Toxicity of pesticides to Chironomus riparius: changes in proteome, biochemical biomarkers and individual responses ; Toxicidade de pesticidas para Chironomus riparius: alterações no proteoma, marcadores bioquímicos e respostas individuais

The application of pesticides in agricultural fields leads to inevitable contamination of adjacent freshwater systems, representing a serious threat to non-target aquatic invertebrate communities. The study of the impact of these stressors on ecologically relevant species is crucial for risk assessment. Traditionally, toxicity testing focuses on organism and population-level responses (e.g. mortality, growth, behavior, and reproduction). However, these responses are often preceded by changes at lower levels of biological organization. In this sense, there is a need to develop sensitive tools that can be used to predict ecological adverse effects of sub-lethal concentrations of pesticides. Assessing sub-organismal endpoints may therefore provide early indicators of pesticide exposure and their possible impacts on natural populations. In this thesis, larvae of Chironomus riparius (Meigen) were exposed to four insecticides with distinct modes of action: amitraz, spinosad, indoxacarb, and fipronil, and their effects evaluated in terms of life-history responses using standard laboratory ecotoxicological tests, and at biochemical level by monitoring specific oxidative stress, neuronal, and energy metabolism biomarkers. Moreover, the effects of spinosad, indoxacarb, and fipronil were assessed at the molecular level using proteomic tools, to determine if proteomics and biochemical biomarkers can be used as reliable and sensitive tools in ecological risk assessment. The results presented here indicate that environmentally relevant concentrations of the insecticides tested can significantly affect several C. riparius life-history traits, with reductions in the larval growth and impairment of emergence endpoints observed for all compounds tested, which ought to compromise the ecological integrity of freshwater ecosystems. At the biochemical level, very distinct responses were observed for each pesticide, probably due to their distinct modes of action. Nonetheless, evidences of high metabolic costs (as indicated by the ...