Efficacy of plant extracts and oils as mosquito repellents.

Some natural products, extract of Achillea millefolium (yarrow), birch/pine tar-, citronella-, clove-, eucalyptus-, geranium-, lavender-, lily of the valley- and peppermint oils have been tested for repellency in the laboratory against Aedes aegypti and in the field predominantly against Aedes communis and A. cinereus. The laboratory tests showed that yarrow extract exhibited a similar repellency as the reference substances N,N-diethyl-m-toluamide and N,N-diethyl-mandelic acid amide. A good repelling effect was also obtained with the oils of birch/pine tar and eucalyptus. The field tests revealed that the extracts and oils with good activity against Aedes aegypti also were effective against A. communis and A. cinereus. Furthermore oils of citronella and lily of the valley showed similar activity and were comparable with the used reference substances mentioned. Each of these natural products contained a great number of constituents when characterized by chromatography/mass spectrometry. Available data in the literature were gathered, both regarding mosquito repellency and toxicity for humans and larger animals, for each product as well as its major constituents.