NATURAL PESTICIDES

PESTICIDES
• A pesticide is a substance that disrupts or kills organisms t
hat we consider to be pests such as weeds, damaging insects
, or microbes that cause disease.
•
Any substance or mixture of substances, intended for prev
enting, destroying, or mitigating any pest, or intended for use
as a plant growth regulator, defoliant or desiccant.
• Pest-
it is any animal, plant or microorganism that trouble, injuries o
r cause destruction of crop.
• Methods of pest control
• - They have two types- natural and artificial pest control.
• Natural pest control- they are prepared in nature due to prey-
predator relationships.
Beneficial insects are those insects which prey on harmful inse
cts or their larvae.
• Artificial pest control-
these are man made methods to control pest
• In agricultural production the synthetic pesticides are used

which has got sometimes carcinogenic, teratogenic and resid

ual toxic effects.
The excessive use of it also causes serious health hazards to liv
e stocks, human life, wild life, fishes, birds and animals.
•
Agriculture control these methods are used to destroy life cycle of
pest eg deep poughing for eradication of weeds, alternate crop rot
ation, hybrid pest resistance crop
• Chemical control-
these are chemicals used to kill pest eg. insecticides, paraciticides
• Biological control-
Living organisms are used to control pest. Eg microorganisms may
be used to kill by causing fatal disease in insects
• Mechanical
manual or mechanical method for collection or destruction of
pest. Eg.hand
picking, pruning, trapping, burning for destruction of eggs, larv
ae, pupae, insects
 Classification of pesticides
Pesticides are classified according to the pest they control;
 Insecticides (Ants, moths, cockroaches)
 Herbicides (Weeds)
 Fungicides (Control fungal diseases)
 Rodenticides (Rats)
cost
 Characteristics of ideal pesticide

should have high margin of safety for plants and animals

easy to handle and apply –
should not be toxic for warm blooded animals –
should not be inflammable or explosive
 should be available easily at affordable
Advantages
1. They are cheap (They are economical
2.They are less harmful to the human beings and more effec
tive against pest
3. They are more stable and can be kept for prolonged perio
d (Degradation is less)
4.They can be used to control the carriers of vector borne di
seases like malarial, sleeping sickness and dengue fever
Dis- advantages:
• The onset of action is slow
•The quantity of pesticide required may be more due to cr
ude components
 HERBICIDES
 Herbicides, also commonly known as weed killers,
These are pesticides used to kill unwanted plants.
 Selective herbicides kill specific targets, while leaving the desired crop rela
tively unharmed.
 Some of these act by interfering with the growth of the weed and are
often synthetic mimics of natural plant hormones.
 Some plants produce natural herbicides, action of natural herbicides,
and other related chemical interactions, is called allelopathy.
 The most frequent application of herbicides occurs in row-
crop farming, where they are applied before or during planting to maximiz
e crop productivity by minimizing other vegetation(weed)
 Fungicides
 Fungicides they are used to control fungal diseases of plants and food crops.
 Fungi can cause serious damage in agriculture, resulting in critical losses of yie
ld, quality, and profit Fungicides can either be contact, translaminar or systemic.
 Contact fungicides are not taken up into the plant tissue, and protect only t
he plant where the spray is deposited;
 translaminar fungicides redistribute the fungicide from the upper, sprayed le
af surface to the lower, unsprayed surface;
 systemic fungicides are taken up and redistributed through the xylem vessels.
 Few fungicides move to all parts of a plant. Some are locally systemic, and some
move upwardly
 Fumigation
 Fumigation is a method of pest control that completely fills an area
with gaseous pesticides or fumigants
to suffocate or poison the pests within.
It is used to control pests in buildings (structural fumigation), soil, gr
ain, and produce, and is also used during processing of goods to
be imported or exported to prevent transfer of exotic organisms.
 Rodenticides
 Rodenticides, rat poison, are pest control chemicals intended to
kill rodents.
Rodenticides are controversial, due to secondary poisoning an
d their risks to children, pets and wildlife.
 Single feed
baits are chemicals sufficiently dangerous that the first dose
is sufficient to kill. rodents will eat a small bit of something and
wait, and if they do not get sick, they continue.
 An effective rodenticides must be tasteless and odorless in le
thal concentrations, and have a delayed effect.
 Tobacco

Tobacco
Synonym : Tobacco
Biological source: Tobacco consist of dried leaves of Nicotiona
tabacum belonging to the family Solanaceae.
colour : green to slightly brown
Odour : characteristic
Taste : bitter and acrid
Mode of action.
 In both insects and mammals, nicotine is an extremely fast
acting nerve toxin. It competes with acetylcholine, the major neuro
transmitter, by bonding to acetylcholine receptors at nerve syn
apses and causing uncontrolled nerve firing.
This disruption of normal nerve impulse activity results in rapi
d failure of those body systems that depend on nervous input for p
roper functioning. In insects, the action of nicotine is fairly sele
ctive, and only certain types of insects are affected.

Chemical constituents
Consists of pyridine , piperidine type of alkaloids among them
1-10% nicotine, nornicotine, anabasine
Uses Insecticidal
free base of nicotine is more toxic than sulphate,
Mostly effective against minute soft body insects like aphides,
white flies, fruit tree borers, termites, cabbage butterfly larvae
Nicotine preparations are safer, easier to handle, less toxic to w
arm blooded animal
 Pyrethrum
Pyrethrum
Synonym; Insect flowers, pyrethrum flowers
Biological source :It consist of dried unexpanded flower-
heads of Chrysanthemum cinerariaefolium
belonging to the family Compositae,
consists of NLT 0.7 % pyrethrins.
Before drying flower heads are non toxic to insect
Mode of action.
 Pyrethrins exert their toxic effects by disrupting the sodium
and potassium ion exchange process in insect nerve fibers a
nd interrupting the normal transmission of nerve impulses.
 Pyrethrins insecticides are extremely fast acting and cause
an immediate “knockdown” paralysis in insects.
 Despite their rapid toxic action, however, many insects are
able to metabolize (break down) pyrethrins quickly. After a
brief period of paralysis, these insects may recover rather th
an die.

 To prevent insects from metabolizing pyrethrins and recoveri

ng from poisoning, most products containing pyrethrins also
contain the synergist, piperonyl butoxide (PBO). Without PB
O the effectiveness of pyrethrins is greatly reduced.
pyrethrins” refers to the six related insecticidal compounds tha
t occur naturally in the crude material, the pyrethrum flowe
rs.

They are extracted from crude pyrethrum dust as a resin tha
t is used in the manufacture of various insecticidal products.
 NEEM tree
The NEEM tree (Azadirachta indica)
belonging to the family Meliaceae) is a tropical evergreen tr
ee native to India and is also found in other southeast countrie
s.

In India, neem is known as “the village pharmacy” because of it
s healing versatility,
 The product known as “neem oil” is more like a vegetabl
e or horticultural oil and acts to suffocate insects. Neem
and neem oil are often confused.
 Mode of action.

 Neem is a complex mixture of biologically active materi

als, and it is difficult to pinpoint the exact modes of acti
on of various extracts or preparations.

In insects, neem is most active as a feeding deterrent, b
ut in various forms it also serves as a repellent, growt
h regulator, oviposition (egg deposition) suppressant,
sterilant, or toxin.
 As a repellent, neem prevents insects from initiating feedin
g. As a feeding deterrent, it causes insects to stop feedin
g. As a feeding, either immediately after the first “tast
e” (due to the presence of deterrent taste factors), or at so
me point soon after the food (due to secondary hormo
nal or physiological effects of the deterrent substance).
 As a growth regulator, neem is thought to disrupt nor
mal development interfering with chitin synthesis. Suscepti
bility to the various effects of neem differs by species
 Neem (leaf and seed) extracts have been found to have ins
ecticidal properties. has anti-bacterial, anti-fungal and anti-
nematicidalproperties and positive effect in combating sev
eral diseases
 DERRIS
DERRIS
Biological source: It consists of dried root
and rhizomes of Derris elliptica and Derris
malaccensis
belonging into the family Leguminosae
Chemical constituents:
It contains isoflavonoid derivative Rotenone
Mode of action
Mode of action of rotenone is a respiratory enzyme inhibitor, acting between NAD+
(a coenzyme involved in oxidation and reduction in metabolic pathways) and c
oenzyme Q (a respiratory enzyme responsible for carrying electrons in some electro
n transport chains), resulting in failure of the respiratory functions
1. It is a Contact poison
2.Used in the form of spray for killing vegetable insects during harvest
ing time such as leaf hopper
3. Insecticidal from the rotenone in the roots.
4.Rotenone has also been found effective against plant lice, leaf beetl
es, aphids, flies, caterpillars, ticks, chicken lice, red spiders and oth
er insects.
5.It has been reported to be more effective than potassium cyanide o
r nicotine and equally effective as pyrethrum, Because of toxicity, r
otenone as insecticidal is being phased out in many eco-
conscious countries
 SABADILLA

 SABADILLA synonym: stickweed.

 Biological source: it consist of dried
ripe seeds of schoenocaulon officinale
 Family:Liliaceae
• Chemical Constituents---
Sabadilla contains several alkaloids, the most important being Cevadine, yi
elding cevine on hydrolysis;
• Veratrine, obtained from the syrupy liquor from which the cevadine has
crystallized; and Cevadilline or Sabadillie, obtained after the extraction o
f the veratrine with ether.
• Mode of action.
 In insects, sabadilla’s toxic alkaloids affect nerve cell membrane action, ca
using loss of nerve cell membrane action, causing loss of nerve function, p
aralysis and death.
 Sabadilla kills insects of some species immediately, while others may survi
ve in a state of paralysis for several days before dying
 RYANIA
• RYANIA Biological source: It consists of dried root and stems of Ryania
speciosa belonging to the family Flacourtiaceae.
• Ryania is a botanical insecticide made from the ground stems of Ryania spe
ciosa, a native plant of tropical America.
• The principal alkaloid in this stem extract is ryanodine, which makes u
p approximately 0.2% of the product.
• Ryania is highly toxic to the fruit moth, coddling moth, corn earworm, Eur
opean corn borer, and citrus thrips, but it is ineffective against the cabbage
maggot, cauliflower worm, and boll weevil.
• Ryania is a complex mixture of many compounds; thus, no single structur
e would represent it
 Mode of action.
• Ryania is a slow-acting stomach poison.
• Although it does not produce rapid knockdown paralysis, it does cause
insects to stop feeding soon after ingesting it.
• The most active compound in ryania is the alkaloid ryanodine, which co
nstitutes approximately 0.2% of the dry weight of stem wood.
 Citrus Oil Extracts
• Citrus Oil Extracts: Limonene and Linalool
Crude citrus oils and the refined compounds d-
limonene (hereafter referred to simply as limonene) and linalool are e
xtracted from orange and other citrus fruit peels.
• Limonene, a terpene, constitutes about 90% of crude citrus oil, an
d is purified from the oil by steam distillation.
Mode of action.
• The modes of action of limonene and linalool in insects are not fully u
nderstood.
• Limonene is thought to cause an increase in the spontaneous acti
vity of sensory nerves.
• This heightened activity sends spurious information to motor nerves an
d results in twitching, lack of coordination, and convulsions.
• The central nervous system may also be affected, resulting in additional
stimulation of motor nerves. Massive over stimulation of motor nerves l
eads to rapid knockdown paralysis
 RODENTICIDES
• Red squill and white squill
Are both varieties of Urginea maritima
Family:Liliacea
The bulb of red squillalso contain the glycosides scilliroside and
scillirubroside
Unlike other mammals,Rodents do not regurgitate the squill bulb
and death follows convulsion and respiratory failure.
• Strychnine ;from strychnos species of family Logaceae.