Bioefficacy of Morinda tinctoria and Pongamia glabra plant extracts against the malaria vector Anopheles stephensi (Diptera: Culicidae)

Mosquito-borne diseases have an economic impact, including loss in commercial and labour outputs, particularly in countries with tropical and subtropical climates; however, no part of the world is free from vector-borne diseases. The aim of the present study was to investigate the larvicidal, adulticidal and ovicidal activity of dried leaf chloroform, ethyl acetate, acetone, aqueous, and methanol extracts of Morinda tinctoria and Pongamia glabra against larvae of Anopheles stephensi (Diptera: Culicidae). Larvae were exposed to varying concentrations of plant extracts for 24 h. All extracts showed moderate larvicidal effects after 24 h of exposure; however, the highest larval mortality was found with the leaf methanol extracts of M. tinctoria and P. glabra against the larvae of A. stephensi lethal concentration (LC)₅₀=136.24 and 141.05 ppm; LC₉₀=342.67 and 368.89 ppm, respectively. The results of the adulticidal activity assays of chloroform, ethyl acetate, acetone, aqueous, and methanol extracts of M. tinctoria and P. glabra showed significant mortality against larvae of A. stephensi. The methanol extract showed maximum activity compared with the other extracts. The greatest effect on mean percentage hatch in the ovicidal assays was observed 48 h post-treatment. Percent hatch was inversely proportional to the concentration of extract, and directly proportional to the number of eggs. A mortality of 100% was observed with 100-400 ppm methanol extracts and 200-400 ppm aqueous extracts of M. tinctoria, and 200-400 ppm aqueous and methanol extracts of P. glabra. This study provides the first report of the larvicidal, adulticidal and ovicidal activities of M. tinctoria and P. glabra plant extracts against the malaria vector, A. stephensi, representing an ideal eco-friendly approach for its control.