Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 18, 2002
Publication Date: May 1, 2003
Citation: DeLoach, C.J., Lewis, P.A., Herr, J.C., Carruthers, R.I., Tracy, J.L., Johnson, J. Host specificity of the leaf beetle, Diorhabda elongata deserticola (Coleoptera: Chrysomelidae) from Asia, a biological control agent for saltcedars (Tamarix: Tamaricaceae) in the Western United States. Biological Control. 2003. v. 27. p. 117-147. Interpretive Summary: Saltcedar is an exotic tree that has invaded river systems throughout the southwestern U.S. and has caused major problems. State and local governments and private organizations spend millions of dollars each year trying to control this plant by spraying herbicides, bulldozing, burning, or by hand-cutting the trees. USDA-ARS researchers have been investigating the potential to release an insect in the U.S. that specifically attacks saltcedar. This insect was thoroughly tested in the laboratory and it was found that it would not feed on or cause damage to native crops or ornamental plants. We anticipate that this insect will reproduce well and will cause significant damage to saltcedar trees in different areas of the U.S. where it is a problem.
Technical Abstract: Saltcedar (Tamarix ramosissima Ledebour) is an exotic, invasive small tree from Asia that causes great damage to riparian ecosystems of the western United States. It displaces native plant communities, degrades wildlife habitat (including that of many endangered species), increases soil salinity, lowers water tables and reduces water available for agriculture and municipalities, and reduces recreational usage. Phytophagous insects are abundant on saltcedar in the Old World and Diorhabda elongata deserticola Chen was selected as a candidate biological control agent because of its high host specificity, broad geographic range, and presumed adaptability in the United States. In quarantine facilities in the United States, we tested it on 27 species and accessions of Tamarix and on 57 species of other plants, in 13 tests of different types, using 1,464 adults and 2,705 larvae, over 9 years. Survival of larvae tended to be greatest on T. ramosissima, and somewhat lower on athel (T. aphylla). Only 3 of 191 neonates completed development on Frankenia spp. No larvae completed their development on any of the other 54 plant species tested, and most larvae died during the first instar. Adults in 4 tests oviposited readily on T. ramosissima accessions but in three of these tests less oviposition occurred on athel. The host range of D.e. deserticola from Kazakhstan was not different from those from China. D.e. deserticola, therefore, appears sufficiently host-specific for field release in North America. This is the first biocontrol agent introduced into the U.S. for biological control of saltcedar.