Evidence for an isobutylamide associated with host-plant resistance to western flower thrips, Frankliniella occidentalis, in chrysanthemum

Bioassay-directed fractionation of extracts of chrysanthemum leaves using a choice test permitted isolation of a fraction that exhibited repellent activity against the western flower thrips (WFT). Analysis of this fraction from cultivars exhibiting varying degrees of host-plant resistance to WFT by high performance liquid chromatography revealed a distinctive peak, the height of which correlated with the degree of resistance of those cultivars to WFT. The peak was attributed to a novel unsaturated isobutylamide, N-isobutyl-(E, E, E, Z)-2,4,10,12-tetradecatetraen-8-ynamide.