The resistance of housefly to chemical insecticides and their natural attenuation trend

Objective To investigate the resistance of the natural housefly(Musca domestica)population to the chemical insecticides and their natural attenuation trend in the laboratory environment,and to provide the rational for the management of the resistance.Methods The natural housefly population collected in fields were fed in the lab and their sensitivities of different generation(from F1 to F21)to three insecticides(cypermethrin,deltamethrin,and Dichlorvos)were bioassayed with the serial dilution spotting procedure.Results the housefly population exhibited a different extent of resistance to cypermethrin,deltamethrin,and Dichlorvos,with a resistance coefficient of 21.52,43.33 and 28.42,respectively.After feeding for 21 generations,the resistance coefficient decreased to 10.22,11.67 and 4.03,respectively,but did not recover to the original sensitivities.Conclusion The resistances of housefly population to three insecticides attenuated slowly,and the stability of these resistances to different insecticides was significantly different.