Tools/Methods of IPM
Curative methods (continuation)
CHEMICAL CONTROL
Chemical Control: Management of insect pests using chemical pesticides
is termed as chemical control. Or Pest control with the help of various
chemicals is called as chemical control.
Pesticides: - The chemicals which applied for control of insect pests are
called as pesticides.
History of insecticides development
Year Chemicals Discovered
900 Arsenites used in China (Inorganic compound)
1690 Tobacco extract used in Europe (Plant/natural product)
1787 Soaps used in Europe
1858 Pyrethrum was first time used for insect control in USA
1867 Paris Green in US
1874 DDT synthezized by Zeidler
1883 Bordeaux Mixture used in France
1892 Lead arsenate was used for control of Gypsy moth in USA
1925 Dinitro compounds used (First synthetic organic insecticide)
1939 Discovered of insecticidal property of DDT by Paul Muller in Switzerland.
(Awarded Nobel Prize in 1948)
1941 BHC used or discovered the insecticidal property in France and UK (in
1942) (BHC is presently called as HCH)
1944 Parathion (Organophosphate) discovered by Gerhard Schrader in
Germany
1945 Chlordane (Cyclodian compound) used in Germany
1947 Carbamate insecticides in Switzerland
1962 Miss Rachel Carson’s wrote the book name ‘Silent Spring’ in US which
gives the impact of insecticides on environment.
1967 First JH mimic (Juvenile Hormone mimic) used in US (Insect growth
regulator)
1970 Development of synthetic pyrethroids (UK) (Fast degradation) (Effective
at very low doses)
1980 Discovery of avermectins (derived from bacteria). Effective at low dose.
Fast degradation.
1990 Discovery of newer groups like (1) Neonicotinoids (Imidacloprid), similar
to natural nicotine, (2) Spinosyns (e.g. Spinosad) derived from actinomycet
Various generations of insecticides
Generation Year Compounds
1. First generation insecticide 1939-1942 BHC and DDT
2. Second generation insecticide 1944-1947 Organophosphates and
Carbamate
3. Third generation insecticide 1967 Hormonal insecticides, JH mimic insect
growth regulators
4. Fourth generation insecticide 1970s Synthetic pyrethroids
Insect Ecology and IPM Including Beneficial Insects 33
Compiled by Prof. A. S. Mochi & Prof. T. B. Ugale (K. K. Wagh College of
Agriculture, Nashik)
Classification of Pesticides/Pesticides Groups
The pesticides are generally classified into various groups based on pest
organism against which the compounds are used, their chemical nature,
mode of entry and mode of action.
1. Based on organism against which the compounds are used
Name of insecticides Definition
1. Insecticides Chemicals used to kill or control insects. E.g. Carbaryl,
malathion
2. Rodenticides Chemicals used to kill the rodents called rodenticides. E.g.
Zinc phosphide
3. Acaricides/Miticides Chemicals used to kill the mites, ticks and spider called
acaricides. E. g. Dicofol, Properguite
4. Avicides Chemicals used to repel the birds. E.g. Anthraquionone
5. Molluscicides Chemicals used to kill the snails and slugs. E.g.
Metaldehyde
6. Nematicides Chemicals used to control nematodes E.g. Ethylene
dibromide
7. Fungicides Chemicals used to control plant diseases caused by fungi.
E.g. Copper oxychloride
8. Bactericide Chemicals used to control plant diseases caused by
bacteria. E.g. Streptomycin sulphate
9. Herbicide Chemicals used to control weeds. E.g. 2,4,D
10. Algicides Chemicals used to control algae.
11. Arboricides Chemicals used to control trees or shrubs.
12. Piscicides Chemicals used to control harmful fishes.
2. Classification based on Mode of entry
a) Stomach poison –
Insecticides applied on leaves and other parts of plants when ingested get
entry in insects & act on digestive system to cause death of the insect. This
type of chemicals is limited mainly to the chewing type of insects like
grasshopper, beetles, caterpillar
etc.
The stomach poison should be sufficiently stable, cheap, and palatable for
the pest, available in large quantities.
These chemicals may be applied in the form of dust or spray or in poison
bait.
E.g. Bt, Organochlorine and organophosphates insecticides etc.
b) Contact poison –
The toxicant which causes death of insect by means of contact with
insecticide.
Insecticides get absorb by the sutures, membrane & tracheal system on
insect body.
This is achieved by direct application of insecticides on pest species.
E.g. Nicotine, Pyrethrum, quinolphos, Malathion, synthetic pyrethroids etc.
Insect Ecology and IPM Including Beneficial Insects 34
c) Fumigants –
Toxicant which in its gaseous state or in vapour form penetrate in insect
through the tracheal system (respiratory poison) through spiracles & kills the
insect.
Their application is limited to plants or plant products in air-tight enclosures.
E.g. Methyl Bromide, Hydrogen cyanide (HCN), ethylene dibromide, DDVP,
Lindane.
d) Systemic poison -
Chemicals when applied to plant or soil are absorbed by foliage (or) roots
and translocated through vascular system and cause death of insect feeding
on plant.
It is effective against the pest having sucking type of mouth parts such as
aphid, jassid, thrips, white fly etc.
E.g. Dimethoate, Imadaclopirid, Phorate, carbofuran etc.
3. Classification based on mode of action: -
a) Physical poison – Chemical which can kill insects by following three ways;
Asphyxiation – A physical poison kill the insects exert by physical effect
through asphyxiation i.e. exclusion of air called physical poison. E.g. effect of
heavy oil & Tar oil on scale insects.
Moisture stress – Loss of moisture from insect body by inert dust, charcoal,
activated clay, ash etc.
Mechanical injury – Epicuticle of insect gets lacerated by abrasive dust like
aluminum oxide & this may cause water loss.
b) Protoplasmic poison –
Toxicant responsible for precipitation of protein, destruction of midgut
epithelium called as protoplasmic poison.
E.g. Heavy metals like mercury, copper, Fluorine.
c) Respiratory poison –
The chemical which block cellular respiration, inactivation of respiration &
respiratory enzymes. This is known as anoxia.
E.g. Hydrogen cyanide (HCN), Carbon monoxide (CO).
d) Nerve poison –
The chemicals which affect the nervous system of the insect or Chemicals
inhibit the production of acetylcholinesterase enzyme in insects called as
nerve poison.
E.g. organophosphate, carbamate, organochlorines, pyrethrum and
nicotine.
e) Chitin inhibition - Chemicals inhibit chitin synthesis. E.g. Diflubenzuron
Reference
Compiled by Prof. A. S. Mochi & Prof. T. B. Ugale (K. K. Wagh College
of Agriculture, Nashik)
