Question

Classification of insecticides based on chemical nature

Answer 1

Early insecticides (natural, based on plant
derivatives, oils, heavy metals).
• Plant derivatives.
Pyrethrum from Chrysanthemum.
Rotenone from roots of derris plant.
Nicotine from tobacco plant.
Neem from neem tree, Azadirachta
indica.
Short-lived, variable mammalian toxicity.
Chemical structure, continued
• Oils.
Work by suffocation.
Some aquatic and plant hazards. Dormant
and summer oils.
Monomolecular films for water surface,
interferes with surface tension.
Affects mostly small and sessile insects, eggs,
and mosquitoes.Heavy metals.
Toxicants based on copper, arsenic,
fluorosilicate, lead, sodium.
Persistent, highly toxic, rarely used now.
Chemical structure, continued
• So-called “modern” synthetic insecticides
Developed during or after World War II.
Most act by interfering with nervous
transmission, hence called “nerve poisons.”
Classes of products include chlorinated
hydrocarbons, organophosphates, carbamates,
avermectins, formamidines, etc.
Chemical structure, continued
Chlorinated hydrocarbons (organochlorines),
began to be developed in 1940s.
First of the truly residual products, often
safe for humans (e.g., DDT).
Persistence led to accumulation.
Products include BHC (HCH), aldrin, dieldrin,
endosulfan, lindane, toxaphene. and much more.......