Studies on the Insecticidal Action of Nereistoxin, 4-N, N-Dimethylamino-1, 2-Dithiolane : IV Role of the Anti-Cholinesterase Activity in the Insecticidal Action to Housefly, Musca domestica L. (Diptera : Muscidae)

The cholinesterase (ChE) inhibition by nereistoxin hydrogen oxalate in adult male housefly, Musca domestica L., was investigated to reveal the role of the inhibitory action in the insecticidal action of this compound. The injected nereistoxin (100μg/g) caused only a slight depression of ChE activity in the fly head. The experiments in vitro using the fly-head homogenate as a ChE preparation showed nereistoxin was a week, competitive, reversible and unprogressive inhibitor of ChE. The known amount of acetylcholine in the insect nervous tissue, the active dosage of nereistoxin in its insecticidal action and the results of the present experiments indicated that the anti-ChE activity of this compound did not play the fundamental role in the insecticidal action. However, it was estimated that high dosages, more than 200μg/g, exerted 50 per cent inhibition of the ChE activity. Therefore the anti-ChE action by such a high dosage might be able to play an additional effect in the toxic action.