Olfaction in Honey Bees: From Molecules to Behavior

Abstract

For more than a century, honey bees have constituted a major model for the study of olfactory detection, processing, learning and memory. This chapter reviews major advances based on three main approaches. Firstly, we address the experimental study of bees’ olfactory behavior, from early experiments on free-flying workers until laboratory-based training protocols on restrained individuals. We describe bees’ impressive discrimination and generalization abilities depending on odor quality and quantity, their capacity to grant special properties to olfactory mixtures as well as to recognize individual components. Secondly, we provide a detailed description of the olfactory pathways of the bee brain that subtend these behaviors, based on anatomical and immunochemical studies. We show how odors are detected by olfactory receptors carried by receptor neurons in the antenna, which convey information to a first processing relay, the antennal lobe (AL). We describe processing circuits within this structure and show how olfactory information is then conducted to higher-order centres, the mushroom bodies (MBs) and the lateral horn (LH), following different pathways through the brain. We finish by discussing the structure of the MBs, their local circuits and output connections and how they may be linked to motor output. Thirdly, we show how functional approaches based on the recording of odor-evoked activity in the bee brain allow following the series of transformations of the olfactory representation through its different centers. Data from electrophysiological and optical imaging approaches are reviewed. Doing so, we explain how coupling behavior with functional approaches allows understanding the perceptual representation of odors.