Electrophysiologically-Active Maize Volatiles Attract Gravid Female European Corn Borer, Ostrinia nubilalis

The European corn borer (ECB) is an important pest of maize in the northern hemisphere, but no reliable techniques exist for monitoring females during their reproductive period. In this study, we aimed to identify host-plant volatiles used by gravid Z-strain females in search for oviposition sites. Headspace of maize plants, to which gravid females orientated in a wind tunnel, was collected, and physiologically-active components were identified by using gas chromatography (GC) coupled with electroantennographic detection followed by GC-mass spectrometry. The antennae of female moths consistently responded to two maize volatiles, nonanal and decanal. Although these compounds are individually not characteristic for maize, a synthetic mix in a ratio found in maize headspace, 1:2.4 at 1 mu g mu l(-1) induced source contact and landing responses similar to maize plants in the wind tunnel. However, fewer females took flight in response to the mix, and those that took flight did so with an increased latency. To our knowledge, this is the first blend of host-plant volatiles that has been found to be physiologically active and to be able to induce attraction of gravid ECB females under laboratory conditions. Future tests will evaluate the attractiveness of the blend to the E-strain of ECB, the attractiveness of the blend in the field, and its potential in monitoring ECB populations.