TOXICOLOGICAL ASSESSMENT OF A FUNGICIDE MIXTURE IN CAERNORHABDITIS ELEGANS.

Resumo

INTRODUCTION: The combined use of pesticides as an alternative for broader-spectrum action is common in agriculture; however, toxicological studies addressing the interactions between such compounds remain scarce. Tebuconazole (TBZ) is among the most widely used fungicides in Brazil and is frequently found in commercial formulations with trifloxystrobin (TFS). Both are extensively applied to soybean, rice, and wheat crops, and studies have indicated their potential environmental toxicity due to indiscriminate use. Despite the increasing application of the TBZ-TFS mixture, its toxicological profile remains uncertain. Caenorhabditis elegans is a small free-living nematode widely used in toxicological analyses as a bioindicator of environmental impact and ecotoxicological risk. Its genome is fully sequenced and highly homologous to that of mammals, enabling the elucidation of toxicological effects at the molecular level. OBJECTIVE: This study aimed to evaluate the isolated and combined effects of TBZ and TFS in the alternative model Caenorhabditis elegans, using environmentally relevant concentrations. MATERIALS AND METHODS: Animals at a critical developmental stage were exposed to different concentrations of TBZ (0.05, 0.1, and 0.2 mg/mL) and TFS (0.025, 0.05, and 0.1 mg/mL), individually and in combination, for 1 hour. After reaching adulthood, the toxicological endpoints evaluated included pharyngeal pumping, defecation cycle, locomotion, egg-laying, and neuronal integrity. RESULTS: The mixture induced increased mortality and alterations in neuronal integrity. TFS alone affected the defecation cycle, while both compounds impaired pharyngeal pumping and locomotion. Egg-laying and neuronal integrity did not show significant changes under the tested conditions. CONCLUSION: These findings suggest that the endpoints exhibit different sensitivities to the compounds and that exposure to the mixture may enhance adverse effects compared to single exposures. Further studies are needed to elucidate the mechanisms involved in TBZ-TFS toxicity and their potential environmental risks.