Professor University of Massachussetts Amherst, Massachusetts
Flowers can be hotspots for bee parasite transmission, and changes in floral abundance over time could alter transmission dynamics. Higher floral abundance has the potential to increase transmission of bee parasites if bees concentrate in patches of flowers, or decrease transmission if increased floral abundance leads to a dilution effect. Here, we manipulated the timing of floral abundance in a cage experiment and evaluated effects on transmission of a bumble bee parasite (Crithidia bombi) from an infected bumble bee microcolony to an uninfected microcolony over a two-week period. In the first treatment, half of the flowers in the cages were bagged during the first week of the experiment, and during the second week all flowers were unbagged, simulating an increase in floral resources. In the second treatment, all flowers were unbagged during the first week, and half of the flowers were bagged during the second week, simulating a decrease in floral resources. We tested transmission on three plant species (Liatris spicata, Penstemon digitalis and Monarda fistulosa), in large replicated tents. We expect to find differences in transmission between plant species, and we hypothesize that having fewer resources during the first week will increase C. bombi transmission due to concentration of foragers in fewer flowers, leading to higher initial contact rates that proliferate pathogen spread.