Pheromone identification and headspace emissions from Eucosma giganteana (Lepidoptera: Tortricidae) in response to conspecifics and host plants

Silphium, also known as the cup plant, is a new plant that has large potential for economic change as it is being developed as a form of biofuel in the midwestern United States. One of its primary pests is Eucosma giganteana, a moth with larva that bore into the roots and stems of the plant, ultimately decreasing the yield of the plant. Research has shown that their population peaks during the summer months, between May and July. As is the case with many pests, there is a push for a reduced-risk pest management system to be developed for this species. However, there is a lack of research on the chemical ecology of this pest, thus the goal of this study was to identify the sex pheromone that this moth produces. We conducted headspace collections for pheromone emissions in chambers with males only, females only, and both sexes present over 48 h periods. Microdissections were also performed to isolate the sex pheromone gland, which were then run using gas chromatography coupled with mass spectrometry. We demonstrated that emissions are primarily nocturnal, corresponding to the natural period of peak activity for E. giganteana. Moreover, we found the putative pheromone was structurally similar to related Eucosma species. This research will greatly contribute to the development of a behaviorally-based management system for E. giganteana and thus to the success of developing Silphium for its multitude of possible uses.