Pesticides bioassays using neotropical aquatic species: Trends during the last twenty years and future challenges in Argentina.

The presence of pesticides in aquatic ecosystems is one of the most relevant stressors which biota usually face. Laboratory tests using model organisms for pesticides toxicity assessment are employed worldwide. The use of these species has been encouraged in the scientific community due to their advantageous features and their acceptation by regulatory and standardization organizations. However, non-model species as well as those belonging particular ecosystems could contribute in the laboratory-field toxicity extrapolation. In this context, this work aims on exploring the state of the ecotoxicological studies of pesticides in neotropical aquatic species, focusing on bioassays performed in Argentina over the last 20 years as a case of study. Furthermore, we analyzed the possible advantages and disadvantages of these studies, possible differential sensitivities among native and model species, and future challenges to be faced. The analysis of more than 150 publications allowed identify the chemical identity of tested compounds, organisms used for the bioassays, characteristics of the experimental designs, and the toxicity endpoints. Particularly, the studied cases showed that the tested chemicals are related to those most used in the agricultural activity in Argentina, the predilection for particular species in some taxonomic groups (e.g. amphibians), and the wide election of biochemical biomarkers in the studies. Regarding the sensitivity comparison between native and non-native species, the amount of data available indicates that there is not a clear difference beyond some particular cases. However, deeper understanding of toxic effects of pesticides on non-model species could help in a more comprehensive ecological risk assessment in different ecosystems.