Larvicidal activity of Plumeria rubra, Tagetes erecta, and Thevetia peruviana extracts against Aedes aegypti and Culex quinquefasciatus larvae.

The larvicidal efficacy of methanol, petroleum ether, and chloroform extracts derived from P. rubra and T. erecta flowers and T. peruviana leaves was evaluated against larvae of Culex quinquefasciatus and Ae. aegypti following WHO guidelines. Soxhlet extraction was used to prepare the plant extracts, and gas chromatography-mass spectrometry (GC-MS) was performed on the most active petroleum ether fractions. The major constituents were further assessed using Molinspiration Cheminformatics software to predict physicochemical properties and bioactivity scores. For T. peruviana, petroleum ether and chloroform extracts showed strong larvicidal activity, with LC₅₀ values of 43.87 and 54.76 mg/L and LC₉₀ values of 96.06 and 132.20 mg/L, respectively, against Cx. quinquefasciatus, and LC₅₀ values of 70.30 and 87.30 mg/L and LC₉₀ values of 156.78 and 186.84 mg/L, respectively, against Ae. aegypti. Petroleum ether extracts of P. rubra and T. erecta showed LC₅₀ values of 39.61 and 49.31 mg/L, respectively, against Cx. quinquefasciatus, and 158.71 and 166.59 mg/L against Ae. aegypti. Molinspiration analysis indicated moderate to high predicted biological activity for several triterpenoids and phytosterols, consistent with the observed larvicidal effects. Overall, the results indicate that extracts from P. rubra, T. peruviana, and T. erecta are promising sources of mosquitocidal compounds that could be further explored for the development of environmentally compatible larvicidal products.