2008 Annual Report 1a.Objectives (from AD-416) To investigate the environmental impact of the invasive weed Arundo donax, carrizo gigante, in Mexico, and to evaluate key candidate biological control agents. 1b.Approach (from AD-416) Sites in Mexico with infestations of Arundo donax will be established to determine the impact of this invasive weed on the native flora and water resources. 3.Progress Report Invasive exotic plant species and other noxious weeds pose a huge and increasing threat to agriculture and native ecosystems throughout North America. In our region, which includes the Rio Grande River watershed, invasive weeds degrade the riparian environment and consume water resources in an arid region impacted by recurrent drought. Arundo donax L. is one of the most serious and widespread invasive weeds in the watershed, and a biological control program is needed because available chemical and mechanical control methods are not applicable over such a large area. The introduction of natural enemies from the origin of the A. donax (Mediterranean Europe) could be an effective solution, but these agents must be rigorously evaluated for both safety and efficacy. This project was initiated in FY 2008 to extend the benefits of the A. donax biological control program to the Mexican part of the Rio Grande Basin (RGB). Collaborators with IMTA have documented the impact of A. donax in the Rio Grande Basin, northern states of Mexico, and the lakes of the central highlands. Pending approval for release in N. America, the biological control agents will be mass reared, released, and evaluated in Mexico. Biological control of A. donax is expected to result in significant water conservation and environmental restoration of riparian areas. The ADODR is in regular contact via email with cooperator.