A Toxicity assessment of metyltetraprole, a novel fungicide inhibitor, to embryo/larval zebrafish (Danio rerio)

Strobilurins are a prominent class of fungicides capable of entering aquatic environments via runoff and leaching from the soil. Findings from previous studies suggest that strobilurins are highly toxic in aquatic environments, and evidence of acute developmental toxicity and altered behavioral responses have been emphasized. The objective of this study was to assess the effects of a new strobilurin, metyltetraprole (MTP), on zebrafish using developmental endpoints, gene expression, and behavioral locomotor assays. We hypothesized that MTP would cause developmental toxicity and induce hyperactivity in zebrafish (Danio rerio). To test this, developing zebrafish embryos/larvae were exposed to environmentally relevant levels of MTP (0.1, 1, 10, and 100 μg/L) until 7 days post-fertilization. Results showed no statistically significant difference in survivorship across the treatment groups. No change in reactive oxygen species production was found, but two genes involved in the mitochondrial electron transport chain (mt-nd3 and uqcrc2) were altered following MTP exposure. Moreover, the highest concentrations (100 µg/L) of MTP caused notable hyperactivity in the zebrafish in the visual motor response test. Overall, results from this study improve our understanding of the sub-lethal effects of MTP, helping to inform risk assessment for aquatic environments.