Bumblebee foraging on vertical inflorescences: optimal or not?

Abstract

Previous studies by Pyke et al. have shown that bumblebees exhibit behavior that is consistent with optimal foraging theory. In this most recent effort, bumblebees were observed foraging on vertical inflorescences and their behavior was compared to a predicted model that would result in a maximum net energy gain as prescribed by optimal foraging theory. The effect of time spent on a flower and a bee’s decision to remain on that inflorescence and bumblebee species distribution across patches of plants were also assessed. Contrary to what was expected, the bumblebees did not behave in a way that could be compared to the expected model. Also, no relationship was found between time spent on a flower and departure behavior. Distribution across patches of multiple species did not result in equal net energy gain for each bee species. It was concluded that the use of optimal foraging theory may not be the most complete way to describe bumblebee foraging behavior.