Carbosulfan And Imidacloprid Resistance Of Field Population Cotton Aphid In Hebei Xingtai And Jiangsu Nanjing District

Cotton aphid (Aphis gossypii Glover) is one of the most important pests in cotton production, which has a wide distribution in China. Using chemical insecticide is one of main methods to control this pest. However, with extensive use of the insecticides, cotton aphid produces resistance to the organophosphorus, carbamates and pyrethrum ester insecticide. That impacts seriously the efficient control in practice and is an urgent problem. The application of carbosulfan and imidacloprid in order to control cotton aphid was promoted by ministry of agriculture in2006.In this study, we measured the resistance of cotton aphid from Nanjiang, Xingtai and Nanjing to carbosulfan and imidacloprid by using bioassay method. The enzymes activities of esterase, P450and GST were analyzed using the kinetic method. The gene expression levels of carboxylesterase and P450were detected by using qRT-PCR.1. We collected field populations from Nanjiang, Xingtai and Nanjing, and measured their resistance to carbosulfan and imidacloprid. The cotton aphid collected from Nanjiang was treated as the susceptible population. Bioassays results showed that the resistances to carbosulfan and imidacloprid in Xingtai populations were1.97and4.87fold. The resistances to carbosulfan and imidacloprid in Nanjing population were1.07and8.72fold, respectively. The sensitivity to carbosulfan was not changed in all field populations. However, the sensitivity to imidacloprid began to decline sharply, so we should pay much attention to it in cotton production.2. The enzymes activities of P450, GST and esterase were measured using the kinetic method. The cotton aphid collected from Nanjiang was treated as the susceptible population. The results showed that there was significant difference of three kinds of enzymes between different populations. The esterase and GST activities from Xingtai and Nanjiang populations were similar, which were1.07and0.76fold, respectively. The P450activity of Xingtai population was lower than that of Nanjiang populations, and was0.28fold. The P450and GST activities from Nanjing and Nanjiang populations were similar, which were0.72and0.96fold, respectively. But esterase activity of Nanjing population was higher than that of Nanjiang populations, and was1.37fold.3. The relative expression of CarE, CYP6CY3-1and CYP6CY3-2were detected using qRT-PCR. The cotton aphid collected from Nanjiang was treated as the susceptible population. The relative expression of CarE in Xingtai population was3.28folds highest, and that of CYP6CY3-1and CYP6CY3-2were similar, and were1.81and1.44fold respectively. The relative expression of CarE in Nanjing population was0.66folds, and that of CYP6CY3-1and CYP6CY3-2were1.33and1.84fold, respectively.