Risk assessment and prediction of resistance to cypermethrin in house fly(Musca domestica)

ObjectiveTo assess resistance risk to cypermethrin and p redict the rate of resistance development in housefly(Musca domestica).MethodsHouseflies collected from natural group were cult ured in laboratory.Resistant strain to cypermethrin in housefly was obtained while LD 50 was determined with the method of topical application. Based on the method described by Tabashnik(1992),the realized heritability(h 2)to cypermethrin in housefly was estimated and the rate of resistance develo pment was predicted.ResultsContinuously selected with cypermethrin for 10 ge nerations at the average survival percentage of 54 5% in laboratory,the strain of housefly had a 50-fold increase in resistance to cypermethrin.The realized h eritability(h 2)of resistance to cypermethrin in housefly was estimated to be 0 157?7 .The rate of resistance development for 10-fold in the housefl y was predicted based on the estimation of the realized heritability(h 2), and it only needs 2 2-4 8 generations under the selected pressure of mortality ranged 50%-90%.ConclusionThe resistance to cypermethrin in housefly in creased rapidly and the realized h eritability(h 2)was stable in 10 generations.