Lessons for biofuels from the experience with invasive giant reed and its biological control

Arundo donax L., giant reed, carrizo cane, is an exotic and invasive weed of riparian habitats in the southwestern U.S. and northern Mexico. Giant reed dominates these habitats, which leads to: loss of biodiversity; stream bank erosion; damage to bridges; increased costs for chemical or mechanical control along irrigation canals and transportation corridors; and impedes access for law enforcement personnel. This invasive weed also competes for water resources in an arid region where these resources are critical to the environment, agriculture and municipalities. Biological control using insects from the native range of giant reed are the best option for long-term management because this technology is environmentally friendly, self-sustaining and applicable for large areas such as the Rio Grande. Arundo donax is a good target for biological control because it has no close relatives in North or South America, and several of the plant feeding insects from Mediterranean Europe and known to only feed on A. donax. Since the program began in 2007, extensive research has been completed and biological control agents have been permitted for release in the U.S. and Mexico, which are the stem-galling arundo wasp, Tetramesa romana and the root-feeding armored scale, Rhizaspidiotus donacis, both were collected from the origin of the invasive weed in Mediterranean Spain. Implementation of a biological control program may reduce the invasiveness and impacts of this exotic weed in natural areas, thereby reducing the environmental risk of utilizing giant reed in managed agricultural biofuel plantings.