Pesticide classification

A. Based on chemical groups:

1. Chlorinated Hydrocarbons: Example: DDT, Aldrin, BHC, Endosulfan.
2. Organophosphate: Example: Rogor, Malathion, Metasystox etc.
3. Carbamate: Examples: Carbaryl, Carbofura
4. Synthetic Pyrethroids: Example: Cypermethrin, Fenvalerate, Deltamethrin etc.

B. Based on target pest:

C. Based on symbol:

D. Based on Effect of pesticide

• Disinfectant used to inactivate micro-organism
• Defoliant used to remove leaves
• Growth regular used to stimulate or retard growth
• Repellent used to repel pest
• Desiccant used speed drying of leaves
• Attractant used to attract pests
• Chemo sterilant used sterilize insect pests
• Pheromone used to attract pests

E. Based on time of development

F. Based on Pesticide hazards:

• According to WHO, 2009 based on their LD50 values the pesticides are classified as following:

Note:LD ₅₀ is the dose of pesticide which is lethal to 50% of the tested population.

G. Mode of entry

1. Contact poison:

• Many pesticides kill insects’ trough contact action because of their solubility in the ion present on the body surface of insects.
• Insecticides penetrate through the point weakness of the integument base of wings and antennae inter-segmental membranes sutures trachea base of hairs etc.
• Nicotine, Rotenone, Phyrethrum etc. are contact.

2. Stomach poison:

• These poisons are ingested and then absorbed through the wall of the alimentary canal.
• Eg lead arsenate calcium arsenate.

3. Fumigation:

• Those insecticides when exposed to air turn into gas and enter the insect’s body through the respiratory system.
• Fumigants can control stored grain insect pests efficiently provided the treated space is air-tight.
• Examples: Aluminum phosphide, ethylene dibromide, dichlorvos etc.

4. Systemic poisons:

• Systemic insecticides when treated onto plant parts are absorbed and move through the vascular system to the entire body and move through vascular system to the entire body of the plant.
• Because of this action, cell saps remain imbibed with poisons and feeding insects get killed.
• These insecticides are effective against insects having piercing and sucking mouthparts such as aphids, leafhoppers, whiteflies, bugs etc.
• Examples: Dimethoate, carbofuran, monocrotophos, methyl demeton etc.

5. Physical poisons:

• Suffocating the insect, clogging its breathing pores and desiccating it to death due to cuticle disruption are the main actions of the physical poisons on insect’s body.
• They are effective against scale insect, mealy bug and thrips.
• Example: Petroleum oil.

H. Mode of Action

1. Physiological poison

• These types of insecticide check the normal function of insect.
• It creates suffocation in insect and change metabolic activities which ultimately kill the insect.

2. Protoplasmic poison

• Most of inorganic insecticides such as fluorids, arsenicals, fluosilicates, borates and organic insecticide like formaldehyde, heavy metal like copper, mercury when ingested cause precipitation of cellular proteins midgut.

3. Respiratory poison

• Some fumigants like HCN, H2S enter the breathing system and interfere the normal metabolism of insects.
• They deactivate respiratory enzyme. Sodium fluoroacetate inhibits carbohydrate metabolism.

4. Nerve poison

• Most of organic insecticides such as Organochlorine, Organophosphorus and Carbamate compounds act in nervous system, which lead to increase excitation, tremor, convulsion paralysis and finally death of toxicated animals.