Abstract
Relationships between the chemical structure of 61 organophosphorus (OP) insecticides and the degree of resistance in the OP-resistant rice stem borer, Chilo suppressalis WALKER, were studied. The resistant strain necessarily showed high levels of resistance to various types of OP insecticides containing the aryl (including the aromatic heterocyclic group) ester bond, such as fenitrothion, cyanophos, pirimiphos-methyl, chlorpyrifos-methyl, pirimiphos-ethyl, EPN, isofenphos, and their oxons. Resistance was higher to dimethyl esters than to their diethyl homologs, and the highest resistance ratios were found with heterocyclic esters. In contrast, essentially no resistance to OP insecticides having the ester bond with aliphatic enol and thioalcohol, such as malathion, phenthoate, azinphos-methyl, malaoxon, tetrachlorvinphos, and monocrotophos was observed. It is, therefore, concluded that a P-O-aryl bond in OP insecticides is prerequisite for the resistance.
