Comparative larvicidal efficacy of essential oils from Cymbopogon citratus stalks and leaves against Anopheles gambiae sensu stricto

Abstract

Mosquitoes transmit several infectious diseases, including malaria. Due to the increasing resistance of mosquitoes to synthetic insecticides and the non-selective nature of these chemicals, larviciding has emerged as an effective and environmentally safer method of mosquito control. This study focused on the larvicidal activity of the essential oils (EOs) isolated from Cymbopogon citratus (lemongrass) stalks and leaves collected in Morogoro, Tanzania, against Anopheles gambiae sensu stricto (s.s.) larvae. The EOs were extracted by hydrodistillation and characterized by Gas Chromatography-Mass Spectroscopy (GC–MS). Larvicidal bioassays were performed on laboratory-reared larvae, and mortality data were analysed using probit analysis to determine LC50 and LC90 values at 95% confidence intervals. A total of 195 and 99 components from the lemongrass leaves and stalks, respectively, were identified. The higher concentration of EOs was obtained from stalks in comparison to the leaf’s counterpart, in which the geranial (31.89%) and neral (27.02%) were determined to be the major components. The EOs isolated from lemongrass stalks demonstrated greater larvicidal activity than those obtained from lemongrass leaves, with LC50 values of 146.6 ppm and 209.5 ppm, respectively. These results demonstrated the potent larvicidal properties of lemongrass stalk EOs against An. gambiae s.s. larvae. The EOs from lemongrass stalks exhibit greater larvicidal efficacy against An. gambiae s.s. larvae compared to those obtained from lemongrass leaves.