Ecotoxicological impacts of imazethapyr herbicide on amphibian larvae: Evidence from Physalaemus cuvieri

Aquatic environments are amongst the ecosystems most impacted by pesticides, with amphibians being a particularly vulnerable group. This study investigated the cytotoxic, body condition and biochemical effects of a commercial formulation of imazethapyr-based herbicide (IBH), on Physalaemus cuvieri tadpoles at developmental stage 25 exposed to a broad concentration gradient (0-500 µg/L) for 14 days. Notably, even the lowest concentration (1 µg/L) significantly reduced body weight, body mass index, and scaled mass index, while inducing multiple erythrocyte nuclear abnormalities (ENAs). All tested concentrations caused these effects in ENAs (e.g., micronuclei, lobed nuclei) and impaired energy allocation patterns. IBH was also neurotoxic and induced oxidative stress at higher concentrations (400-500 µg/L). The cellular damage observed suggests the difficulty for tadpoles in maintaining energy reserves for growth and metamorphosis, as evidenced by significant body weight loss. Together, these results indicate that IBH is cytotoxic at environmentally relevant concentrations and may consequently compromise the health of P. cuvieri populations.