Submitted to: Southwestern Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2009
Publication Date: 12/1/2009
Citation: Goolsby, J., Spencer, D.F., Whitehand, L.C. 2009. Pre-release assessment of impact on Arundo donax by the candidate biological control agents, Tetramesa romana (Hymenoptera: Eurytomidae) and Rhizaspidiotus donacis (Homoptera: Diaspididae) under quarantine conditions. Southwestern Entomologist. 34(4):359-376. Interpretive Summary: Arundo donax, giant reed, is an invasive weed in the Southwestern U.S. It is native to Mediterranean Europe. The Arundo wasp, Tetramesa romana, and the Arundo scale, Rhizaspidiotus donacis, are also from the native range in Europe and are candidate biological control agents of this invasive weed. Controlled quarantine greenhouse studies were conducted to measure the impact of these agents on A. donax. Over a period of 12 weeks the wasp and the wasp +scale combination suppressed growth of the plant by more than 92%. We concluded that both insects are likely to be effective biological control agents of giant reed.
Technical Abstract: Impact by two potential biological control agents, Tetramesa romana Walker and Rhizaspidiotus donacis (Leonardi), on the invasive weed, giant reed, Arundo donax L., was assessed in a quarantine greenhouse before release. Tetramesa romana alone and T. romana plus R. donacis significantly damaged A. donax by suppressing leaf and stem lengths and stimulated production of side branches during a 12-week period. R. donacis plus T. romana produced only slightly more plant impacts than did T. romana alone, most likely because of the longer life cycle of R. donacis that may require a longer period of time to cause measurable damage. No negative interactions were observed between the two candidate biological control agents. Therefore, based on their potential to significantly damage A. donax under greenhouse conditions and their narrow host ranges, T. romana and R. donacis are suitable candidates for biological control of this invasive reed grass in North America.