Probit Model-Based Toxicity Evaluation of Tea Saponin against Achatina fulica

To clarify the control efficacy of tea saponin against Achatina fulica, the molluscicidal effects of tea saponin at concentrations of 0.25%, 0.5%, 1.0%, 1.5%, 2.0%, and 2.5% were evaluated using a laboratory spray method, with distilled water as the blank control and 6% metaldehyde granules as the positive control. The results showed that the molluscicidal effect of tea saponin against A. fulica increased with increasing concentration and prolonged treatment time. At 72 h, as the concentration increased from 0.25% to 2.5%, the corrected mortality rose from 26.7% to 93.1%, which was comparable to that of the positive control（6% metaldehyde). Probit-based toxicity evaluation revealed that the LC₅₀ decreased significantly with treatment time, with values of 2.69%, 1.16%, and 0.65% at 24, 48, and 72 h, respectively. The 72 h dose-response curve fitted by the Probit model exhibited a standard sigmoidal shape, with the LC₅₀ located in the rapidly ascending segment and showing good goodness-of-fit. Collectively, these findings indicate that tea saponin has potential for development as a plant-derived molluscicide for the control of Achatina fulica.