Online

Burnham, Phillip A.

Biology

2021

Ph. D.

Maintaining healthy pollinator communities is vital both for ensuring food security and ecological diversity. However, managed honeybees and wild bee communities are under threat from an array of stressors including habitat loss, global change, pesticide use, poor beekeeping, and various pests and pathogens. Pathogens have been shown to be spilling over from managed bees into wild bee populations and are known to adversely affect colony function as well as increase mortality. Understanding transmission mechanisms related to general dynamics in this system will not only benefit pollinator health, but also gives us insight into important and understudied topics in disease ecology. In the following chapters, I experimentally tested if flowers can act as bridges that facilitate spillover of RNA viruses between bee genera and constructed an ODE model of the system in order to identify potential mitigation strategies. Using an agent-based modeling approach, I examined the role of floral abundance and diversity on disease transmission between bee genera. Finally, I conducted a longitudinal survey to examine the role of temporal variation and bee and floral diversity on patterns of coinfection, amplification, and dilution. Here I provide evidence that RNA viruses are able to spread between bee genera through shared flowers and that increasing floral abundance and diversity may decrease overall transmission. I found that temporal variation drove patterns of coinfection, however, the process appeared to be additive in nature rather than synergistic. Bee diversity and floral diversity influenced disease prevalence and load. However, amplification or dilution effects were found to be dependent upon the disease, the metric of diversity used, and the scale it was measured at. In examining spillover, temporal variation, coinfection and dilution in this system, I furthered our understanding of disease transmission in bee communities and offered strategies for decreasing transmission between and within bee genera. Additionally, I provided an example how disease transmission might occur in a multi-host, multi-pathogen disease system.