No evidence of non-target use of native or economic grasses and broadleaf plants by Arundo donax biological control agents

Authors: Goolsby, John; HATHCOCK, CHRIS - Us Fish And Wildlife Service; VACEK, ANN - University Of Texas Rio Grande Valley; KARIYAT, RUPESH - University Of Texas Rio Grande Valley; Moran, Patrick; MARTINEZ JIMÉNEZ, MARICELA - Instituto Mexicano De Tecnologia Del Aguas

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2020
Publication Date: 6/1/2020
Citation: Goolsby, J., Hathcock, C., Vacek, A., Kariyat, R., Moran, P.J., Martinez-Jiminez, M. 2020. No evidence of non-target use of native or economic grasses and broadleaf plants by Arundo donax biological control agents. Biocontrol Science and Technology. 30(8):795-805. https://doi.org/10.1080/09583157.2020.1767038.
DOI: https://doi.org/10.1080/09583157.2020.1767038

Interpretive Summary: Arundo donax, also known as giant reed or carrizo cane, is an invasive weed native to Mediterranean Europe. It was introduced into the Rio Grande Basin from Spain and has become invasive in the riverine habitats of the southwestern United States and northern Mexico including the Rio Grande River. Arundo donax has historically dominated these habitats where it competes for scarce water resources, lowers riparian biodiversity, reduces access and visibility for law enforcement, and facilitates the invasion and survival of cattle fever ticks from Mexico. Two biological control insects, Tetramesa romana, a stem-feeding wasp, and the arundo scale, a root-feeder, have been established in Texas, USA and Morelos, Mexico for ten years. Surveys were conducted in these areas to determine if there was any feeding on plants other than giant reed. No evidence was found of feeding or development on any other plant species, including the most closely related plant species, common reed, which grows with giant reed in riverine environments, and Texas wild rice, an endangered aquatic grass on the San Marcos River in Central Texas. The field results from these surveys matched the results from lab testing and records from Europe where they are native. The biological control agents proved to be environmentally safe and effective.

Technical Abstract: Arundo donax, also known as giant reed or carrizo cane, is an invasive weed native to Mediterranean Europe. It was introduced into the Rio Grande Basin from Spain and has become invasive in the riverine habitats of the southwestern United States and northern Mexico including the Rio Grande River. Arundo donax has historically dominated these habitats where it competes for scarce water resources, lowers riparian biodiversity, reduces access and visibility for law enforcement, and facilitates the invasion and survival of cattle fever ticks from Mexico. Two Arundo donax biological control agents, Tetramesa romana, the Arundo wasp, and Rhizaspidiotus donacis, the Arundo scale, have been established in Texas, USA and Morelos, Mexico for ten years. Surveys were conducted in these areas to determine if there was any use of non-target plant species, especially where the biological control agents occurred at high densities. No non-target use was found in examinations of over 1300 plant specimens representing 5 native grasses, 6 introduced grasses, 2 crop grasses, and one broadleaf species. Surveys included over 700 specimens, including the most closely related plant species, Phragmites australis, common reed, which is sympatric with A. donax in riparian habitats, and also Zizania texana, Texas wild rice, an endangered aquatic grass in Central Texas. The field (realized) host range of T. romana and R. donacis confirms the predicted host range of these species from quarantine host range testing.