Insights into the gut microbiome of local steppe-vegetation inhabitant bees: microbial community analysis of Bombus niveatus niveatus, Bombus niveatus vorticosus, Bombus terrestris, and Apis mellifera

Bumble bees and honey bees are pollinivorous and nectarivorous insects. We classify them as "important pollinators" because of their feeding behaviors. The gut microbiota of these pollinators is essential in nutrition, detoxification, and resistance to diseases. Evaluating the diversity of microbiomes for pollinator taxa may give a chance to understand the ecological relationships among them and the related plants. We investigated the gut bacteria and fungi communities of four taxa distributed in a local steppe-vegetation habitat: wild populations of Bombus terrestris, Bombus niveatus niveatus, Bombus niveatus vorticosus and, as a manageable pollinator, Apis mellifera. The composition of fungi and bacteria within the gut was identified using Illumina MiSeq metabarcoding of the ITS1 and 16S rRNA genes. We found that the dominant bacteria detected in the phyla among the three bumble bee taxa were Firmicutes, Bacteroidota, and Proteobacteria while for A. mellifera, Proteobacteria, Firmicutes, and Bacteroidota, respectively. For fungi, Candida was predominant among bumble bee taxa, whereas Penicillium, Fusarium, and Candida were detected predominantly in A. mellifera.