Bees prefer foods containing neonicotinoid pesticides

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The impact of neonicotinoid insecticides on insect pollinators is highly controversial. Sublethal concentrations alter the behaviour of social bees and reduce survival of entire colonies1,2,3. However, critics argue that the reported negative effects only arise from neonicotinoid concentrations that are greater than those found in the nectar and pollen of pesticide-treated plants4. Furthermore, it has been suggested that bees could choose to forage on other available flowers and hence avoid or dilute exposure4,5. Here, using a two-choice feeding assay, we show that the honeybee, Apis mellifera, and the buff-tailed bumblebee, Bombus terrestris, do not avoid nectar-relevant concentrations of three of the most commonly used neonicotinoids, imidacloprid (IMD), thiamethoxam (TMX), and clothianidin (CLO), in food. Moreover, bees of both species prefer to eat more of sucrose solutions laced with IMD or TMX than sucrose alone. Stimulation with IMD, TMX and CLO neither elicited spiking responses from gustatory neurons in the bees’ mouthparts, nor inhibited the responses of sucrose-sensitive neurons. Our data indicate that bees cannot taste neonicotinoids and are not repelled by them. Instead, bees preferred solutions containing IMD or TMX, even though the consumption of these pesticides caused them to eat less food overall. This work shows that bees cannot control their exposure to neonicotinoids in food and implies that treating flowering crops with IMD and TMX presents a sizeable hazard to foraging bees.

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We thank M. Thompson for beekeeping, A. Radcliffe for help with experiments, and C. Rowe, S. Waddell, M. Palmer and N. Millar for comments. This work was funded jointly by a grant from the BBSRC, NERC, the Wellcome Trust, Defra, and the Scottish Government under the Insect Pollinators Initiative (BB/I000143/1) to G.A.W., a Leverhulme Trust research project grant (RPG-2012-708) to G.A.W., a Science Foundation Ireland grant (10/RFP/EOB2842) to J.C.S., a US National Science Foundation Graduate Research Fellowship awarded to E.J.T. (Grant No. 2010097514), and an Irish Research Council's EMBARK Postgraduate Scholarship Scheme grant (RS/2010/2147) to E.J.T.

Author information

Author notes

    • Sébastien C. Kessler
    •  & Erin Jo Tiedeken

    These authors contributed equally to this work.


  1. Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK

    • Sébastien C. Kessler
    • , Kerry L. Simcock
    • , Samantha Softley
    •  & Geraldine A. Wright
  2. Botany Department, Trinity College Dublin, Dublin 2, Ireland

    • Erin Jo Tiedeken
    •  & Jane C. Stout
  3. School of Biology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

    • Sophie Derveau
  4. Centre for Neural Circuits and Behaviour, Tinsley Building, University of Oxford, Oxford OX1 3SR, UK

    • Jessica Mitchell
  5. Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE2 4HH, UK

    • Amy Radcliffe


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S.C.K. performed the ephys experiments, spike-sorted the ephys data and wrote portions of the manuscript, E.J.T., K.L.S., S.D., J.M., S.S. and A.R. performed the choice experiments, E.J.T. and J.C.S. wrote portions of and edited the manuscript, and G.A.W. designed the experiments, analysed all data, and wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Geraldine A. Wright.

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