Cytochrome P450 Mediates The Function Of Imidacloprid And Thiamethoxam Resistance From Aphis Gossypii Glover

Neonicotinoid insecticides have played an important role in pest control due to their unique mechanism of action.However,after years of insecticide pressure selection,pest populations in the field have developed varying levels of resistance to neonicotinoids.This study focuses on the cotton aphid(Aphis gossypii)and explores the mechanism of resistance to two important neonicotinoid insecticides,imidacloprid and thiamethoxam,in order to find ways to delay the development of resistance in A.gossypii populations in the field.Cytochrome P450(P450)is one of the important detoxification metabolic enzyme systems in insects,and is widely expressed in tissues and organs such as the fat body,midgut,Malpighian tubules,nervous system,and antennae of insects.In this paper,through synergist bioassay and transcriptome sequencing,it is preliminarily determined that the P450 gene in A.gossypii may be involved in the formation of imidacloprid and thiamethoxam resistance.Transgenic Drosophila and RNA interference technology were used to investigate the role of P450 in A.gossypii resistance to imidacloprid and thiamethoxam.The bioassay results of laboratory sensitive A.gossypii strains(SS)and Shandong field strains(SDR)showed that SDR has a higher level of resistance to imidacloprid and thiamethoxam.However,under the co-treatment of the P450 inhibitor piperonyl butoxide(PBO),the resistance level of SDR significantly decreased,indicating that the P450 of A.gossypii may be related to its resistance to imidacloprid and thiamethoxam.By comparing the transcriptome data of SS and SDR strains of A.gossypii,it was found that most of the candidate differential genes were enriched in the pathway of P450 detoxification metabolism,and 18 P450 genes were selected as up-regulated in the resistant strains and possibly related to imidacloprid and thiamethoxam resistance.The GAL4/UAS system was used to overexpress these18 P450 genes in transgenic Drosophila,and functional verification was carried out.The biological assay results of transgenic Drosophila showed that overexpression of CYP6CY9,CYP6CZ1,CYP6DB1,CYP4CK1,CYP6CY22,and CYP6CY18 significantly increased their resistance to imidacloprid and thiamethoxam.Among them,the Act5C>CYP6CY9 line and Act5C>CYP6DB1 line both showed more than seven-fold resistance to imidacloprid and thiamethoxam,and the Act5C>CYP6CY9line showed a 24.03-fold increase in resistance to thiamethoxam and a 10.24-fold increase in resistance to imidacloprid.Based on the results of the Drosophila biological assay,P450 genes with higher tolerance to imidacloprid and thiamethoxam were selected for RNA interference experiments,and the results showed that inhibiting CYP4CK1,CYP6CY9,CYP6CY18,CYP6CY22,CYP6CZ1,and CYP6DB1 expression in SDR-resistant A.gossypii significantly increased their mortality rate more than 20%.In summary,the functional study of P450 genes in the SDR strain suggests that P450 may be involved in the detoxification of A.gossypii to imidacloprid and thiamethoxam,and six P450 genes(CYP4CK1,CYP6CY9,CYP6CY18,CYP6CY22,CYP6CZ1,and CYP6DB1)may play important roles resistance of A.gossypii to imidacloprid and thiamethoxam.