(More than) Hitchhikers through the network: The shared microbiome of bees and flowers

Authors: KELLER, ALEXANDER - University Of Wurzburg; MCFREDERICK, QUINN - University Of California; DHARAMPAL, PRARTHANA - University Of Wisconsin; Steffan, Shawn; DANFORTH, BRYAN - Cornell University; LEONHARDT, SARA - Technical University Of Munich

Submitted to: Current Opinion in Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2020
Publication Date: 9/28/2020
Citation: Keller, A., Mcfrederick, Q., Dharampal, P., Steffan, S.A., Danforth, B., Leonhardt, S. 2020. (More than) Hitchhikers through the network: The shared microbiome of bees and flowers. Current Opinion in Insect Science. 44(April 2021):8-15. https://doi.org/10.1016/j.cois.2020.09.007.
DOI: https://doi.org/10.1016/j.cois.2020.09.007

Interpretive Summary: The concept that pollen-borne microbes are critical symbionts of developing bee larvae has gained much recent attention. This concept highlights the importance of considering microbial symbionts when crafting bee conservation strategies. The current paper examines how local pollination network architecture and patterns of specialization/generalization determine the potential dispersal routes for microbes. For solitary bee populations missing vertical symbiont transmission routes, microbial sharing between individual bees via flower 'hubs' may facilitate inter-generational transmission. Collectively, this sets up new cost-benefit relationships among the players, with shared microbes emerging as considerable drivers rather than passive hitchhikers within pollination networks.

Technical Abstract: Growing evidence reveals strong overlap between microbiomes of flowers and bees, suggesting that flowers are hubs of microbial transmission. Whether floral transmission is a main driver of bee microbiome assembly, and whether functional importance of florally sourced microbes shapes bee foraging decisions are intriguing questions that remain unanswered. We suggest that interaction network architecture as well as specialization are central in microbiome assembly by defining potential transmission routes. Yet species filtering by each host limits actually realized transmissions. Functionally, shared floral microbes can provide benefits for particular bees by enhancing nutritional quality, detoxification, and disintegration of pollen. Flower microbes alter the attractiveness of floral resources. Working together, these mechanisms may in turn affect the structure of the flower-bee interaction network.