Dehydrochlorination of DDT by Resistant Houseflies and Mosquitoes

Abstract

THE recent characterization of DDT dehydrochlorinase in resistant houseflies¹ has prompted an investigation of this enzyme and of the production of 2,2-bis(p-chlorophenyl)-1,1-diehloroethylene (DDE) in mosquitoes, in which DDT-resistance is now developing². As an initial step, two strains of resistant house-flies were assessed for DDT-dehydrochlorinase content. The DDT-45 strain showed no less activity than originally reported¹, the DDE production in 3 hr. by the equivalent of six flies averaging 98 µgm. for homogenates and 52 µgm. for acetone powders. The Dilan strain, developed by two years of dilan pressure without any exposure to DDT, showed an enzymic DDE production of 100 µgm. for homogenates and 34 µgm. for acetone powders. This Dilan strain resembled the DDT-45 strain in having an LD90 exceeding 50 µgm. and being able to convert 90 per cent of 10 µgm. of DDT topically applied to DDE in 24 hr.