Location: Crop Bioprotection Research
2019 Annual Report
Objectives
1. Demonstrate production potential for baculovirus for insect control (such as black cutworm MNPV), evaluate formulations for storage stability and residual efficacy, and identify and evaluate insect semiochemicals such as attractants or feeding stimulants that can be integrated into formulations to improve control of major insect pests of turf or other crops.
2. Determine the relationship between microbial communities and the characteristics of weeds (such as bindweed, medusahead grass, or quack grass) that make them harmful to turf, natural ecosystems, and agricultural commodities.
3. Identify viruses that can target potential key endophytes or microorganisms that contribute negative characteristics of weeds.
4. Identify, describe, and preserve microorganisms isolated from weeds as part of the characterization of microbial communities associated with important weeds.
Approach
Grasses planted as turf and pasture represent a commodity that has been underserved when considering the use of biological control based on microbial agents. For urban and athletic turf grasses, a newly discovered baculovirus offers the opportunity to develop a biological pesticide for control of the black cutworm. Research will focus on basic and applied aspects of production, formulation, and efficacy of this baculovirus for development as a biological insecticide.
Invasive weed species among range grasses such as Medusahead may obtain enhanced fitness as a result of associations with endophytic microbes. Research will utilize classic microbial and newly developed molecular techniques to characterize endophytic microbes of the weedy plants and identify those providing competitive advantages to the weeds. Subsequent research will strive to discover mycoviruses to attach the endophytes of the weedy plant, to convert the competitive advantage back to the desired crop plant.
Progress Report
Significant progress has been made in meeting the project objectives through four years of research. For Objective 1, the goal was to develop baculoviruses for insect control in turf and other major crops. In year four of the project, the baculovirus that specifically infects the black cutworm (AgipMNPV) was shown to provide effective control of this pest of bentgrass turf. Field experiments demonstrated that virus treatments were as effective as a standard chemical insecticide for controlling small and medium-sized larvae, resulting in obviously less insect feeding damage to golf course greens managed turfgrass. The baculovirus treatment was more effective when compared with other biological microbes (fungus and bacteria) applied alone or in combinations with the baculovirus demonstrating that the baculovirus can serve as a stand-alone biological replacement for chemical insecticides for control of the black cutworm in turf. Additional efforts to improve the insecticidal activity of the virus were unsuccessful in that plant-based compounds shown to improve the activity of other baculoviruses provided no beneficial effect for this virus. For Objective 2, the goal was to determine the relationship between microbial communities and the characteristics of invasive weeds. In year four of the project, microbial communities of various plant parts were determined for samples of bindweed, medusahead grass, and quack grass. The research shows the microbial communities vary significantly across the samples, with the time of season providing the biggest effect. The research has highlighted the difficulty of conducting comparisons between locations when the locations and the ability to sample the locations occur at different times. This knowledge provides valuable information on how to design future experiments on microbial communities in plants. For Objective 3, the milestone was to identify viruses that can target key endophytes that contribute to the negative characteristics of weeds. This milestone was modified due to the inability to identify key endophytes that meet these requirements. The milestone was broadened to include characterizing microbes isolated from these weeds species to include microbes that may also provide beneficial traits to agriculturally important plants. This work has identified several new species microbes previously unknown to science, which are currently being evaluated for their impact on agronomic traits. In addition, the unique nature of this collection of microbes, isolated from weeds, has attracted interest from commercial entities interested in exploring these microbes for novel traits.
Accomplishments
1. Identifying microbes transmitted in the seeds of invasive weeds. The goal of this research was to identify novel methods of controlling the invasive weed, medusahead. Medusahead is an important weed in the western U.S. and represents a serious threat to ranchers, since it can greatly reduce the grazing capacity of pastures. The current research provides the first characterization of the microbes the weeds pass to other generations through their seeds. Microbes are known to provide plants with beneficial properties that help their survival in stressful environments and may help weeds outcompete beneficial plants. In this research, ARS researchers at Peoria, Illinois, compared microbes from the seeds of plants in their native range (Europe) with seeds of plants in the U.S. and identified significant differences between the plants. The research shows the seeds of introduced plants contain several families of fungi not seen in the European strains. This research allows us to understand how these microbes are vertically transmitted by the weeds and which of these microbes may provide the weed with a competitive advantage. This research provides knowledge that may be useful in developing novel strategies to control invasive weeds by targeting the microbes that provide beneficial traits to weeds, which would directly benefit ranchers and nature ecosystems impacted by these weeds.
Review Publications
Knight, C., Bowman, M.J., Frederick, L., Day, A., Lee, C., Dunlap, C.A. 2018. The first report of antifungal lipopeptide production by a Bacillus subtilis subsp inaquosorum strain. Microbiological Research. 216:40-46. https://doi.org/10.1016/j.micres.2018.08.001.
Johnson, E.T., Dunlap, C.A. 2019. Phylogenomic analysis of the Brevibacillus brevis clade: a proposal for three new Brevibacillus species, Brevibacillus fortis sp. nov., Brevibacillus porteri sp. nov. and Brevibacillus schisleri sp. nov.. Antonie Van Leeuwenhoek. 112: 991-999. https://doi.org/10.1007/s10482-019-01232-4.
Mascarin, G.M., Junior, R.P., Fernandes, E.K., Quintela, E.D., Dunlap, C.A., Arthurs, S.P. 2018. Phenotype responses to abiotic stresses, asexual reproduction and virulence against whiteflies among strains of the entomopathogenic fungus Cordyceps javanica (Hypocreales: Cordycipitaceae). Microbiological Research. 216:12-22. https://doi.org/10.1016/j.micres.2018.08.002.
Dunlap, C.A. 2019. Taxonomy of registered Bacillus spp. strains used as plant pathogen antagonists. Biological Control. 134:82-86. https://doi.org/10.1016/j.biocontrol.2019.04.011.
Martins, S.J., Rocha, G.A., De Melo, H.C., Georg, R.D., Ulhoa, C.J., Dianese, E.C., Oshiquiri, L.H., Da Cunha, M.G., Da Rocha, M.R., De Araujo, L.G., Vaz, K.S., Dunlap, C.A. 2019. Plant-beneficial bacteria mitigate drought stress in soybean. Plant Physiology and Biochemistry. 25:13676–13686. https://doi.org/10.1007/s11356-018-1610-5.
Wang, X., Li, C., Dunlap, C.A., Rooney, A.P., Du, Z. 2018. Marinicella sediminis sp. nov., isolated from marine sediment. International Journal of Systematic and Evolutionary Microbiology. 68:2335-2339. https://doi.org/10.1099/ijsem.0.002839.
Schisler, D.A., Yoshioka, M., Vaughan, M.M., Dunlap, C.A., Rooney, A.P. 2018. Nonviable biomass of biocontrol agent Papiliotrema flavescens OH 182.9 3C enhances growth of Fusarium graminearum and counteracts viable biomass reduction of Fusarium head blight. Biological Control. 128:48-55. https://doi.org/10.1016/j.biocontrol.2018.09.006.
