Stability of the Gut Microbiome in Honey Bees During Harsh Winters and Overwintering Storage

Honey bee gut microbiota play a number of specific roles in promoting host growth and physiology. While the gut microbiota of honey bee queens, workers, and larvae has been extensively studied, less is known about the role and composition of gut microbiota in the winter worker bees. This study investigates the dynamics of the gut microbiota in overwintering adult worker bees, focusing on two commercial bee strains: Bolton™ bees and Mann Lake™ bees. The strains were investigated under different storage conditions (indoor storage at 6°C and outdoor storage in natural conditions) during the winter months (October, November, and December). Utilizing 16S rRNA gene amplicon sequencing, we characterized the microbial composition of the whole gut. We observed a stable microbiota with slight variations in host-associated bacterial communities with Lactobacillus genus dominating in all the overwintering honey bee guts. Bolton bees exhibited higher abundance levels of Bartonella , Bifidobacterium , and Wolbachia , while Mann Lake bees showed increased abundance of Commensalibacter . Our results suggest that alpha diversity is influenced by the month rather than by the bee strain or storage conditions. We also found significant differences in beta diversity by month. Overall, in this study a stable gut microbiota was observed in both indoor and outdoor environmental conditions across different months with slight differences in abundance between bee strains. Considering all potential benefits of the honey bee gut microbiome to health and nutrition, this study suggests that beekeepers need not be concerned about whether overwintering storage conditions affect the gut microbiome.