Relationship between Metabolism and Differential Toxicity of Malathion in Insects and Mice1

Abstract

An attempt has been made to account for the selective toxicity of malathion on the basis of differences in its metabolism by various species. Eleven metabolites were found in the German cockroach (Blattella germanica (L.)), and American cockroach (Periplaneta americana (L.), and house fly (Musca domestica L.), seven in the mouse. Most metabolites were identified. Degradation of malathion is much more extensive in the mouse than in the insect and malaoxon production is correspondingly lower; these effects account satisfactorily for the low toxicity of malathion to the mouse. The low toxicity of topically applied malathion to the German cockroach is attributable to poor penetration through the integument.