7, and 84.6% at 15 days of processing and 92.6, 92.2, 92.9, higher concentration of nutrients than that of O. rosea and
and 94.3% at 60 days of processing in the vermicompost O. phillotti.
produced by E. eugeniae, E. fetida, P. excavatus and in sole Further, it was found that the OC, N, P, K, Ca, Mg was
compost more than that of the substrate. 85.4, 164.7, 127.3, 800.0, 785.7, and 325.0%, respectively
The considerable enrichment of nutrients of the vermi- increased in MW than that of FW, and the nutrients were
composts of the three species of earthwormsE. eugeniae also significantly higher in the vermicompost and compost
E. fetida and P. excavatuscompared to that of composts of of MW than that of FW (P < .05). The vermicompost of
substrates, that is, MW and FW (P < .01) were in consistence MW produced by E. eugeniae showed 84.9, 76.0, 107.7, 182.3,
with the findings of earlier reports [2, 25, 26, 30]. At the 203.7, and 93.7% increase at 15 days and 84.8, 89.9, 66.2,
end of the experiment, the increase in OC, N, P, K, Ca, 150.0, 158.2, and 50.8% increase at 60 days of processing in
and Mg was 55.8, 56.9, 43.2, 40.0, 31.8, and 36.7% in the OC, N, P, K, Ca, Mg than that of FW; whereas the increase
vermicompost of MW and 57.7, 58.6, 45.1, 60.5, 75.1, and was 95.8, 68.6, 78.1, 241.7, 153.1, and 81.5% at 15 days of
64.6% in that of FW produced by E. eugeniae; 34.5, 34.1, composting and 51.4, 51.8, 74.5, 172.4, 155.6 and 50.0% at
30.2, 27.8, 17.6, and 26.2% in that of MW and 48.6, 49.4, 60 days in the vermicompost produced by E. fetida, and the
29.1, 48.3, 70.2, and 58.9% in that of FW produced by E. increase of OC, N, P, K, Ca, and Mg (Figures 1 and 2) in
fetida; and 22.5, 24.3, 14.1, 17.4, 10.1, and 13.9% in that of vermicompost of MW produced by P. excavatus than that
MW and 36.3, 36.9, 20.4, 31.8, 55.3, and 45.2% in that of FW of FW was 104.7, 74.4, 62.9, 371.4, 244.4, and 183.3% and
produced by P. excavatus, compared to that of sole compost, 58.5, 64.6, 59.2, 213.6, 251.5, and 71.4% after 15 and 60 days
respectively. of processing, respectively. The compost of MW was higher
The nutrients and OC were found higher in MW by 181.1 and 92.9% in OC, 119.0 and 97.6% in N, 78.9 and
compared to that of FW, which was most probably because 71.8% in P, 733.3 and 280.0% in K, 622.2 and 606.8% in
of mosaic nature of the MW. In all the vermicompost and Ca, and 228.6 and 169.6% in Mg after 15 and 60 days of
compost of the present study the nutrients increased and processing, respectively compared to that of FW.
OC, C/N ratios and C/P ratio decreased significantly with
the passage of time (from 0 to 15, 30, 45, and 60 days), from
3.10. Total N. The total nitrogen content of vermicompost
the substrate (organic waste) to compost and vermicompost,
of the tree earthworm species was higher than that of
respectively [2]. The present findings are in agreement with
compost and substrate. The increasing trend of N in the
the findings of earlier workers: Nagavallemma et al. [35],
vermicomposts produced by the earthworm species in the
Uthaiah [55], Muthukumarasamy et al. [56], Parthasarathi
present study corroborated with the findings of earlier
and Ranganathan [57], and Khwairakpam and Bhargava
reports [62, 63]. The enhancement of N in vermicompost
[58]. The waste materials ingested by the earthworms
was probably due to mineralization of the organic matter
undergo physical decomposition and biochemical changes
containing proteins [3, 8] and conversion of ammonium-
contributed by the enzymatic and enteric microbial activities
nitrogen into nitrate [1, 64]. Earthworms can boost the
while passing through the earthworm gut due to the grinding
nitrogen levels of the substrate during digestion in their
action of the muscular gizzard releasing the nutrients in the
gut adding their nitrogenous excretory products, mucus,
form of microbial metabolites enriching the feed residue
body fluid, enzymes, and even through the decaying dead
with plant nutrients and growth promoting substances in an
tissues of worms in vermicomposting subsystem [25]. The
assimilated form, which is excreted in the form of vermi-cast
vermicompost prepared by all the three earthworm species
[31, 59].
showed a substantial dierence in total N content (P <
Comparing the nutrients of vermicompost produced by
.01), which could be attributed directly to the species-
the three earthworm species (E. Eugeniae, E. fetida, and P.
specific feeding preference of individual earthworm species
excavatus), it was found that the vermicompost of E. eugeniae
and indirectly to mutualistic relationship between ingested
possessed significantly higher concentrations of the nutrients
microorganisms and intestinal mucus [1].
followed by E. fetida and P. excavates, and the sole compost,
in the order of E. Eugeniae > E. fetida > P. excavatus >
compost, which may indicate that the earthworm is more 3.11. OC. Total organic carbon decreased with the passage
ecient in recovering nutrients from the waste through of time during vermicomposting and composting processes
vermicomposting process [2, 60]. However, the findings of in both the substrates. These findings are in consistence
10 Applied and Environmental Soil Science
with those of earlier authors [12, 46]. The organic carbon 3.15. Ca and Mg. The higher Ca content in vermicompost
is lost as carbon dioxide through microbial respiration and compared to that of compost and substrate is attributable
mineralization of organic matter causing increase in total N to the catalytic activity of carbonic anhydrase present in
[65]. Part of the carbon in the decomposing residues released calciferous glands of earthworms generating CaCO3 on the
as CO2 and a part was assimilated by the microbial biomass fixation of CO2 [60]. The higher concentration of Mg
[11, 66, 67]; microorganisms used the carbon as a source in vermicompost reported in present study was also in
of energy decomposing the organic matter. The reduction consistence with the findings of earlier workers [60, 77].
was higher in vermicomposting compared to the ordinary
composting process, which may be due to the fact that 4. Conclusions
earthworms have higher assimilating capacity. The dierence
between the carbon loss of the vermicompost processed by It is concluded that among the three species, the indigenous
E. eugeniae, E. fetida, and P. excavatus could be due to the species, P. excavates, exhibited better growth and reproduc-
species-specific dierences in their mineralization eciency tion performance compared to the other two exotic species.
of OC. E. eugeniae was more ecient in bioconversion of urban
green waste into nutrient rich vermicompost compared to
3.12. C/N Ratio. The C/N ratios of vermicomposts of E. fetida and P. excavatus; the vermicompost produced by E.
three earthworm species were around 20 : 1; such ratios eugeniae possessed higher nutrientsN, P, K, Ca and Mg
make nutrients easily available to the plants. Plants cannot compared to that of E. fetida and P. excavatus. Vermicom-
assimilate mineral N unless the C/N ratio is about 20 : 1, posts produced by all the earthworm species showed higher
and this ratio is also an indicative of acceptable maturity contents of nutrients compared to that of the sole compost
of compost [68]. The C/N ratio of the substrate material as well as substratesthe green waste (vegetable market and
reflects the organic waste mineralization and stabilization floral waste). Moreover, the vermicompost and compost of
during the process of composting or vermicomposting. vegetable market waste possessed higher nutrient contents
Higher C/N ratio indicates slow degradation of substrate probably because it comprised of a mosaic of materials
[69], and the lower the C/N ratio, the higher is the eciency compared to that of floral waste. Thus, vermicomposting was
level of mineralization by the species. Lower C/N ratio in proved to be a better technology than that of sole composting
vermicompost produced by E. eugeniae implied that this and may be preferred for the management and nutrient
species enhanced the organic matter mineralization more recovery from the urban waste such as market waste and
eciently than E. fetida and P. excavatus [1, 60]. The loss floral waste.
of carbon through microbial respiration and mineralization
and simultaneous addition of nitrogen by worms in the form
of mucus and nitrogenous excretory material lowered the Acknowledgments
C/N ratio of the substrate [25, 7072]. The University Grants Commission (New Delhi) provided
grants in the form of a Major Research Project for this
3.13. P. The total P was higher in the vermicompost research, which covered a project fellowship to the first
harvested at the end of the experiment compared to that author The earthworm species were procured from the
of the initial substrate [8, 25, 73]. The enhanced P level in Vermiculture unit of Lake Estate (Auorbindo Ashram,
vermicompost suggests phosphorous mineralization during Puducherry, India).
the process. The worms during vermicomposting converted
the insoluble P into soluble forms with the help of P-
solubilizing microorganisms through phosphatases present References
in the gut, making it more available to plants [1, 60, 74].
[1] S. Suthar and S. Singh, Vermicomposting of domestic waste
This was buttressed by increased trend of EC showing by using two epigeic earthworms (Perionyx excavatus and
enhancement of exchangeable soluble salts in vermicompost Perionyx sansibaricus), International Journal of Environment
of all the three earthworm species. Science and Technology, vol. 5, no. 1, pp. 99106, 2008.
[2] R. M. Venkatesh and T. Eevera, Mass reduction and recovery
3.14. K. Vermicomposting proved to be an ecient process of nutrients through vermicomposting of fly ash, Applied
for recovering higher K from organic waste [1, 25, 73]. Ecology and Environmental Research, vol. 6, pp. 7784, 2008.
The present findings corroborated to those of Delgado et [3] S. Bansal and K. K. Kapoor, Vermicomposting of crop
al. [75], who demonstrated that higher K concentration in residues and cattle dung with Eisenia foetida, Bioresource
the end product prepared from sewage sludge. The increase Technology, vol. 73, no. 2, pp. 9598, 2000.
in K of the vermicompost in relation to that of the simple [4] A. Singh and S. Sharma, Composting of a crop residue
through treatment with microorganisms and subsequent
compost and substrate was probably because of physical
vermicomposting, Bioresource Technology, vol. 85, no. 2, pp.
decomposition of organic matter of waste due to biological 107111, 2002.
grinding during passage through the gut, coupled with [5] M. V. Reddy and Okhura, Vermicomposting of rice-straw and
enzymatic activity in worms gut, which may have caused its eects on sorghum growth, Tropical Ecology, vol. 45, pp.
its increase [76]. The microorganisms present in the worms 327331, 2004.
gut probably converted insoluble K into the soluble form by [6] K. E. Lee, Earthworms: Their Ecology and Relationships with
producing microbial enzymes [48]. Soils and Land Use, Academic Press, London, UK, 1985.
Applied and Environmental Soil Science 11
[7] R. M. Atiyeh, S. Lee, C. A. Edwards, N. Q. Arancon, terms of their temperature requirements, Soil Biology and
and J. D. Metzger, The influence of humic acids derived Biochemistry, vol. 24, pp. 12951307, 1992.
from earthworm-processed organic wastes on plant growth, [24] C. A. Edwards, J. Dominguez, and E. F. Neuhauser, Growth
Bioresource Technology, vol. 84, no. 1, pp. 714, 2002. and reproduction of Perionyx excavatus (Perr.) (Megascole-
[8] P. Kaushik and V. K. Garg, Vermicomposting of mixed solid cidae) as factors in organic waste management, Biology and
textile mill sludge and cow dung with the epigeic earthworm Fertility of Soils, vol. 27, no. 2, pp. 155161, 1998.
Eisenia foetida, Bioresource Technology, vol. 90, no. 3, pp. 311 [25] S. Suthar, Nutrient changes and biodynamics of epigeic
316, 2003. earthworm Perionyx excavatus (Perrier) during recycling of
[9] R. D. Kale, K. Bano, and R. V. Krishnamoorthy, Potential of some agriculture wastes, Bioresource Technology, vol. 98, no.
Perionyx excavatus for utilizing organic wastes, Pedobiologia, 8, pp. 16081614, 2007.
vol. 23, no. 6, pp. 419425, 1982. [26] P. Garg, A. Gupta, and S. Satya, Vermicomposting of dierent
[10] V. Tomati, A. Grappel, E. Galli, and W. Rossi, Fertilizers types of waste using Eisenia foetida a comparative study,
from vermiculturean option for organic wastes recovery, Bioresource Technology, vol. 97, no. 3, pp. 391395, 2006.
Agrochimica, vol. 27, no. 2-3, pp. 244251, 1983. [27] J. Nair, V. Sekiozoic, and M. Anda, Eect of pre-composting
[11] C. Elvira, L. Sampedro, E. Bentez, and R. Nogales, Vermi- on vermicomposting of kitchen waste, Bioresource Technology,
composting of sludges from paper mill and dairy industries vol. 97, no. 16, pp. 20912095, 2006.
with Eisena andrei: a pilot-scale study, Bioresource Technology, [28] L. K. Wang, K. S. Nazih, and H. Yung-Tse, Vermicomposting
vol. 63, no. 3, pp. 205211, 1998. process, in Biosolids Treatment Processes, vol. 6, pp. 689704,
[12] V. K. Garg and P. Kaushik, Vermistabilization of textile mill Humana Press, Totowa, NJ, USA, 2007.
sludge spiked with poultry droppings by an epigeic earthworm [29] P. Pramanik, G. K. Ghosh, P. K. Ghosal, and P. Banik,
Eisenia foetida, Bioresource Technology, vol. 96, no. 9, pp. Changes in organicC, N, P and K and enzyme activities in
10631071, 2005. vermicompost of biodegradable organic wastes under liming
[13] S. Suthar, Potential utilization of guar gum industrial waste and microbial inoculants, Bioresource Technology, vol. 98, no.
in vermicompost production, Bioresource Technology, vol. 97, 13, pp. 24852494, 2007.
no. 18, pp. 24742477, 2006.
[30] R. Gupta and V. K. Garg, Vermiremediation and nutrient
[14] P. L. Graziano and G. Casalicchio, Use of worm-casting
recovery of non-recyclable paper waste employing Eisenia
techniques on sludges and municipal wastes: development
fetida, Journal of Hazardous Materials, vol. 162, no. 1, pp. 430
and application, in On Eurthworms, A. M. B. Pagliai and P.
439, 2009.
Omodeo, Eds., pp. 459464, Mucchi Editore, Modena, Italy,
[31] M. S. Kitturmath, R. S. Giraddi, and B. Basavaraj, Nutri-
1987.
ent changes during earthworm, eudrilus eugeniae (Kinberg)
[15] J. Frederickson and D. Knight, The use of anaerobically
mediated vermicomposting of agro-industrial wastes, Kar-
digested cattle solids for vermiculture, in Earthworms in
nataka Journal of Agriculture Science, vol. 20, pp. 653654,
Waste and Environmental Management, C. A. Edwards and
2007.
E. F. Neuhauser, Eds., pp. 3347, SPB Academie, The Hague,
[32] C. A. Edwards and J. Dominguez, Vermicomposting of
Netherlands, 1988.
sewage sludge: eect of bulking materials on the growth and
[16] J. Frederickson, K. R. Butt, R. M. Morris, and C. Daniel,
reproduction of the earthworm E. andrei, Pedobiologia, vol.
Combining vermiculture with traditional green waste com-
44, no. 1, pp. 2432, 2000.
posting systems, Soil Biology and Biochemistry, vol. 29, no. 3-
4, pp. 725730, 1997. [33] J. Peigne and P. Girardin, Environmental impacts of farm
[17] V. Karthikeyan, G. L. Sathyamoorthy, and R. Murugesan, scale composting practices, Water, Air, and Soil Pollution, vol.
Vermi composting of market waste in Salem, Tamilnadu, 153, no. 14, pp. 4568, 2004.
India, in Proceedings of the International Conference on [34] L. M. Zibilske, Composting of organic wastes, in Principles
Sustainable Solid Waste Management, pp. 276281, Chennai, and Applications of Soil Microbiology, D. M. Sylvia, J. J.
India, September 2007. Fuhrmann, P. G. Hartel, and D. A. Zuberer, Eds., pp. 482497,
[18] C. D. Jadia and M. H. Fulekar, Vermicomposting of veg- Prentice Hall, Upper Saddle River, NJ, USA, 1999.
etable waste: a bio-physicochemical process based on hydro- [35] K. P. Nagavallemma, S. P. Wani, L. Stephane, et al., Vermi-
operating bioreactor, African Journal of Biotechnology, vol. 7, composting: recycling wastes into valuable organic fertilizer,
pp. 37233730, 2008. Journal of SAT Agricultural Research, vol. 2, no. 1, pp. 117,
[19] A. Walkley and I. A. Black, An examination of the Degtjare 2006.
method for determining soil organic matter and prepared [36] C. A. Edwards and J. E. Bater, The use of earthworms in
modification of the chronic acid titration method, Soil environmental management, Soil Biology and Biochemistry,
Science, vol. 34, pp. 2938, 1934. vol. 24, no. 12, pp. 16831689, 1992.
[20] M. L. Jackson, Soil Chemical Analysis, Prentice Hall of India [37] N. B. Singh, A. K. Khare, D. S. Bhargava, and S. Bhattacharya,
Private Limited, New Delhi, India, 1st edition, 1973. Optimum moisture requirement during vermicomposting
[21] J. M. Anderson and J. S. I. Ingram, Soil organic matter and using Perionyx excavatus, Applied Ecology and Environmental
organic carbon, in Tropical Soil Biology and Fertility: A Hand Research, vol. 2, pp. 5362, 2004.
Book of Methods, J. M. Anderson and J. S. I. Ingram, Eds., p. [38] C. Liang, K. C. Das, and R. W. McClendon, The influence
221, CAB International, Wallingford, UK, 1993. of temperature and moisture contents regimes on the aerobic
[22] R. R. Simard, Ammonium acetate extractable elements, in microbial activity of a biosolids composting blend, Biore-
Soil Sampling and Methods of Analysis, R. Martin and S. Carter, source Technology, vol. 86, no. 2, pp. 131137, 2003.
Eds., pp. 3943, Lewis, Boca Raton, Fla, USA, 1993. [39] A. Mitchell and D. Alter, Suppression of labile aluminium in
[23] A. J. Reinecke, S. A. Viljoen, and R. J. Saayman, The suitability acidic soils by the use of vermicompost extract, Communica-
of Eudrilus eugeniae, Perionyx excavatus and Eisenia fetida tions in Soil Science and Plant Analysis, vol. 24, no. 11-12, pp.
(Oligochaeta) for vermicomposting in southern Africa in 11711181, 1993.
12 Applied and Environmental Soil Science
[40] J. Haimi and V. Huhta, Comparison of composts produced (Kinberg) and Eudrilus eugeniae (Kinberg), Biology and
from identical wastes by vermistabilization and conventional Fertility of Soils, vol. 30, no. 4, pp. 347350, 2000.
composting, Pedobiologia, vol. 30, no. 2, pp. 137144, 1987. [58] M. Khwairakpam and R. Bhargava, Vermitechnology for
[41] G. Tripathi and P. Bhardwaj, Comparative studies on biomass sewage sludge recycling, Journal of Hazardous Materials, vol.
production, life cycles and composting eciency of Eisenia 161, no. 2-3, pp. 948954, 2009.
fetida (Savigny) and Lampito mauritii (Kinberg), Bioresource [59] B. K. Senapati, Vermitechnology: an option for recycling
Technology, vol. 92, no. 3, pp. 275283, 2004. cellulosic waste in India, in New Trends in Biotechnology, pp.
[42] T. C. Loh, Y. C. Lee, J. B. Liang, and D. Tan, Vermicomposting 347358, Oxford and IBH Publications, Calcutta, India, 1992.
of cattle and goat manures by Eisenia foetida and their growth [60] P. K. Padmavathiamma, L. Y. Li, and U. R. Kumari, An exper-
and reproduction performance, Bioresource Technology, vol. imental study of vermi-biowaste composting for agricultural
96, no. 1, pp. 111114, 2005. soil improvement, Bioresource Technology, vol. 99, no. 6, pp.
[43] P. M. Ndegwa, S. A. Thompson, and K. C. Das, Eects 16721681, 2008.
of stocking density and feeding rate on vermicomposting of [61] P. Sangwan, C. P. Kaushik, and V. K. Garg, Vermiconversion
biosolids, Bioresource Technology, vol. 71, no. 1, pp. 512, of industrial sludge for recycling the nutrients, Bioresource
2000. Technology, vol. 99, no. 18, pp. 86998704, 2008.
[44] L. Guoxue, F. Zhang, Y. Sun, J. W. C. Wong, and M. [62] M. Bouche, F. Al-addan, J. Cortez, et al., Role of earthworms
Fang, Chemical evaluation of sewage composting as mature in the N cycle: a falsifiable assessment, Soil Biology and
indicator for composting process, Water Air Soil Sludge Biochemistry, vol. 29, no. 3-4, pp. 375380, 1997.
Pollution, vol. 132, pp. 333345, 2001. [63] V. Balamurugan, M. Gobi, and G. Vijayalakshmi, Compar-
[45] J. H. Crawford, Composting of agriculture waste, in Biotech- ative studies on degradation of press mud using cellulolytic
nology: Applications and Research, P. N. Cheremisino and R. fungi and exotic species of earthworms with a note on its gut
P. Onellette, Eds., vol. 71, Technomic Publishing, Lancaster, microflora, Asian Journal of Microbiology, Biotechnology and
Pa, USA, 1985. Environmental Sciences, vol. 1, pp. 131134, 1999.
[46] C. Tognetti, F. Laos, M. J. Mazzarino, and M. T. Hernandez, [64] R. M. Atiyeh, S. Lee, C. A. Edwards, S. Subler, and J. D.
Composting vs. vermicomposting: a comparison of end Metzger, Earthworm processed organic wastes as compo-
product quality, Compost Science and Utilization, vol. 13, no. nents of horticulture potting media for growing marigolds and
1, pp. 613, 2005. vegetable seedlings, Compost Science and Utilization, vol. 8,
[47] F. Fares, A. Albalkhi, J. Dec, M. A. Bruns, and J. M. Bollag, pp. 215223, 2000.
Physicochemical characteristics of animal and municipal [65] J. H. Crawford, Review of composting, Process of Biochem-
wastes decomposed in arid soils, Journal of Environmental istry, vol. 8, pp. 1415, 1983.
Quality, vol. 34, no. 4, pp. 13921403, 2005. [66] M. L. Cabrera, D. E. Kissel, and M. F. Vigil, Nitrogen
[48] Kaviraj and S. Sharma, Municipal solid waste management mineralization from organic residues: research opportunities,
through vermicomposting employing exotic and local species Journal of Environmental Quality, vol. 34, no. 1, pp. 7579,
of earthworms, Bioresource Technology, vol. 90, no. 2, pp. 169 2005.
173, 2003. [67] M. Fang, M. H. Wong, and J. W. C. Wong, Digestion activity
[49] C. D. Jadia and M. H. Fulekar, Vermicomposting of veg- of thermophilic bacteria isolated from ash-amended sewage
etable waste: a bio-physicochemical process based on hydro- sludge compost, Water Air and Soil Pollution, vol. 126, pp. 1
operating bioreactor, African Journal of Biotechnology, vol. 7, 12, 2001.
pp. 37233730, 2008. [68] F. M. C. Morais and C. A. C. Queda, Study of storage
[50] C. A. Edwards, Earthworm Ecology, CRC Press LLC, Boca influence on evolution of stability and maturity properties
Raton, Fla, USA, 2nd edition, 2004. of MSW composts, in Proceedings of the 4th International
[51] E. Albanell, J. Plaixats, and T. Carbrero, Chemical changes Conference of ORBIT Association on Biological Processing of
during vermicomposting (Eisenia fetida) of sheep manure Organics: Advances for a Sustainable Society, Perth, Australia,
mixed with cotton industrial wastes, Biology and Fertility of May 2003.
Soils, vol. 6, pp. 266269, 1988. [69] R. T. Haug, The Practical Handbook of Compost Engineering,
[52] C. Tognetti, M. J. Mazzarino, and F. Laos, Improving the Lewis, CRC Press, Boca Raton, Fla, USA, 2nd edition, 1993.
quality of municipal organic waste compost, Bioresource [70] M. C. Dash and B. K. Senapati, Vermitechnology, an option
Technology, vol. 9, pp. 10671076, 2007. for organic wastes management in India, in Verms and
[53] J. C. P. Short, J. Frederickson, and R. M. Morris, Evaluation Vermicomposting, M. C. Dash, B. K. Senapati, and P. C. Mishra,
of traditional windrow-composting and vermicomposting for Eds., pp. 157172, Sambalpur University, Sambalpur, Orissa,
the stabilization of was e paper sludge (WPS), Pedobiologia, India, 1986.
vol. 43, pp. 735743, 1999. [71] S. C. Talashilkar, P. P. Bhangarath, and V. B. Mehta, Changes
[54] T. Saradha, The culture of earthworms in the mixture of pond in chemical properties during composting of organic residues
soil and leaf litter and analysis of vermi fertilizer, Journal of as influenced by earthworm activity, Journal of the Indian
Ecobiology, vol. 9, pp. 185188, 1997. Society of Soil Science, vol. 47, pp. 5053, 1999.
[55] P. A. Uthaiah, Acceleration of pressmud decomposition by micro- [72] M. A. V. Christry and R. Ramaligam, Vermicomposting of
bial inoculation for quality product, M.S. thesis, University of sago industrial soild waste using epigeic earthworm Eudrilus
Agricultural Sciences, Bangalore, India, 1997. eugeniae and macronutrients analysis of vermicompost, Asian
[56] R. Muthukumarasamy, G. Revathi, V. Murthy, S. R. Mala, Journal of Microbiology, Biotechnology and Environmental
M. Vedivelu, and A. R. Solayappan, An alternative carrier Sciences, vol. 7, pp. 377381, 2005.
material for bio-fertilizers, Co-Operative Sugar, vol. 28, pp. [73] M. C. Manna, S. Jha, P. K. Ghosh, and C. L. Acharya,
677680, 1997. Comparative ecacy of three epigeic earthworms under
[57] K. Parthasarathi and L. S. Ranganathan, Aging eect on dierent deciduous forest litters decomposition, Bioresource
enzyme activities in pressmud vermicasts of Lampito mauritii Technology, vol. 88, no. 3, pp. 197206, 2003.
Applied and Environmental Soil Science 13