Abstract: 【Aim】 To analyze and compare the community structure and diversity of the gut bacteria in adult males of Odontolabis fallaciosa with different mandibular forms. 【Methods】 The total DNA of guts from 31 male adults of O. fallaciosa with three mandibular forms (large, medium and small mandible forms) (including 15 adult males of large mandible form, 10 adult males of medium mandible form and 6 adult males of small mandible form) were extracted. The 16S rDNA gene fragments (V3-V4 region) of gut bacteria were sequenced by Illumina MiSeq, and the number of operational taxonomic units (OTUs), species composition, abundance, and alpha and beta diversity were analyzed. 【Results】 A total of 2 238 637 high quality sequences were obtained and clustered into 3 256 OTUs at a 97% similarity threshold. Analysis showed that they could be annotated into 42 phyla, 328 families and 542 genera. Among them, four phyla (Proteobacteria, Bacteroidetes, Firmicutes and Tenericutes) were prevalent in the gut bacteria communities of male adults, and four genera (Acinetobacter, Dysgonomonas, Bartonella and Chryseobacterium) were dominant. The alpha diversity analysis showed that the gut bacteria were quite abundant in these male samples of O. fallaciosa, and the beta diversity revealed that the composition of OTUs was different among the large, medium and small mandible males. 【Conclusion】 Using Illumina MiSeq sequencing technology, the structure and composition of the gut bacterial community in adult males of O. fallaciosa were analyzed. The microbial community composition in guts of adult males of O. fallaciosa has significant difference between the large and medium mandible adult males, whereas no significant difference exists between the large and small mandible adult males, or between the medium and small mandible adult males.

Key words: Odontolabis fallaciosa, gut bacteria, 16S rDNA, bacterial community composition, community diversity