Presenter: Reese Charlotte Crouse Baxter

Faculty Sponsor: Lynn Adler

School: UMass Amherst

Research Area: Biological Organisms

Session: Poster Session 6, 4:15 PM - 5:00 PM, Auditorium, A44

ABSTRACT

            In plants, secondary metabolites behave as a defense system, protecting vital tissues from herbivores and deterring ineffective pollinators or nectar robbers. Secondary metabolites may also affect beneficial pollinators, providing insects like bees with medicinal pollen and nectar. I worked with the common eastern bumblebee, Bombus impatiens, a generalist pollinator in eastern North America. A prevalent parasite of this species is Crithidia bombi, a trypanosomatid which spreads via fecal-to-oral contact and reduces both worker foraging efficiency and the ability of queens to survive hibernation and successfully establish a colony.

            I examined the effects of the nectar secondary metabolites α-pinene, α-phellandrene, and estragole, which are present in the extensively cultivated herb basil (Ocimum basilicum), to reduce C. bombi infection in B. impatiens. The experiment consisted of week-long trials in which I inoculated bumblebees with C. bombi before feeding them individual treatment diets. These diets were contained in small petri dishes, and consisted of sucrose mixed with α-pinene, α-phellandrene, estragole, or a negative control (sucrose only). Each chemical diet had a concentration of 0.025 ppm and was available to the bees via a cotton wick. After each trial, I dissected all bees to isolate their guts. Infection was measured by placing the resulting solution onto a hemocytometer slide and counting the number of C. bombi cells under a light microscope. Preliminary analyses suggest that individual chemical diets yield different levels of C. bombi reduction, indicating that some of these chemicals have medicinal properties for bumblebees at ecologically relevant concentrations.

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