Insecticides are chemicals that control insects. Similarly, the chemicals used to control mites (Acarina) are called as Acaricides or miticides.
Insects cause damage to the crops by sucking the plant sap from roots, leaves, stems, by defoliating the plant and by boring the stem, flowers and fruits, resulting in significant reduction in crop yields. In order to control different types of insect pests, the recommended insecticides and dose by the SAUs / ICAR Institutes based on the type of insects and their nature of damage, should be adopted.
The crops are also attacked by different types of mites e.g. red mite, yellow mite etc., which suck the cell sap from the leaves, resulting weakening of the plant, dropping of flowers and fruits and finally reduction in crop yields. The mites belong to a different class i.e. Acarinia, hence they require specific Acaricide (miticide) like Omite for their effective control.
Classification of Insecticides
Different insecticides may be classified according to the chemical nature and mode of action.
- Organochlorine (Chlorinated hydrocarbons) – Endosulfan, DDT.
- Organophosphates – Triazophos, Monocrotophos, Profenophos, Acephate etc.
- Pyrethroids –Cypermethrin, Bifenthrin, Fenvalerate, Lambda-Cyhalothrin, etc.
- Neonicotinoids – Imidacloprid, Acetamiprid, Thiamethoxam
- Carbamates – Methomyl, Carbosulfan, Carbofuran, etc.
- Nereistoxin analoques – Cartap hydrochloride
- Pyrazoles- Fipronil
- Macrocyclic lactone- Emamectin, Spinosad, etc,
- Botanicals- Neem
- Biological- Bacillus thuringiensis, NPV, etc.
- Insect growth regulators- Buprofezin, Diflubenzuron, Novalron, etc.
Mode of action
There are 3 classes of insecticides based on the mode of action, as detailed below.
- Contact insecticides:- Any insecticide that kills insects by being absorbed through the cuticle, inter-segmental membrane, tarsai or by blocking the spiracle.
- Stomach insecticides:- Stomach insecticides are ingested along with the food to the insects and must reach into alimentary canal.
- Systemic insecticides:- These are absorbed by the plant tissues. When insects suck the sap from the treated plant, insecticide enters into the alimentary canal, thereby killing the insects.