Journal of Chemical Ecology (2004) 30, 1969-1983

Christopher M. Ranger, Rudolph E.K. Winter, George E. Rottinghaus, Elaine A. Backus, Mark R. Ellersieck and David W. Johnson (2004)
Bioactivity of lipophilic metabolites from glandular trichomes of Medicago sativa against the potato leafhopper
Journal of Chemical Ecology 30 (10), 1969-1983
Abstract: Medicago sativa cv. G98A is highly resistant to the potato leafhopper, Empoasca fabae. Glandular trichome extracts from G98A were fractionated using flash chromatography and tested for settling deterrency against the potato leafhopper. A fraction of intermediate polarity exhibited strong, dose-dependent deterrency when applied to the surface of an artificial diet sachet. Deterrency was not detected, however, when the fraction was applied to the internal surface of the sachet membrane (i.e., when contact was limited to only the leafhoppers' stylets). Major components of the highly deterrent fraction, determined by gas chromatography - mass spectrometry, were a homologous series of fatty acid amides C_nH²ⁿ⁺¹NO (n = 19-23) and trace components were 12:0, 13:0, 14:0, 15:0, 16:0, 17:0, 18:0, and possibly 18:1 free fatty acids. Deterrency declined slightly, but was still strong, after fatty acids were removed from crude extracts. When the crude extracts were separated further, a fraction containing only the fatty acid amides was also deterrent. Activity increased when this fraction was supplemented with authentic (C12:0 through C18:0, and C18:1) free fatty acids. However, the authentic free fatty acids were not deterrent when tested without the lipophilic amides. Fatty acid amides and free fatty acids in trichomes of M. sativa G98A may synergize and together function in deterring settling by the potato leafhopper.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Elaine A. Backus

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Empoasca fabae	Alfalfa/lucerne (Medicago sativa)