Comparing bee species responses to chemical mixtures: Common response patterns?

PLoS One. 2017 Jun 22;12(6):e0176289. doi: 10.1371/journal.pone.0176289. eCollection 2017.

Abstract

Pollinators in agricultural landscapes can be exposed to mixtures of pesticides and environmental pollutants. Existing mixture toxicity modelling approaches, such as the models of concentration addition and independent action and the mechanistic DEBtox framework have been previously shown as valuable tools for understanding and ultimately predicting joint toxicity. Here we apply these mixture models to investigate the potential to interpret the effects of semi-chronic binary mixture exposure for three bee species: Apis mellifera, Bombus terrestris and Osmia bicornis within potentiation and mixture toxicity experiments. In the potentiation studies, the effect of the insecticide dimethoate with added propiconazole fungicide and neonicotinoid insecticide clothianidin with added tau-fluvalinate pyrethroid acaricide showed no difference in toxicity compared to the single chemical alone. Clothianidin toxicity showed a small scale, but temporally conserved increase in exposure conducted in the presence of propiconazole, particularly for B. terrestris and O. bicornis, the latter showing a near three-fold increase in clothianidin toxicity in the presence of propiconazole. In the mixture toxicity studies, the dominant response patterns were of additivity, however, binary mixtures of clothianidin and dimethoate in A. mellifera, B. terrestris and male O. bicornis there was evidence of a predominant antagonistic interaction. Given the ubiquitous nature of exposures to multiple chemicals, there is an urgent need to consider mixture effects in pollinator risk assessments. Our analyses suggest that current models, particularly those that utilise time-series data, such as DEBtox, can be used to identify additivity as the dominant response pattern and also those examples of interactions, even when small-scale, that may need to be taken into account during risk assessment.

Publication types

  • Comparative Study

MeSH terms

  • Agrochemicals / pharmacology*
  • Animals
  • Bees / drug effects*
  • Bees / physiology
  • Drug Synergism
  • Pollination
  • Species Specificity

Substances

  • Agrochemicals

Grants and funding

This work was supported by a research grants awarded by the European Food Safety Authority to Centre for Ecology and Hydrology, UK on “Toxicity of exposure to multiple chemicals in bees and modelling the effect on bee population dynamics using DEB‐TOX models”. Contract/grant number: OC/EFSA/SCER/2013/02. JB was supported by the EU Marie Curie Actions - Research Fellowship Programme 2012 (FP7-PEOPLE-2012-IEF), BIOME, contract nr 328931. The Natural Environment Research Council (NERC) supported additional bee experimental work through National Capability funding project NEC05585 for apiary maintenance.