Integrated biomarker assessment of sublethal effects of a tebuconazole-based fungicide in Rhinella arenarum larvae

Abstract

Agricultural intensification increases agrochemical use, exposing aquatic organisms to sublethal toxicants capable of disrupting key physiological pathways. This study assessed the biochemical and physiological responses of Rhinella arenarum larvae exposed to a commercial tebuconazole-based fungicide (Trigal®, 43% active ingredient). Acute (96 h) exposures to 0.005, 0.01, and 0.05 mg/L were performed to evaluate biomarkers related to oxidative stress, neurotoxicity, and genotoxicity. The integrated biomarker response (IBR) index was used to combine these endpoints into a single global measure of physiological stress. Tebuconazole caused oxidative imbalance, with CAT, GST, and GSH activities inhibited by 20–60% across all concentrations, while SOD increased 24% at 0.05 mg/L. Lipid peroxidation and micronuclei frequency rose by 3-fold at 0.01–0.05 mg/L, indicating redox disruption and membrane damage. Significant BChE inhibition further evidenced neurophysiological impairment. The IBR index revealed a concentration-dependent increase, with the highest value observed at 0.05 mg/L, indicating a clear overall biological effect of exposure. Given the ecological role of amphibians as key components of food webs, these findings suggest that tebuconazole may impair larval performance and ultimately reduce recruitment in amphibian populations exposed to agricultural runoff.