Humans often transport organisms over long distances and bring into contact species that were once geographically separated. If similar species can interbreed when in contact, hybrids will be created. Hybridization is therefore increasing, but the ecological consequences are not well understood. Herbivorous insects often respond to hybrid plants differently than they would to the original plant species. The response of insects to hybrids affects the abundance of insect herbivores and the success of other organisms that feed on the insects.
This research investigates the phenomenon of hybrid resistance, in which fewer herbivores are found on hybrid plants than on the original parental species. Hybrid resistance has been documented on hybrids of cattail species (Typha). The moth Limnaecia phragmitella is less abundant on hybrids but the reasons for this resistance are not known. The first objective of this project is to determine whether insect species other than the moth respond in a similar way to hybrids. The second objective is to discover why moths are less abundant on hybrids. There are two possibilities: (1) Female moths do not recognize hybrids and avoid laying eggs on them, and (2) Larval survival on hybrids is poor.
The results of this study will help predict and manage the outcomes of other hybridization events. There is also growing concern over the hybrid cattail, because it is an aggressive competitor and excludes other plants in wetlands. Herbivore resistance may contribute to the hybrids' competitiveness and lower the value of hybrid-dominated marshes as habitat for other organisms.
