Abstract
BackgroundNative mosquito repellent plants have a good potential for integrated mosquito control in local settings. Ocimum forskolei, Lamiaceae, is used in Eritrea as a spatial mosquito repellent inside houses, either through crushing fresh plants or burning dry plants. We verified whether active repellent compounds could be identified using gas-chromatography coupled electroantennogram recordings (GC-EAD) with headspace extracts of crushed plants.ResultsEAD active compounds included (R)-(-)-linalool, (S)-(+)-1-octen-3-ol, trans-caryophyllene, naphthalene, methyl salicylate, (R)-(-)-α-copaene, methyl cinnamate and (E)-ocimene. Of these compounds (R)-(-)-linalool, methyl cinnamate and methyl salicylate reduced landing of female Aedes aegypti on human skin-odor baited tubes. The latter two are novel mosquito repellent compounds.ConclusionsThe identification of mosquito repellent compounds contributes to deciphering the mechanisms underlying repulsion, supporting the rational design of novel repellents. The three mosquito repellent compounds identified in this study are structurally dissimilar, which may indicate involvement of different sensory neurons in repulsion. Repulsion may well be enhanced through combining different repellent plants (or their synthetic mimics), and can be a locally sustainable part in mosquito control efforts.
Highlights
Native mosquito repellent plants have a good potential for integrated mosquito control in local settings
Jirovetz et al [21] found O basilicum essential oil to be characterised by linalool (30%), though less than 1% was found in O. americanum, O. gratissimum and O. sanctum
Methyl cinnamate was dominant in O. americanum and O. basilicum, but not detected in O. gratissimum and O. sanctum, beta-caryophyllene made up 16% of the essential oil of the latter
Summary
Native mosquito repellent plants have a good potential for integrated mosquito control in local settings. Ocimum forskolei, Lamiaceae, is used in Eritrea as a spatial mosquito repellent inside houses, either through crushing fresh plants or burning dry plants. Olfaction is the principal sensory modality used in host recognition and location. This is especially true for disease vector mosquitoes, many species of which locate their vertebrate hosts during scotophase [1]. Tropical regions are affected, largely due to the economic and logistical problems associated with conventional control methods, such as insecticide sprays. Early efforts to control vectors with insecticides were highly effective, their reliance on spraying inside houses to kill resting females has raised environmental and public health concerns [2]. The contrasting behaviour of different mosquito vector species leads to variation in the effectiveness of different methods
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