Abstract: 【Aim】The gut bacteria of bees play an important role in the host health, physiological characteristics and interaction with the surrounding environment. This study aims to reveal the composition and functional characteristics of the gut bacteria of adult Xylocopa rufipes of different sexes. 【Methods】The gut bacterial community composition of adult X. rufipes of different sexes was determined using 16S rRNA high-throughput sequencing technology. Alpha-diversity analysis, beta-diversity analysis and functional prediction of the gut bacteria of adult X. rufipes of different sexes were performed using mothur software, Bray-Curtis distance algorithm and PICRUSt2 software, respectively. 【Results】A total of 120 operational taxonomic units (OTUs) of bacteria in the gut of adult X. rufipes were annotated, belonging to 56 species of 36 genera of 20 orders of 10 classes of 7 phyla. Among them, the dominant bacterial phyla were Bacillota, Pseudomonadata and Actinomycetota, with the relative abundance of 49.70%, 40.95% and 8.59%, respectively. The detection rates of the dominant bacterial genera Lactobacillus, Gilliamellaand Bifidobacteriumwere over 90%. At the species level, Apilactobacillus micheneri exhibited significantly higher relative abundance in the gut of female adults than in the gut of male adults, while Gilliamella apicola showed no significant difference in relative abundance between sexes. There was no significant difference in alpha-diversity of the gut bacterial community between female and male adults of X. rufipes, but significant difference in bata-diversity of the gut bacterial community between female and male adults of X. rufipes was observed. The relative abundance of genes enriched in metabolic function pathways of the gut bacteria of male adults of X. rufipes was higher than that of female adults.【Conclusion】The gut of adult X. rufipes harbors a stable core bacterial community associated with social bees. Differences in the relative abundance of the dominant gut bacterial community between sexes may be linked to variations in their physiological structures and lifestyles.

Key words: Xylocopa rufipes, sex, gut bacteria, high throughput sequencing, 16S rRNA