Assessment of pesticide toxicity in tadpoles under varying thermal regimes in controlled and semi-natural environments

• Grant number: 25/09175-5
• Support Opportunities: Regular Research Grants
• Start date: February 01, 2026
• End date: January 31, 2029
• Field of knowledge: Biological Sciences - Zoology - Physiology of Recent Groups
• Principal Investigator: Juliane Silberschmidt Freitas
• Grantee: Juliane Silberschmidt Freitas
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• City of the host institution: Bauru
• Associated researchers: Cassiana Carolina Montagner ; Daniel Schlenk ; Daniela de Melo e Silva ; Eduardo Alves de Almeida ; Evaldo Luiz Gaeta Espindola ; Raquel Aparecida Moreira

Abstract

Amphibians are currently the most threatened group of animals on the planet, despite their fundamental ecological role in ecosystems. Among the main factors contributing to their species decline are climate change and environmental contamination. In Brazil, numerous anuran species develop in temporary ponds formed in agricultural areas, habitats highly vulnerable to pesticide accumulation and water warming. Elevated temperatures can accelerate pesticide uptake in tadpoles and alter physiological processes related to biotransformation and elimination, thereby increasing toxicity. This scenario becomes particularly critical in light of the increasing global average temperatures observed in recent years. This project aims to evaluate the toxicity of widely used pesticides in Brazil on lethal and sublethal responses of different species of tadpoles, considering distinct thermal gradients, under controlled and semi-field conditions. Acute toxicity assays will be conducted in the laboratory using different active ingredients and temperatures to determine the median lethal concentration (LC50) for native tadpoles. These results will be used to estimate hazardous concentrations for 5% of species (HC5) and safety factors across different thermal gradients. Sublethal chronic effects will be evaluated in tadpoles exposed to environmentally predicted concentrations of pesticides (PECs) under controlled temperature regimes in laboratory and natural thermal fluctuations in mesocosms. Biomarkers at multiple biological levels will be assessed, including biochemical, genotoxic, morphological, physiological, and behavioral endpoints. Our results will enhance the understanding of pesticide mechanisms of action in amphibians under environmental conditions typical of tropical regions and projected scenarios of rapid climate change. (AU)