Question

How does insecticide kill?

Answer 1

Chemical substances that are used to kill insects are known as insecticides. The insecticides are sprayed on the surface of plant leaves and fruits. When an insect comes in direct contact with an insecticide, it produces toxicity inside the insect and the insect dies at an instant.

Complete answer:
Insecticides can both be organic and inorganic. There are two types of insecticides:
Contact insecticides: These insecticides kill the insects when they come directly in contact with it.
Systemic insecticides: This insecticide incorporates itself into the plant cell structure. When an insect eats the plant and ingests the insecticide chemical, it wrecks the digestive system of the insect and kills it.
Insecticides enter the insect’s body in three different way:
Dermal entry: The insecticide enters the body through the skin. The skin of insects has a small cuticle-like structure that enables the entry of poison. This happens when the aerosol droplets of the insecticide hit the insect or the insect walks over the sprayed plant leaf.
Oral entry: The insecticide enters the body when the insect ingests the sprayed part of the plant. These are known as ingested poisons. This insecticide enables swelling of the gut that results in water buildup in the intestine. This ultimately leads to the bursting of the gut that kills the insect.
Respiratory entry: The insects inhale the fumes of the poison which kills them.

Note:
Organochlorines are used in insecticides to open to sodium channels in the neurons of nerve cells in the insects that make the insect go into spasm and eventually die. Organophosphates are also used that disable cell-to-cell communication of nerve cells in insects.