Submitted to: International Symposium on Biological Control of Weeds
Publication Type: Proceedings
Publication Acceptance Date: March 1, 2007
Publication Date: April 27, 2007
Citation: Center, T.D., Pratt, P.D., Tipping, P.W., Rayamajhi, M.B., Wright, S.A., Purcell, M.F. 2007. Biological Control of Melaleuca quinquenervia: Goal-based Assessment of Success.. International Symposium on Biological Control of Weeds. 655-667. Interpretive Summary: Biological control is often called upon to solve intractable weed problems only after all other methods have failed. As a result, the success rate of biological control programs is often depicted as poor. Evaluations of success are often based on opinions of bystanders rather than on the attainment of the objectives established by the project originators. This paper suggests that objectives should be announced and advertised early during the course of a weed biological control project so that success can be properly credited when it occurs. The recent melaleuca project is used as an example wherein the goal was not to eliminate stands of this large Australian tree but rather to reduce its ability to reinfest areas where it has been removed and prevent its further spread. These goals have largely been met so this projects should be deemed successful. Additional effort is likely to further add to the benefits of this program.
Technical Abstract: Success means different things to different people. Unfortunately, the success or failure of weed biological control projects is often evaluated by non-participants lacking knowledge of the original goals set by project architects. The Australian tree Melaleuca quinquenervia, which is an aggressive invader of the Florida Everglades, is probably the largest plant ever targeted for biological control. We realized early on that biological control agents would not remove the many tons of woody biomass that comprised these infestations and so would be unlikely to reduce the infested acreage. Control of this plant by other means, however, was complicated by the billions of canopy-held seeds that are released following injury to the tree. A plan was developed in coordination with land management agencies wherein the goal of biological control was to curtail melaleuca expansion and suppress regeneration while other means would be employed to remove mature trees. Three insects have been released and others are under consideration. These agents, supplemented by the impacts of an adventive rust fungus and a pestiferous scale insect, have met established goals and this project shows clear signs of an emerging success. Criteria for success should match objectives and goals should be clearly articulated so that success can be properly archived for future synthesis.