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 Platanthera bifolia 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 .