Abstract: 【Aim】 Picromerus lewisi is a significant predatory natural enemy insect distributed in multiple countries of Asia, such as China, Korea and Japan, primarily used for controlling lepidopteran pests. Venom plays a crucial role in causing rapid paralysis and death of preys during hunting. The aim of this study is to understand the transcriptomic characteristics of the venom glands of P. lewisi, explore the diversity of toxins in P. lewisi, and establish a foundation for further research on the composition and function of the venom in P. lewisi.【Methods】Transcriptome sequencing was conducted on the venom glands of adults and the 5th instar nymphs of P. lewisi collected from Qianxinan Prefecture, Guizhou Province using the high-throughput Illumina NovaSeq 6000 platform. The resulting data were annotated using the NR, NT, Pfam, KOG/COG, Swiss-Prot, KEGG and GO databases. Gene expression in the venom gland samples of P. lewisi was assessed using the FPKM method, and DESeq was employed for the differential expression analysis of venom gland transcriptomes between adult and the 5th instar nymph. The differentially expressed genes (DEGs) between the adult and the 5th instar nymphal venom gland transcriptomes were screened using the criteria of |log₂(Fold change)|>1 and P<0.05, followed by GO functional enrichment analysis and KEGG pathway enrichment analysis of the identified DEGs. The 33 215 transcripts obtained from the sequenced venom gland transcriptomes of adults and the 5th instar nymphs of P. lewisi were subjected to BLAST comparisons in the UniProt database.【Results】Transcriptome sequencing of the venom glands of adults and the 5th instar nymphs of P. lewisi assembled to 22 242 unigenes with an average length of 949 bp. A total of 15 364 unigenes were annotated to the NR, NT, Pfam, Swiss-Prot, GO, KOG/COG and KEGG databases, corresponding to 10 closely related species including three species of true bugs and two species of spiders. A total of 344 DEGs were screened between the venom gland transcriptomes of adults and the 5th instar nymphs of P. lewisi, with 218 genes up-regulated and 126 genes down-regulated. A total of 443 sequences encoding 33 distinct types of toxin-related proteins were identified.【Conclusion】The transcriptome data from the venom glands of both the 5th instar nymphs and adults of P. lewisi were sequenced and obtained in this study. Differential proteins between the venom gland transcriptomes of adults and the 5th instar nymphs were screened, and sequences associated with toxin proteins were identified. This research lays a theoretical foundation for the identification of components in the venom of P. lewisi and the investigation of their biological functions.

Key words: Picromerus lewisi, venom gland, transcriptome, high-throughput sequencing, bioinformatics