# Dynamics of the hindgut microbiota of the Japanese honey bees (Apis cerana japonica) throughout the overwintering period

## TL;DR

This study examines how the gut bacteria of Japanese honey bees change during winter and identifies potential new bacteria that may help them survive.

## Contribution

The study identifies potential novel bacterial species in the hindgut microbiota of Japanese honey bees and their abundance changes during overwintering.

## Key findings

- The hindgut microbiota of Japanese honey bees is dominated by six core genera, some of which may represent novel species.
- Bifidobacterium, Bombilactobacillus, and Lactobacillus were more abundant during overwintering.
- The microbiota composition of Japanese honey bees is similar to other Apis cerana populations, suggesting phylogenetic influence.

## Abstract

Honey bees play crucial roles as pollinators in natural, agricultural, and ecological systems. The role of gut microbiota in the overwinter survival of honey bees is gaining attention. Compared with Western honey bees (Apis mellifera), Eastern honey bees (Apis cerana) are more tolerant to low-temperature stress. This study compared the hindgut microbiota of the Japanese honey bees (Apis cerana japonica), a subspecies of A. cerana, during the overwintering period (December) with that before overwintering (October) and after overwintering (March) to estimate beneficial hindgut bacteria contributing to survival during the overwintering period. Overall, the hindgut microbiota of A. c. japonica was occupied by Actinobacteriota, Bacteroidota, Firmicutes, and Proteobacteria at the phylum level and Apibacter, Bifidobacterium, Bombilactobacillus, Gilliamella, Lactobacillus, and Snodgrassella at the genus level. The hindgut microbiota composition of A. c. japonica was similar to that of A. cerana in other regions, suggesting that phylogeny influenced the composition. Many sequences assigned to these six core genera showed <98.7% similarity to type strains, indicating potential novel bacterial species. The relative abundance of Bifidobacterium, Bombilactobacillus, and Lactobacillus was higher during overwintering than in other periods. Our findings highlight changes in the core bacteria of the hindgut microbiota of A. c. japonica during overwintering and also suggest the presence of novel candidate bacterial species. The roles of the bacteria that were increased during the overwintering period require further elucidation.