Biting Deterrent and Larvicidal Activity of Essential Oils of Magnolia grandiflora Against Aedes aegypti

In the search for mosquito biting deterrent and larvicidal compounds from natural sources, we investigated essential oils from different plant parts of Magnolia grandiflora L. (Magnoliaceae). We separately obtained essential oils from air dried samples of seeds, deseeded unripe and mature fruits and leaves of M. grandiflora by water distillation. Chemical composition of the oils was analyzed by GC-FID and GC-MS analyses. The following are the major constituents found in different plant parts: Seeds with aril: 8.8% β-caryophyllene, 7.3% β-phellandrene, 6.2% octanol and 5.5% p-cymene; deseeded unripe fruit: 12.9% β-elemene, 12.7% β-pinene, 7.9% β-caryophyllene and 5.1% α-terpineol; deseeded mature fruit: 12.2% 1,8 cineole, 7.2% caryophyllene oxide, 6.9% β-pinene and 5.7% β-elemene; leaves: 23.0% β-pinene, 13.6% β-elemene and 6.3% α-pinene. All essential oils were subjected to biting deterrent and larvicidal activity against Aedes aegypti. All essential oils showed larvicidal and biting deterrent activity. The LD₅₀ values of three of essential oils ranged between 51.5 and 54.7 ppm against first instar larvae. Biting deterrent activity of one of the essential oils was equivalent to DEET with proportion not biting value of 0.94 versus 0.90, respectively. Acknowledgements. This study was supported by USDA, ARS grant No. 56 – 6402 – 1-612 and Deployed War-Fighter Protection (DWFP) Research Program and the U.S. Department of Defense through the Armed Forces Pest Management Board (AFPMB).