Fenamiphos is an organophosphate insecticide and nematicide used for the control of nematodes and sucking insects (including aphids and thrips) on food and non-food crops, and for the control of nematodes in the turf. Fenamiphos blocks the enzyme acetylcholinesterase in the target pests. Fenamiphos is a highly toxic poison that acts by inhibiting cholinesterase (ChE) enzymes in the blood and central and peripheral nervous systems. Inhibition of plasma cholinesterase activity is the most sensitive toxicological endpoint in acute and short-term studies on experimental animals. Fenamiphos is applied on a variety of plants such as tobacco, turf, bananas, pineapples, citrus, and other fruit vines, some vegetables, and grains. In Brazil, this pesticide has been extensively used in tomato crop at planting and also in melon.