The corn earworm, Helicoverpa zea, is one of the major agricultural pests in the US, and has developed resistance to a number of conventional pesticide treatments. H. zea overwinters in pupal diapause, and diapause is terminated in the spring by a neuropeptide called diapause hormone. Our lab is interesting in developing structural agonists and antagonists to diapause hormone, in an attempt to disrupt development as a means of controlling H. zea populations. We have developed a number of synthetic compounds that mimic diapause hormone action, even some that are more potent than the hormone itself. These compounds revealed the structural characteristics of diapause hormone that are essential for its action and identified potential chemical agents for prematurely terminating diapause in H. zea. In future studies we will attempt to modify the structure of these agonists so that they can be applied topically or orally.
Figure 1. Optimum temperature for activity of diapause hormone (left) and the ability of structural analogs of diapause hormone to terminate diapause in H. zea. (right)