Abstract Description

While pollen serves as a fundamental protein source for honey bees, it also introduces external microbes that integrate with the host's existing gut community. Despite the ecological significance of African savannah honey bees (Apis mellifera scutellata), the specific influence of nutrition on their internal microbial ecosystem remains largely unexamined. This study compared the gut profiles of naturally foraging honey bees against microbially depleted workers reared in semi-sterile conditions. Newly hatched bees were isolated in hoarding cages and provided with one of four protein sources: raw sunflower pollen, casein, or sterilised versions of these diets. High-throughput 16S rRNA DNA metabarcoding was utilised to evaluate microbial shifts across these groups. The findings indicated that lab-reared, microbially depleted bees possessed greater species richness and diversity than wild populations. Across all experimental treatments, non-core bacterial genera, particularly Bartonella, Commensalibacter, and Bifidobacterium, were most prevalent. Notably, the core bacterium Gilliamella was missing from all samples, whereas Apibacter was restricted to wild individuals. Furthermore, plant-linked microbes such as Devosia and Pedobacter appeared exclusively in the digestive tracts of bees consuming natural pollen. Predicted functional analysis highlighted essential enzymes, including β-glucosidase and pyruvate dehydrogenase, which are vital for nutrient processing and energy metabolism. These results emphasise the complex synergy between diet and microbial acquisition, identifying nutrition as a primary architect of the gut microbiome in African honey bees.