Toxicity of trifluralin on the embryos and larvae of the red-bellied toad, Bombina bombina


Abstract: Many amphibian populations are in decline throughout the world, and one of the most important proposed causes for this decline is agrochemicals, especially pesticides. This study considers the effects of 120 h exposure of embryos and larvae of the red-bellied toad, Bombina bombina, to trifluralin, an herbicide, with renewal acute toxicity tests at 22 ± 1 °C. Adult males and females were induced to breed by gonadotropin injection to obtain test organisms. Lethal concentration values were determined through PROBIT analysis. The 120 h LC_{50} of trifluralin for the larvae was 11.80 mg L^{-1}, while the LC_{50} and EC_{50} for the embryos were 9.40 and 5.58 mg L^{-1}, respectively. Trifluralin concentrations representing LC_{10}, LC_{50}, and LC_{90} from 24 to 120 h were plotted as toxicity profile curves for larval-toxicity tests. The teratogenic index for trifluralin was 1.69, which points out a significant teratogenic risk. Abnormal behaviors, improper gut coiling, delayed development, reduced growth rate, edema, and malformations such as axial abnormalities, tail flexure, and wavy tail fins were observed in the embryos and larvae exposed to trifluralin.

Keywords: Herbicide, trifluralin, teratogenic effect, lethality, malformation, Amphibia, red-bellied toad, Bombina bombina

Full Text: PDF