Relative Fitness and Inheritance Mode of Deltamethrin Resistance of Plutella xylostella L

The effects of deltamethrin resistance on fitness of Plutella xylostella L were evaluated by constructing life table of resistant strain(R),hybrid F1(RS:R♀×S♂,SR:R♀×S♂) and susceptible strain(S).The inheritance mode of resistance to dehamethrin in P.xylostella L was analyzed using log-dosage probit mortality curves constructed from the response of third instar larvae to deltamethrin treatment.It was shown from the life-table,for resistant strain,that larval duration was extended,pupa weight decreased,female deposited less eggs,and hatching rate of eggs decreasing when compared with the susceptible strain(S),and that the relative fitness(Ir/Is) of the R,RS and SR was 0.58,0.82 and 0.81,respectively.It suggested genetically that dehamethrin resistance in the P.xylostella L might be controlled by two or more autosomal genes,and the dominance degrees(D) of the F1 progenies from the reciprocal cross(RS,SR) were-0.97 and-0.98,respectively.Thus,it was inferred that the major genes involved might incompletely recessive heredity.