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

Area of Science:

• Environmental Toxicology
• Ecotoxicology
• Pollinator Health

Background:

• Bees face complex exposures to multiple pesticides and pollutants in agricultural settings.
• Understanding joint toxicity is vital for accurate pollinator risk assessment.
• Existing models like concentration addition, independent action, and DEBtox offer frameworks for mixture toxicity analysis.

Purpose of the Study:

• To apply and evaluate established mixture toxicity models for semi-chronic binary exposures in three key bee species.
• To investigate potentiation and mixture toxicity effects of specific pesticide combinations.
• To assess the utility of models, particularly DEBtox, in interpreting complex pollinator exposure scenarios.

Main Methods:

• Experiments involved semi-chronic binary mixture exposures of Apis mellifera, Bombus terrestris, and Osmia bicornis.
• Potentiation studies examined insecticide dimethoate with propiconazole, and clothianidin with tau-fluvalinate.
• Mixture toxicity studies assessed interactions between clothianidin and dimethoate.
• Data were analyzed using concentration addition, independent action, and the DEBtox framework.

Main Results:

• Potentiation studies showed no significant increase in toxicity for most tested combinations.
• Clothianidin toxicity increased slightly in the presence of propiconazole for B. terrestris and O. bicornis.
• Mixture toxicity studies predominantly revealed additive responses.
• Antagonistic interactions were observed in binary mixtures of clothianidin and dimethoate for A. mellifera, B. terrestris, and male O. bicornis.

Conclusions:

• Mixture toxicity models, especially time-series models like DEBtox, are valuable for identifying dominant additive patterns and specific interactions.
• Accurate pollinator risk assessment necessitates the inclusion of mixture effects.
• Further research using mechanistic models can refine our understanding of complex chemical exposures in bees.