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Harvard Forest Symposium Abstract 2013

• Title: Effects of a floral resource pulse on pollen use by Bombus impatiens
• Primary Author: Dash Donnelly (Harvard Forest)
• Additional Authors: Elizabeth Crone (Tufts University)
• Abstract:

  Food resources for bumble bees vary in space and time. Bees use pollen as a primary source of protein that is necessary for larval growth and egg production. Increases in resources have been shown to increase body and colony size, but we don’t know how resource availability affects what food sources bees are using. We tested the effects of increased resources using pollen load analysis of bees in six Bombus impatiens colonies. Three colonies were given access to patches of flowering Phacelia, as well as the ability to forage in the wild (hereafter "pulse" colonies). Three control colonies were given no supplemental resources. Each week bees were marked and measured while also taking a pollen load sample. In the lab we analyzed the contents of each bee load with light microscopy to determine the number of different species as well as the number of pollen grains present. To aid this analysis, we developed a pollen library containing all of the plant species present at Harvard Forest. Not surprisingly, bees used Phacelia more in pulse cages, but there was no difference in the species richness of pollen from other species. Pulse colonies produced smaller bees, in contrast to past studies, while still producing more workers than control colonies, which is consistent with past studies. Analyses of species diversity of pollen from bees in both treatments are in progress.

• Research Category: Physiological Ecology, Population Dynamics, and Species Interactions