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Harvard Forest REU Symposium Abstract 2012

  • Title: Does bumblebee body size affect foraging distance or flight maneuverability?
  • Author: Kelsey S McKenna (Harvard College (Harvard University))
  • Abstract:

    Bumblebee worker size can vary considerably within the same colony and even within the same brood. Larger workers are thought to be better physically suited to flying larger distances, but likely to be less maneuverable. It is not known how movement distance relates to intra-colony body size variation. I investigated whether body size variation within colonies relates to worker foraging range and flight maneuverability. I measured mass [0.08 g – 0.25 g], intertegular span (the distance between wing base joints on the bee’s thorax) [1.5 cm – 5.2 mm], thorax width [3.6 mm – 7.1 mm], and body length [10.2 mm – 15.9 mm] of 28 Bombus impatiens workers from three colonies in order to compare these body size indices to foraging range through pollen load. In favor of a conservation estimate, in this study “maximum foraging distance” is defined as the distance from the bee colonies to the nearest patch of the farthest species of plant identified after swabbing each bee. Each bee was measured and swabbed for pollen after returning to the hive and slides of the pollen loads were examined for flower species. I searched the local landscape and mapped the locations of potential pollen sources. Maximum foraging distance did not appear to relate to any indicator of body size. Pollen species richness was weakly positively correlated with mass (R^2=0.12295), and moderately positively correlated with body length (R^2=0.21418), thorax width (R^2=0.25457), and IT Span (R^2=0.22748). Factors other than bee body size, like distribution of resources, are potentially important in determining bee foraging patterns. In order to investigate bee maneuverability, foam tunnels varying in circumference from 5 to 12 mm were serially attached to the entrance of a B. impatiens hive, and workers were filmed with a high-speed camera upon return to the hive through the tunnel. Wing kinematics were identified through analysis of these videos. Although analysis has not yet been completed, preliminary observations show that sampled bees respond to the tunnel obstacles similarly, but potentially in proportion to their body size.

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