Location: Invasive Species and Pollinator HealthTitle: Release, establishment and realized geographic distribution of Diorhabda carinulata and D. elongata (Coleoptera:Chrysomelidae)in California, U.S.A.
|CARRUTHERS, RAYMOND - Retired ARS Employee|
|PITCAIRN, MICHAEL - California Department Of Food And Agriculture|
|VILLEGAS, BALDO - California Department Of Food And Agriculture|
|KELLEY, BRENT - Former ARS Employee|
Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2019
Publication Date: 3/26/2019
Citation: Pratt, P.D., Herr, J.C., Carruthers, R., Pitcairn, M., Villegas, B., Kelley, B. 2019. Release, establishment and realized geographic distribution of Diorhabda carinulata and D. elongata (Coleoptera:Chrysomelidae)in California, U.S.A.. Biocontrol Science and Technology. 29:7. https://doi.org/10.1080/09583157.2019.1587739.
Interpretive Summary: Saltcedar (in the genus Tamarix) are shrubs that invades creek and river banks in the western USA. The exotic plant grows very aggressively in these wet environments, displacing native plants and the animals that thrive there. Herbicides and chainsaws are effective ways of control the tree but are not cost effective. The use of insects, or biological control, to help suppress the shrubs in California started with the release of a beetle (Diorhabda carinulata) in 1999 followed by another beetle (Diorhabda elongata) in 2003. This article summarizes the release and evaluations of these beetles following their introduction. We discovered that, after 10 years, the beetles have not established well in California and have not dispersed far from their original release sites. Unfortunately, the beetles don't provide sufficient control of the weed and other methods are still needed to suppress the exotic saltcedars.
Technical Abstract: We summarize efforts to establish Diorhabda carinulata and D. elongata in California as biological control agents of invasive saltcedars (Tamarix spp.). Over 14,500 D. carinulata individuals were released in California between 1999 and 2002 but beetles only established at one of four locations. Over 236,000 D. elongata individuals were released between 13 sites from 2003-2009 and establishment was limited to two sites. The D. carinulata population did not disperse beyond the release site but D. elongata spread at ca. 14 km per year. A survey of 122 Tamarix stands in 15 California counties revealed that neither introduced beetle colonized other host patches. Despite exclusive use of T. parviflora for ca. 36 generations, field collected D. elongata adults demonstrated strong preferences for T. ramosissima over T. parviflora when selecting both resting and ovipositional sites in caged choice tests.