This research will investigate a three trophic level interaction in a hybrid zone of cattails. The three levels of interactions include: the cattails and the hybrid, herbivores that eat the seeds of the cattails, and parasites that infect the seed-eating herbivores. To study how herbivory varies among the three types of cattails, field experiments will examine the herbivore loads sustained by these cattails over a broad geographic range. The role that hybridization and introgression play in influencing rates of herbivory and parasitoidism will be addressed with a transplant study using potted plants of various crosses. Herbivore exclusion and addition experiments will examine 1) whether the pattern of reduced herbivory on the hybrid cattails can be attributed to plant properties or parasites, 2) the degree of dependence that one species of seed eating herbivore has on the presence of another. %%% ALthough hybridization of plants has been responsible for 30-70% of the genetic variation in and among plant species, little is known about the three-way interactions that occur in zones of hybridization. By focussing on the patterns of herbivory and the herbivore-natural enemy interactions, the dynamic nature of plant hybrid zones will be elucidated. This research will make an important contribution to understanding the role of hybridization and control of natural enemies in plant populations.
