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

Abstract

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 <em>Morinda</em> <em>tinctoria</em> and <em>Pongamia</em> <em>glabra</em> against larvae of <em>Anopheles</em> <em>stephensi</em> (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 <em>M. tinctoria</em> and <em>P. glabra</em> against the larvae of <em>A. stephensi</em> 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 <em>M. tinctoria</em> and <em>P. glabra</em> showed significant mortality against larvae of <em>A. stephensi</em>. 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 <em>M. tinctoria</em>, and 200-400 ppm aqueous and methanol extracts of <em>P. glabra</em>. This study provides the first report of the larvicidal, adulticidal and ovicidal activities of <em>M. tinctoria</em> and <em>P. glabra</em> plant extracts against the malaria vector, A. stephensi, representing an ideal eco-friendly approach for its control.