Dynamics of the Honeybee (Apis mellifera) Gut Microbiota Throughout the Overwintering Period in Canada

Abstract

Microbial symbionts inhabiting the honeybee gut (i.e., gut microbiota) are essential for food digestion, immunity, and gut protection of their host. The taxonomic composition of the gut microbiota is dynamic throughout the honeybee life cycle and the foraging season. However, it remains unclear how drastic changes occurring in winter, such as food shortage and cold weather, impact gut microbiota dynamics. The objective of this study was to characterize the gut microbiota of the honeybee during the overwintering period in a northern temperate climate in Canada. The microbiota of nine honeybee colonies was characterized by metataxonomy of 16S rDNA between September 2017 and June 2018. Overall, the results showed that microbiota taxonomic composition experienced major compositional shifts in fall and spring. From September to November, Enterobacteriaceae decreased, while Neisseriaceae increased. From April to June, Orbaceae increased, whereas Rhizobiaceae nearly disappeared. Bacterial diversity of the gut microbiota decreased drastically before and after overwintering, but it remained stable during winter. We conclude that the honeybee gut microbiota is likely to be impacted by the important meteorological and dietary changes that take place before and after the overwintering period. Laboratory trials are needed to determine how the observed variations affect the honeybee health.

Overwintering honeybees maintained dynamic and stable intestinal bacteria

“…For example, the Phylum Cyanobacteria, which exists widely in water in the natural environment (Bartram et al 1999), was almost only found in the before overwintering sample. Notably, after overwintering, the dominant species composition of the samples in winter honeybees was the same, and there was no signi cant difference in their abundance; however, there was a large difference in beta diversity, which was consistent with the results of a previous study (Bleau et al 2020). Compared with other winter honeybees, honeybees defecated their waste and thus have a new intestinal environment after overwintering.…”

Characterization of Apis mellifera Gastrointestinal Microbiota and Lactic Acid Bacteria for Honeybee Protection—A Review

“…Their bodies are colonized by microbial communities orally by means of social interactions with nurse bees within a few days of emergence [ 51 , 52 ]. During metamorphosis into pupae, the gut bacteria are excreted via defecation along with the gut epithelium, and the next colonization starts due to trophallaxis, contact with other bees, as well as from the hive [ 53 ]. The abundance of bacteria in the whole gut reaches its peak 3–5 days post-adult emergence [ 54 ].…”

“…There are two Gram-positive species belonging to phylum Firmicutes that are ubiquitous and abundant; namely, Lactobacillus Firm-4 and Lactobacillus Firm-5, which inhabit the distal rectum [ 2 , 59 ]. In the majority of adult workers, Bifidobacterium asteroides is also found (albeit with much lower abundance) [ 53 , 61 ]. The mentioned bacterial species clusters are the most essential microorganisms in the honeybee gut, the so-called “core bacteria” [ 64 ].…”

“…There are also less-abundant/stable species from Proteobacteria: The Gammaproteobacteria Frischella perrara (Orbaceae family); the Alphaproteobacteria Parasaccharibacter apium , Bombella favorum , Bombella mellum , Bombella apis (Acetobacteraceae family, Alpha 2.2); and Commensalibacter sp. (Alpha 2.1) and Bartonella apis (Alpha 1) from the Rhizobiaceae family [ 50 , 53 , 59 , 63 , 65 , 66 ]. Representatives of phylum Bacteroidetes have also been identified in the honeybee gut— Apibacter adventoris and Apibacter mensalis [ 67 , 68 ].…”

“…Few studies have shown how extreme modifications impact gut microbiota dynamics during overwintering. However, seasonal changes in the honeybee microbiome in Canada were investigated by Bleau et al [ 53 ], and they observed a decrease in the abundance of Enterobacteriaceae from September to November, while the relative abundance of Neisseriaceae increased. Subotic et al [ 69 ] found that the honeybee microbiome changes seasonally.…”