2010 Annual Report
1a.Objectives (from AD-416)
Objective 1: Develop and coordinate biological control programs to achieve sustained suppression of Lepidium draba L. (Brassicaceae), Centaurea spp., Hieracium spp. (Asteraceae), Tamarix spp. (Tamaricaceae), Euphorbia esula L. (Euphorbiaceae), and other invasive plants by: 1a) determining the systematics and phylogeography of target species; 1b) identifying, testing and releasing new arthropods and plant pathogens alone and in synergistic combinations; 1c) assessing rates of establishment, population growth, dispersal and impacts of agents on target weeds, native plants, and associated soil microbial communities; and 1d) integrate biological control agents with chemical, cultural and other control methods to enhance the impact of weed management programs.
Objective 2: Identify key factors and mechanisms affecting the success of biological control programs and plant invasions including: 2a) genetic and phenotypic traits of target weeds that determine the success of invasive plant species in distinct ecological regions; 2b) genetic and phenotypic traits of biological control agents affecting their establishment, population growth, and impact; 2c) the biotic, edaphic, and environmental factors and mechanisms affecting weed establishment and expansion, and success of biological control agents; and 2d) integrate population information from Objectives 1 and 2 with remote sensing imagery and other spatial/temporal databases to develop spatial models of weed invasion risk.
1b.Approach (from AD-416)
Exotic invasive weeds cause about $27 billion annually in economic losses in addition to environmental impacts ranging from displacement of species of conservation concern to altered ecosystem functions. Biologically-based control methods can provide cost-effective, sustainable means of limiting the adverse impacts of invasive plants over extensive rangeland and natural areas. Our studies will focus on increasing the success of biological control efforts through better scientific understanding of: mechanisms underlying both the impact of agents and patterns of weed and agent dispersal; genetic variation within target weeds and biological control agents; evolutionary relationships of target weeds and agents;
synergisms between plant pathogens, deleterious microbes, and arthropod agents; direct and indirect effects of biological control introductions on nontarget organisms in a risk analysis context; environmental factors affecting weed and biological control agent dynamics and invasion risk; and follow-on effects following suppression of weeds by biological control agents. Anticipated products of our project include new biological control agents, improved systematic and phylogeographic understanding of target weeds and control agents, improved systems for assessing and monitoring weed and insect populations; elucidation of factors and mechanisms limiting the establishment and success of biological control releases.
This is the report for the bridging project #5436-22000-015-00D that replaced the project #5436-22000-013-00D “Biological Control of Invasive Plants of the Northern Great Plains,” which terminated on February 16, 2010. The replacement project is currently in peer review and will be implemented in FY 2011.
Hawkweed Invasion: We discovered and collected the potential classical weed biocontrol agent Puccinia hieracii on hawkweed populations in France, an occurrence not previously reported.
Restoration after Invasion: We established new methods for identifying microbial species that are numerically predominant in soils around invasive weed roots. These methods allow a more complete picture of the accumulation of plant pathogens derived from weed monocultures. This knowledge is being integrated into strategies for restoration of native plant communities.