Abstract: -【Aim】 Intestinal microbes play important roles in metabolism, growth and development, and immunity in host insects. This study aims to explore the community structure of the intestinal microbes of Picromerus lewisi adults and their ability to metabolize carbon sources. 【Methods】The intestinal microbes were isolated and purified from P. lewisi adults by in vitro culture and identified by molecular biology technologies. The bacterial 16S rDNA and fungal ITS genes were sequenced by Illumina high-throughput sequencing technology to analyze the structure and diversity of the intestinal bacterial and fungal communities of P. lewisi adults. PICRUSt and FUNGuild were used to predict the function of bacteria and fungi and their genes. Biolog ECO technique was used to analyze the carbon source metabolic function of the intestinal bacteria and fungi of P. lewisi adults. 【Results】A total of 10 strains of Enterococcus sp. were isolated from the intestinal culturable dominant bacteria of P. lewisi, and the dominant bacterium was E. faecalis. The results of high-throughput sequencing showed that the dominant phyla in the intestine of P. lewisi adults were Proteobacteria (relative abundance: 58.51%) and Firmicutes (relative abundance: 38.92%), and the most dominant fungal phylum was Ascomycota (relative abundance: 56.53%), followed by Basidiomycota (relative abundance: 11.34%). The most dominant bacterial genus in the intestine of P. lewisi adults was Enterococcus (relative abundance: 25.05%), followed by Lactococcus (relative abundance: 12.23%), Serratia (relative abundance: 11.48%) and Providencia (relative abundance: 2.38%), and the most dominant fungal genus was Biappendiculispora (relative abundance: 18.30%), followed by Cladosporium (relative abundance: 11.83%), Vishniacozyma (relative abundance: 517%), and Phallus (relative abundance: 3.62%). The community structure of the intestinal bacteria and fungi of P. lewisi adults showed high species richness and diversity, and strong metabolic ability on carbon sources, being able to efficiently metabolize 27 carbon sources including α.cyclodextrin, L.serine, sutrescine, D.malic acid etc. Functional predictions showed that the intestinal bacterial taxa of P. lewisi adults were mainly distributed in metabolism, environmental information processing, genetic information processing etc., and the fungal taxa were mainly distributed in unassigned taxa, plant saprotroph, undefined saprotroph, endophyte.plant pathogen, fungal parasite.undefined saprotroph, leaf saprotroph, and animal pathogen.endophyte.plant pathogen.wood saprotroph. 【Conclusion】 P. lewisi adults have a high variety and diversity of intestinal bacteria and fungi. The dominant bacterial genera were Enterococcus, Lactococcus, Serratia and Providencia, and the dominant fungal genera were Biappendiculispora, Cladosporium, Vishniacozyma and Phallus, with a strong metabolic ability on carbon sources..

Key words: Picromerus lewisi, intestinal microbes, community structure, carbon source metabolism, high.throughput sequencing