Mar 9, 2011

Glossary

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Insecticide

A substance used to kill harmful insects or their larvae.

Insecticides are used in agriculture and forestry, to protect stored products and materials and to contain infectious diseases in humans and animals where the pathogens are transmitted by insects.

Most insecticides attack the insect’s nervous system and are lethal; others inhibit further development by e.g. disrupting the sloughing process. Insects can take in insecticides through their respiratory tracts, when feeding or simply through physical contact.

There are natural insecticides, which include alkaloids (nicotine), synthetic inorganic insecticides, e.g. arsenic and copper compounds, and synthetic organic insecticides, which include DDT (dichlorodiphenyltrichloroethane). Many of the insecticides in this group are heavily restricted today.

Where a particular chemical or biological pesticide is used on a large scale over several years, it is bound to lead to selection of the most resistant individuals. These are the individuals that are better able to reproduce under the conditions associated with the plant protection product than other individuals of the same species. The same applies to most insecticides, and if they are used persistently, insects will develop resistance to them. This resistance will be effective even against other insecticides that make use of the same mechanism.

Insecticides can also be obtained from fungi, nematodes, bacteria (e.g. from Bacillus thuringiensis (Bt)) and viruses.