Recommended
More Related Content
What's hot
What's hot (20)
Similar to Insecticides
Similar to Insecticides (20)
Recently uploaded
Recently uploaded (20)
Insecticides
- 2. DEFINITION • Substances which are used to kill insects • PESTICIDE: includes insecticide, fungicides, rodenticides, herbicides, disinfectant, repellants and other chemicals used for the control of pests • Have brought vast economic and social benefits through better health and increased food production
- 3. INSECTICIDES CONTACT POISONS STOMACH POISONS FUMIGANTSNATURAL SYNTHETIC Pyrethrum Rotenone Derris Nicotine Mineral Oils Organo-chlorine compounds Organo- phosphorus Insecticides Carbamates DDT HCH Lindane Chlordane Heptachlor Dieldrin Aldrin REPELLANTS Meta-diethyltoluamide Benzyl-benzoate Indalone Dimethyl phthalate Ethyl hexanediol Chlorthion Diazinon Dioxathion Demethoate Malathion Fenthion Abate Parathion Carbaryl Propoxur Pyrolan SYNTHETIC PYRETHROIDS Resmethrin Bio resmethrin Pothrin Paris Green Sodium flouride Hydrogen cyanide Methyl bromide Sulphur dioxide Carbon disulphate
- 4. 1. DDT(DICHLORO-DIPHENYL-TRICHLOROETHANE) • Synthesized in 1874, by a German chemist, Zielder • 1939 : insecticidal properties were discovered by Swiss scientist, Paul Muller • PROPERTIES: white amorphous powder with a mild, but not unpleasant smell, insoluble in water, dissolves in most organic solvents • Contains 70-80% of para-para isomer which is the most active fraction of DDT • ACTION: contact poison, acts on the nervous system of insects • Permeates into the insect body through the cuticle, after dissolving the waxy covering of feet, causes paralysis of legs and wings, convulsions and death • May act as long as 18 months, on mud walls the prolonged action is decreased • No repellant action on insects • APPLICATION: dosage: 100-200 mg per square foot area
- 5. • Formulation: 5% suspension of DDT which when sprayed at a rate of 1 gallon over an area of 1000 sq feet, gives a dosage of 200 mg per sq ft • Strength: 5-10% for control of lice, fleas, ticks and bugs • Aerosol & Space-sprays: DDT is one of the main constituents • Environmental pollutant • Persistance on living organisms and plants and adverse effects on certain species. • Restricted in some countries • Benefits of application of DDT outweigh the hazards
- 6. 2. HCH(HEXA CHLOROCYCLO-HEXANE • Benzene Hexachloride/Gammaexane/Hexidol • Synthesized by Michael Faraday in 1825 • Its insecticidal activities were discovered in 1933 • PROPERTIES: white or chocolate coloured powder with a musty smell, irritating to eyes, nose and skin • Gamma isomer: most active constituent • Technical HCH:13-16 % of gamma isomer • Pure HCH: 99% of gamma isomer- lindane/gamma isomer • More insecticidal than ddt, but not as prolonged • ACTION: kills insects by direct contact, short residual action: 3 months • Also kills insects by its vapour effect
- 7. • Application: used as DDT • Dose: 25-50 mg of gamma HCH per sq ft 3. MALATHION • Least toxic of all the organophosphorus compound • Technical product: yellow or clear brown liquid with an unpleasant smell • Used in doses of 100-200 mg per sq ft, every 3 months • Because of its low toxicity, recommended as an alternative to DDT • As a low volume spray, widely used for killing adult mosquitoes to prevent/ interrupt DHF, mosquito-borne encephalitis epidemics
- 8. 4. ABATE • Organophosphorus compound • Brown viscous liquid, soluble in petroleum solvents • Because of low toxicity, extensively used in India for the control of A. stephensi in wells in domestic water containers at a dosage not more than 1.0 ppm 5. DIAZINION • Liquid product • Kills by not only direct contact but also by fumigant action • Effective in control of DDT-resistant insects • Dosage: 60-100 mg per sq. foot: control of flies and mosquitoes • More toxic to man than malathion and fenthion
- 9. 6. FENTHION • Brown liquid smelling slightly of garlic • Insoluble in water • As effective as DDT • Usual dosage: 100 mg/sq ft • Very powerful as a larvicide 7. DICHOLOROVOS • Highly volatile liquid insecticide • When combined with solid substances like wax : fashioned into tablets or bricks 8. PROPOXUR • As a substitute to DDT in areas where resistance to anophelines
- 10. 9. PYRETHRUM • Extracted from flowers Crysanthemum • Prepared: soaking ½ to 1 lb of dried powdered flowers in 1 gallon of kerosene oil for 72 hours (contains 0.1% of pyrethrins) • Kills adult mosquitoes and insects • Fine atomization of solution is necessary ( doors and windows kept closed for ½ hour) • No residual action 10. PYRETHRUM & DDT • Added for synergistic action • WHO: Pyrethrum 1.6% + DDT 11. SYNTHETIC PYRETHROIDS • 10 times as effective as natural pyrethroids
- 11. 11. ROTENONE • Obtained from roots of Plant Derris elliptica • Was once widely used in control of ticks, fleas, lice, mites and ticks 12. MINERAL OILS • Suffocate Aquatic stages of Mosquito • Dangerous to aquatic vegetation and Fish 13. PARIS GREEN • Emerald green microcrystalline powder, insoluble in water • Used before advent of DDT
- 12. INSECTICIDAL RESISTANCE • Definition: development of an ability to tolerate doses of toxicants which would prove lethal to majority of individuals in normal population of same species • Due to genetic ( through genes) or biochemical factors (toxicant is converted to non-toxicant form by various enzymes) • Organo-chlorine insecticide resistance: resistant to DDT and its analogue and to HCH-deldrin group • Double resistance: switch to organo phosphorus and carbamates • Cross resistance
- 13. TOXICITY OF INSECTICIDE • ORGANO-CHLORINE COMPOUNDS • Nerve poisons: increase nervous excitability: tremors and convulsions • DDT : least toxic • Dieldrin: more frequently- absorbed through skin • TREATMENT: barbiturates and phenobarbitone, stomach washouts, purgatives • ORGANOPHOSPHORUS COMPOUNDS AND CARBAMATES • Interfere with mechanism of transmission of nerve impulses: inhibit cholinesterase • SYMPTOMS: Headache, giddiness, apprehension, restlessness, cold sweating, salivation, uncontrolled urination, defecation • TREATMENT: Atropine, removal of contaminated clothes, washing of exposed skin with soap and water