Screening putative microbial biocontrol agents for effect on pollinator feeding preference

Sustainable microbial biocontrol is seen as a vital alternative to reliance on chemical pesticide treatments within the agricultural industry, which can result in development of pathogen resistance and harmful non-target effects on beneficial insects. This is especially true for flowering fruit and nut trees, which are susceptible to blossom based diseases during bloom and rely heavily on pollination services. However, the application of microbial biocontrol agents (BCAs) during bloom has the potential to impact pollination services as the presence of microbes on flowers and in nectar has been shown to influence pollinator foraging behaviors. Therefore, it is important to understand how putative microbial BCAs can affect pollinator behavior; however, these effects are rarely examined. The capillary feeder (CAFE) assay provides a way to screen putative BCAs for negative effects on pollinator behavior. We screened a series of eighteen putative BCAs, isolated from natural and agricultural flowering populations, for their effects on honey bee feeding preference. Overall, we found that floral microbes have limited effects on honey bee feeding and that there were no significant effects of microbial kingdom or isolation source (natural vs. agricultural) on feeding preference. These results support floral microbes as a rich resource of potential biocontrol options. Further research on the effects of putative BCAs on honey bee health, such as survival and reproduction are needed.