Volatiles from flowers of Platanthera bifolia (Orchidaceae) attractive to the silver Y moth, Autographa gamma (Lepidoptera : Noctuidae)

We examined the attractiveness of a natural headspace sample of [i]Platanthera bifolia[/i blossoms, synthetic blends and Single compounds to the silver Y moth, Autographa gamma, in a flight tunnel. The synthetic blend consisted of previously identified electrophysiologically active compounds from P. bifolia: benzyl benzoate, benzyl salicylate, cinnamyl alcohol, lilac aldehydes, methyl benzoate and methyl salicylate. This blend had a similar attractivity as the natural headspace sample. Subtraction of lilac aldehydes significantly decreased attractiveness of the synthetic blend. When a mixture of lilac aldehydes was tested alone. it showed attractiveness similar to that of the synthetic blend. One or a mixture of lilac aldehydes accounts for the attraction of moths to P. bifolia. All other Compounds elicited significantly lower responses. Results are discussed in relation to the pollination biology of P. bifolia.