α-Farnesene Identified from Sansevieria roxburghiana Exhibits Selective and Environmentally Safe Larvicidal Activity Against Aedes aegypti and Culex quinquefasciatus

Abstract

The widespread use of synthetic insecticides has led to increasing resistance in mosquito populations and harmful effects on non-target organisms, highlighting the urgent need for eco-friendly alternatives. In this study, the larvicidal and pupicidal potential of α-Farnesene, a major phytochemical derived from Sansevieria roxburghiana, was evaluated against the disease-transmitting mosquitoes Aedes aegypti and Culex quinquefasciatus. GC–MS analysis of the methanolic leaf extract revealed a rich profile of sesquiterpene hydrocarbons and terpenoids, with α-Farnesene identified as a major phytocomponent. This is the first report highlighting α-Farnesene from S. roxburghiana with a high selectivity index against mosquito larvae. Toxicity bioassays demonstrated a strong, time-dependent larvicidal activity of α-Farnesene, with 48-hour LC₅₀ values of 6.1 ppm for Aedes aegypti and 7.4 ppm for Culex quinquefasciatus. Pupicidal activity was also observed, although higher concentrations were required compared to larvicidal effects in the same species. Histopathological analysis revealed severe damage to the larval midgut, including epithelial disintegration and necrosis, indicating disruption of digestive function. Acute toxicity assays conducted on non-target organisms, Poecilia reticulata and Eisenia fetida, showed very low mortality even at concentrations much higher than larvicidal doses, resulting in high selectivity indices and a wide safety margin. Overall, these findings demonstrate that α-Farnesene is a potent and environmentally safe mosquitocidal agent, supporting its potential as a sustainable botanical larvicide for use in integrated vector management programmes.