Effect of organophosphorus insecticides on cholinesterase activity in mosquitoes

ABSTRACT

The toxicity and the in vivo and in vitro cholinesterase [ChE] inhibitory action of malathion, diazinon and dipterex were of a higher rate against the fourth larval instar of Anopheles pharoensis than of Culex pipiens. In both species, malathion was the most toxic and potent in vivo ChE inhibitor, followed by diazinon and dipterex respectively. However, diazinon was the most potent in vitro ChE inhibitor, followed by dipterex and malathion respectively. The inconsistancy of in vitro inhibition with the order of toxicity is discussed