D3111: Multimodal learning of compound stimuli in honey bees

Honey bees (Apis mellifera) are renowned for their generalist foraging lifestyle despite individual foragers tending to exhibit flower constancy. Hence, it is reasonable to postulate that a forager pays attention to as many sensory cues from its chosen floral species as possible so as not to be distracted by similar but incorrect floral species. The flowers of some species may closely resemble one another when considering only a single sensory modality, but they may be easier to distinguish when considering multiple sensory modalities (e.g., a yellow rose versus a yellow carnation). With the well-known fact that animals (including humans) learn multimodal associations more quickly than unimodal associations, it can be assumed that a forager bee performs multimodal learning to increase foraging efficiency. While multimodal learning has been studied for more than half a century in humans, it has never been tested in honey bees in tightly controlled laboratory conditions. Therefore, in this study, harnessed bees were conditioned to associate a compound cue (a particular colour/odour pair) with a sucrose reward. Using the proboscis-extension-response protocol, bees’ responses were recorded during (short-term memory) and 20 h after (long-term memory) the conditioning process. With anticipatory responses to the correct stimulus pair indicating successes, our results show bees quickly exhibit anticipatory responses to the correct stimulus pair at a significantly higher rate than to incorrect stimulus pairs (wrong colour, odour, or both). Thus, the results support the hypothesis that honey bee foragers pay attention to and learn multisensory information.