The Bee as a Model to Investigate Brain and Behavioural Asymmetries.

Elisa Frasnelli,Gianfranco Anfora,Albrecht Haase,Elisa Rigosi,Giorgio Vallortigara,Lesley Rogers

doi:10.3390/insects5010120

Elisa Frasnelli, Gianfranco Anfora + Show 4 more

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https://doi.org/10.3390/insects5010120

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Abstract

The honeybee Apis mellifera, with a brain of only 960,000 neurons and the ability to perform sophisticated cognitive tasks, has become an excellent model in life sciences and in particular in cognitive neurosciences. It has been used in our laboratories to investigate brain and behavioural asymmetries, i.e., the different functional specializations of the right and the left sides of the brain. It is well known that bees can learn to associate an odour stimulus with a sugar reward, as demonstrated by extension of the proboscis when presented with the trained odour in the so-called Proboscis Extension Reflex (PER) paradigm. Bees recall this association better when trained using their right antenna than they do when using their left antenna. They also retrieve short-term memory of this task better when using the right antenna. On the other hand, when tested for long-term memory recall, bees respond better when using their left antenna. Here we review a series of behavioural studies investigating bees’ lateralization, integrated with electrophysiological measurements to study asymmetries of olfactory sensitivity, and discuss the possible evolutionary origins of these asymmetries. We also present morphological data obtained by scanning electron microscopy and two-photon microscopy. Finally, a behavioural study conducted in a social context is summarised, showing that honeybees control context-appropriate social interactions using their right antenna, rather than the left, thus suggesting that lateral biases in behaviour might be associated with requirements of social life.

Highlights

The honeybee Apis mellifera L. (Hymenoptera: Apidae), with a brain of only 960,000 neurons [1]and the ability to perform sophisticated cognitive tasks (e.g., [2±5]), has become an excellent model in life sciences and in particular in cognitive neurosciences
Since it has been hypothesized that lateralization at the population level may emerge as a result of social selective pressures [33], it could be that the pattern observed in these species of Hymenoptera Apidae is due to the different degrees of sociality of the species
Overall the various studies of laterality in bees show that social bees are lateralized at the population level in tasks of odour association with a food reward

Summary

Introduction

The honeybee Apis mellifera L. (Hymenoptera: Apidae), with a brain of only 960,000 neurons [1]. The ability to perform sophisticated cognitive tasks (e.g., [2±5]), has become an excellent model in life sciences and in particular in cognitive neurosciences. This insect has been used in our laboratories to investigate brain and behavioural asymmetries using a number of different methods [6]. The first study that reported evidence of lateralization of olfaction in the honeybee A. mellifera was conducted by Letzkus and colleagues [14], who investigated asymmetries in olfactory learning performance using two different versions of the PER paradigm. Since the test used was one requiring the bee to recall memory of the task on the day after training and not of learning per se, there is another explanation of the results: viz., bees with use of their left antenna only could learn but not recall the task (discussed further below)

Electrophysiological and Molecular Studies

Morphological Studies

Conclusions

Findings

Conflicts of Interest