IntBIO: Collaborative Research: Integrating molecular, cellular, organismal and community scales to understand how plants structure pollinator-pathogen dynamics

Pollinators are critical for plant reproduction and human food security, but many pollinator species are declining due to stressors, including pathogens. The recent discoveries that sunflower pollen dramatically reduces infection by a common gut pathogen in bumble bees, and that flower species differ in how they affect pathogen transmission raises two key questions that will be addressed by this research: How do plant species affect disease dynamics in their pollinators, and what are the mechanisms responsible for those effects? The project work involves a new collaboration between a molecular biologist, ecologists, and a mathematical modeler. The work will combine molecular and ecological studies to understand how pollen shapes infection and to assess how pathogens are transmitted at flowers. The project will also partner with land managers creating new pollinator habitats to model and test how floral resources affect pollinator health. The project will conduct extensive public outreach, develop an after-school curriculum for middle-school students from an underserved community, and train graduate students in inclusive teaching practices. Taken together, this work will build bridges between disciplines to understand how flowers affect pollinator health and will train a new diverse generation of scientists.

Food resources are key factors mediating host-pathogen dynamics, but they may have opposing effects at different biological levels of organization. For example, resource quality or quantity could stimulate the host immune system and reduce infection at the organismal level, yet increase host densities and contact rates at the community level, exacerbating pathogen spread. This research will integrate experiments to determine the impacts of resource quality and quantity on host-pathogen dynamics at the molecular, cellular, organismal, species interactions, and community levels using a highly tractable laboratory and field system of bees and a trypanosomatid pathogen that is transmitted via shared floral resources. Using 25 plant species, studies will assess effects of pollen diets on pathogen molecular and cellular processes in vitro, infection dynamics in vivo, likelihood of transmission during foraging, and visitation networks and pollinator population dynamics in the field. Plants to be targeted include the species from the Asteraceae, one of the most ubiquitous vascular plant families, because recent research shows that pollen from this family consistently reduces infection in bumble bees. Data from all objectives will be integrated using mathematical modeling that connects processes at multiple scales to predict how plant community composition shapes pathogen infection in pollinators. The project will provide equitable STEM pedagogy training for graduate students while creating middle school science programming in under-served communities, collaborating with a STEM educator focused on equitability to maximize effectiveness. Engagement with multiple groups creating pollinator habitat will provide an ideal platform for fostering communication between scientists and stakeholders.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.