DDT-Dehydrochlorinase in Aedes aegypti

Abstract

DDT-dehydrochlorinase has been demonstrated in vitro for the larvae of Aedes aegypti (L.) provided they are homogenized under glutathione and nitrogen protection. The optimum pH is 7.4. The dehydrochlorination of DDT was found to be correlated with the DDT-resistance level in strains of American origin. The same correlation was found for the dehydrochlorination of DDD, which proceeded faster, and of methoxychlor, which proceeded more slowly. The mosquito DDT-dehydrochlorinase was inhibited by DMC and WARF Antiresistant. Unlike this enzyme in the house fly, Musca domestica L., it could dehydrochlorinate O-chloro-DDT but not deutero-DDT. From DDT the only metabolite was DDE, except that highly resistant material produced a small amount of a Kelthane-like substance. In strains of Asiatic origin the dehydrochlorination of DDD but not of DDT was found proportional to the DDT-resistance level. It is however concluded that in all strains of A. aegypti DDT-dehydrochlorinase is the principal mechanism for DDT resistance.