Agrochemicals interact synergistically to increase bee mortality

Harry Siviter*, Emily J. Bailes, Callum D. Martin, Thomas R. Oliver, Julia Koricheva, Ellouise Leadbeater, Mark J.F. Brown

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

158 Citations (Scopus)


Global concern over widely documented declines in pollinators1–3 has led to the identification of anthropogenic stressors that, individually, are detrimental to bee populations4–7. Synergistic interactions between these stressors could substantially amplify the environmental effect of these stressors and could therefore have important implications for policy decisions that aim to improve the health of pollinators3,8,9. Here, to quantitatively assess the scale of this threat, we conducted a meta-analysis of 356 interaction effect sizes from 90 studies in which bees were exposed to combinations of agrochemicals, nutritional stressors and/or parasites. We found an overall synergistic effect between multiple stressors on bee mortality. Subgroup analysis of bee mortality revealed strong evidence for synergy when bees were exposed to multiple agrochemicals at field-realistic levels, but interactions were not greater than additive expectations when bees were exposed to parasites and/or nutritional stressors. All interactive effects on proxies of fitness, behaviour, parasite load and immune responses were either additive or antagonistic; therefore, the potential mechanisms that drive the observed synergistic interactions for bee mortality remain unclear. Environmental risk assessment schemes that assume additive effects of the risk of agrochemical exposure may underestimate the interactive effect of anthropogenic stressors on bee mortality and will fail to protect the pollinators that provide a key ecosystem service that underpins sustainable agriculture.

Original languageEnglish
Pages (from-to)389-392
Number of pages4
Issue number7872
Publication statusPublished - 19 Aug 2021

Bibliographical note

Funding Information:
Acknowledgements We thank all authors who made data available to us upon request (C. Alaux, K. Antunez, B. Baer, B. Blochtein, C. Botias, B. Dainat, M. Diogon, A. G. Dolezal, V. Doublet, K. Fent, D. C. de Graaf, G. de Grandi-Hoffman, P. Graystock, E. Guzman-Novoa, R. M. Johnson, E. G. Klinger, I. M. de Mattos, N. A. Moran, M. Natsopoulou, F. Nazzi, P. Neumann, R. Odemer, R. Raimets, G. Retschnig, R. M. Roe, E. Ryabov, B. M. Sadd, C. Sandrock, F. Sgolastra, R. Siede, H. V. V. Tome, I. Toplak, S. Tosi, M. Tritschler, V. Zanni and Y. C. Zhu); and J. Bagi and A. J. Folly for helping with the initial screening of titles and abstracts. H.S. was supported by a Royal Holloway University of London Reid PhD Scholarship and by contributions from the High Wycombe Beekeeper’s Association. This project has received funding from the European Horizon 2020 research and innovation programme under grant agreement no. 773921 and ERC Starting Grant BeeDanceGap 638873, and from the Biotechnology and Biological Sciences Research Council, grant/award number BB/N000668/1.

Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Limited.


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