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Title: Economic implications for the biological control of Arundo donax: Rio Grande Basin

Author
item SEAWRIGHT, EMILY - Texas A&M University
item RISTER, EDWARD - Texas A&M University
item LACEWELL, RONALD - Texas A&M University
item MCCORKLE, DEAN - Texas A&M University
item STURDIVANT, ALLEN - Texas A&M University
item Yang, Chenghai
item Goolsby, John

Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2009
Publication Date: 12/5/2009
Citation: Seawright, E.K., Rister, E.M., Lacewell, R.D., McCorkle, D.A., Sturdivant, A.W., Yang, C., Goolsby, J. 2009. Economic implications for the biological control of Arundo donax: Rio Grande Basin. Southwestern Entomologist. 34(4):377-394.

Interpretive Summary: Arundo donax giant reed is an invasive weed in the Southwestern U.S. It is native to Mediterranean Europe. Giant reed competes for scarce water resources in the Rio Grande Basin and other watersheds of the Southwestern U.S. Control of giant reed could lead to significant water savings in terms of increased run-off into reservoirs. A biological control program has been initiated by the U.S. Dept. of Agriculture, Agricultural Research Service to reduce the shear size and magnitude of this invasive weed in the Rio Grande Basin. Two biological control agents, the Arundo wasp, Tetramesa romana, and Arundo scale, Rhizaspidiotus donacis, have been recommended for release in North America to combat invasive giant reed. Both insects are from the native range of A. donax in Europe and have been extensively studied to assure that they are safe for field release and will not harm native or economic plants. This economic study investigates the potential benefits of water conservation from the A. donax biological control program. With even modest amounts of control, the program is expected to produce favorable economic returns.

Technical Abstract: Giant reed, Arundo donax L., is a large, bamboo-like plant native to the Mediterranean region. It has invaded several thousand hectares of the Rio Grande riparian habitat in Texas and Mexico. The United States Department of Agriculture-Agricultural Research Service (USDA-ARS) is investigating four herbivore insects as potential biological control agents for giant reed. One of the most important reasons for targeting this invasive weed is to reduce its impact on available water supplies, especially in the Rio Grande Basin. This study examined selected economic implications of this program for agricultural water users in the U.S. The research included (a) estimating the value of the water saved (to agricultural purposes) by reduction of giant reed, (b) benefit-cost analyses, (c) regional economic impact analyses, and (d) an estimate of the per-unit life-cycle cost of water saved during a 50-year planning horizon (2009 through 2058). Positive results related to the benefit-cost ratio, economic impact analyses, and competitive results for the per-unit life-cycle cost of saving water are associated with the biological control project for giant reed. The benefit-cost ratio, calculated with normalized prices, indicates a return of $4.38 for every dollar spent on the project. According to 2009 results for the economic impact analyses, economic output is $22,000, value-added is $11,000, and no employment is supported by the water savings from giant reed. Additionally, the per-unit cost of water saved is $44.08, a value comparable to other water conservation projects for the region. These results indicate this program will have positive net economic implications for the U.S. and the Lower Rio Grande Valley of Texas.