Rice Black Bugs Sem
Rice Black Bugs Sem
Rice Black Bugs Sem
1. INTRODUCTION
Rice is the staple food for more than 60 per cent of the global
population and the total area under rice cultivation in India is 44.6 million
hectares with a production of 90 million tonnes (Ghule et al., 2008). Rice is
ravaged by various pest problems starting from its seedling stage to maturity.
About 300 insect species have been reported to damage rice crop in India. At
least 20 species of insects have been found to be serious causing more than
50 per cent yield loss (Arora and Dhaliwal, 1996). Among the insect pests of
rice, The Rice Black bug is a serious pest of rice (Oryza sativa) (Ooi, 1981)
2. TAXONOMY
Order : Hemiptera
Suborder : Heteroptera
Family : Pentatomidae
Genus : Scotinophara Stal
Species : before = 41 species
now = 60 ‐ 71 spp.
2.1. COMMON NAMES:
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pentatomid bugs. Scotinophara coarctata is an important pest of rice in
Cambodia, China (including Taiwan), India, Indonesia, Malaysia,
Philippines, Thailand, and Vietnam. Scotinophara lurida occurs in China
(including Taiwan), India, Japan, and Sri Lanka.
There are about 11 spp. common in rice fields. They were S.coarctata,
S.lurida, S. parva, S. tarsalis, S. scotti, S. harvathi, S. inermiceps, S.
latiuscula, S. affinis, S. inermis and S. ochracea (Reissig et al., 1986).
However in India only five species were common i.e. S. coarctata Fabricus
(Pathak. M. D, et al., 1994), S. lurida Burmeister, S. bispinosa Fabricus, S.
scottii Hovarth, S. westwoodi Westwood (Ravi et al., 2008). According to
Magsino, 2009 there were 71 spp. In recent days, it was found in many parts
of rice growing areas in district like Thiruvarur, Nagapattinam, Vellore,
Thanjavur, Tirur and Tirunelveli in Tamil Nadu. Species prevalent in
Cauvery delta zone were identified as Scotinophara coarctata (F) and S.
bispinosa (F).
3. OCCURRENCE
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1918. Since 1983 its numbers have increased because of the staggered
planting of the rice crop. In the Philippines, the pest was first recorded in
September 1979 in southern Palawan; it later spread to central and northern
Palawan. The black bug problem in Palawan is partly related to double
cropping of irrigated rice since the introduction of high-yielding cultivars
and high N levels. Black bug infestation is most serious in poorly drained
ricefields around marshes. (Pathak, 1994)
Scotinophara lurida is a major pest of rice in China and Japan. Before
1940 the pest was recorded as anoccasional rice pest in Sri Lanka. Since then
it has become economically important, occurring periodically in large
numbers and causing extensive damage to rice crops in most parts of the
country.
4. LIFE CYCLE
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during daytime and feed at night. The RBB adult is brownish black with few
distinctly yellowish spots on the thorax that bear spines below the anterior
angles. It is oval shaped and about 8-9 mm long. They are very well adapted
to variable conditions and may stay alive for seven months.
The adults may survive throughout the period and between seasons by
resting hidden and inactive in soil cracks, grassy areas or in any area where
relative humid atmosphere seems to provide a good shelter. The adult gives
off an offensive odor when disturbed. Adults are attracted to street lights and
full moon when they congregate and fly in search of a new area for invasion.
Large number of the pest is carried by strong winds and land on new area or
vegetation. Both nymph and adult feed during daytime and mainly at the
base of the rice stem but they may feed on panicles during evening, early
morning or an overcast day. During daytime, the adults are lethargic and
avoid sunlight. A behavioral characteristic of RBB is their ability to stay
underwater when disturbed though more than two hours submersion will
cause them death. (Wilma, 2007)
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9 V instarnymph 8 10
10 Adult longevity 203 210 (Jalaludin et al.,
Unpublished)
5. HABITAT
Black bugs were Abundant in ill drained rice fields. Population is low
under rainfed conditions and increases with expanded irrigation (Anon.,
1983). Bugs were sluggish in day time, congregate at base of plants just
above the water level and active in night, move upwards and suck the sap
(Pathak et al., 1994). Crowding was high on full moon day.. It also have the
habit of aestivate in soil (Ravi et al., 2008)
Full moon cycle affects the RBBs flight activity. This is significant to
pest surveillance and forecasting. Checking for black bugs should take place
2 days before until 3 days after the full moon.
Quality of available food is another important factor. The bug's flight
activity increases when deprived of food. It is highly probable that migration
and dispersal are less when the rice plants are readily available as food in the
field. (Hilario el al., 2000)
6. HOST RANGE.
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Although some weeds and other cultivated crops have been listed as
alternate host plants of MBB, rice is its most important host. Some
commonly occurring alternate hosts of MBB are corn, gabi, grasses, sedges,
and broadleaves.
7. SYMPTOMS
The initial symptom includes, chlorotic lesions and reddish brown leaf
and yellowing of plants. Continuous feeding results in decreased tillering,
stunted plant growth, poor panicle emergence and wilting of plant. In severe
condition the plant dries in patches and the symptom is called "Bug Burn".
The bug burn symptom was usually seen in crop at panicle initiation and in
maturity phase. The bug burn symptom differs from Brown pant hopper
damage by the absence of honey dew deposits and sooty mold growth on the
base. The feeding also cause half-filled and empty grain and dead heart and
white ear damage as that of stem borer. Unlike that of stem borer damage the
dead heart and white ear damage due to black bug feeding cannot be pulled
at the bases. Damage to the panicle resulted in reduced grain yield.
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“Deadhearts” - A condition of the plant wherein the damaged tillers‟ center
leaves turn brown and die. This damage occurs when the infestation happens
during the tillering stage
“White ear” - Panicles with empty grains or underdeveloped panicles. This
damage occurs when the infestation happens during the booting stage.
“Bugburn”. A condition of the plant wherein the leaves turn reddish brown,
resulting to crop loss. This damage occurs when the infestation happens from
the seed bed, maximum tillering up to harvesting stage.
8. DAMAGE
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rice lands affecting 2,430 farmers who suffered a production loss estimated
at 2.2 million in 1992 (Fernandez, 1993) and 10,000 hectares of ricelands in
1995 (Apao et al., 1998). In the Visayas, the RBB hit about 6,202 hectares of
rice fields in Leyte provinces in 2000 (Tempo, 2004).
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8.1 DAMAGE IN CAUVERY DELTA REGION
Black bug problem in rice is new to Cauvery delta zone, Tamil Nadu.
However black bug is considered as endemic in northern part of Tamil Nadu
(Tirur). Outbreak of the pest was observed (bug burn) in the summer 2004
season. The variety most suffered was ADT 43. In a village Andalam
Pettai, Thiruvidaimaruthur Taluk, Thanjavur District a farmer has lost his
ADT 43 seed crop (6 acres) due to bug burn symptom. In subsequent years,
though the pest was prevalent there was no outbreak situation encountered.
Recently in summer 2006 black bug outbreak was observed in a village
Paruthikkottai near Thanjavaur. There were two rice varieties (ADT 43 and
ADT 36) suffered due to black bug incidence in Paruthikkottai village, of
them ADT 43 suffered bug burn symptom in 4 acre. (Ravi et al., 2008)
9. POPULATION DYNAMICS
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Table 4. Effect of different intensity of light on rice black-bug occurrence at
Rice Research Station, Tirur. (Saroja, 1993)
The adult black rice bug movement of insects in the rice ecosystem at
Tamil Nadu Rice Research Institute, Aduthurai was monitored by the use of
light trap with 125 W mercury vapour lamp from April 2009 to March 2010.
The corresponding meteorological data were also collected and compiled.
Daily catches between 6pm to 6 am were reordered. Adult species of
Scotinophora were sorted out and identified adapting taxonomic characters
described by Barrion & Listinger (1994).
Japanese black rice bug, Scotinophora lurida appeared in the light trap
in large numbers during April „09, August ‟09 and March 2010. The total
catches in the months being 7077, 24,890 and 403 respectively with a peak
catch during Aug‟09. Ferar and Shepard (1987) studied light trap catches of
black bugs and recorded high inerdence in mid-August. Significant
correlations of light trap catches and abiotic factors were lacking in the data
collected during the experiment. Close observation of taxonomic
character‟s, species shift/dominance over crop stages, season, light trap
catches, correlation with abiotic factors and cropping year which warrents
close investigations.
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Table 5. Black rice bug Scotinophora lurida (Blumeister) catches in light
trap during
Month Catches(Nos.)
April 09 7077
May 0
June 15
July 0
August 24,890
September 93
October 46
November -
December -
January 10 330
February 3395
March 2380
Both adults and nymphs feed at the base of the plant. (Heinrichs et al.,
1986) suggested that 6 bugs / hill was above the ET level. (Heinrichs et at.,
1987) also stated that 3 bugs/hill will cause economic injury. About 10
adults per hill can cause losses of up to 35%.
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11. MANAGEMENT
Direct-seeded rice crop has less number of tillers per hill which is not
favored by RBB. Few tillers expose the RBB to sunlight and other mortality
factors that prevent further increase of RBB population.
On the other hand, closely spaced plants shade each other, making rice
plants more vulnerable to brown planthopper due to increased humidity,
greater plant surface area for oviposition, and less crowded feeding
conditions. A field with a 10 x 10 cm hill spacing has greater chances of
suffering bugburn than a field with a 20 x 20 hill spacing. Dense planting
increases populations of black bugs.
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11.4. USE OF RESISTANT/TOLERANT VARIETY.
IR1314 and ADT 37, TKM 1, ADT 38, ASD ADT 36, TKM 9,
IR44526 TKM 2, TKM 10 16, ASD 17, CO CO 43, IR 50
CO 37 45, IR 20
11.5. MONITORING.
Inspect rice fields weekly or twice a week throughout the cropping season
for the presence of egg, nymph, and adult RBB. Monitor the base of 20
randomly selected rice plant hills. Employ control strategy when there are
five or more RBB nymphs or adults per hill.
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outbreaks, light trap should be set up every night to obtain the most number
of bugs.
Install light traps in areas near the rice field where you can easily
collect the bugs.
Use 20-watt fluorescent tubes or mercury bulbs mounted 5 m from the
ground.
Turn on the light from 6PM to 6AM.
Collect the light trap catches before sunrise or early morning. After
sunrise, RBBs become active and move to other fields. Place the
collected RBBs in sacks until they die or bury the bugs in the soil.
(Hilario, 2000)
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Figure 3. Light trap catch of Black bugs
By covering the paddy water surface with Azolla (water fern) during
the early vegetative stage, the incidence of whorl maggot is reduced. Such
covering of paddy water is also suitable for natural enemies, especially
predators, in assisting their movement from hill to hill in search of prey.
Alternate flooding and draining for 5-7 days, can minimize insect
pests such as black bugs, planthoppers, gall midge, hispa, and most stem
borers. Draining stimulates calcium uptake, which hardens plant tissues and
makes them more resistant to pests. However, draining may also stimulate
weed growth. Frequency of action is important because alternative flooding
and draining can cause high losses of nitrogen.
Water management plays an important role in IPM [integrated pest
management] of rice pests. a study was conducted at PhilRice, Midsayap,
Bual Norte, and Midsayap North Cotabato [Philippines] to determine the
effect of water level on the rice black bug population, crop damage and yield
under screenhouse and field conditions. The results showed that water level
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significantly affected the rice black bug population. At 30 days after
infestation (DAI) nymph population on plants at 2 cm water level was
significantly higher than those at 10 cm water level. Under field conditions,
no significant difference was obtained on the population of rice black bug
when water level was varied from 2-10 cm, however, RBB damage
(whitehead) was significantly lower at 10 cm than at 2 cm water level. Yield
was significantly higher at 10 cm (2.31 t/ha) than at 2 cm water level (1.7
t/ha) (Tadle et al, 2002)
Raising the water to a level higher than the egg masses drives the
female black bug off the mass and also results in reduced egg hatch.
Implications of using water level for black bug control were discussed.
(Parducho, 1988)
High rates of nitrogen fertilizer will provide more plant nutrition, resulting
in higher yield. However, high nitrogen fertilizer rates also:
Increase weed populations in the current and subsequent crops
Increase the incidence of fungal and bacterial diseases by increasing
tissue susceptibility and tiller density and
Encourage the multiplication of black bugs. Under high nitrogen fertilizer
conditions, insects generally grow larger, cause more damage, produce
more offspring, grow faster, and complete more generations per crop.
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11.10. USE OF DUCKS
The most common beneficial organisms observed in the field are Telenomus
triptus and Metarhizium anisopliae. If these natural enemies cannot regulate
RBB population even when conservation has been made, rear(grow) these
organisms in the laboratory and release them repeatedly on the crop to keep
RBB population down. Release the organisms early in the cropping season,
before field populations of T. triptus appear. This is in order to establish the
natural enemy population before it grows too large to control. Or, release the
organisms during high RBB population.
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Table 7. List of Natural enemies of Rice Black bugs
11.12. INSECTICIDES
Greatest number of light trap catches occur during harvest when the
RBBs start to move to other areas to look for food. So, plow and submerge
the stubbles immediately after harvest to bury these insects, particularly the
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nymphs, under the mud/ soil and to completely eradicate the bugs' food
source.
12. CONCLUSION
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REFERENCES
Barrion A.T & James A. Listinger (1994). Taxonomy of rice insect pests
and their arthropod parasites and predators. In: Biology and
Management of rice insects. E.A. Herrichs (Ed) Wiley Eastern
limited, New Age International Limited (India) & IRRI (Phillippines),
13-362.
Ferer, E.R and Sheperd (1987). Sampling Malayan black bugs (Heteroptera:
Pentatomidae) in rice. Environ Entomol., 16: 259-263.
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Fernandez. R. A. 1993. Rice black bug ravaging crops in Western Mindanao.
PhilRice Newsl. 6(4): 5.
Ghule, S.D., K.G. Patel and H.V. Pandya. 2008. Seasonal incidence of rice
earhead bug (Leptocorisa acuta) of paddy in south Gujarat. Insect
Environ., 14(1):7-8.
Magsino. L., 2009. Rice Black Bugs: The Experiences and Strategies of
Laguna Farmers. SEARCA‟s Agriculture & Development Seminar
Series. Feb. 17, 2009
Ooi, P. A. C., 1981. The Paddy Black Bugs. Nature Malashiyana. 6:33-35
Parducho, M.A.; Arida, G.S.; Perez, V.; Shepard, B.M. 1988. Biology of the
black bug, Scotinophara coarctata (Hemiptera: Pentatomidae) in
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Palawan [Philippines] with special reference to its control.
International Rice Research Inst., Los Banos, Laguna. Philippines.
Ravi, G.,K. Chozhan and S. Jebaraj. 2008, Rice blackbug menace in cauvery
delta zone. DRR Newsl., 4(3):4-5.
Saroja, R., M. Subramanian and A. Abdul Kareem. 1993. Rice black bugs
(Scotinophara sp). Rice research station,. Tamilnadu Agricultural
University, Tirur. p 29.
Tadle, F.P.J., Batay-an, E.H., Balleras, G.D., Estoy, A.B. and Tabien, R.E.
2002. Influence of water level on rice black bug population, crop
damage and yield. Philippine Rice Research Inst. North Cotabato.
Philippines.
Zahirul Islam. 2006. Control of rice insect pests. IRRI Training Center, Los
Banos, Philippines.
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