Insecticide resistance monitoring and diagnostics of resistance mechanisms in cotton-melon aphid, Aphis gossypii Glover in Central China

Aphis gossypii Glover is one of the most serious pests in China, and the management of this pest mainly relies on insecticides. However, the resistance status of A. gossypii in Central China is still unknown. Therefore, in this study, we firstly determined the susceptibility of 15 A. gossypii field populations from Central China to six chemical insecticides using leaf-dipping method during 2020 and 2021 and explored the potential resistance mechanisms of these populations. Most of the field populations of A. gossypii have evolved low to high levels of resistance to imidacloprid (RR = 5.98-2352.96-fold), thiamethoxam (RR = 5.98-2194.96-fold), flonicamid (RR = 7.18-306.07-fold), and pirimicarb (RR = 6.90-283.00-fold); however, 13 tested field populations remained susceptible to chlorpyrifos. For ?-cyhalothrin, most populations have evolved low to moderate levels of resistance (RR = 5.72-47.38-fold). The results of correlation analysis indicated that there was a prominent positive correlation between the enzyme activity of cytochrome P450 and the logarithm of LC50 to thiamethoxam and pirimicarb. Carboxylesterase (CarE) was positively correlated with ?-cyhalothrin, while glutathione S-transferase (GST) was negatively correlated with ?-cyhalothrin. Furthermore, we found that multiple resistance associated target site mutations (V62I, R81T, A302S, S431F, M918L) can be detected in the field populations of A. gossypii. Aphis gossypii in Central China have developed different degrees of resistance to tested insecticides and enhanced detoxification of cytochrome P450 and carboxylesterase and co-existed resistance mutations contribute to the multiple resistance of these field populations. Our results provide valuable information about the status of insecticide resistance in China and are helpful for designing sustainable management strategies of A. gossypii.

Automated summary

This study determined the susceptibility of 15 field populations of Aphis gossypii in Central China to six chemical insecticides and explored the potential resistance mechanisms of these populations. The results showed that most populations have evolved varying degrees of resistance to imidacloprid, thiamethoxam, flonicamid, and pirimicarb. However, they remained susceptible to chlorpyrifos, and showed low to moderate levels of resistance to ?-cyhalothrin. Correlation analysis revealed that the enzyme activity of cytochrome P450 and carboxylesterase were associated with the resistance to certain insecticides. Additionally, multiple resistance-associated target site mutations were detected in the field populations. These findings provide important information for understanding insecticide resistance in China and designing effective strategies for managing A. gossypii.