Dr. Laura Figueroa—currently an NSF Postdoctoral Research Fellow and incoming Assistant Professor in the Department of Environmental Conservation at the University of Massachusetts, Amherst, USA—shares her recently accepted paper: “Sunflower spines and beyond: mechanisms and breadth of pollen that reduce gut pathogen infection in the common eastern bumble bee.”
About the paper
Flowers provide foraging bees with a broad diversity of key resources, including pollen as a primary source of protein. Pollen from different plant species varies considerably in chemical composition, protein content, and shape. A few years ago, Lynn Adler and her colleagues made the discovery that sunflower pollen, which has a spiny outer shell and is chemically diverse, has a strong medicinal effect for common eastern bumble bees infected with a gut pathogen called Crithidia bombi. Eating sunflower pollen strongly reduced infection. We wanted to figure out whether sunflower pollen’s medicinal effect was driven by its spiny outer shell or its chemistry, or whether the combination was necessary. To see if pollen from other species in the sunflower family—all of which have some degree of spines on their outer shells, also had similar effects—we screened seven additional plant species.
We found that sunflower pollen’s spiny shells, with the chemistry removed, reduced infections as much as whole sunflower pollen, while sunflower pollen chemicals without spiny shells resulted in much more severe infections. We also found that pollen from four of the seven other sunflower family species reduced pathogen infection similarly to sunflowers. This research raises the question of how the spiny sunflower shells provide this medicinal effect: are they scraping the pathogens off the bee gut? Are they harming the pathogen cells directly? We don’t yet know the answers to these follow-up questions, but are currently working to figure them out!
About the research
Given bees’ ecological and economic importance, reports highlighting declines of certain species is worrisome. In response, there has been a push to plant pollinator-friendly habitats, especially in agricultural and urban areas. There are many important factors to consider in the planting of pollinator habitats, for example ensuring that the species are native and well suited to the climate and soil of the location, that the seed mix includes flower species of different shapes and sizes that can be pollinated by a broad diversity of bees, and that the combination of species enables near constant bloom (instead of an intense peak for a couple of weeks and then a dearth of resources). Previous work has shown that flowers can act as hubs of disease transmission, where infected bees deposit pathogens when foraging on flowers, which susceptible bees can inadvertently pick up when visiting the same flower moments later.
We currently are very limited in our understanding of how different pathogens, such as Crithidia bombi, influence the health of bees (beyond honey bees and bumble bees), but recent field surveys have found widespread prevalence at the community level and laboratory experiments have revealed that solitary bees can become infected too. Our findings that the medicinal effect of sunflower extends to other members in the family is important because the sunflower family is one of the most speciose families in the world and the common eastern bumble bee is one of the most dominant species in the Northeast of the United States. Understanding how the planting of different species of sunflower relatives influences bee health in nature, including whether and how it mediates disease dynamics at the community level, is an important open question we are exploring with funding from the National Science Foundation (DBI-2128221).
About the Author
As clichéd as it may be, I got involved in ecology because I love nature and wanted to devote my life to not only understanding how ecological communities work, but also to contributing in whichever way I can to conservation in the face of human-induced stressors. There are many things I love about being an ecologist, including the flexibility that this career provides, the privilege of working with fantastic students, and the ability to do field work in amazing places (e.g. surveying for vulture bees in tropical forests in Costa Rica!).
I am delighted to begin an Assistant Professor position this Fall in the Department of Environmental Conservation at UMass Amherst. In addition to my collaboration with Dr. Adler, described above, a large focus of my lab will be exploring how human-altered landscapes influence bee communities. To explore this, I have been developing an automated machine-learning model that can monitor bees based on sound, which is a tool I plan to use to understand phenological patterns at spatial and temporal scales that would otherwise be out of reach (think tree canopies!). I am also leading projects studying stingless bee ecology in the neotropics (mainly Costa Rica and Colombia), as well as understanding how to enable agroecological systems to simultaneously maintain sustainable yields while ensuring the wellbeing of the people tending the land and broader biodiversity that enables the system to function effectively. I am looking for new lab members who are kind, collaborative, self-motivated and passionate about pollinator ecology and conservation. If that is you, please reach out! More information can be found here!
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