Resistance of Field Population Aphis gossypii Glover to Carbosulfan and Imidacloprid in Xingtai and Nanjing District

【Objective】 The objective of this study is to monitor the insecticide resistance of Aphis gossypii Glover in filed to carbosulfan and imidacloprid,and to provide a better understanding of resistance mechanism.【Method】The cotton aphids were collected from fields in Nanjiang city of Xinjiang Uygur Autonomous Region(XJ),Xingtai city of Hebei Province(HB),and Nanjing city of Jiangsu Province(JS).The resistances of field cotton aphid to conventionally used insecticides imidacloprid and carbosulfan were investigated.The cotton aphids from Xinjiang were treated as the sensitive strain.The bioassay,enzyme activities and mRNA relative expression levels by qPCR were performed to study the resistance ratios and their potential molecular mechanisms.【Result】A.gossypii of Xingtai city of Hebei Province(HB) and Nanjing city of Jiangsu Province(JS) were still sensitive to carbosulfan,but their insecticide resistance to imidacloprid reached 4.87 and 8.72 folds.Three field populations of cotton aphids had significantly different activities of oxidases,esterase and glutathione-S-transferase.The activities of esterase in Nanjing city of Jiangsu Province were the highest among three field populations.Compared with XJ strain,quantitative real-time PCR indicated that the relative expression level of carboxylesterase gene was the highest,which was 3.28-fold higher.【Conclusion】The cotton aphid has developed low-level resistance to imidacloprid.The increased esterase activity confers the low-level resistance to imidacloprid.