A Comparison of Herbivore Damage on Three Invasive Plants and Their Native Congeners: Implications for the Enemy Release Hypothesis


Varma-Rose J. Williams

Additional Authors:

Heather F. Sahli


June 2016


Enemy Release Hypothesis, Fallopia japonica, invasive species, Persicaria perfoliata, Rubus phoenicolasius

ABSTRACT One explanation for the success of exotic plants in their introduced habitats is that, upon arriving to a new continent, plants escaped their native herbivores or pathogens, resulting in less damage and lower abundance of enemies than closely related native species (enemy release hypothesis). We tested whether the three exotic plant species, Rubus phoenicolasius (wineberry), Fallopia japonica (Japanese knotweed), and Persicaria perfoliata (mile-a-minute weed), suffered less herbivory or pathogen attack than native species by comparing leaf damage and invertebrate herbivore abundance and diversity on the invasive species and their native congeners. Fallopia japonica and R. phoenicolasius received less leaf damage than their native congeners, and F. japonica also contained a lower diversity and abundance of invertebrate herbivores. If the observed decrease in damage experienced by these two plant species contributes to increased fitness, then escape from enemies may provide at least a partial explanation for their invasiveness. However, P. perfoliata actually received greater leaf damage than its native congener. Rhinoncomimus latipes, a weevil previously introduced in the United States as a biological control for P. perfoliata, accounted for the greatest abundance of insects collected from P. perfoliata. Therefore, it is likely that the biocontrol R. latipes was responsible for the greater damage on P. perfoliata, suggesting this insect may be effective at controlling P. perfoliata populations if its growth and reproduction is affected by the increased herbivore damage.