Environmental Effects on Phytochemical Composition and Larvicidal Activity of Calotropis procera (Aiton) W.T.Aiton Leaf Extracts Against Aedes aegypti

---

Résumé

The increasing resistance of mosquito vectors to synthetic insecticides poses a major challenge to vector control and global public health, underscoring the urgent need for sustainable, environmentally safe alternatives. This study evaluated the larvicidal activity of aqueous, ethanolic, methanolic, and hydroethanolic extracts of Calotropis procera (Aiton) W.T.Aiton leaves against Aedes aegypti larvae. Significant variations in activity were observed across extraction solvent, ecological zone, and harvest season, with hydroethanolic extracts—particularly those collected in Kombissiri during the dry season—exhibiting the lowest LC50 values among the tested extracts (LC50 < 1600 ppm), indicating moderate larvicidal activity. Phytochemical profiling by high-performance thin-layer chromatography (HPTLC) revealed the presence of several classes of secondary metabolites, including flavonoids, phenolic compounds, tannins, sterols/triterpenes, saponins, coumarins, alkaloids, and cardenolides. Correlation analysis revealed strong negative correlations between larvicidal activity and the concentrations of flavonoids and phenolic compounds, suggesting that higher levels of these metabolites are associated with increased larvicidal effectiveness and may contribute to the observed bioactivity, although these associations remain correlative and do not establish direct causality. These findings highlight the potential of C. procera as a source of plant-based larvicides and demonstrate the influence of environmental factors on their efficacy. From an environmental health perspective, such plant-derived solutions could provide preliminary data for the future optimization of sustainable vector control strategies, while reducing ecological impact and reliance on synthetic insecticides.

Mots-clés

Calotropis procera; Aedes aegypti; larvicidal activity; biopesticides; phytochemical composition; sustainable vector control