Resistance dynamic of different Aphis gossypii populations in Hebei Province to six insecticides

To clarify the resistance level and development trend of different Aphis gossypii populations to main insecticides in Hebei Province, the susceptibility of A. gossypii from Baoding, Cangzhou and Handan to 6 insecticides was determined by dipping method during 2014-2020 in China. Comparing with the historical sensitivity baselines in China, the resistance of A. gossypii in Hebei Province to β-cypermethrin, carbosulfan, imidacloprid and sulfoxaflor had all reached high or extremely high levels, with the highest resistance ratios of 242, 13353, 1367 and 205-fold, respectively. The resistance to omethoate and thiamethoxam were also reached medium or high resistance levels. Paired comparisons of the logLC₅₀ values of insecticides tested for all the A. gossypii populations in Hebei Province showed that the resistance of Baoding population to imidacloprid and sulfoxaflor (r = 0.77, p = 0.041), thiamethoxam and sulfoxaflor (r = 0.98, p < 0.001) was significant positively correlated. The resistance of Cangzhou population to β-cypermethrin and carbosulfan (r = 0.81, p = 0.027), β-cypermethrin and thiamethoxam (r = 0.90, p = 0.006), carbosulfan and thiamethoxam (r = 0.91, p = 0.005) was also significantly positive. Handan population also had a significant positive correlation between β-cypermethrin and thiamethoxam (r = 0.83, p = 0.022), β-cypermethrin and sulfoxaflor (r = 0.97, p < 0.001), carbosulfan and sulfoxaflor (r = 0.77, p = 0.045). These results showed that A. gossypii population in Hebei Province had significant resistance to 6 insecticides and may have severe cross resistance.