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Title: Development and impact of biological control of giant reed, Arundo donax, in the Rio Grande Basin of the U.S. and Mexico

item Goolsby, John
item Moran, Patrick
item Everitt, James
item Yang, Chenghai
item Spencer, David

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2008
Publication Date: 7/12/2008
Citation: Goolsby, J., Moran, P.J., Everitt, J.H., Yang, C., Contreras-Arquieta, B., Watts, D., Moore, G., Spencer, D.F., Seaqright, E., Lacewell, R. 2008. Development and impact of biological control of giant reed, Arundo donax, in the Rio Grande Basin of the U.S. and Mexico. Meeting Abstract. CDROM.

Interpretive Summary:

Technical Abstract: Giant reed (Arundo donax L.) also known as giant cane or carrizo cane, is an exotic perennial grass that has infested over 60,000 hectares along riparian corridors in the southwestern U.S. The most severe infestations are in the Lower Rio Grande Basin, where giant reed along the Rio Grande and Mexican tributaries threatens critical water resources in Texas and northern Mexico. Giant reed removes water valued at up to $20 million per year, alters stream flow patterns, increases stream bank erosion, exacerbates flood damage to water resource and transportation infrastructure, fuels wildfires along rivers, displaces native plants and the animals that depend on them, and hinders law enforcement. Giant reed infestations have typically required expensive chemical and mechanical control, with collateral damage to native ecosystems. The USDA-Agricultural Research Service has developed a biological control program for giant reed involving several insects. Studies on the host range and biology of a stem-galling wasp, Tetramesa romana, and a juice-sucking scale insect that feeds on leaves and roots, Rhizaspidiotis donacis, have been completed and petitions for the release of these agents into the field in North America are in review. We have shown that these agents do not harm non-target native grasses, crops, or habitat associates. Laboratory experiments on the wasp and scale insect and studies of an adventive population of T. romana wasps near Laredo, Texas, demonstrated that both of these agents produce many offspring on giant reed, complete multiple generations per year, and can be mass-reared, demonstrating that they can rapidly establish on mature and regrowth shoots in giant reed infestations. In greenhouse studies, the wasp and the scale insect reduced plant height and water use, altered shoot branching patterns and increased shoot mortality compared to plants protected from attack. Laboratory studies are underway on additional biological control agents that feed on and kill young giant reed shoots as they emerge from the soil, or destroy leaf blades. Technology is now being developed to inundate field infestations of giant reed with biological control agents to reduce the ecological and economic impacts of this harmful invader.