Location: Emerging Pests and Pathogens Research
Project Number: 8062-22620-005-00-D
Project Type: In-House Appropriated
Start Date: Nov 2, 2015
End Date: Nov 1, 2020
Biological control is considered the only long-term control option for many invasive plants. Enhancing the probability of successful biological control requires the identification of not only host-specific biological control agents (although non-specific agents may be feasible in certain situations) but also effective agents. This in turn depends upon a fundamental knowledge of a target weed’s biology, genetics, and population dynamics to inform agent selection. Long-term monitoring is needed to verify the specificity and efficacy of field-released agents. It is also important to understand why biological control may not be feasible with currently available agents. Our objectives are to: Objective 1: Evaluate host specificity, efficacy, or other biological traits of biological control agents of invasive plants, especially swallow-wort and eastern knapweeds; and determine the biology, ecology and demography of these weeds. Subobjective 1a: Assess agents of swallow-wort and knapweed. Subobjective 1b: Elucidate the genetic structure of knapweed populations in the Northeast. Subobjective 1c: Determine demographic rates for swallow-wort and knapweed. Objective 2: Release approved biological control agents and evaluate their establishment, phenology, and impact on weed populations and other flora, for invasive plants such as swallow-wort.
European swallow-worts (Vincetoxicum spp.) and knapweeds (Centaurea spp.) are invasive weeds of continued or increasing concern, respectively, in the northeastern U.S. They invade a variety of natural and managed terrestrial ecosystems. A biological control program for swallow-worts has been in development since 2004. This project will evaluate remaining potential insect and fungal agents of swallow-wort for host range and/or life history traits and plant impact in laboratory, greenhouse and (as appropriate) field studies, and implement a biological control agent (a defoliating moth that is anticipated for approval) to control pale and black swallow-wort. Long-term monitoring plots, already established at several sites, will help document the released agent’s impact on swallow-wort and resulting responses of invaded plant communities. A remaining knowledge gap of swallow-wort demography (years to first reproduction) will continue to be investigated in a field experiment. The genetics of the fertile hybrid meadow knapweed and demography of northeastern populations of spotted and meadow knapweed will be investigated through field and common garden studies. Initial assessment of a seed-feeding biological control agent on meadow knapweed will be made in the greenhouse to understand its potential impact. Successful implementation of this program should lead to the suppression of the two swallow-wort species in some of the habitats they have invaded, and define future control measures to be implemented against knapweeds.