Identity of the Acetylcholine-like Substance in the Housefly

THE hypothesis that the organophosphate insecticides kill insects by inhibiting the cholinesterase of the nervous system has been questioned, partly on the grounds that acetylcholine has not been demonstrated in insects1. That insects contain a substance with pharmacological activity similar to acetylcholine has been amply demonstrated2; but the identity of this substance remains in doubt. Chemical methods have indicated that the substance is not acetylcholine3; on the other hand, combined chromatography and pharmacological methods have indicated that the substance is acetylcholine4. We have used the chemical method, chromatography and electrophoresis to examine the pharmacologically active substance extracted from the housefly, Musca domestica L. The results show consistently that the acetylcholine-like substance in the housefly is identical with acetylcholine itself.