The impact of drought and herbivory on the invasive annual vine Persicaria perfoliata

Mile-a-minute weed, Persicaria perfoliata, is an invasive annual vine currently established in 12 mid-Atlantic and northeastern states. A fully factorial greenhouse experiment exposed mile-a-minute to drought and herbivory conditions over an eleven week period. Drought was maintained by withholding water until plants showed signs of water stress. The herbivory treatment consisted of caging the biological control agent Rhinoncomimus latipes (Coleoptera: Curculionidae) with the plants. Both the total number of seeds produced and base stem thickness of the plants were significantly reduced by both the drought and herbivory treatments. The final dry biomass of the plants was only reduced by drought, while seed weight was not significantly affected by either treatment. The environmental factors that influence the weed’s interactions with its control agent may be important for managing new and established populations over its range.