2. • Insecticides are further grouped or classified according to their
nature and source.
• some insecticides are inorganic, lacking carbon atoms, and others
are organic, possessing carbon atoms.
• Most modern insecticides are organic, and these are even further
subdivided as natural or synthetic.
• Natural insecticides are produced by refining natural substances.
These consist mainly of botanical insecticides made from plants,
and mineraloils, obtained by refining petroleum. Botanical
insecticides have wide usage, but oils are used mainly for
suppression of fruit-tree insects and mosquito larvae.
• Most insecticides used today are synthesis, manufactured by
chemically joining elements or simple compounds.
• The most precise method of grouping insecticides is according to
their chemical makeup, several classes of compound can be
designated according to active ingredients (chemical responsible
for the toxic effect).
• The four major classes are Organochlorine,Organophosphate,
carbamate, and pyrethroids.
3. 1-Organochlorines(OCs)
• These are organic compounds with five or more chlorine
atoms.
• Organochlorines were the first synthetic organic pesticides
to be used in agriculture and in public health.
• This category, which was developed in the 1930s and
1940s, includes the chlorinated ethanes, chlorinated
cyclodienes, and other chlorinated compounds.
• Most of them were widely used as insecticides for the
control of a wide range of insects, and they have a long-
term residual effect in the environment since they are
resistant to most chemical and microbial degradations.
• Organochlorine insecticides act as nervous system
disruptors leading to convulsions and paralysis of the insect
and its eventual death.
4. • Some of the commonly used representative examples of
organochlorine pesticides are DDT, lindane, endosulfan,
aldrin, dieldrin and chlordane
• Dichloro diphenyl trichlorethane (DDT) is the most famous
of the chlorinated insecticides. First synthesized in 1943, it
was used extensively (worldwide) in agriculture from the
end of World War II until 1972, when it was banned in the
United States.
• It was first used to control disease-carrying insects such as
body lice and mosquitoes that spread malaria.
• DDT also provided effective against a variety of agricultural
pests and was extensively used on crops
5.
6. 2-Organophosphate (Ops)
• Organophosphates are derived from Phosphoric acids &
are some of most toxic insecticides.
• They are unstable in the presence of light and quickly
breakdown into non toxic compounds.
• Organophosphorus compounds do not persist in the
environment and have an extremely low potential to
produce cancer; thus insecticides based on these
compounds have largely replaced the chlorinated
hydrocarbon insecticides
• In fact,they are most widely used group of insecticides.
• Most common used are
Profenofos, Chlorpyrifos, dimethoate,Trichlorfon.
9. • Carbamate insecticides are broad spectrum
insecticides widely used in homes, gardens, and
agriculture.
• They affect the functioning of the nervous
system in ways similar to the organophosphates.
• The effects are usually reversible in humans.
10. 4-Pyrethroids
• Pyrethroids are synthetic versions of the naturally occurring
chemical pyrethrin, which is found in chrysanthemum flowers.
• Pyrethrins are used mainly for indoor pest control. Synthetic
pyrethroids are used in agriculture because they are designed
to be more stable in the natural environment.
• Some synthetic pyrethroids are toxic to the nervous system
• Pyrethrins and pyrethroids are insecticides included in over
3,500 registered products, many of which are used widely in
and around households, including on pets and in treated
clothing, in mosquito control, and in agriculture.
• The use of pyrethrins and pyrethroids has increased during
the past decade with the declining use of organophosphate
and carbamate pesticides, which are more acutely toxic to
birds and mammals than the pyrethroids.
• They work by altering nerve function, which causes paralysis
in target insect pests, eventually resulting in death.
11. • Pyrethroids are modified to increase their stability in
sunlight.
• Most pyrethrins and some pyrethroid products are
formulated with synergists, such as piperonyl butoxide and
MGK-264, to enhance the pesticidal properties of the
product.
• These synergists have no pesticidal effects of their own
but enhance the effectiveness of other chemicals.
• Common used examples are
Cypermethin,deltamethrin,Bifenthrin,Lambda cyhalothrin
