The effect of insect herbivores on plant population dynamics (current project)

 

Knowledge about what controls plant population size is fundamental to our understanding of natural systems, and is also at the root of applied problems with invasive and weedy species. While the importance of competition with other plants is widely recognized, the effect of herbivores on plant populations is more contentious. In particular, biologists hold strong but opposing views about the role of insect herbivores in suppressing and regulating plant populations: some contend that insect herbivores have little effect, while others argue that insect herbivores can strongly limit plant population size. The persistence of these conflicting opinions indicates that the nature and prevalence of herbivore effects remains unresolved. Our goal is to fully characterize herbivore effects on the population dynamics of a plant by incorporating effects of herbivores on both population growth rates and density dependence (change in growth rate with plant density) across the life cycle of the plant. In this project Stacey Halpern (Pacific University) and I are using a combination of density manipulation experiments and demographic modeling to investigate whether and how insect herbivores affect population dynamics in the perennial herb Solanum carolinense.

 

Solanum carolinense in captivity