Study of the resistance of Musca domestica against beta-cypermethrin through selective breeding.

Objective To determine the mechanisms of development and hereditary patterns of the resistance against pyrethroids in Musca domestica using beta-cypermethrin-resistant strain domestically produced by selective breeding,providing scientific basis for the establishment of practical management strategies to restrain the development of insecticide resistance for effective control of houseflies.Methods Beta-cypermethrin of median lethal concentration applied to each generation of susceptible M.domestica strains,the resistance selective breeding was performed in compliance with the National Standard GB 13917.1-13917.8-92,Laboratory efficacy test methods and criterions of public health insecticides for pesticide registration.Bioassay methods were utilized to determine the LD50 of generations of M.domestica from which the resistance index was generated.Results Continuous affection of beta-cypermethrin on twenty-two generations of selective breeding gave arise to rapid development of strong resistance in susceptible M.domestica strains,resulting in a resistant line with the resistance index of 104.23 folds.Conclusion The occurrence and development of resistance in M.domestica was the result of the directional selection favoring traits of resistance genes exerted by the insecticide.The stronger the selection pressure is,the faster the resistance develops.Different methods of insecticide application pose significant influence on selective breeding for resistance.