Abstract: 【Aim】This study aims to lay the foundation for further research on the detoxification mechanisms of insects through identifying the genes and metabolites related to detoxification metabolisms in Lycorma delicatula.【Methods】Indoor toxicity of imidacloprid to adult L. delicatula was determined using the leaf dipping method to definite the sublethal concentration LC₁₀ value and the median lethal concentration (LC₅₀) value in 24 h. Adult L. delicatula treated with LC₁₀ of imidacloprid underwent high-throughput sequencing via the Illumina HiSeq 2000 and TripleTOF 6600+platforms. The nonredundant sequences of genes and metabolites were annotated against NR, Swiss-Prot, Pfam, GO, COG/KOG, KEGG and TrEMBL databases to obtain the annotation information of unigenes. The differentially expressed detoxification enzyme genes and detoxification-related metabolites were screened by DESeq2［with the thresholds of ｜log₂(fold change)｜≥1 and false discovery rate (FDR)≤0.05］ and PLS-DA［variable important in projection (VIP)>1, P<0.05］, respectively. The differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) were annotated against the KEGG database to identify the commonly enriched metabolic pathways, so as to explore the associations between DEGs and DEMs.【Results】 The LC₁₀ and LC₅₀ values of imidacloprid to adult L. delicatula in 24 h were 20.799 and 68.707 mg/L, respectively, with the toxicity regression equation of y=-4.533+2.467x. A total of 93 157 unigenes and 179 317 transcripts were obtained by transcriptome sequencing of adult L. delicatula treated with LC₁₀ of imidacloprid. The KEGG annotation result revealed that 168 DEGs involved in 11 metabolic pathways were screened from the transcriptomes between the group treated with LC₁₀ of imidacloprid and the clean water control group, with the DEGs involved in carbohydrate metabolism (50 DEGs) and amino acid metabolism (24 DEGs) being the most prominent. Six detoxification-related DEGs from the cytochrome P450 and UGT families were screened between the group treated with LC₁₀ of imidacloprid and the clean water control group. In addition, 134 DEMs were screened from the metabolomes between the group treated with LC₁₀ of imidacloprid and the clean water control group, including 87 down-regulated metabolites and 47 up-regulated metabolites, predominantly benzene derivatives, amino acids and their metabolites, organic acids and their derivatives, heterocyclic compounds, aldehydes, ketones, and esters. 【Conclusion】 The transcriptome and metabolome databases for adult L. delicatula treated with LC₁₀ of imidacloprid was established, and the key detoxification-related DEGs (for example, cytochrome P450 and UGT genes) and some DEMs were identified. These findings preliminarily elucidate the detoxification mechanisms of L. delicatula, providing a reference for research on the other hemipteran insects and laying a foundation for functional analysis of detoxification enzyme genes and further detoxification mechanism studies of L. delicatula.

Key words: Lycorma delicatula, imidacloprid, detoxification enzyme genes, transcriptome, metabolites