The γ-BHC resistance of the flesh flies collected from some districts

Abstract

Both adults and larvae of the flesh fly, Boettcherisca peregrina originally collected from Inokashira of Tokyo in 1966 and from Gyoda of Saitama Prefecture in 1965, were tested for γ-BHC resistance after being reared in laboratory. The final instar larvae were tested undre "the dilution contact method" in which the larvae were exposed for 48 hours to a thin layer of desired concentration of insecticide emulsion. The adults were assessed by the topical application test. The LC_<50> value in the larval tests was 3, 800 ppm for Inokashira colony and was 82 ppm for the Gyoda colony. The γ-BHC resistance of the Inokashira colony was enough high as to be 200 times than that of a susceptible colony. The Gyoda colony, on the contrany, showed only 4.3 times of the value as the resistance ratio. However, these resistant two colonies were found to be still susceptible to organophosphorus insecticides such as diazinon and fenthion. The LD_<50> value of the adult flies was 1.6μg per female fly in the Inokashira colony and was 0.11μg in the Gyoda colony.