Background and Objective: Schistosomiasis, a parasitic disease of major public health concern in sub-Saharan Africa, is transmitted through contact with water harboring larval Schistosoma species released by freshwater snails such as Biomphalaria pfeifferi. While chemical molluscicides are commonly used for snail control, they often pose risks to aquatic ecosystems and non-target species. This study aimed to evaluate the bioactive metabolites and molluscicidal potential of methanolic extracts of Azadirachta indica (neem) and Vernonia amygdalina (bitter leaf) as safer, plant-based alternatives for controlling B. pfeifferi.
Materials and Methods: Methanolic extracts of neem and bitter leaf were subjected to phytochemical screening using standard protocols to detect flavonoids, tannins, alkaloids, and saponins. Molluscicidal activity was assessed by exposing ten adult B. pfeifferi snails to six concentrations (10, 20, 40, 80, 160, and 240 mg/L) of each extract for 24 hours. Mortality was recorded post-exposure, and lethal concentrations (LC₅₀ and LC₉₀) were calculated using probit regression analysis. Statistical significance between treatments was determined at P < 0.05.
Results: Both plant extracts demonstrated a dose-dependent increase in snail mortality. The LC₅₀ and LC₉₀ values for neem extract were 57.984 mg/L and 129.285 mg/L, respectively, while those for bitter leaf extract were 72.042 mg/L and 132.465 mg/L. Neem extract showed significantly greater molluscicidal potency than bitter leaf (P < 0.05).
Conclusion: The findings confirm that A. indica and V. amygdalina contain effective bioactive compounds with molluscicidal properties. Neem extract, in particular, showed strong potential for use as an eco-friendly alternative to synthetic molluscicides. Further studies are recommended to isolate active constituents and evaluate ecological safety under field conditions.