Physiological and Genetical Studies on Resistance to DDT Substitutes in Aedes aegypti1

Abstract

Selection with a 1:1 mixture of WARF anti-resistant (N,N-dibutyl-p-chlorobenzenesuifonamide! and DDT, with Prolan (1,1-bis(p-chlorophenyl)-2-nitropropane) or with malathion induced in larvae of the yellow-fever mosquito., Aedes aegypti (L.), a DDT-resistance characterized by increased DDT-dehydrochlorinase activity. Mixture selection at first reduced the resistance levels of DDT-resistant strains, but ultimately induced high resistance to the DDT and to the mixture; Mixture-resistance derived from genetic influences on chromosome 3 in addition to the regular DDT-resistance gene on chromosome 2. Prolan selection developed the DDT-resistance and in addition a resistance mechanism of reduced Prolan absorption. Malathion selection induced the regular DDT-resistance on chromosome 2 as well as a malathion-resistance connected with multiple genes on chromosomes 2 and 3.