How do bumblebees first find flowers? Unlearned approach responses and habituation

To examine how bees distinguish between possible food sources and nonrewarding objects in the absence of previous experience with flowers, we presented flower-naïve bumblebees, Bombus impatiens, with unrewarding stimuli (colours or patterns) in a radial arm maze and compared their approach responses to each stimulus. Bees showed a significant preference for yellow and blue over other colours, and for radial patterns over concentric patterns or unpatterned discs. Habituation was demonstrated when the proportion of choices for the same pattern by the same bees decreased over two testing sessions. When an attractive novel pattern was presented in the third session, the trend was reversed. The results of this study confirm both that truly flower-naïve bees have unlearned colour and pattern preferences and that learning not to approach stimuli occurs in the absence of reward.