Pesticide

Pesticides (which come from the Latin cida, to kill, and the English pest, troublesome) are substances used in agriculture to combat organisms which harm crops.

The pesticides can be classified into four major classes:

• herbicides intended to kill weeds which stifle the growth of the desired plants ;
• insecticides intended to destroy insects which feed on or lay eggs on crops ;
• fungicides which kill microscopic fungi responsible for rot, and ;
• antiparasitics which kill parasitic worms.

However, there are many other categories of pesticides (nematicides, bactericides, rodenticides, virucides, etc).

The pesticides are often non-natural chemicals developed in the chemical revolution at the start of the XX^th century (organochlorides, organophosphates, DDT, 2,4-D), many of which are harmful to human health.