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Acute exposure to urban air pollution impairs olfactory learning and memory in honeybees


While the ecological effects of pesticides have been well studied in honeybees, it is unclear to what extent other anthropogenic contaminants such as air pollution may also negatively affect bee cognition and behaviour. To answer this question, we assessed the impacts of acute exposure to four ecologically relevant concentrations of a common urban air pollutant—diesel generated air pollution on honeybee odour learning and memory using a conditioned proboscis extension response assay. The proportion of bees that successfully learnt odours following direct air pollution exposure was significantly lower in bees exposed to low, medium and high air pollutant concentrations, than in bees exposed to current ambient levels. Furthermore, short- and long-term odour memory was significantly impaired in bees exposed to low medium and high air pollutant concentrations than in bees exposed to current ambient levels. These results demonstrate a clear and direct cognitive cost of air pollution. Given learning and memory play significant roles in foraging, we suggest air pollution will have increasing negative impacts on the ecosystem services bees provide and may add to the current threats such as pesticides, mites and disease affecting colony fitness.

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The authors thank T. Latty and C. Perry for feedback during manuscript writing.


Authors (RJL, TJP, PI, CM and DFH) received no funding for this project.

Authors’ contributions

RJL, TP, PI, CM and DFH conceived the project; RJL collected the data; TP and PI conducted chemical. analyses; RJL, TP, CM and DF wrote the manuscript. All authors gave final approval for publication.

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Correspondence to Ryan J. Leonard.

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Leonard, R.J., Pettit, T.J., Irga, P. et al. Acute exposure to urban air pollution impairs olfactory learning and memory in honeybees. Ecotoxicology 28, 1056–1062 (2019).

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  • Air pollution
  • Honeybee
  • Pollinator
  • Proboscis extension reflex response
  • Behaviour