An integrated approach to the restoration of areas invaded by mile-a-minute weed (Persicaria perfoliata) using biological control and herbaceous native seeding
University of Delaware
Disturbed areas frequently experience invasion by introduced plant species and subsequently a drop in species richness and ecosystem services. Research on the best means of removing these species abounds, but typically does not include techniques to restore the invaded habitat. Without such restoration the introduced species often re-occur, or an alternate introduced invasive plant fills the opened niche. This study investigated an integrated approach to controlling the introduced annual Persicaria perfoliata [L.] H. Gross (mile-a-minute weed) using the Asian biocontrol weevil Rhinoncomimus latipes Korotyaev (Coleoptera: Curculionidae) and establishment of native plants from seed. The native seed mix used was comprised of five widely adapted plant species, three grasses and two forbs. A fully factorial design integrated weevils and seeding, using a systemic insecticide as a control. In a field setting, areas of well-established mile-a-minute weed were sown with natives in early spring when the weed germinated. A weevil population had been established at the site one year prior to sowing and was augmented both years of the experiment. By year two there was significantly lower P. perfoliata mean biomass and percent cover in plots integrating weevils and native seeds than seed-only or control plots. Further, the integrated plots had about half the mile-a-minute biomass and percent cover of the weevil-only treatment. Greenhouse experiments of the same basic design produced similar results. There was little evidence of native plant establishment during the first year in the field. Year two resulted in significantly higher native plant species richness in the integrated weevil and native seed-treated plots. These results indicate that removal of introduced invasive plant species should be accompanied by re-vegetation to aid in restoration.