The Bioscientist (Jun 2023)
Screening of Locally Available Lemon Grass (Cymbopogon citratus) for Repellency Action against Aedes aegypti
Abstract
In Nigeria, re-emergence of diseases caused by Aedes mosquito borne pathogens, and challenges associated with existing control tools occur. This necessitates an improved insecticide-based tool for use in Integrated Vector Management. So, repellent action of Cymbopogon citratus essential oil (EO) on Aedes aegypti (Linn.) was tested. The EO from C. citratus plant sourced from Awka, was extracted by hydro distillation, and the phytochemicals analyzed by Gas Chromatography-Mass Spectrometry. Repellent action of the EO on unfed Ae. aegypti was assessed using "WHO arm-in-cage" method. In triplicate, arms of human volunteers were treated with different concentrations (50.0, 25.0, 12.5, 6.25 and 3.125 % v/v) of the EO and submitted to 25-caged, unfed Ae. aegypti for 1 minute in every 30 minutes. β-cedrenes, kaempferol, and thujopsene dominated the 13 phytochemicals identified. The standard (Odomos®) and all EO concentrations recorded 100 % repellency on application. At 30 minutes, EC99.9 value was25.0 %, concentrations ≥ 62.5 % v/v gave 100 % repellency (p > 0.05). At 60 minutes, EC99.9 value was 30.68 %, concentrations ≥ 12.5 % v/v gave 100 % repellency (p > 0.05). At 90 to 120 minutes, 50 % concentration maintained 100 % repellency (p < 0.05), EC99.9 value was 48.79 % at 120 minutes. Recording 120 minutes protection time with no adverse effect, 50 % concentration showed equal potency as Odomos®. Research to isolate the active ingredients in the EO for incorporation into beneficial health and economic products is desirable.
