Thiamethoxam Resistant Strain Establishment、Cross-Resistance Spectrum And Transcriptome Difference Analysis In Aphis Gossypii Glover

The susceptible strain(SS) and the thiamethoxam resistant strain(Th R) cotton aphid(Aphis gossypii) were used in this study. The cross-resistance to other insecticides in the Th R strain of A. gossypii was determinated. The resistance mechanism of Th R strain was explored by transcriptomic analysis, and q-PCR combind with bioinformatics analysis.The resistant strain has been selected for 50 generations with thiamethoxam. Adult aphids of the Th R strain showed about 13.77-fold resistance to thiamethoxam compared to the susceptible strain. Compared the SS strain, the Th R strain developed high level cross resistance to cyfluthrin(17.9-fold) and bifenthrin(88.27-fold), but low level cross resistance to methidathion(5.34-fold) and esfenvalerate(6.85-fold). However, the Th R strain showed no cross resistance to malathion, omethoate, acephate, chlorpyrifos, methomyl, alpha-cypermethrin, sulfoxaflor and imidacloprid. Piperonyl buoxide(PBO) result shows that 3 fold synergist ratios in the thiamethoxam resistant strain compared with control. Solexa sequencing technology was employed to identify differentially expressed genes(DEGs) between the susceptible and thiamethoxam resistant cotton aphid. A total of 22569311 and 21,317,732 clean reads were obtained from Th R and SS c DNA libraries respectively. These reads were assembled into 35,222 non-redundant(Nr) consensus sequences. A total of 14,913, 9,220, 7,922, 4,686 and 4,314 sequences were annotated using Swiss-Prot, NR(Non-redundant), Gene Ontology(GO), Kyoto Encyclopedia of Genes and Genomes(KEGG) and Clusters of Orthologous Groups(COG) database. The Th R strain had 435 significantly changed unigenes compared to the SS strain, all of which 270 genes were up-regulated and 165 genes were down-regulated(P ≤ 0.001). Expression levels of ribosomal proteins, ATP synthase, cytochrome c oxidase, ecdysteroid UDP-glucosyltransferase and esterase were up-regulated significantly in the Th R strain compared to the SS strain. The genes of cuticle proteins, salivary proteins and fibroin heavy chain decreased dramatically. One nicotinic acetylcholine receptor(n ACh R) α subunit was down-regulated in the Th R strain. The expression levels of these genes(five cuticle proteins, a salivary proteins and fibroin heavy chain) were down-regulated. The expression levels of two ATP synthase were up-regulated. The expression levels of these genes were detected by q PCR, and the expression trend of these genes were in constistance with the Solexa expression profiles.The expression levels of UGT and cuticular protein genes were determinated by q-PCR. The transcriptional levels of UDP-glucuronosyltransferase genes( U28090 、 U27583) were down-regulated in the Th R strain, while some UDP-glucuronosyltransferase genes(U1814、U16894、U25824)were up-regulated in the Th R strain. The expression levels of cuticular protein genes(C20319)were up-regulated in the Th R strain, and other cuticular protein genes(C10919、C27245)were down-regulated in the Th R strain.Analyzing the thiamethoxam-resistance has important significance for resistance management.The results of cross-resistance are usefull to guide using of pesticides in field. Transcriptomic analysis provides an important theoretical basis for the resistance mechanism to thiamethoxam. It provides valuable information for control of A.gossypii.