Pesticides – types and categories

pesticides classification

1. Pesticides – types & categories by - J. Joselin

2. Pesticides Pesticide is any toxic substance used to kill animals, fungi, or plants that cause economic damage to crop, which are hazardous to the health of domestic animals or humans. All pesticides interfere with normal metabolic processes in the pest organism . They deter , incapacitate ,kill pests.

3. Types or categories of pesticides They are classified based on Target pest Source Chemical composition Mode of action Formulation Persistency

4. Based on target pest Herbicides used for killing weeds or herbs. e.g.Gramoxone Insecticides- used for killing insects. e.g. sevin , DDT Fungicides- used for killing fungi. e.g. mankocide Nematicides - used for killing nematode e.g. Furadan

5. Rodenticides- use for killing rodents (rat, mice) e.g.Klerat Acaricides- used for killing aracnids (mites) e.g new mectin Molluscicides - used for killing Molluscs (snails, slugs) e.g. Slugit Slimicides are used for killing algae , bacteria and slime moulds. Ex; bromium, aldehydes Virucides are used for killing virus ex; benzalkonium chloride

6. Based on source Natural pesticides; Biochemical –Biochemical pesticides are made from naturally occurring substances such as baking soda, diatomaceous earth (DE), canola oil, neem oil, tea tree oil, cayenne pepper, and other compounds to kills pests. Microbial – Microbial agents stem from bacteria, fungi, algae, naturally occurring viruses, or protozoans. These either introduce a disease to a certain insect population, produce a toxin or limit reproduction . Bacillus thuringenesis (Bt) & its various strains are used to control insect pests. It kills only target insect pest and non toxic to others. Botanical – Botanical pesticides come from plants. Nicotine, Neem , Rotenone, Sabadilla , and Pyrethrins are all derived from other plants. Pyrethrins come from the chrysanthemum plant and are effective on flying insects and to flush out larvae and grubs. Mineral – Mineral pesticides include sulfur and lime-sulfur. Both are sprayed as part of the control of common insect pests

7. Chemical/Synthetic pesticides ; Synthetic pesticides are products that are produced from chemical alteration. Organic - t hey are subdivided into 4 categories based on chemical forms - organochlorines , organophosphates , carbamates , pyrethroids . some examples ; Organochlorines - DDT ( dichloro diphenyl trichloroethane ) ,BHC ( beta hexachloro cyclo hexane) Organophosphates - malathion , fenthion Carbamates - carbaryl Pyrethroids – deltamethrin , premethrin Inorganic - inorganic pesticides do not contain carbon and are usually derived from mineral ores extracted from the earth ; ex; aluminium phosphide, copper sulphate,etc ,.

8. Based on chemical composition Organochlorine ; It has Carbon atoms, chlorine, hydrogen and occasionally oxygen. They are nonpolar and lipophilic - Soluble in lipids, they accumulate in fatty tissue of animals, are transferred through the food chain; toxic to a variety of animals, long-term persistent. Ex; DDT, aldrin, lindane, chlordane, mirex.

9. Organophosphates; Organophosphates are phosphoric acid esters or thiophosphoric acid esters. Possess central phosphorus atom in the molecule. In relation with organochlorines, these compounds are more stable and less toxic in the environment . Soluble in organic solvents but also in water. less persistent than chlorinated hydrocarbons; some affect the central nervous system. They are absorbed by plants, transferred to leaves and stems, which are the supply of leaf-eating insects ex; malathion,Methyl parathion, diazinon

10. Carabamates ; Carbamates are esters of N-methyl carbamic acid, it is also naturally obtained in c hemical structure based on a plant alkaloid  Physostigma venenosum. (leguminous plant ) kill a limited spectrum of insects, but are highly toxic to vertebrates. Relatively low persistence ex; carbaryl,sevin.

11. Pyrethroids ; They often contain some 2,2 dimethylcyclo propane carboxylic acid derivative, like chrysanthemic acid, which is esterified with a large alcohol. Also naturally available in form of alkaloids obtained from petals of  Chysanthemun cinerariefolium . Affect the nervous system; are less persistent than other pesticides; are the safest in terms of their use, some are used as household insecticides. Ex; pyrethrin

12. Based on mode of action For insecticides ; Contact – kill only insects they are sprayed or dusted onto. e.g. DDT , malathion Stomach acting - kill only insects that eat plant parts sprayed with insecticide e.g. Dipel Systemic – This type of insecticide is transported within the plant and kill insects when they eat parts of the plant ex; organophosphates • Fumigant- kill insects that inhale toxic vapours of the chemical e.g. phostoxin , Nicotine

13. For fungicides ; Contact (Protectant)- kill only fungi sprayed or dusted with the fungicide, or fungal spores, which come into contact with the fungicide. e.g.Kocide Systemic (Eradicant) - This type of fungicides is transported within the plant and kills fungi growing within tissue of the plant.

14. For herbicides ; Pre-emergence – a herbicide applied to the soil during the period after planting and before germination (usually 1-5 days after land preparation). e.g.Gesaprim Selective – a herbicide that kills small weeds and seeds but leave the crop unharmed e.g Gesagard . Post-emergence – a herbicide applied to growing weeds after crop emergence or transplanting e.g.Fusilade , Gramoxone , Round-up. Contact - a herbicide that kill only soft green parts of weeds sprayed with the herbicide e.g Gramoxone . Systemic - a herbicide that is absorbed into the plant after spraying, and is transported to other plant parts where it causes death e.g Round-up. Non-selective - a herbicide that kills all plants sprayed. e.g Round-up.

15. Based on formulations Dust - pesticide prepared as dry fine particles e.g Sevin 85 WP Granules (G )- Pesticides prepared as large dry particles e.g Furadan . Wettable Powders (WP )- consist of finely divided particles with other substances that enable the powder to be mixed with water to form a stable suspension e.g. kocide . Emulsifiable concentrate (EC)- a pesticide dissolved in an organic solvent to which an emulsifier is added to enable proper mixing. Dry Bait-pesticide mixed with edible products to form dry pellets, which are attractive to pests. e.g Klerat . Smokes - the pesticide is mixed with an oxidant and combustible material, which generates hot gas e.g , mosquito coil.

16. Based on persistency Persistent – a pesticide that remains in the environment for a long time e.g ; Hyvar -x Non-persistent- a pesticide that remains in the environment for a very short time. e.g.Dipel

17. Thank you .