The Altered Lipid Composition and Key Lipid Metabolic Enzymes in Thiacloprid-Resistant Myzus persicae, with Special Attention Paid to the Function of MpTHEM6a

Neonicotinoid resistance is increasingly prevalent in the agricultural pest <i>Myzus persicae</i>. Lipids play a critical role in insect defense systems, but their contribution to insect neonicotinoid resistance is disregarded. We conducted metabolomics and transcriptomics studies on <i>M. persicae</i> thiacloprid-resistant (THG-R) and -susceptible (FFJ-S) populations. A total of 149 lipid metabolites were identified, with 90 upregulated and 59 downregulated in THG-R compared to in FFJ-S. Metabolites in the arachidonic acid (AA) pathway substantially varied between THG-R and FFJ-S. For example, arachidonic acid, (±)11-HETE, and prostaglandin B1 were significantly upregulated, while prostaglandin A1, tetranor-PGDM, 8,15-diHETE, and (±)11(12)-EET were significantly decreased in THG-R. Transcriptomics profiles and qPCR indicated that lipid metabolic enzymes, including fatty acid synthase (FAS), the elongase of very-long-chain fatty acids (ELO), fatty acid desaturase (FAD), and phospholipase (PL) genes, were not overexpressed in THG-R. Among the twelve thioesterase genes, only <i>MpTHEM6a</i> was significantly upregulated in THG-R. Knocking down the expression of <i>MpTHEM6a</i> in THG-R significantly increased the toxicity of the three neonicotinoids, reduced the lifespan of adults, and decreased the number of nonviable nymphs produced by female adults. The metabolites AA, (±)11-HETE, and prostaglandin B1 are potential biomarkers in neonicotinoid-resistant <i>M. persicae</i>. <i>MpTHEM6a</i> may become a potential target for combating neonicotinoid-resistant <i>M. persicae</i>.