ARS | Publication request: Eupatorium capillifolium essential oil: chemical composition antifungal activity and insecticidal activity

Submitted to: Natural Product Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 2010
Publication Date: September 15, 2010
Citation: Tabanca, N., Bernier, U.R., Tsikolia, M., Becnel, J.J., Sampson, B.J., Werle, C.T., Demrici, B., Baser, K., Blythe, E.K., Pounders Jr, C.T., Wedge, D.E. 2010. Eupatorium capillifolium essential oil: chemical composition, antifungal activity and insecticidal activity. Natural Product Communications. 5(9):1409-1415.

Interpretive Summary: Eupatorium capillifolium (dog-fennel) is an herbaceous perennial in the family Asteraceae. Eupatorium capillifolium is native to North America and found primarily in the southeastern United States. E. capillifolium is characterized by its fine-textured leaves, narrow leaf segments, and very distinctive odor. It is considered one of the 10 most problematic weeds in southeastern U.S. The chemical composition, antifungal and insecticidal activities of essential oil obtained by hydrodistillation of E. capillifolium aerial parts were investigated in this study. The oil showed weak antifungal activity against the plant pathogens Colletotrichum acutatum, C. fragariae, and C. gloeosporioides in direct bioautography assay. The main constituents were found to be thymol methyl ether (=methyl thymol) (36.3%), 2,5-dimethoxy-p-cymene (20.8%) and myrcene (15.7%) in the total of oil. The E. capillifolium oil showed promising repellent activity against the yellow fever mosquito Aedes aegypti, whereas the oil exhibited moderate activity against the mosquito’s first instar larvae in a high throughput bioassay. ), The oil killed greater than 95% of adult bugs at 1% concentration after 3h exposure against azalea lace bug (Stephanitis pyrioides).

Technical Abstract: Natural plant extracts often contain compounds that are useful in pest management applications. The essential oil of Eupatorium capillifolium (dog-fennel) was investigated for antifungal and insecticidal activities. Essential oil obtained by hydrodistillation of aerial parts was analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC/MS). The major components were determined to be thymol methyl ether (=methyl thymol) (36.3%), 2,5-dimethoxy-p-cymene (20.8%) and myrcene (15.7%). Antifungal activity of the essential oil was weak against the plant pathogens Colletotrichum acutatum, C. fragariae, and C. gloeosporioides in direct bioautography assay. The E. capillifolium oil showed promising repellent activity against the yellow fever mosquito Aedes aegypti, whereas the oil exhibited moderate activity against the mosquito’s first instar larvae in a high throughput bioassay. Topical applications of the oil showed no activity against the blood-feeding female adults of Ae. aegypti. Eupatorium capillifolium essential oil showed a linear dose response between adult lace bug (Stephanitis pyrioides) mortality and increasing oil concentration in an adulticidal activity bioassay. The dog-fennel oil was more potent than the conventional insecticide malathion. In conclusion, these combined results showed Eupatorium capillifolium oil is a promising novel source of a biological insecticide with multiple modes of action.