Specific Function and Assembly of Crucial Microbes for Dendroctonus armandi Tsai et Li

Dendroctonus armandi is a native bark beetle that infests healthy Pinus armandii Franch. in western China. The complex symbiotic relationships with diverse microbes are critical to hosts for survival and outbreak dynamics. Understanding the potential functions and assembly metabolisms of these symbiotic microbes to host colonization are therefore crucial. Metagenomic analysis revealed that gut microbial communities differed from cuticular ones significantly. The cuticle exhibited greater fungal diversity, while the gut supported a significantly higher bacterial diversity. Our findings indicated that gut unclassified Burkholderiales, Escherichia, Bacteroides and Prevotella may play a crucial role in degrading terpenes, phenols and polysaccharides rather than cuticular microbes. Stochastic processes appeared to be served as the primary drivers shaping the core microbial community structures. Cuticular dominant and functional microbial community assemblies except for Escherichia may be primarily driven by stochasticity to adapt the unstable habitats. The direct comparison of gut and cuticular microbiomes may provide valuable insights into the specific functions of symbiotic microbes, and offer critical molecular data for broader understanding of symbiotic relationship between bark beetles and microbes.