Comparison of Sublethal Effects of Chlorpyrifos on Resistant and Susceptible Populations of Laodelphax striatellus

In order to study the sublethal effect of chlorpyrifos on resistant and susceptible Laodelphax striatellus populations,life parameters of L.striatellus were analyzed by construction of life tables.The results showed that the population development of the resistant or susceptible strain was significantly inhibited by the sublethal doses of chlorpyrifos(LC14).Compared with that of the untreated populations,nymph mortality was significantly increased,developmental duration extended,adult longevity shortened,fecundity declined,and the intrinsic growth rate and relative fitness decreased in chlorpyrifos treated populations.Moreover,fecundity decline of the resistant strains(19.89%) was significantly lower than that of the susceptible strain(39.29%) and relative fitness decrease of the resistant strain(24%) was significantly lower than that of the susseptible strain(48%) after treated with LC14 of chlorpyrifos,implying the less inhibition of chlorpyrifos on the resistant strain than on the susceptible strain.