Different types of Insectisides
- 1. Study Different types of Insecticide M. Sc. (Final) Entomology UNIVERSITY OF ALLAHABAD
- 2. • Meaning:- Chemicals which kill insects arecalled as insecticides.
- 3. • Definition Insecticide may be defined as a substanceor mixture of substances intended to kill,repel or otherwise prevent the insects. • General properties of insecticides 1.Pesticides are generally available in aconcentrated form which are to be diluted andused except in ready to use dust and granules. 2.They are highly toxic and available indifferent formulations.
- 4. • Properties of an ideal insecticide 1. It should be freely available in the marketunder different formulations. 2. It should be toxic and kill the pest requiredto be controlled. 3. It should not be phytotoxic to the crops onwhich it is used. 4.It should not be toxic to non target specieslike animals, natural enemies etc. 5. It should be less harmful to human beingsand other animals.
- 5. • Classification of insecticides 1. Based on chemical composition 2. Based on the mode of entry of insecticides intothe body of the insect 3. Based on mode of action 4. Based on toxicity 5. Based on stage specificity
- 6. • Based on chemical composition: 1. Inorganic insecticides 2.Organic Insecticides • Inorganic insecticides: Comprise compounds of mineral originand elemental sulphur. This group includes arsenate and fluorinecompounds as insecticides. Sulphur as acaricides and zincphosphide as rodenticides•
- 7. • Organic Insecticides: 1. Insecticides of animal origin: Nereistoxin isolated from marineannelids, fish oil rosin soap from fishes etc. 2. Plant Origin insecticides or Botanical insecticides: Nicotinoids,pyrethroids, Rotenoids etc. 3. Synthetic organic insecticides: Organochlorines,Organophosphorus, Carbamate insecticides etc. 4.Hydrocarbon oil etc.
- 8. • Based on the mode of entry of insecticides in to the body of the insect : Contact Insecticides Stomach Insecticides Fumigants or Gaseous Poisions Systemic Insecticides
- 9. • Contact insecticides: These insecticides are capable of gaining entry intothe insect body either through spiracles and trachea or through thecuticle itself. Hence, these poisons can kill the insects by mere coming incontact with the body of the insects. Eg: DDT. Stomach poisons: The insecticides applied on the leaves and other partsof plants when ingested act on the digestive system of the insect andbring about the kill of the insect. Eg: Calcium arsenate, lead arsenate. • Stomach Insecticides:
- 10. • Fumigants or Gaseous poisons: A fumigant is a chemical substance which is volatile atordinary temperatures and sufficiently toxic to the insects. Eg: Aluminiumphosphide, Carbon disulphide. • Systemic Insecticides: Chemicals that are capable of moving through thevascular systems of plants irrespective of site of application andpoisoning insects that feed on the plants. Eg: Methyl demeton,Phosphamidon, Acephate.
- 11. • Physical poisons: • Bring about the kill of insects by exerting a physical effect. Eg:Heavy oils, tar oils etc. which cause death by asphyxiation. Inert dusts effect lossof body moisture by their abrasiveness as in aluminium oxide or absorb moisturefrom the body as in charcoal. • Protoplasmic poisons: • A toxicant responsible for precipitation of proteinespecially destruction of cellular protoplasm of midgut epithelium. Eg. Arsenicalcompounds.
- 12. Respiratory poisons: Chemicals which block cellular respiration as in hydrogencyanide (HCN), carbon monoxide etc. Nerve poisons: Chemicals which block Acetyl cholinesterase(AChE) and effect thenervous system. Eg. Organophosphorus, carbamate. Chitin inhibitors: Chitin inhibitors interfere with process of synthesis of chitin dueto which normal moulting and development is disrupted. Ex Novaluron, Lufenuron,Buprofezin General Poisons: Compounds which include neurotoxic symptoms after someperiod and do not belong to the above categories. Eg.Chlordane, Toxaphene
- 14. Ovicides:- A Substance or agent that kills eggs, especially the eggs of insects, mites, or nematodes. Larvicides:- A larvicide is an insecticide that is specifically targeted against the larval life stage of an insect Pupicides:- A suicide is an insecticide that is specifically targetedagainst the pupa of an insect. Adulticides:- A pesticide designed to kill adult insects rather than theirlarvae.
- 15. • Phytotoxicity: Meaning:- Ability of a substance to Injure the plant.The application of pesticides or insecticides on plants isintended to control the pests without causing adverse orharmful effects to plants. It is common to see some adverseinsecticides in fields which is called phytotoxicity. Types: 1. Temporary phytotoxicity which allows the plant to recover aftershowing phytotoxicity. 2. Permanent phytotoxicity leading to the death of the effectedpart or whole plant.
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