Southeast Exotic Pest Plant Council

BIOLOGICAL CONTROL: WHAT IS UNDERWAY AND WHAT IS POSSIBLE AND IMPOSSIBLE. Ted D. Center, USDA Agricultural Research Service, Invasive Plant Research Laboratory, 3225 College Ave., Davie, FL 33314 (


Long-term suppression of the most dangerous invasive plants in the southeastern US will not be possible without the intervention of biological control. The time-tested practice of selecting and carefully screening specialist plant-feeding insects, mites, and plant pathogens as biological control agents has repeatedly proven to be very safe, although never completely without risk. Many of the insects that have been released worldwide to combat invasive plants are causing substantial damage to their respective targeted weeds. However, the degree of control achieved has been variable. Some of these biological control agents have produced complete control while others have produced no control, but the vast majority falls within the gray area between these two extremes. In these cases, some level of suppression has resulted but other methods (or additional agents) are still needed to reduce the weed to acceptable levels. Unrealistic expectations may cause the outcomes of biological control attempts to be perceived as failures when the target weed is not brought under complete and total control. However, biological control agents that cause even moderate levels of damage to the targeted weed can have considerable value. The way forward is to develop carefully crafted management plans that employ biological control as the basic tactic within a fully integrated strategy that capitalizes upon the strengths of all methods of control. Success must be measured against expectations, so expected results should be clearly defined and advertised beforehand. Each biological control agent should be thoroughly evaluated so that appropriate management strategies, including herbicidal and mechanical control, can be integrated in a manner that maximizes the performance of the biological control agents. Examples of projects from around the world will be discussed. The availability of new, modern, state-of-the-art quarantine facilities will greatly enhance our ability to provide biological control options for use in weed control programs.

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