Sandy Gillespie

Joint PhD Candidate in Organismic and Evolutionary Biology, and Entomology

Research Interests: I am interested in understanding how mutualisms interact with, and are affected by the larger community. More specifically, I seek to understand whether mutualisms can mediate trophic cascades, and whether the occurrence and strength of cascades is affected by the degree to which the mutualism is obligate. I intend to address this question via 3 approaches:

(1) Theoretical models: I am developing a continuous difference equation model of mutualist population dynamics that incorporates three populations: a producer, its mutualist, and an antagonist of the mutualist. I will use this model to investigate the impacts of that antagonist on the population dynamics of the two mutualists.

(2) Field surveys of bumble bee parasites: I am conducting surveys of parasite prevalence in Bombus sp. at multiple sites in western Massachusetts. Pilot surveys over 2 years show considerable site-to-site and year-to-year variation in parasitism, as well as correlations between parasite abundance and plant reproduction. I will document these patterns over more sites for an additional year, and conduct a more extensive study addressing the potential impacts of parasites on plant reproduction.

(3) Behavioral studies of parasitized bumble bees: To determine if parasitoid flies influence bumble bee behavior and plant reproduction, I will conduct experiments in a flight cage to examine how parasitism affects foraging and pollen deposition.