Carbamate Insecticides and Ali-Esterase Activity in Insects 1

Studies with the house fly ( Musca domestica L.) indicated that aliphatic esterase activity, like acetylcholinesterase, is susceptible to inhibition both in vivo and in vitro by the insecticidal carbamates Sevin® (1-naphthyl N -methylcarbamate) and Isolan® (5-(1-isopropyl-3-methylpyrazolyl) dimethylcarbamate). Ali-esterase activity in the mosquito Culex tarsalis Coq. differed in not being inhibited by either of the carbamates studied. In contrast to the pattern exhibited by organophosphorus-resistant strains of house flies, markedly lower levels of ali-esterase activity were not found to be related to carbamate-resistance in this insect.