Insecticides

An insecticide is a form of pesticide that is used against insects in all of their forms. These insecticides include ovicides and larvicides, which are designed to be used against the eggs and larvae of insects. Insecticides are used in nearly every facet of life…agriculture, medicine, industry and the in the household. The use of insecticides is thought to be one of the major contributing factors for the increase in agricultural productivity during the 20th century. Nearly all insecticides can radically alter ecosystems; a large number of pesticides are very toxic to humans; and others are heavily concentrated within the food chain. It is of paramount importance to balance agricultural needs with environmental and health issues when using any pesticides.

Heavy metals, such as lead, arsenic, and mercury as well as naturally occuring plant toxins like nicotine has been used for many years. Various plants have been used as folk insectides for thousands of years…including tobacco, pyrethrum, and citronella.

With the advent of the modern chemical industry it became possible to make chemicals called organochlorides. An organochlorine insecticide such as DDT or lindane does not directly kill the insect. DDT works by opening the sodium channels in the nerve cells of the insect. It works much the same way Mustard Gas did when it was used in World War 2.

The next large classes of new chemicals developed were the organophosphates. Both the insecticides and the chemical warfare agents like sarin gas, tabun, and some others work in the same way. These chemical compounds bind to the neurotransmitter acetylcholinesterase and the other cholinesterases. This causes the disruption of nerve impulses which either kills the insect or interfers with its ability to function.

To simulate the activity of the natural compound pyrethrum type of pesticides, pyrethroid pesticides, have been developed over the last several years. These are much less severly toxic than organophosphates and several of other aforementioned chemical pesticides.

Recent efforts to reduce broad-spectrum toxins added to the environment by man-made pesticides have cuased natural insecticidestp become more popular. The discovery of the Neem tree’s anti-fungal, anti-parasitical, insecticidal properties has been a great boon to people who wanted a natural non-toxic insecticide. Another example is the development and increased use of Bacillus thuringiensis, a bacterial disease of Butterflies and a few other insects. It is used as a larvicide against a large variety of caterpillars. Because it has little or no effect on other organisms, it is considered more environmentally friendly than synthetic pesticides. The toxin from Bacillus thuringiensis has been incorporated directly into plants through the use of genetic engineering.