Tebuconazole-based fungicide impairs embryonic development of the South African Clawed Frog Xenopus laevis

Tebuconazole (TBZ) is a broad-spectrum fungicide that disrupts fungal cell membrane. Due to its extensive application in agriculture, TBZ is frequently detected in aquatic ecosystems, posing potential risks to amphibians. However, the effects of TBZ-based formulations on amphibian development remain poorly understood. The present study investigates the effects of the TBZ-based fungicide Tebucur on the embryogenesis of the South African clawed frog. Two-cell stage embryos were exposed to varying concentrations of Tebucur (0.01-100 mg a.i./L) in a static non-renewal bioassay. The exposure time varied between four and 14 days, depending on the desired developmental stage of the embryos and the analysis method. Tebucur exposure resulted in mortality with a LC50-value of 8.0 mg a.i./L at 14 days. As well, various morphological abnormalities during neural and cardiac development emerged. Additionally, a reduction of overall mobility was observed. This underlines the need for strict regulation of the use of TBZ-formulations.