Quantitatively Monitoring the Effects of the Biocontrol Agent _Diorhabda elongata deserticola_ on Salt Cedar Resprouts to Determine the Efficacy of Long-term Biocontrol at Various Reclamation Release Sites in the Western United States

Project ID: 6397
Principal Investigator: Denise Hosler
Research Topic: Invasive Species
Funded Fiscal Years: 2006, 2007 and 2008
Keywords: None

Research Question

The primary research questions of this project are:

* How well will _Diorhabda elongata deserticola_ control salt cedar resprouts after initial salt cedar control activities have occurred ?

* Will the type of salt cedar control treatment (biocontrol, chemical treatments, mechanical treatments, or burning) affect the activity level of biocontrol insects?

This research quantifies the effects of _Diorhabda_ on salt cedar resprouts utilizing a Trimble Global Positioning System (GPS) unit with data dictionaries designed for data collection on belt transects and monotypic tree stands. The GPS unit will allow data collection in the exact location of the original mature tree. This Science and Technology (S&T) Program research project will quantify the effects of _Diorhabda_ on resprouting salt cedar. This research will be performed at current Reclamation salt cedar control sites using the applicable monitoring protocols established by the Salt Cedar Biocontrol Consortium. Tree data and transect data sets have been collected since 2005 and compiled in electronic spreadsheets for future analysis.

Need and Benefit

Reclamation has the authority and responsibility to manage Reclamation project waters and facilities in a manner that delivers optimum benefit to Reclamation project water and power users. Salt cedar is found along many of the rivers, canals, drains and reservoirs that Reclamation manages. Reclamation has been trying to control salt cedar for more than 60 years with limited success. Salt cedar clogs waterways, contributes to salinity levels, may consume more water than native vegetation, contributes to volatile fuels, reduces natural wildlife habitat, and restricts recreational access has invaded most riparian areas (approximately 1.6 million acres) of the arid Western United States. Some research has shown salt cedar uses approximately four acre feet of water per year. Control of salt cedar will increase and sustain increased amounts of water in western river systems and reservoirs and contribute to increased power generation.

Reclamation has been one of the lead Federal agencies developing the biocontrol methods. Widespread use of the biocontrol agent will not totally eradicate salt cedar, but it will significantly control its presence in the Western United States. At the same time biocontrol will enhance riparian areas, prime habitat for many western species of plants and animals, including threatened and endangered species, particularly with the southwestern willow flycatcher.

Biocontrol appears to be a sustainable, effective method of controlling salt cedar, however the long-term ability of the _Diorhabda_ to control resprouting salt cedar regardless of previous control method used (biocontrol, chemical, mechanical or burning) has not been determined. The long-term value of this research is multi-faceted from the stand point of understanding the long-term impacts of the biocontrol agent to control saltcedar resprout and the environmental recovery response. This information will be a useful addition for salt cedar control and recovery projects throughout Reclamation, particularly in the areas where some of these removal activities have already begun. This information is not currently available from any source anywhere in the world.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Effects of the Biological Control Agent Diorhabda elongata deserticola on Resprouted Saltcedar (interim, PDF, 3.7MB)
By Rebecca Siegle
Report completed on May 16, 2013

In 2001, the saltcedar biological control agent,a beetle originating in Fukang, China, was released at a site near Pueblo, Colorado. In June of 2000, Bureau of Reclamation's Technical Service Center (TSC) began monitoring to determine effects of the biocontrol on the target species and indirect effects to secondary vegetation. In the project area at the base of Pueblo Dam on the Arkansas beetles were found on resprouts and not in the original old tree stand.

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Last Updated: 6/22/20