DIELDRIN RESISTANCE IN HYLEMYA BRASSICAE (DIPTERA: ANTHOMYIIDAE) IN ALBERTA

Abstract

AbstractDieldrin resistance has been confirmed in adults of the cabbage maggot, Hylemya brassicae (Bouché), from the Edmonton area of Alberta. The resistance of this heterogeneous strain had increased from 30% in 1967 to about 80% in 1972. The change in resistance is attributed to selection pressures on H. brassicae by dieldrin residues in the soil. Dieldrin resistance is suspected in the Fincastle area but was not detected in the Lethbridge area.Toxicity data were established for the Lethbridge and Edmonton strains with alternative insecticides currently recommended in Alberta. There were no differences in the toxicity of the alternative insecticides between strains. Carbofuran and chlorfenvinphos were equal to dieldrin whereas fensulfothion was about six times less effective.A discriminating dose technique for detecting changes in insecticide susceptibility is discussed.