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Mid-Atlantic Invasive Plant Council Biological Control Work Group Report

Biological Control Work Group




Biological control agents help manage invasive plants beyond where we cut, pull and spray.


Purpose and Scope

The group will investigate biological control agents relevant to the mid-Atlantic region and the eastern U.S., affecting aquatic and terrestrial species and ecosystems and provide updates and status reports to the board.  We will ensure that the board is kept informed of relevant research, concerns and approvals and provided with information needed to obtain and use them.



  1. Provide review and current status of research on candidate biological control agents.
  2. Provide land managers practical up-to date information on how to obtain and use approved biological control agents.
  3. Provide the latest information on current distribution and success of available biological control agents in controlling target, non-native invasive plants at the established sites.
  4. Describe potential or actual measures of damage by biological control agents to non-target plants at these sites.

Work Group Members

Marc Imlay, PhD (Chair)

Conservation Biologist

MNCPPC Prince Georges County

Park Ranger Office

Natural and Historical Resources Division

Non-native Invasive Plant Control Coordinator

(301) 442-5657 cell



William L. Bruckart III

Research Plant Pathologist

USDA, ARS, Foreign Disease-Weed Science Research Unit (FDWSRU)

1301 Ditto Ave.

Ft. Detrick, MD 21702

Phone: 301/619-2846

FAX: 301/619-2880



Judy Hough-Goldstein


Dept. Entomology & Wildlife Ecology

University of Delaware

531 South College Ave.

Newark DE 19716-2160

(302) 831-2529 phone



John Peter Thompson

Principal Investigator, Bioeconomic Policy Analyst

Chair, Prince George’s County Historic Preservation Commission

President, National Agricultural Research Alliance-Beltsville

Upper Marlboro, MD

(301) 440 8404



Robert H. Tichenor, Jr.

National Policy Manager Biological Control

USDA APHIS PPQ Plant Health Programs

4700 River Rd, Unit 133, Riverdale, MD 20737

(301) 851-2198





Our tool kit for successful control of non-native invasive plants includes: preventing new invasive species from coming into the United States; manually removing established plants; treating infestations with carefully targeted herbicides; and releasing host-specific biological control agents.

Classical biological control involves the importation and release of host-specific natural enemies to help regulate pest populations (Van Driesche et al. 2010). This strategy is used to manage invasive non-native species that lack effective natural enemies in the region where they have been introduced. In order to avoid direct damage to non-target species, biological control agents must be highly host specific.  Agents are brought over after being tested for host specificity in their native range and then tested in quarantine conditions in the United States. Protocol for evaluating candidate plant pathogens (Berner and Bruckart 2005) is very thorough and similar to that for development of insects and other organisms.


Safety is paramount in the use of biological control agents, particularly if they are of foreign origin.  Agents are only approved for release if testing indicates a very low likelihood of non-target effects, as determined by the Technical Advisory Group for Biological Control Agents of Weeds (TAG), a group of experts that report to USDA, Animal and Plant Health Inspection Service (APHIS). Because some agents introduced into the U.S. prior to the 1980s were not completely host-specific, more value is now placed on conservation of native species; and some of these agents would not be approved for importation today (Van Wilgen et al. 2013). Although such species may provide some control, we do not recommend deliberate release where they have not yet dispersed on their own. .  The safety record in the current regulatory environment is very good, including that of both insects (Pemberton 2000, Van Wilgen et al. 2013), and plant pathogens and other microbials (Barton 2004, 2012; Cook et al. 1996).



Effectiveness of classical biological control can vary, but of 49 invasive plant projects considered in a recent review (Van Driesche et al. 2010), 27% (13) achieved complete control, 33% (16) provided partial control, and 49% (24) were still in progress. Biological control can be dramatic, but results often vary depending on weather and ecological conditions, which can impose different effects on a biological control agent, the target plant, and the competitive ability of the resident community. Suppression of a target plant can also sometimes allow other non-native invasive plants to take over, and therefore restoration planting may be required in some situations (Cutting and Hough-Goldstein 2013; Lake et al. 2013).


Several invasive plant species in Mid-Atlantic natural areas (Swearingen et al. 2010) have one or more host-specific insect species that have been tested and approved for release, while others have had extensive studies conducted on host-specific insects, with petitions for release submitted to TAG, but with proposed releases still under review (TAG Petitions, 2013; see species updates, below).  For some species, biological control agents may already exist in the U.S. in the form of native insects and pathogens that have adapted to the invasive species over time, or non-native species that were accidentally introduced.  These are also included in the species updates, below.MAIPC_BiocontrolWG_Feb 12016

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