Simulated herbivory reduces seed production in Vincetoxicum rossicum

Vincetoxicum rossicum (Kleopow) Barbar. (Apocynaceae) is an exotic invasive perennial vine that is spreading rapidly throughout northeastern North America. Its spread threatens native plant communities and the animals that depend on them. While V. rossicum is known to have specialist insect herbivores in its native range, it has escaped herbivory in its introduced range. A biological control program is currently being developed to identify an insect agent that could be released in North America to control V. rossicum. In this study, we simulated leaf and root herbivory on individual plants in naturally occurring populations of V. rossicum to estimate the impact of different feeding guilds and damage levels on seed production in sunny and shady sites. Damage intensity (0%, 30%, 60%, or 90% tissue removal) had a greater impact on seed output than damage type (root vs. leaf), although root damage was slightly more effective than leaf damage. We discuss the implications for biological control programs targeting this invasive exotic plant.