Larvicidal Activity of Inorganic Salts Against Anopheles Stephensi and Culex Quinquefasciatus

Mosquitoes transmit serious human diseases, causing millions of deaths worldwide every year and the development of resistance to chemical insecticides resulting in rebounding vectorial capacity. In this study, the larvicidal bioassays for activities of aqueous solutions of weak acid [(NH4)2SO4 and NaH2PO4] and weak base (Na2CO3 and NaHCO3) inorganic salts against late instar larvae of disease vectors Anopheles stephensi and Culex quinquefasciatus were carried out under laboratory settings. The four inorganic salts showed varied levels of larvicidal activities after 24 h-exposure on Anopheles stephensi and Culex quinquefasciatus larvae in a dose-dependent fashion. However, the larvicidal activities were relatively higher in Na2CO3 (LC50 = 3162 and 447 ppm) and NaHCO3 (LC50 = 5623 and 398 ppm) solutions as compared to those in (NH4)2SO4 (LC50 = 7943 and 1995 ppm) and NaH2PO4 (LC50 = 7943 and 7120 ppm). The present study showed that the inorganic salts Na2CO3, NaHCO3, (NH4)2SO4 and NaH2PO4 could serve as potential larviciding agents considering their low toxicity. Therefore, this study provides a first report on the larvicidal activity of the inorganic salts on mosquito larvae of disease vectors.