Location: Mosquito and Fly Research Unit
Title: Biting deterrence and larvicidal activity of Ruta chalepensis L. essential oil and its major individual constituents against mosquitoes Authors
|Ali, Abbas -|
|Demirci, Betul -|
|Kiyan, Hulya -|
|Khan, Ikhlas -|
|Baser, Kemal Husnu -|
|Tabanca, Nurhayat -|
Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 20, 2013
Publication Date: N/A
Interpretive Summary: Mosquito-borne diseases such as malaria, dengue fever and West Nile neuroinvasive disease negatively impact human health worldwide. In some areas, natural repellents may be the only economically feasible means of personal protection for humans and in cases for their animals. Scientists the Center for Medical, Agricultural, and Veterinary Entomology, USDA, ARS, Gainesville, Florida and Natural Products Utilization Research Unit in University, MS have collaborated with researchers at the University of Mississippi, the Anadolu University in Turkey, and King Saud University in Saudi Arabia to evaluate the mosquito repellency of the oil and individual compounds found in the date palm. The substances were evaluated for toxicity and screened by two different systems to determine the ability of the compounds to repel or prevent feeding by mosquitoes. Two species of mosquito, one that transmits malaria and another that transmits yellow and dengue fevers were used for these experiments. The oil itself was found to be repellent, but not as potent as the standard DEET. The results of this research may be useful to other researchers, health care professionals and groups interested in the development of natural product alternatives to synthetic repellents.
Technical Abstract: The essential oil from aerial parts of Ruta chalepensis L. (Rutaceae) was obtained by hydrodistillation and its chemical profile was identified using gas chromatography and gas chromatography-mass spectrometry. 2-Undecanone (43.2% ± 0.8), 2-nonanone (27.9% ± 0.8) and 2-nonyl acetate (10.6% ± 0.2) were the major constituents of the oil. We evaluated R. chalepensis essential oil and its major compounds for mosquito biting deterrence and larvicidal activity against Aedes aegypti L. Ruta chalepensis oil at 10 µg/cm2 and 2-undecanone, 2-nonanone and 2-nonyl acetate at 25 nmol/cm2 concentration showed significantly lower biting deterrent activity than DEET at 25 nmol.cm2. R. chalepensis oil at 50 µg/cm2 and 2-undecanone at 50 nmol/cm2 concentration showed significantly higher biting deterrent activity than DEET at 25 nmol/cm2 while the activity of 2-nonanone and 2-nonyl acetate was similar to DEET. Feeding deterrent activity of R. chalepensis oil at 50 µg/cm2 was statistically similar to DEET at 25 nmol/cm2 against An. quadrimaculatus whereas activity was lower in the pure compounds tested. R. chalepensis oil showed repellent activity down to a minimum effective dosage (MED) of 187 µg/cm2 in the cloth patch assay. The most potent individual compound was 2-undecanone with an MED value of 641 nmol/cm2 compared to 2-Nonanone and 2-nonyl acetate were much less potent with MED values of 1760 and 1392 nmol/cm2, respectively. In larval bioassays, R. chalepensis essential oil had LD50 value of 21.25 (19.6-23.7) ppm while 2-undecanone with LC50 value of 14.37 (12.67-16.26) was significantly more active than oil against 1-d old A. aegypti larvae. 2-Nonanone had LD50 of 106.9 (95.2-119.9) ppm and 2-nonyl acetate did not show any activity. In An. quadrimaculatus, R. chalepensis essential oil with LD50 value of 14.9 (11.8 – 18.8) ppm and 2-undecanone with LC50 value of 14.2 (11.3 -17.6) were statistically similar. 2-Undecanone showed similar toxicity in both species while toxicity of R. chalepensis essential oil and 2-nonanone was significantly higher in An. quadrimaculatus than Ae. aegypti.