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 - they 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 chemical 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