Differences in the phototaxis of pollen and nectar foraging honey bees are related to their octopamine brain titers

Ricarda Scheiner,Anna Toteva,Andrew B Barron,Eirik Sã¸Vik,Tina Reim

doi:10.3389/fphys.2014.00116

Ricarda Scheiner, Anna Toteva + Show 3 more

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https://doi.org/10.3389/fphys.2014.00116

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Abstract

The biogenic amine octopamine is an important neuromodulator, neurohormone and neurotransmitter in insects. We here investigate the role of octopamine signaling in honey bee phototaxis. Our results show that groups of bees differ naturally in their phototaxis. Pollen forgers display a lower light responsiveness than nectar foragers. The lower phototaxis of pollen foragers coincides with higher octopamine titers in the optic lobes but is independent of octopamine receptor gene expression. Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis. These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness.

Highlights

The biogenic amine octopamine is a pivotal insect neurotransmitter, neurohormone and neuromodulator (Evans, 1980; Roeder, 1999; Blenau and Baumann, 2003; Scheiner et al, 2006)
Increasing octopamine brain titers reduces responsiveness to light, while tyramine application enhances phototaxis. These findings suggest an involvement of octopamine signaling in honey bee phototaxis and possibly division of labor, which is hypothesized to be based on individual differences in sensory responsiveness
Taken together, our findings imply that responsiveness of bees to light is modulated by octopamine and tyramine

Summary

Introduction

The biogenic amine octopamine is a pivotal insect neurotransmitter, neurohormone and neuromodulator (Evans, 1980; Roeder, 1999; Blenau and Baumann, 2003; Scheiner et al, 2006). It has many and diverse physiological functions including the modulation of complex behaviors such as aggression in crickets (Stevenson et al, 2005) or learning and memory in honey bees (Behrends and Scheiner, 2012). Octopamine enhances responsiveness to gustatory stimuli (Scheiner et al, 2002), improves appetitive learning (Behrends and Scheiner, 2012) and increases the ability of bees to discriminate nestmates from non-nestmates (Robinson et al, 1999). As the highest concentration of octopamine receptors in the brain can be found in the optic lobes (Roeder and Nathanson, 1993), it can be assumed that octopamine has important modulatory functions in the visual system of honey bees

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