The new mechanism of rapid evolution of resistance of cotton aphid to Sulfoxaflor was revealed by the Plant Protection Institute

The Intelligent Plant protection innovation team of IPP·CAAS published the title "Hormesis"" effects of Sulfoxaflor on Aphis gossypii feeding, growth, reproduction behaviour and the related mechanisms” in Science of the Total Environment (IF=9.8) ". 

This study revealed a new mechanism by which Sulfoxaflor improves population fitness of resistant cotton aphid and accelerates resistance evolution by promoting feeding and reproduction of cotton aphid.

Cotton aphid, one of the most resistant agricultural pests, has developed serious resistance to pyrethroids, neonicotinoids and other types of insecticides, which seriously threatens the production safety of cotton. Sulfoxaflor is one of the most widely used alternative agents in the management of resistant aphids. However, the results of resistance monitoring show that the resistance of cotton aphid to the new insecticide Sulfoxaflor is increasing, and cotton aphid in Xinjiang, Shandong and other places have developed a high level of resistance to Sulfoxaflor.

Studies on the mechanism of resistance show that: The resistance of cotton aphid to Sulfoxaflor is closely related to the overexpression of cytochrome P450 gene CYP6CY13-2. Silting the expression of this gene can greatly improve the sensitivity of cotton aphid to Sulfoxaflor, and CYP6CY13-2 protein can metabolize Sulfoxaflor, thus significantly reducing the cytotoxicity and virulence of Sulfoxaflor to cotton aphid.

In addition, the overexpression of UDP-glucosyltransferase genes UGT350A2, UGT351A4, UGT350B2, UGT343C2 and ABC transporter genes ABCA1 and ABCD1 were also involved in the resistance of aphid to Sulfoxaflor.

On the basis of this study, it was found that the resistant cotton aphid induced by Sulfoxaflor had more frequent probing feeding, more rapid response to uncomfortable probing sites, longer feeding time in phloem, and more energy intake. Further, the gene expression and protein content of vitellinogen (Vg) and vitellinogen receptor (VgR) were increased, which induced the proliferation of resistant cotton aphid and improved population fitness.

After interfering the expression of Vg and VgR genes, the breeding amount of cotton aphid decreased greatly. Moreover, the induced effects of low dose (LC10) Sulfoxaflor on reproductive genes of cotton aphid could be transmitted in the progeny, and the expression of Vg and VgR genes and proteins in the progeny of cotton aphid F0 exposed to the agent could be up-regulated. Under the continuous stress of Sulfoxaflor, the resistance of cotton aphid was accompanied by the continuous up-regulated expression of Vg and VgR.

Therefore, Sulfoxaflor can increase the energy intake of cotton aphid by promoting the exploration and feeding of cotton aphid, and then increase the expression of genes related to reproduction of cotton aphid, induce the proliferation of cotton aphid, improve the population fitness of resistant cotton aphid, and accelerate the speed of resistance evolution. This study breaks the traditional understanding of the cost of resistance fitness and provides a new perspective for the resistance management of cotton aphid.