Autosomal sex-associated pyrethroid resistance in a strain of house fly (Diptera: Muscidae) with a male-determining factor on chromosome three.

Mechanisms and genetics of resistance to pyrethroid insecticides were investigated in a strain of house fly (ASPR) collected from a cattle ranch in Miyagi, Gunma Prefecture, Japan. Flies were selected in the laboratory with the pyrethroid insecticide permethrin. Both sexes were resistant to pyrethroids; however, females were 22- to 245-fold more resistant than males. Permethrin resistance could be partly suppressed by the monooxygenase inhibitor piperonyl butoxide in females, but not in males. In this strain, sex was determined by a male factor on the third autosome. The relationship of the autosomal male factor to the lower resistance levels observed in the males and the mechanisms of resistance expressed in each sex are discussed.