Forty-two compounds in eleven essential oils elicit antennal responses from Aedes aegypti

Essential oils of various plants can be effective at repelling mosquitoes. The repellent properties are often ascribed to their dominant constituents. Our objective was to analyse several essential oils by coupled gas chromatographic-electroantennographic detection (GC-EAD) on the premise that those compounds that are detected by the antennae of the yellow fever mosquito, Aedes aegypti L. (Diptera: Culicidae), are candidate repellents even though they may be minor constituents and thus be overlooked in GC-mass spectrometric analyses of essential oils. In the essential oils of catnip, cinnamon, citronella, cumin, eucalyptus, geranium, ginger, melissa, peppermint, rosemary, and thyme, 42 components induced antennal responses, most commonly beta-caryophyllene, linalool, 1,8-cineole, geraniol, and geranial. Some of these 42 components are known insect repellents, indicating that GC-EAD screening of essential oils is a viable analytical technique to detect quantitatively minor constituents, which could be potent repellents when tested at an appropriate dose.