Abstract: In order to clarify the cross-resistance and the change in related enzymes of the imidacloprid-resistant population of Aphis gossypii to other neonicotinoid insecticides, the bioassay method was used to determine the cross-resistance of different resistant populations of imidacloprid-resistant A. gossypii to dinotefuran and nitenpyram, and the synergism of three detoxification enzyme inhibitors to imidacloprid and other two neonicotinoid insecticides using cotton aphids of the imidacloprid-resistant population selected in the laboratory, the Xiajin resistant population in the field in Shandong and the susceptible population. The activities of detoxification enzymes and AChE of three populations of cotton aphid and the inhibition effect of insecticides were determined through biochemical analysis. The results showed that the imidacloprid-resistant population and the Xiajin resistant population exhibited no cross-resistance to dinotefuran, but showed 5.28-fold and 4.89-fold cross-resistance to nitenpyram, respectively. Dinotefuran could significantly inhibit the activities of CarE, GST and AChE of the imidacloprid-resistant cotton aphid. Nitenpyram showed little effect on the activities of CarE, GST and AChE of the imidacloprid-resistant cotton aphid. Carboxylesterase inhibitor TPP and mixed-functional oxidase inhibitor PBO had obvious synergism to imidacloprid and nitenpyram, while had little synergism to dinotefuran. Glutathione-S-transferase inhibitor DEM showed no obvious synergism to the three insecticides. Dinotefuran and nitenpyram could inhibit the activities of detoxification enzymes and AChE of the imidacloprid-resistant conton aphid, with dinotefuran showing significant effect. The results demonstrate the great application value of dinotefuran in control of the imidacloprid-resistant cotton aphid, and its structure can provide a reference to the development of neonicotinoid insecticides in the future.

Key words: Aphis gossypii, imidacloprid, dinotefuran, nitenpyram, cross-resistance, resistant mechanism