Meeting Abstract

8.1  Saturday, Jan. 4 08:00  Bigger but not always better: Tradeoffs between maneuverability and flight speed with body size in bumblebees CRALL, JD*; RAVI, S; MOUNTCASTLE, AM; COMBES, SA; Concord Field Station, Harvard University; Concord Field Station, Harvard University; Concord Field Station, Harvard University; Concord Field Station, Harvard University jcrall@oeb.harvard.edu

Body size has important consequences for nearly every aspect of phenotype, including locomotion. For example, scaling predicts increased speed but decreased accelerations and maneuverability with larger body size. Despite strong a priori predictions, however, tradeoffs between flight speed and maneuverability in flying insects have rarely been tested. Here, we examine this tradeoff in bumblebees (Bombus impatiens) in a novel but ecologically relevant flight context; maneuvering around three-dimensional objects. In agreement with predictions, top flight speed increased with body size, while speed through an obstacle course decreased, supporting the prediction of a tradeoff between top flight speed and maneuverability with body size. However, in contrast to predictions from scaling, maximum accelerations and turning rates increased rather than decreased with body size. Larger bumblebees took longer flight paths through the obstacle course, as well as flying at lower instantaneous speeds. Surprisingly, obstacle orientation (i.e. whether bees were forced to fly up and down or side-to-side through the course) had no significant effect on mean flight speed. Together, these results indicate that locomotion through complex environments may be limited by collision avoidance rather than simply maximum force production and top flight speed. These results also have important implications for the evolution of body size of insects in complex three-dimensional environments.