Additional beneficial impacts are expected in the U.S. The USDA-ARS arundo biological control project has reduced the ability of arundo to dominate river-side habitats along the Rio Grande, fostering increased plant diversity. A third insect, a leaf-mining fly, has been permitted for release and studies to rear it are underway. Both insects are established in California as well. Along over 500 river-miles of the Rio Grande between Brownsville and Del Rio, the arundo wasp has reduced live weight of arundo shoots by up to 54%, and in the release plots, in a localized manner, the armored scale has reduced live weight by an additional 55%. Both agents were released in the Lower Rio Grande Basin of Texas and Mexico from 2009 to 2013, and since then in the Big Bend area of western Texas and in northern California. Another almost microscopic insect, known as the arundo armored scale, sits immobile on the root or 'rhizome' of arundo and feeds on juices in the rhizome. A tiny black wasp that is harmless to humans, known as the arundo wasp, lays eggs in shoot tips, causing plant tumors, known as galls, to form, and the larvae eat the gall. ARS found two insects in the native range of this invasive grass in Mediterreanean Europe. ARS undertook this project because arundo consumes and wastes water, spreads wildfires, destroys flood control structures and displaces native plants and animals in the southwestern U.S. Biological control of weeds is the process of discovering and testing insects from the weed's native range, then obtaining permits, releasing and evaluating insects that feed and reproduce only on the targeted weed, and cause a lot of damage. Interpretive Summary: The USDA-Agricultural Research Service (ARS) developed a biological control program targeting the non-naive, invasive giant grass known as arundo or giant reed. Food Security, Forestry, and Biodiversity. Contributions of Classical Biocontrol to the U.S. In: Van Driesche, R.G., Winston, R.L., Perring, T.M., Lopez, V.M., editors. Biological control of arundo, an invasive grass threatening water resources and national security. Food Security, Forestry, and Biodiversity, 1985-2022Ĭitation: Moran, P.J., Goolsby, J. Submitted to: Contributions of Classical Biocontrol to the U.S.

Increase in gall fly biocontrol agents