Location: Pest Management Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine proper taxonomic identification and/or knowledge of evolutionary relationships of key emerging invasive plant species, including perennial pepperweed (Lepidium latifolium), Russian olive (Elaeagnus angustifolia), dyer’s woad (Isatis tinctoria), Dalmatian toadflax (Linaria spp.), common tansy (Tanacetum vulgare), oxeye daisy (Leucanthemum vulgare) and their potential biological control agents. (Gaskin and Delaney) Objective 2: Investigate reproductive strategies of key emerging invasive plant species, including perennial pepperweed (Lepidium latifolium) and hawkweeds (Hieracium spp.), and use this information in decision tools for selecting potential biological control agents. Objective 3: Develop insect and pathogen biological control agents, and synergies of these agents, for invasive plants of the Northern Great Plains, including saltcedar (Tamarix spp.), whitetop or hoary cress (Lepidium draba), leafy spurge (Euphorbia esula), and hawkweeds (Hieracium spp.). Objective 4: Investigation of the pathogenicity to native forbs and grasses of Fusarium spp. isolates associated with Tamarix biomass. Objective 5: Determine the effects of biological control on restoration efforts of rangeland and public land and develop restoration protocols that complement future biological control efforts.
1b. Approach (from AD-416):
Exotic invasive weeds cause about $35 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, but improvements in methodology are warranted. We propose that by better understanding invasive plant taxonomy, evolutionary relationships, origins, population structure and reproductive biology, we can identify more effective and lower risk insect and pathogen biological weed control agents. Additionally, understanding ecological interactions between insect and pathogen agents will let us employ their synergistic action. Biological control of weeds is a step towards returning to desired landscapes, with significantly reduced densities of noxious weeds and increased cover of native or other desired species. Establishing desired species cover in previously infested areas may require the application of successful restoration programs. We will examine the ecological and evolutionary processes that maintain desired communities, and then use this knowledge to improve rates of success in restoration. Additionally, successful biological control can leave a legacy of increased inoculum of soilborne pathogens, and we will investigate if this inhibits restoration efforts. This more holistic view of invasive weed management, starting with a better understanding of the basic biology of the invasion, including ecological and evolutionary studies of the biological control and restoration processes, will enhance our ability to replace invaded areas with ecologically sound and economically useful landscapes.
3. Progress Report:
Russian olive removal/restoration: ARS researchers from Sidney and Miles City, MT continue to monitor vegetation changes after invasive Russian olive removal and the success of restoration plantings. Funding from the Bureau of Land Management allowed the purchase of soil moisture monitors that give information on how plant water availability in the plots changes with the rise and fall of the Yellowstone river. Researchers also installed plots in SD, MT, WA, and OR to determine how the location of restoration seed production farms influences seed performance. Emergence data has been collected and analyzed and shows that two commonly used restoration species exhibit significant performance differences depending on where they are produced. The study at Theodore Roosevelt National Park is nearing completion: biomass from the plants has been collected in 2012 and will be collected in 2013 to determine if a single generation of agronomic growing conditions affects seed performance compared to wild-collected seeds of restoration species. Weevil and fungus attack weed together: In a field experiment on insect/pathogen interactions involving the invasive weed Lepidium draba and host-specific root-galling weevil Ceutorhynchus assimilis, treatments in which the fungus Rhizoctonia solani was placed in soils were all positive for root infection by the pathogen. In soils without the fungus, no such infections were detected. These results confirm under controlled conditions an insect/pathogen interaction shown to occur in the field. The association of the weevil with soilborne pathogens suggests initial releases would be most effective for biocontrol at sites with high amounts of soilborne pathogens. Invasive Russian olive: Molecular markers (microsatellites) for Russian olive have been developed by ARS Sidney, MT, and these are being used to determine the distribution of different genotypes of this plant invasion that spans from the west coast to the Midwest states. The information will help make sure that biological control agents being developed for this invasive are effective on the full range of genetic diversity found in the invasion.
Bean, D., Kazmer, D.J., Gardner, K., Thompson, D., Reynolds, B., Keller, J.C., Gaskin, J.F. 2013. Molecular genetic and hybridization studies of Diorhabda spp. released for biological control of tamarix. Journal of Invasive Plant Science and Management. 6(1): 1-15.