High abundance of lactobacilli in the gut microbiome of honey bees during winter

Honey bee gut microbiota play specific roles in promoting host growth and
physiology by regulating the immune system, behavior, metabolism, and
neurological processes. While the gut microbiota of honey bee queens,
workers, and larvae has been extensively studied, less is known about the
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. These Apis mellifera 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 the Lactobacilli
dominated in all the overwintering honey bee guts with a significantly
higher abundance of unclassified Lactobacillus species in November, while
Lactobacillus apis showed significantly higher abundance in October.
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, taxonomical abundance was not affected by whether the
hives were stored outside or in constant temperature indoor storage.
However, various bacterial species showed differences in abundance across
different months, with slight variations observed between bee strains.
Given the potential benefits of the honey bee gut microbiome for health
and nutrition, our data suggests that the genus Lactobacillus may play a
significant role in bee health during winter and overwintering storage.