In vitro metabolism of insecticides during midgut penetration

A study of the metabolism of ¹⁴C-labeled dieldrin, DDT, malathion, and carbaryl during penetration of the isolated midgut of two insects (Blaberus discoidalis and Manduca sexta) and a section of the intestine of a mammal (Mus musculus) is reported. There was appreciable metabolism of malathion during penetration, including differences in the activation reaction to malaoxon, between insects and mammals. Metabolism was relatively slow during penetration of carbaryl and the chlorinated hydrocarbon insecticides, and little difference in metabolic patterns was noted among the three species. The penetration studies were supported by experiments in which insecticides were incubated with intact and homogenized midgut preparations.