Biological Control of Exotic Weeds in California
Exotic and Invasive Weeds Research
2010 Annual Report
1a.Objectives (from AD-416)
Will collect natural enemies of invasive weeds and evaluate host specificity under quarantine conditions. Will conduct field monitoring of released weed biological control agents. Will conduct research on revegetation of native species in ripian habitats such as the Walker River of Nevada.
1b.Approach (from AD-416)
New natural enemies of weeds such as Tamarix, Arundo & Yellow starthistle will be identified and collected through foreign exploration in countries of origin. For most of the target weeds of interest this will be done working with cooperators at USDA-ARS overseas laboratories, in Europe and China. Following location and proper taxonomic assessment, colonies of these beneficial natural enemies will be established and held under quarantine conditions. Environmental assessments will be written to support requests for field release of these natural enemies by ARS scientists. Once approved by USDA-APHIS & other regulatory groups, these agents will be field released and monitored to determine their establishment and impact on both target and non-target plants. A combination of field & laboratory experiments will be used to identify methods of establishing native species in areas where invasive weeds have been eliminated. The initial focus will be on seed physiology production & dispersal, & artificial seeding of beneficial species. Documents Reimbursable with (BLM) Bureau of Land Management. Log 40320.
This agreement was established in support of Objective 2 of the inhouse CRIS Project to help evaluate the effectiveness of the newly collected biological control agents for various invasive weed targets in the western United States.
Foreign exploration was continued in Europe and Asia for natural enemies of Lepidium latifolium, and new work initiated in South America for Egeria densa, and Ludwigia hexapetala. Quarantine evaluations were continued on a psyllid identified as having potential to control French broom. Initial tests showed inadequate impact of this agent to justify release based on short-term feeding tests on seedlings. Additional tests are continuing to evaluate longer-term impacts of this agent under higher density situations.
Work continued on the field assessment of Diorhabda elongata that was established in Northern California and specifically on BLM land along Bear Creek near Woodland. This agent defoliated invasive saltcedar on over 25 miles of riparian habitat in 2008 and spread farther during 2009.
Population levels declined as the saltcedar was severely defoliated and thus beetle food was limited in some test areas. Periodic monitoring is being continued as the beetles are expected to spread throughout the BLM infected properties in this area during 2010. The project is now considered finalized in USDA-ARS and cooperating Agencies such as the California Department of Food and Agriculture are now in the process of redistributing this natural enemy within the state. New project planning is now being conducted to determine foreign exploration plans for a new set of invasive weed species, and a new ADODR will soon be taking over project responsibilities.