Submitted to: Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2005
Publication Date: 7/1/2005
Citation: Chauhan, K.R., Klun, J.A., Debboun, M., Kramer, M. 2005. Feeding Deterrent Effects of Catnip Oil Components Compared with Two Synthetic Amides Against Aedes aegypti. Journal of Medical Entomology. 42:643-646. Interpretive Summary: The control of mosquitoes that vector human disease is becoming difficult because of resistance to insecticides and there is growing concern about the safety of deet, which is probably the most commonly used mosquito repellent in the world. Formulations containing natural products and essential oils have been claimed to be safer and effective alternatives to deet. However, the claimed effectiveness of insect repellents containing natural product is often uncertain or overstated. In the present study we evaluated the repellent efficacy of the natural product catnip oil that was claimed to be ten times more effective than deet. We compared its effectiveness with two established repellents deet, and SS220, in tests using human volunteers against a mosquito that is a serious disease carrier. We found, contrary to the claim, that catnip oil is significantly less effective that deet or SS220. The results indicate that extraordinary claims for marketed natural product formulations should be carefully studied. In addition, the information will be useful for scientists investigating insect repellents.
Technical Abstract: Recently Catnip (Nepeta cataria, Lamiaceae) essential oil has been formulated and marketed as an alternative repellent for protection against biting arthropods by several vendors. We isolated the major active components of catnip oil, E,Z and Z,E-nepetalactone, and quantitatively measured their repellent efficacy compared to the repellents N,N-diethyl-3-methylbenzamide (deet) and chiral (1S, 2'S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide (SS220) against biting by the yellowfever mosquito Aedes aegypti (Linnaeus) using human volunteers. In bioassays of the compounds each applied at 2.4 x 10-2 ' mol compound/cm2 skin, neither the individual isomers nor racemic nepetalactone deterred mosquito biting as effectively as SS220 or DEET. We conclude that nepetalactone is relatively ineffective against Aedes aegypti biting compared to deet or SS220.