The Bugwood Network

Biological Control of Invasive Plants in the Eastern United States


In: Van Driesche, R., et al., 2002, Biological Control of Invasive Plants in the Eastern United States, USDA Forest Service Publication FHTET-2002-04, 413 p.

Invasive plants are species that, after they have been moved from their native habitat to a new location, spread on their own. Some invasive plants reach high densities and cause economic or environmental harm or harm to humans (National Invasive Species Council, 2001).

Problems caused by invasive species have increased dramatically in recent decades due, in part, to an increasing human population (e.g., increased international travel, globalization of world trade). In response, the President issued Executive Order 13112 on Invasive Species in February 1999. The Order established the National Invasive Species Council to provide national leadership to prevent the introduction of invasive species and provide for their control and to minimize the economic, ecological, and human health impacts that invasive species cause.

The Weed Science Society of America recognizes about 2,100 invasive plant species (i.e., noxious or weedy plants) in the United States and Canada. Currently, 94 kinds of invasive plant species are officially recognized as Federal Noxious Weeds and many more species are designated on State noxious weed lists. In the United States, invasive plant species comprise from 8 to 47 percent of the total flora of most States. In 1994, the economic impact of weeds on the United States economy was estimated to be $20 billion annually (Westbrooks, 1998).

Once an invasive plant species becomes established it is not easily suppressed nor eliminated as these species often possess characteristics that favor their population increase, such as early maturation, profuse reproduction by seeds and/or vegetative structures, long life of seeds in the soil, adaptation for spread, and production of biological toxins that suppress the growth of other plants. In addition, many invasive plants are free of attack in their invaded range by specialized insects or plant pathogens, allowing plant resources to be shifted from defense to growth and reproduction.

Integrated invasive plant management relies on a combination of control technologies. These include biological, mechanical, chemical, and cultural applications. Before the mid-1950s, chemical and mechanical applications were the main tactics used to suppress invasive plants in the continental United States. In the 1940s, classical biological plant control efforts were initiated and significantly increased in the United States and since then, biological control has become the most widely used tactic for weed suppression.

Biological control is the science of reconnecting invasive plants with the specialized natural enemies that often limit their density in their native ranges. This process consists of surveys in the plant’s area of origin to discover candidate natural enemies, studies on their biology and host specificity and release and evaluation of their impacts on the target plant. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is responsible for controlling introductions of species brought into the United States for biological control of plants, in accordance with the requirements of several plant quarantine laws, the National Environmental Policy Act, and the Endangered Species Act. Petitions for release of plant biological control agents are judged by a Technical Advisory Committee (TAG), which represents the interests of a diverse set of federal and other agencies.

Biological weed control has been most successful outside of crop lands, primarily in rangeland, pastures, and water bodies. Many projects have been conducted on grazing lands in the semiarid western United States. In the eastern United States, projects have been targeted against aquatic, pasture, and forest weeds. Projects in the western United States have been summarized previously by the W-84 project (Nechols et al., 1995). No such compilation has yet been done for the eastern United States.

The purpose of this book is to provide a reference guide for field workers and land managers concerning the historical and current status of the biological control of invasive plant species in the eastern United States. Weeds associated with lakes, ponds and rivers (Section I); wetlands (Section II); prairies and grasslands (Section III); old fields and pastures (Section IV); and forests (Section V) are discussed. Authors are leaders in research on biological control of the plant species they discuss. Each chapter compiles published articles, unpublished reports and personal experiences of the authors, and provides the most up-to-date and accurate information concerning biological control of each invasive plant species.

The choice of plant species included in this book was based on information found in Julien and Griffiths’ World Catalog of Agents and Their Target Weeds (1998) and 5 years (1995-1999) of programs from National Meetings of the Entomological Society of America. This initial list was reviewed by leading weed biological control scientists (Bernd Blossey, Gary Buckingham, Alex McClay, Loke Kok and Jack DeLoach) before settling on the 31 invasive plant species included here.

We provide this information to assist in the planning and execution of weed biological control projects in the region. We believe that weed biological control projects will increasingly be seen as an essential approach to protecting natural areas, waterbodies, forests, and pastures in the region.


Julien, M. H. and M. W. Griffiths (eds.). 1998. Biological Control of Weeds: A World Catalog of Agents
     and Their Target Weeds. 4th ed. CABI-Bioscience, Wallingford, United Kingdom.

National Invasive Species Council. 2001. Meeting the Invasive Species Challenge: Management Plan.
     Washington, D.C.

Nechols,, J. R., L. A. Andres, J W. Beardsley, R. D. Goeden, and C. G. Jackson (eds.). 1995.
     Biological Control in the Western United States: Accomplishments and Benefits of Regional Project
     W-84, 1964-1989. Division of Agriculture and Natural Resources, Publication 3361, University of
     California, Oakland, California.

Westbrooks, R. G. 1998. Invasive Plants, Changing the Landscape of America: Fact Book. Federal
     Interagency Committee for the Management of Noxious Weeds, Washington, D.C.

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USDA Forest ServiceUSDA APHIS PPQThe Bugwood Network University of Georgia Bargeron, C.T., D.J. Moorhead, G.K. Douce, R.C. Reardon & A.E. Miller
(Tech. Coordinators). 2003. Invasive Plants of the Eastern U.S.:
Identification and Control. USDA Forest Service - Forest Health
Technology Enterprise Team. Morgantown, WV USA. FHTET-2003-08.