Insecticides are chemicals and living organisms that are designed to kill insects that are pests, transmitters of diseases and destroyers of gardens. Insecticide developers are continually trying to develop insecticides that effectively kill pests while not harming humans, beneficial insects and other life forms. New insecticides have achieved many of these results by focusing on the physiology of specific insects and developing ways to disrupt it.
Most insecticides are delivered through insect consumption. Some insecticides are put on the surface of the plant. Insects then crawl over the surface, lick the insecticide off of their bodies and then die. Other insects feed on the plant, ingesting the insecticide along with it. However, some insects penetrate into the plant and suck out the interior of the plant. Systemic insecticides are needed for these plants, which are absorbed by the plant.
Many insecticides interfere with the insect's nerve impulses. Nerve impulses are transmitted among synapses through the aid of chemicals. Insecticides sometimes interfere with these chemicals, causing uncoordinated muscle movements, tremors, convulsions, paralysis and eventually death, according to the University of New Hampshire. Organophosphates are nerve inhibitors that are not reversible, while carbamates can be reversed.
Some insecticides act as growth regulators. Insects often go through different stages of development that are signaled by certain hormones produced in the insect's body, according to the University of New Hampshire. The growth regulators cause these insects to begin growing prematurely, which causes the insects to develop bodies that they are not ready for, causing them to die.
Certain viruses only harm and kill insects. Like viruses that infect humans, the insect viruses infect healthy cells and turn these cells into virus producing cells. These cells produce several viruses and then eventually burst, according to the University of New Hampshire. Insects usually consume these viruses and then die when their guts become infected and burst.
Bacterial insecticides infect the stomach of the insect when they are swallowed. These bacteria then eat their way through the insects, eventually killing them, according to the University of New Hampshire. Fungus insecticides contact the outside of an insect's body and eat through the outer skin, growing throughout the insect's body and eventually consuming it.
Soaps are often recommended as organic forms of insecticide, according to the University of New Hampshire. Spraying soapy water on plants infected with pests causes the pests to dry out on the outside and lose moisture, which causes dehydration and death.