Absence of food alternatives promotes risk-prone feeding of unpalatable substances in honey bees.

Lucie Desmedt,Lucie Hotier,Maria Gabriela De Brito Sanchez,Rodrigo Velarde,Martin Giurfa

doi:10.1038/srep31809

Abstract

The question of why animals sometimes ingest noxious substances is crucial to understand unknown determinants of feeding behaviour. Research on risk-prone feeding behaviour has largely focused on energy budgets as animals with low energy budgets tend to ingest more aversive substances. A less explored possibility is that risk-prone feeding arises from the absence of alternative feeding options, irrespectively of energy budgets. Here we contrasted these two hypotheses in late-fall and winter honey bees. We determined the toxicity of various feeding treatments and showed that when bees can choose between sucrose solution and a mixture of this sucrose solution and a noxious/unpalatable substance, they prefer the pure sucrose solution and reject the mixtures, irrespective of their energy budget. Yet, when bees were presented with a single feeding option and their escape possibilities were reduced, they consumed unexpectedly some of the previously rejected mixtures, independently of their energy budget. These findings are interpreted as a case of feeding helplessness, in which bees behave as if it were utterly helpless to avoid the potentially noxious food and consume it. They suggest that depriving bees of variable natural food sources may have the undesired consequence of increasing their acceptance of food that would be otherwise rejected.

Highlights

The question of why animals sometimes ingest noxious substances is crucial to understand unknown determinants of feeding behaviour
Our results reveal that the availability of food choices is more determinant of the bees’ feeding behaviour than their energy budget: in the absence of better, alternative food sources, fed and starved bees abandon their food preferences and consume non-preferred food, providing that it did not induce high mortality
Our study contrasted two different hypotheses to explain noxious food acceptance in adult honey bees: the individual’s energy budget and the availability of an alternative feeding choice. While the former posits that energy-depleted individuals are more risk-prone in food acquisition than those on a positive energy budget[3,4,34], the latter maintains that when individuals have neither escape nor an alternative feeding choice, they may consume noxious food

Summary

Introduction

The question of why animals sometimes ingest noxious substances is crucial to understand unknown determinants of feeding behaviour. When bees were presented with a single feeding option and their escape possibilities were reduced, they consumed unexpectedly some of the previously rejected mixtures, independently of their energy budget. These findings are interpreted as a case of feeding helplessness, in which bees behave as if it were utterly helpless to avoid the potentially noxious food and consume it. With harnessed bees usually subject these insects to starvation in order to increase appetitive responses[25] Under these conditions, bees may be prone to accept noxious food. While free-flying bees can perform such a comparison by flying from a distracter punished with an aversive solution to a target rewarded with sucrose solution, harnessed bees fed uniquely with toxic food have neither escape nor an alternative for comparison; they may, behave as if it were utterly helpless to avoid the toxic food and consume it

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