Larvicidal activity of Acorus calamus leaf extracts against the Aedes aegypti and Culex quinquefasciatus

Abstract

Mosquitoes are the important carriers of disease-causing pathogens responsible for serious health effects in humans. The vector control management mainly focuses on synthetic insecticides and their overuse creates resistance in mosquitoes. Henceforth, there is a need to develop insecticides that are effective and help in overcoming resistance development in mosquitoes. An attempt is made here to bring effective management of larval mosquitoes with herbal-based preparations since it is eco-friendly and causes no ill effects on humans. In this study, aqueous and solvent extracts of Acorus calamus leaves were tested for their anti-mosquito activity against third instar larvae of Aedes aegypti and Culex quinquefasciatus. Among the tested extracts, the crude hexane leaf extract of A. calamus showed the highest percentage of mortality with LC₅₀ of 151.86 ppm and LC₉₀ of 536.36 ppm against A. aegypti and LC₅₀ of 174.70 ppm and LC₉₀ of 696.73 ppm against C. quinquefasciatus. The treatment showed significant changes in the larval morphology such as damaged body parts, enlarged mid-gut, and lesions on the thoracic region. Similarly, histopathological analysis of treated larvae after 24 hours of treatment was observed with dislocations of cells, augmented nucleus, and ruptured epithelial cells. GC-MS analysis of the effective crude hexane leaf extract of A. calamus showed the presence of asarone to the level of 50.18% and that could have been thought to be insecticidal in nature which is probably responsible for the effective larval anti-mosquito activity.