What if aquatic animals move away from pesticide-contaminated habitats before suffering adverse physiological effects? A critical review

Several pesticides were developed to be repellent to the targeted pest. However, non-target species could also move away from pesticide-contaminated habitats. These populations would face local extinction due to emigration, even without adverse physiological effects on organisms. Little is known about what pesticides cause spatial avoidance and at what concentrations, because traditional toxicity evaluations use forced exposure to determine effects, both in single-species testing and multi-species mesocosm studies. This traditional approach only considers pesticides as poisons at the individual level (sola dosis facit venenum, Paracelsus dixit), thus neglecting the potential role of pesticides as habitat disturbers and, eventually, habitat fragmentors. In the present review, we compiled the published information on pesticide-driven emigration by aquatic animals. Available data are enough to conclude that pesticide risks are currently being underestimated. Therefore, we recommend a paradigm shift in ecotoxicology through the inclusion of non-forced exposure testing to evaluate repellence to non-target species in the ecological risk assessment of pesticides. [GRAPHICS] .