Bee wisdom: exploring bee control strategies for food microflora by comparing the physicochemical characteristics and microbial composition of beebread

Abstract

ABSTRACT Beebread serves not only as a vital food source for bees but also as a significant reservoir of microbes for their intestinal tracts. The distribution of beebread in honeycomb cells is characterized by distinct vertical patterns; however, the vertical distribution patterns of the physicochemical characteristics and microbial composition of beebread remain unclear. In this study, we collected beebread samples from nine colonies in three representative ecosystems (forest, forest-urban, and urban-farmland ecosystems) and systematically assessed the physicochemical characteristics and bacterial diversity in three beebread layers (lower, middle, and upper). We found that upper beebread samples had lower pH; higher proportions of fructose and sucrose; and lower proportions of total solids, crude protein, and ash compared to lower samples. Moreover, 16S rDNA sequencing showed that the dominant bacterial phyla and genera were relatively simple and highly conserved across the three ecosystems. Overall, the microbial community richness of upper beebread was significantly higher than that of lower beebread, and Bacteroidetes and Acidobacteria were significantly decreased in lower compared to upper beebread. Meanwhile, the relative abundance of dominant taxa in the same beebread layer differed by ecosystem types. These findings suggest that bees employ fermentation processes to selectively enrich microbes present in flower pollen, leading to homogenous and relatively stable microbial diversity in beebread. Our study expands on the current understanding of beebread and highlights the significance of fermentation in its production. Furthermore, our findings provide a useful reference for further in-depth exploration of the interactions between food, food microbes, and bee gut microbes. IMPORTANCE Bees are a valuable model for investigating the relationship between environmental factors, gut microbiota, and organismal health. Beebread, produced from collected pollen, is a natural food source and a primary reservoir of gut microorganisms. Although pollen typically has diverse bacterial species, beebread has low species richness and bacterial abundance. Consequently, considerable attention has been paid to the adaptive strategies employed by honey bees to cope with the microorganisms within their food environment during co-evolution with plants. This study identified the distribution patterns of beebread's physicochemical characteristics, showing how bees use fermentation to enrich specific microbes. These findings help understand the relationship between environmental and food-associated microbes and bee intestinal microbiota. They also bridge gaps in the literature and provide a valuable reference for studying the complex interplay between these factors.