2009 Annual Report
1a.Objectives (from AD-416)
Conduct research with USDA/BLM on weeds that are problems on BLM lands. Weeds
include saltcedar, yellowstar thistle, hoary cress, field bindweed, Canada thistle, leafy spurge and the knapweeds. The search for new biological control agents will be conducted by USDA/ARS/EBCL. Research on saltcedar biological control will be conducted by USDA/ARS Sino-American Biological Control Lab-China and by Exotic and Invasive Weeds Research Lab-Albany, CA. Insects cleared for use in U.S. will be released and/or evaluated by ARS, Sidney, MT.
1b.Approach (from AD-416)
Exploration will be conducted in Europe, Eurasia, and China for insects and
pathogens which show potential as control agents for priority noxious weeds. Once
identified, the agents will be tested for host-specificity and efficacy. Tests on
saltcedar and yellowstar thistle insects may be conducted in quarantine in Albany, CA. This is a long-term process, extending over three to six years for new agents. Once tests are completed on a Technical Advisory Group (TAG) list of plants, a report of the test results will be submitted to APHIS/PPQ and TAG. Agents approved for quarantine and/or release via quarantine will be collected and sent to the appropriate quarantine facility for processing. Cleared biological control agents will be released on BLM administered lands by ARS, Sidney, MT. Post-release monitoring for establishment and impact on the targeted weed species will follow these releases. All programmatic changes must be approved in advance by NPS.
We are completing the 10th year of monitoring for the Saltcedar Biocontrol Experimental Release Program on the Bighorn River in northern Wyoming. The saltcedar leaf beetle has successfully overwintered each year since the first field cage releases in 1999, but this year adult numbers are low, perhaps due to an extra generation developing at the end of last season, and failing to develop into adults before cold weather. This summer has been unusually cold also, which could affect development in this season. We will continue monitoring until fall.
Additional releases of the beetle have been made at Ft. Peck Reservoir (2 locations), the confluence of the Yellowstone and Big Horn Rivers, Big Horn River near Hardin, Yellowstone River near Miles City, and Yellowstone River near Laurel. The beetle has failed to establish at the Ft. Peck Reservoir site despite the release of nearly 300,000 adult beetles since 2003. This year, beetles in sleeve cages at Ft. Peck are reproducing well. The more recent releases at the other MT sites have also not resulted in good establishment. We are still evaluating 2 hypotheses to account for the highly variable success of the beetle. Beetle survivorship did vary with the amount of water supplied to potted saltcedar plants where survivorship was highest on plants receiving the least water. Predator censuses and exclusion experiments at field release sites showed that predation on beetle larvae is high at all sites although it is not yet clear if the degree of success at each site is correlated with predation intensity. The primary monitoring activity for this project is an annual fall meeting that was organized by the state of Wyoming and BLM, held in Riverton, WY in 2009.