Chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate) is a broad-spectrum organophosphorus insecticide and acaricide that has been widely used since the 1960s (Cho et al., 2002) in direct soil applications for the control of foliar insects in cotton and paddy fields; grain, fruit, and vegetable crops; and pastures.