Linking the evolution of brain asymmetries and social behaviour in honeybees

The honeybee (Apis mellifera L.) has been shown to be an excellent model to investigate cognitive abilities such as learning and memory. Studying the mechanisms of learning, storage and recall of memory in bees is very important because these mechanisms are of vital importance for honeybees to be able to forage for nectar, learn and remember where flowers are located, as well as to find their way home to the hive. In fact, the failure of bees to return to the hive after foraging has been shown to be the primary symptom of the colony collapse disorder which has devastated honey bee populations world-wide since about 2006. Here a series of studies are presented to understand the cognitive abilities of honeybee foragers in learning, discriminating, memorizing and recalling different odours. A population-level asymmetry in the use of the antennae has been found: bees use their right antenna to learn and recall short-term memory, whereas the left antenna allows recall of long-term memory. Recently, it has been suggested that the alignment of lateralization at the population level may have evolved as an evolutionary stable strategy (ESS) when individually-asymmetrical organisms must coordinate their behaviour with that of other asymmetrical organisms. Game-theoretical models based on ESS suggest that population-level lateralization is more likely to evolve in social than in non-social species. This hypothesis has been tested by comparing olfactory responses of the right and the left antenna using behavioural (conditioning of the Proboscis Extension Reflex, PER), physiological (ElectroAntennoGraphy, EAG) and morphological (Scanning Electron Microscopy, SEM) measurements in three species of Hymenoptera Apoidea that show different levels of sociality: eusocial honeybees (Apis mellifera L.), solitary mason bees (Osmia cornuta L.) and bumble bees (Bombus terrestris L.), an annual eusocial species. The connection between the evolution of population-level asymmetries and the evolution of social behaviour is discussed on the basis of communication mechanisms in honeybees