Location: Livestock Arthropod Pests ResearchTitle: Field impacts of the arundo scale, Rhizaspidiotus donacis (Homoptera: Diaspididae) on Arundo donax on the Rio Grande
Submitted to: Subtropical Agriculture and Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2019
Publication Date: 9/4/2019
Citation: Goolsby, J., Moran, P.J. 2019. Field impacts of the arundo scale, Rhizaspidiotus donacis (Homoptera: Diaspididae) on Arundo donax on the Rio Grande. Subtropical Agriculture and Environments. 70:11-16.
Interpretive Summary: The armored scale insect, which is a biological control agent of the invasive weed, Arundo donax a.k.a carrizo cane or giant reed, was released by USDA-ARS in 2009 and became established at multiple sites on the Rio Grande between Del Rio and Brownsville, TX. The arundo scale was found to be environmentally safe for release and was permitted for release in the U.S. and Mexico where giant reed is a serious weed and is consuming economically-significant amounts of water, impacting border security (visibility), facilitating invasion of cattle fever ticks, and other serious environmental impacts. The arundo scale was found to have a significant impact on A. donax in its native range in Mediterranean Europe. Populations of the scale were originally collected from giant reed in Rivesaltes on the Roboul River, near Peripignan in southeastern France, and from Villafranqueza on the Rio Seco near, Alicante, on the southeastern Mediterranean coast of Spain. Field studies conducted in 2019 in Los Indios (Brownsville) and Laredo, TX, found that the scale was having significant impacts on growth of giant reed. As scale populations build, the giant reed is weakened allowing for revegetation of native trees along the Rio Grande and other rivers in the Southwestern U.S. and northern Mexico. The scale in combination with the arundo wasp, released in 2009, are expected to produce significant benefits to agriculture, the environment, and law enforcement in the Rio Grande Basin.
Technical Abstract: The arundo scale, Rhizaspidiotus donacis is a biological control agent of the giant reed, Arundo donax (Poaceae: Arundinoideae), which is an invasive weed in the riparian habitats of the Rio Grande Basin of Texas, the southwestern U.S.A. and northern Mexico. Nine years after its release in 2010 in Texas, studies were conducted to measure its impact on A. donax. The above ground biomass of stands of A. donax with both the arundo scale, R. donacis and the previously-released arundo wasp, Tetramesa romana were compared to adjacent stands with only T. romana. Stands with R. donacis and the wasp had significantly (55%) reduced biomass compared to stands with wasps alone. The arundo scale was found to be an effective biological control agent. The dispersal rate from release sites on the Rio Grande River has limited the impact of the giant reed.