El-Sayed, A.M, Byers, J.A., Manning, L.M., Jürgens, A., Mitchell, V.J., and Suckling, D.M. 2008. Floral scent of Canada thistle and its potential as a generic insect attractant. Journal of Economic Entomology 101:720-727.
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Abstract--
The Flowers of Canada thistle, Cirsium arvense (L.), attract a wide range of insects,
including pollinators and herbivorous species. This attraction is primarily mediated by floral odor,
which offers potential for developing generic insect attractants based on odor. In this study, we have
analyzed the chemical composition of the volatiles produced by Canada thistle flowers. Nineteen floral
compounds were identified in the headspace, including phenylacetaldehyde (55%), methyl salicylate
(14%), dimethyl salicylate (8%), pyranoid linalool oxide (4.5%), and benzaldehyde (3.5%). Other
minor compounds include benzyl alcohol, methylbenzoate, linalool, phenylethyl alcohol, furanoid
linalool oxide, p-anisaldehyde, 2,6-dimethyl-1,3,5,7-octatetraene, benzylacetate, benzyl tiglate, (E,E)-
alpha-farnesene, benzyl benzoate, isopropyl myristate, and 2-phenylethyl ester benzoic acid. The relative
attractiveness of various doses of the main floral volatile compound phenylacetaldehyde (i.e., 10, 100,
200, and 400 mg) was tested for insect attraction. Both the total catch and the biodiversity of insect
species trapped increased as the loading of phenylacetaldehyde increased. Volatiles were chosen from
the odors from the flowers of Canada thistle and formulated and tested in the field. An 11-component
blend was the most attractive of several floral blends tested. These findings indicate that chemical
components of flower odors of Canada thistle can serve as a generic insect attractant for monitoring
of invasive pest species.
Chemical Ecology