INITIAL RESULTS OF BIOLOGICAL CONTROL OF SALTCEDAR (TAMARIX SPP.) IN THE UNITED STATES

Authors: Milbrath, Lindsey; Deloach Jr, Culver; KNUTSON, ALLEN - TEXAS A&M UNIVERSITY

Submitted to: Saltcedar and Water Resources in the West Symposium
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2003
Publication Date: 7/1/2003
Citation: Milbrath, L.R., DeLoach, C.J., Knutson, A.E. 2003. Initial results of biological control of saltcedar (Tamarix spp.) in the United States. Proceedings of the Symposium, Saltcedar and Water Resources in the West. p. 135-141.

Interpretive Summary: Saltcedars are exotic shrubs or trees that have invaded river systems throughout the Western U.S., causing major problems. Little feeding by insects occurs on saltcedar in the U.S., whereas over 300 insects specifically attack saltcedar in the Old World. Researchers at the USDA-ARS have investigated the potential to release insects in the U.S. to control saltcedar. A leaf-feeding beetle was tested and considered to be safe for non-saltcedar plants. It was released and has established in northern areas of the U.S., in some locations defoliating large numbers of trees. Other populations of the beetle are being studied that we anticipate will establish in southern areas such as Texas and cause significant damage to saltcedar. Control of saltcedar will improve native plant communities and wildlife habitat, and insure water supplies for agriculture and municipalities.

Technical Abstract: Saltcedars (Tamarix spp.: Tamaricaceae) are exotic, invasive shrubs or trees that are degrading riparian habitats in the Western U.S. Over 300 insects are reported to specifically attack saltcedar in Eurasia, whereas little feeding by insects occurs on saltcedar in the U.S. The leaf beetle Diorhabda elongata deserticola (Coleoptera: Chrysomelidae) from Fukang, China and Chilik, Kazakhstan was studied in quarantine and considered to be safe to release in the U.S. for the control of saltcedar. Beetles were released into field cages in 1999 and 2000 at 10 research sites in six Western states. Open field releases were made in 2001 at six sites. The beetle successfully overwintered at the four sites located north of the 38th parallel. Extensive defoliation of saltcedar occurred at Lovelock, NV and Pueblo, CO in 2002. Lack of overwintering at the southern sites in Texas and California was likely due to premature diapause of the beetle due to short summer daylengths. Other populations of the beetle remain reproductively active at shorter daylengths, one of which overwintered successfully at Temple, TX last winter. They may therefore provide control in southern areas of saltcedar infestation.