Location: Pest Management Research
2020 Annual Report
Objectives
Objective 1: Identify and bridge critical knowledge gaps in the taxonomy, native origin, population structure, and reproductive strategies of key invasive weeds, as necessary to support the successful development of classical biological control programs. [NP304, Component 1, Problem Statements 1A, 1B, and 1C; Component 2, Problem Statement 2B2]
Subobjective 1.A: Determine the correct taxonomy and extent of hybridization of invasive weeds.
Subobjective 1.B: Determine the origins, population structure and reproductive mode of invasive weeds.
Objective 2: Develop novel, effective biological weed control and rangeland restoration methods that synergize ecological interactions, such as herbivory, weed population heterogeneity, invasion-dynamics, competition between weeds and native vegetation, and plant-soil interactions. [NP304, Component 2, Problem Statements 2B2, 2B3 and 2B4]
Subobjective 2.A: Understand insect community composition and assembly in response to restoration and prior to the release of Russian olive biological control.
Subobjective 2.B: Determine plant population, community and soil characteristics that contribute to the control of invasions.
Approach
Weeds in pastures and croplands in the U.S. result in billions of dollars per year in lost production and control costs. The goal of our project is to decrease weed abundance by increasing the efficacy of biological control agent development and improving the establishment success of plant community restorations that resist invasion. Our team’s research spans multiple aspects of weed control, from the taxonomy required for effective development of weed management strategies, demographic and ecological research to optimize biological control management efficacy, and identification of the inputs required in restoration that support productive invasion-resistant landscapes. We will address critical gaps in genotype-specific information regarding the reproductive strategies, origin and invasiveness of some of the most important invasive weeds in the U.S., thus guiding effective control methods including effective biological control agents. We will identify ecological, demographic, and biological factors limiting invasion potential for weeds with different life histories. This will generate strategies that limit the spread of target weeds and provide a general framework of biologically- and ecologically-based weed control methods. We will also create realistic targets for restoration that benefit landscapes. This work develops science-based, economical weed management that reduces costs, promotes food security and minimizes negative environmental impacts of weed control.
We focus on rangeland weeds in the Northern Great Plains and extend this research nationally across a range of habitats. By communicating our results through on-going relationships with land management agencies, farmers and ranchers, academic societies, industry and state extension services, this research supports innovative strategies vital to the sustainability and health of U.S. agroecosystems.
Progress Report
ARS scientists in Sidney, Montana, continued DNA collections of critical invasive species in the western United States and from their putative origins in Eurasia, including Russian knapweed, whitetop, leafy spurge, mullein, common reed and flowering rush. They are now using molecular markers to determine the correct invasive species identification, major mode of reproduction, as well as specific origin of these invasions. This information is being used to develop more effective foreign biological control agents to fight against invasive plants in the United States. As part of a $2M U.S. Department of Agriculture's National Institute of Food and Agriculture (NIFA) Organic Agriculture Research and Extension Initiative grant, scientists in Sidney, Montana, have performed genetic sampling of bindweed and Canada thistle to determine its mode of reproduction in organic cropping systems, which will help producers control these top two weeds in organic systems.
Under a U.S. Forest Service Biological Control of Invasive Native and Non-Native Plants (BCIP) grant, ARS Sidney continues to lead a multi-state, multi-stakeholder project quantifying the efficacy of leafy spurge biocontrol across broad habitat gradients, with the goal of developing management recommendations and informing future biocontrol agent development. Data collection on population structure and taxonomy of North American populations has been completed, and researchers continue to monitor agent communities and leafy spurge density across Idaho, Montana, and North Dakota. The multiple biocontrol agents released for leafy spurge have proven to be a valuable tool for farmers, ranchers, and land managers, particularly in areas where chemical control is unfeasible. This study will provide the information needed to improve biological control of leafy spurge in habitats and regions where biocontrol management has had uncertain success.
New collaborative research between ARS in Sidney and Miles City, Montana, was initiated to identify a pipeline reclamation approach to reduce crested wheatgrass invasion. Data on functional response traits related to resource use and acquisition (e.g. specific leaf area, photosynthetic rate, and nutrient contents) were mined from plant traits databases for crested wheatgrass and 30 native plants occurring in the study area. These data will help determine the best plant mixes to resist crested wheatgrass invasion according to two prominent theories of community assembly. The efficacy of these mixes will be tested in a greenhouse setting this fall and seeded into 24 crested wheatgrass invaded plots in the spring. This study will provide critical insight into restoration methods to reduce weeds and improve rangeland health.
A project aimed at converting a monoculture of crested wheatgrass to native grasses and forbs was initiated. Following two years of short-duration, high-intensity cattle grazing, blocks of land were designated into six herbicide/seeding treatments. All herbicide and seeding occurred in May 2020. Beginning in July 2020, ARS Sidney, Montana, began continuously sampling arthropods and ground nesting bees and also quantified flowering vegetation and foraging pollinators visiting flowering plants. These data bridge a gap between methods to restore quality rangeland and the consequences for important arthropod communities.
Accomplishments
1. Invasive weed origins found. Common mullein is an invasive weed in the United States that causes economic and ecological damage in pastures, rangeland, and disturbed and natural areas, especially in California and Hawaii, from sea level to 13,000+ ft. elevation. ARS researchers in Sidney, Montana, using molecular tools, have determined that the invasion is mostly dominated by a single genotype that exists across the western states, with origins of Belgium and Germany. Further research involving these common genotypes can help land managers protect against development of herbicide resistance in the invasion, and helps researchers ensure that future biological control agents will have the highest control efficacy against the most common genotypes.
2. Herbivore seed predators can drive long-term declines in plant populations. ARS researchers from Sidney, Montana, with collaborators, used demographic data and long-term seed addition experiments to link seed availability and plant mortality at different life stages to local plant abundance. Strong seed limitation affected the abundance of seedlings, and the number of seedlings that survived to adulthood. However, variation in mortality pressures between sites and life stages suggests declines in plant abundance due to seed feeders will not be consistent in the landscape. This approach provides a framework for managers and biocontrol practitioners deploying seed feeding agents and assessing risk to better understand the impact of candidate agents on target and non-target populations.
Review Publications
Espeland, E.K., Schreeg, L., Porensky, L.M. 2019. Managing risks related to climate variability in rangeland-based livestock production: What producer driven strategies are shared and prevalent across diverse dryland geographies? Journal of Environmental Management. 255:109889. https://doi.org/10.1016/j.jenvman.2019.109889.
Banerjee, A.K., Harms, N.E., Mukherjee, A., Gaskin, J.F. 2020. Niche dynamics and potential distribution of Butomus umbellatus under current and future climate scenarios in North America. Hydrobiologia. https://doi.org/10.1007/s10750-020-04205-1.
Harms, N., Shearer, J., Cronin, J., Gaskin, J.F. 2019. Geographic and genetic variation in susceptibility of Butomus umbellatus to foliar fungal pathogens. Biological Invasions. https://doi.org/10.1007/s10530-019-02109-3.
Gaskin, J.F., Coombs, E., Kelch, D., Keil, D., Porter, M., Susanna, A. 2020. A species of plumeless thistle, Carduus cinereus (Asteraceae), new to North America. Madrono. 66(4):142-147. https://doi.org/10.3120/0024-9637-66.4.142.
Rapo, C.B., Schaffner, U., Eigenbrode, S.D., Hinz, H.L., Price, W., Morra, M., Gaskin, J.F., Schwarzlaender, M. 2019. Feeding intensity of insect herbivores is associated more closely with key metabolite profiles than phylogenetic relatedness of their potential hosts. PeerJ. https://doi.org/10.7717/peerj.8203.
Rand, T.A., West, N.M., Russell, F., Louda, S.M. 2020. Post-dispersal factors influence recruitment patterns but do not override the importance of seed limitation in populations of native thistle. Oecologia. 193(1):143-153. https://doi.org/10.1007/s00442-020-04656-2.
Swaminathan, P., Ohrtaman, M., Carinder, A., Deuja, A., Gaskin, J.F., Fennell, A., Clay, S. 2020. Water deficit transcriptomic responses differ in the invasive Tamarix chinensis and T. ramosissima established in the southern and northern United States. Plants. 9(1):86. https://doi.org/10.3390/plants9010086.
Reilly, J., Artz, D., Biddinger, D., Bobiwash, K., Boyle, N.K., Brittain, C., Brokaw, J., Campbell, J., Daniels, J., Elle, E., Ellis, J., Fleischer, S., Gibbs, J., Gillespie, R., Gundersen, K., Gut, L., Hoffman, G., Joshi, N., Lundin, O., Mason, K., Mcgrady, C., Peterson, S., Pitts Singer, T., Rao, S., Rothwell, N., Ward, L., Williams, N., Wilson, J., Isaacs, R., Winfree, R. 2020. Crop yield in the USA is frequently limited by a lack of pollinators. Proceedings of the Royal Society B. 287(1931). https://doi.org/10.1098/rspb.2020.0922.
