Illumina-based 16S metagenomic analysis of the indigenous gut microbiota of cavity-nesting bee Megachile centuncularis: a comparison with the cavity-nesting wasp Ancistrocerus antilope

Insect guts are colonized by different species of microorganisms, most of which are benign or beneficial to their host. However, little is known about how the microbial gut communities vary among different host species. In this study, using 16S metagenomic sequencing, we compared the indigenous gut microbiota in adult of two solitary cavity-nesting Hymenoptera, a bee (Megachile centuncularis)and a wasp (Ancistrocerus antilope). The richness of operational taxonomic units (OTUs)was estimated in the guts of freshly eclosed imagoes, which had had no contact with the environment. We obtained 123,237 total reads from M. centuncularis and 125,942 from A. antilope. Three phyla, Proteobacteria, Actinobacteria, and Firmicutes, were dominant. Nine OTUs in M. centuncularis and five OTUs in A. antilope represented ?1 percent of all reads. Wolbachia, a well-known insect endosymbiont, dominated in both species, representing 27 percent of reads in M. centuncularis and 48 percent in A. antilope. The most abundant in the gut of M. centuncularis was Arthrobacter (38 percent ), while the dominants in the gut of A. antilope were Microbacterium (18 percent ) and Erwinia (14 percent ). These differences in microbiota richness and composition between bee and wasp are likely to be caused by their disparate trophic specialization.