Behavioural and electrophysiological lateralization in a social (Apis mellifera) but not in a non-social (Osmia cornuta) species of bee.

Recent evidence suggests that asymmetry between the left and right sides of the brain is not limited to vertebrates but extends to invertebrates as well. We compared olfactory lateralization in two species of Hymenoptera Apoidea, the honeybee (Apis mellifera), a social species, and the mason bee (Osmia cornuta), a solitary species. Recall of the olfactory memory 1 h after training to associate an odour with a sugar reward, as revealed by the bee extending its proboscis when presented with the trained odour, was better in honeybees trained with their right than with their left antenna. No such asymmetry was observed in mason bees. Similarly, electroantennographic responses to a floral volatile compound and to an alarm pheromone component were higher in the right than in the left antenna in honeybees but not in mason bees. These findings seem to support recent game-theoretical models suggesting that population-level lateralization is more likely to have evolved in social than in non-social species.