Inhibition of House Fly Ali-Esterase and Cholinesterase Under in vivo Conditions by Parathion and Malathion

Abstract

Ali-esterase (Ali-E) in adult female house flies (Musca domestica L.) was rapidly inhibited in vivo following treatment with parathion or malathion. When dosages were such that some or all of the insects survived the insecticide treatment, levels of Ali-E activity returned to normal within 24 hours. The observed patterns of inhibition were similar with both insecticides and did not appear to he directly related to their toxic action. Cholinesterase activity was more slowly and less reversibly inhibited and the inhibition was closely correlated with the observed symptoms of poisoning. Patterns of inhibition of both symptoms of similar in strains of flies resistant and susceptible to parathion.