Transmission of microbes from flowers to honey bees : A comparison of five common plant families

Sammanfattning

The mutualistic relationship between flowers and bees is well known, but a less obvious part of this symbiosis is the microbes. Both flowering plants and honey bees have associated microbes which have many different effects, ranging from beneficial to harmful. Honey bees unintentionally move microbes from flowers to the hive and vice versa. Considering the importance of pollinators and their increasing threats, knowledge impacting their health is vital. The aim of this study was to assess how bacteria and fungi are shared between flowers and honey bees, and how different plant families contribute to the overall microbiome of honey bees by sequencing bacterial, fungal, and plant DNA from honey and flower samples. Bacteria had a higher proportion of floral genera found in honey overall than fungi. The fungal genera found in honey were dominated by one genus (Metschnikowia), while several of the bacterial genera shared between flowers and honey bees were ones that would expectedly have a higher transmission, such as pathogens and bee microbiota. Plant families differed in the proportion of genera shared between plants and honey bees for both bacteria and fungi. Bacterial floral genera found in honey also differed in community composition depending on plant family, but this was not the case for fungi. Larger, wider flowers share more microbes with honey bees than small flowers. This could be as they are highly attractive to different pollinators, leading to more microbial exposure for the flowers, showing how different characteristics of interacting species impact which microbes are shared.