Selection For Chlorantraniliprole Resistance In Spodoptera Exigua (hübner) And Investigation On The Resistance Biochemical Mechanisms

Beet armyworm, Spodoptera exigua (Hübner), a world-wide polyphagous pestwith a host range of35families,138species of plants, and it causes sever damages tovegetables, cotton and other economic crops. Chlorantraniliprole is a highly effectivebroad spectrum insecticide. In current study, we used beet armyworm (a representativefrom Lepidoptera Noctuidae) as our working model. After repeated selection with dietdncorporation bioassay in the laboratory, the chlorantraniliprole resistance strain wasselected. By using the same method, we tested the synergistic activity of threeinhibitors (PBO (piperonyl butoxide), DEM (maleic acid diethyl ester) and TPP(triphenyl phosphate)) on third instar from the susceptible and resistant strains. Wealso determined the activity of three detoxification enzymes (CarE, GST and MFO) onchlorantraniliprole sensitive and chlorantraniliprole resistant strains. The main resultsare listed as follows:1. After18generations selection of the field S. exigua strain by chlorantraniliprole,the resistant strain was gained with the31.1-fold resistance compared with thesusceptible strain.2. The synergism of PBO, DEM, and TPP to chlorantraniliprole in the susceptiblestrains was significant with13.2,2.34and1.65fold respectively. The synergism ofPBO, DEM, and TPP to resistant strains was also significant with15.6,3.29and2.37fold respectively. Overall, PBO is the best inhibitor that works synergistically withchlorantraniliprole. Biochemical studies showed that the specific activity of CarE was0.0073μmol/min/mg Pr., which was high but not significantly in the resistant straincompared with the susceptible strain. It is consistent with the data that there was nosynergistic effect on the chlorantraniliprole susceptible and resistant strain with theCarE inhibitor-TPP. The specific activity of GST was1.6966μmol/min/mg Pr., which was high but not significantly in the resistant strain compared with the susceptiblestrain, which is compatible with the data that there was no synergistic effect on thechlorantraniliprole susceptible and resistant strains with the GST inhibitor-DEM.These data suggested that CarE and GSH do not play a role in the chlorantraniliproleresistance on S. exigua.