Toxicities and synergy effects of sulfoxaflor and other ten insecticides against Aphis gossypii Glover

In order to develop high-efficiency synergistic insecticide combinations against Aphis gossypii Glover, the toxicities of sulfoxaflor and other ten insecticides against A. gossypii were determined by the leaf dipping method. The results showed that among all the eleven insecticides tested, sulfoxaflor showed the highest toxicity against A. gossypii, and pymetrozine exhibited the lowest toxicity 24 h after the treatment, with the LC₅₀ values of 10.15 mg/L and 369.63 mg/L, respectively. When the results obtained after 48 h were considered, sulfoxaflor was still the highest effective insecticide to A. gossypii, and the lowest toxic insecticide became lambda-cyhalothrin, with the LC₅₀ values of 2.35 mg/L and 117.57 mg/L, respectively. Based on these results, the co-toxicities of different insecticides combinations were determined, and the following insecticides combinations showed obvious synergism against the aphid: flunicotamid plus pymetrozine (1 : 1), flupyradifurone plus pymetrozine (1 : 5), sulfoxaflor plus pymetrozine (1 : 3), flupyradifurone plus lambda-cyhalothrin (1 : 5), and sulfoxaflor plus lambda-cyhalothrin (1 : 5). And the co-toxicity coefficients (CTC) were 1 271, 820, 561, 1 277 and 478, respectively. These results have provided a scientific basis for the efficient chemical control of A. gossypii.