Identification of mosquito repellent odours from Ocimum forskolei
1 Division of Chemical Ecology, Department of Crop Science, Swedish University of Agricultural Sciences PO 44, Alnarp, SE-23053 Sweden
2 Department of Biology, University of Asmara, Asmara, Eritrea
3 Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, Uppsala SE-750 07, Sweden
Parasites & Vectors 2011, 4:183 doi:10.1186/1756-3305-4-183Published: 22 September 2011
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. We verified whether active repellent compounds could be identified using gas-chromatography coupled electroantennogram recordings (GC-EAD) with headspace extracts of crushed plants.
EAD 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.
The 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.