A Preliminary Study of the Genetics of Ddt Resistance in Houseflies

Abstract

A detailed study is reported of the knockdown responses of a highly resistant "Illinois" strain of houseflies and of a non-resistant "Canberra" strain to topical applications of DDT and to exposure to a residual film of DDT. The dosage response curve for the Illinqis strain is highly asymmetric, no increase in mortality being observed above a dose of 4 f1g. DDT per fly. It is suggested that the resistant population i; genetically heterogeneous, being composed of "weak" and "strong" individuals with respect to resistance to DDT.