Effect of Pesticide Residues on the Natural Enemies of Citrus Mealybug12

Abstract

The toxic residual activities of four pesticides, phosmet, carbaryl, diazinon and dimethoate, were tested against natural enemies of the citrus mealybug, Planococcus citri (Risso). Species tested included four parasites, Pauridia peregrina Timberlake, Leptomastidea abnormis (Girault), Leptomastix dactylopii Howard, and Anagyrus pseudococci (Girault), and two predators, Cryptolaemus montrouzieri Mulsant and Sympherobius barberi (Banks). These natural enemies were exposed 24 h to pesticide residues on leaves of commercially treated citrus at intervals of 1, 9, 16, 23, and 30 days posttreatment to determine their susceptibility to and the persistence of toxic residues. Phosmet and carbaryl had significantly high toxic residual activity up to 30 days posttreatment against the majority of natural enemies tested. Diazinon and dimethoate toxic residue activity decreased significantly in 9 days against the majority of species tested.