Location: Integrated Cropping Systems Research
2016 Annual Report
Objectives
Objective 1. Develop strategies to manage insects in cropping systems, focusing on biology with regards to resistance evolution, insect health and diversity, and the value of these strategies to sustainable crop production. [NP304, Component 3, Problem Statement 3A2].
Subobjective 1a. Assess the risk to susceptible western corn rootworm, and hence insect resistance management, from adult feeding on corn tissue expressing toxic Bacillus thuringiensis (Bt)-proteins.
Subobjective 1b. Evaluate neonicotinoid seed treatments for usefulness to U.S. crop production.
Subobjective 1c. Compare pest and beneficial insect levels between a soybean pest-management system that uses an aphid-resistant cultivar versus one that relies on conventional insecticides.
Subobjective 1d. Compare pest and beneficial insect levels, soil properties, plant growth, yield, and seed composition of soybean when grown alone and with an oilseed relay crop.
Subobjective 1e. Evaluate cover-cropping scenarios within crop rotations that encourage ecosystem services from beneficial insects.
Subobjective 1f. Develop procedures for hazard assessments of pesticides to non-target organisms.
Subobjective 1g. Establish exposure pathways for pesticides and non-target organisms and determine how plant diversity within the farmscape affects these exposure pathways.
Objective 2. Develop innovative strategies for managing weeds in dynamic cropping systems, and assess the benefits of these strategies that rely on bottom-up approaches to weed management (such as the use of cover crops) within diverse crop rotations. [NP304, Component 2, Problem Statement 2A2].
Subobjective 2a. Develop a methodology to convert red clover to cropland without tillage.
Subobjective 2b. Determine the best annual clovers to use as cover crops to control post-harvest weeds without tillage.
Approach
Pest management is crucial in cropping systems, and strategies to control weeds and insect pests need to be integrated with agronomic and other management goals to achieve sustainable cropping systems. In the northern Great Plains, corn rootworms, soybean aphids, and weeds greatly reduce agricultural productivity and profitability through yield loss and costly control measures. Widely adopted management tactics have initially reduced economic loss from these pests, but their utility needs reassessment in light of herbicide-tolerant weeds, insect adaptation to resistance transgenes, secondary pest outbreaks, and unwitting impacts on pollinators, natural enemies, and soil health. This project plan proposes research to address strategies used against major pests such as corn rootworms and soybean aphid, refine tactics for weed management in organic production systems, and determine the value and drawbacks to pest management and ecosystem services from diversifying crop rotations, incorporating cover crops, and using various plant-incorporated protectants. The research will be instrumental in developing management practices that increase farming efficiency and improve environmental and economic sustainability.
Progress Report
Progress was made on several objectives of this new project, but a critical vacancy prevented work on the impact of pest management practices on beneficial insects and non-target organisms (Subobjectives 1e, 1f and 1g). Nonetheless, the research project made substantial progress, producing fundamental, yet practical knowledge about the ecology of insect pests and weeds. Results of the current project may be used to reduce the impacts of weeds and insect pests on crops in Northern Plains farming systems via ecologically- and economically-sound IPM strategies, in accordance with the NP 304 Action Plan.
New research on corn rootworms is challenging the assumption that adult beetles will be equally fit when they feed on various transgenic corn varieties expressing the Cry3Bb1 toxin, as toxin levels may differ among varieties. To investigate this, we developed a greenhouse procedure that supplies ample leaves, silks, and pollen from corn plants to feed adult beetles year-round in experiments. We are using the procedure in a preliminary test to vet acceptably high survival of adults for use in future mating experiments.
Research on the management of soybean aphid progressed with the start of field evaluations of the efficacy and impact of a soybean variety that has been pyramided with two genes that confer resistance to soybean aphid. This field research is a logical follow-up to greenhouse and laboratory studies in the previous project that identified new sources of resistance to soybean aphid.
Work also continued refining tactics to manage clovers that organic producers use to suppress weeds in row crops in lieu of tillage. Research plots were established to evaluate fall mowing on the re-growth of red clover such that corn seedlings can successfully establish in the following year without the need for tillage. Plots were also established to evaluate whether annual clovers underseeded in small grains will control post-harvest weeds but winterkill so that tillage is not needed.
Accomplishments
1. Improving insect resistance management strategies for northern corn rootworms. Corn rootworm resistance to Bt corn has become a problem in the U.S. sooner than predicted. An accelerated rate of resistance development might have arisen if Bt exposure favors survival of larger male rootworms and if larger male rootworms have a mating advantage over smaller ones, thereby setting up a self-amplifying cycle that hastens resistance evolution. ARS scientists in Brookings, South Dakota validated half of this cycle in northern corn rootworms by finding that large males mate more frequently than small males, with no difference in longevity. Thus, future population models designed to predict the resistance development to Bt toxins in corn may need to account for male body size of northern corn rootworms.
2. Importance of agricultural landscape structure in conserving native pollinators. Pollinator communities face numerous challenges in the U.S., including finding suitable habitat. ARS scientists at Brookings, South Dakota examined how agricultural landscape characteristics influence native pollinator communities in eastern South Dakota. Overall, pollinators became more abundant but dominated by a few agriculturally adapted species as the proportion of cropland increased. Incorporating pollinator-friendly crops at the farm level throughout the region is likely to enhance future pollinator diversity and partially compensate for the negative effects of large monocultures.
3. The diversity of bacterial symbionts within insect guts reflects the potential for ecosystem services of agricultural lands. Insects like crickets have symbiotic bacteria living within their stomachs that allow them to digest particular foods and thus enable them to exploit food resources that vary among habitats. ARS scientists at Brookings, South Dakota tested whether the bacterial diversity found within cricket stomachs is linked with the biodiversity of particular habitats such as prairies, pastures, and cornfields. Bacterial gut diversity in crickets paralleled the plant and insect diversity within each habitat. Cornfields had approximately 25% of the biodiversity found in prairies and pastures, and there was correspondingly low diversity in gut biomes of the crickets. If bacterial symbiont communities are reduced alongside the diversity of other organisms within monoculture fields, then the potential ecosystem services therein may also be diminished.
4. Interseeding berseem clover in cereals eliminates herbicide use. The interseeding of annual clovers in cereal grains can control weeds after grain harvest and by rhizobium fixation, provide nitrogen for future crop use. ARS scientists at Brookings, South Dakota found that planting berseem clover in mid-April is the most effective for establishing a stand and for seedlings to survive cool temperatures. Seedling survival was reduced considerably when clover was planted on April 1. Berseem clover readily winterkills in the fall, so no control action is needed to eliminate clover plants the following year. This provides a sequence for organic producers to no-till during an interval of small grains in a rotation with corn and soybean. Organic producers would like to integrate no-till practices into their systems to restore soil health.
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Review Publications
Vemmer, M., Schumann, M., Beitzen-Heineke, W., French, B.W., Vidal, S., Patel, A.V. 2016. Development of a CO2 releasing co-formulation 1 based on starch, Saccharomyces cerevisiae and Beauveria bassiana attractive towards western corn rootworm larvae. Pest Management Science. doi: 10.1002/ps.4245.
Coates, B.S., Alvez, A., Wang, H., Zhou, Z., Nowastski, T., Chen, H., Rangasamy, M., Robertson, H.M., Whitfield, C.W., Walden, K.K., Kachman, S.D., French, B.W., Meinke, L.J., Hawthorne, D., Abel, C.A., Sappington, T.W., Siegfried, B.D., Miller, N.J. 2016. Quantitative trait locus mapping and functional genomics of an organophosphate resistance trait in the western corn rootworm, Diabrotica virgifera virgifera. Insect Molecular Biology. 25(1):1-15. doi: 10.1111/imb.12194.
Nemec, K.T., Beckendorf, E.A., Hesler, L.S., Riedell, W.E., Lundgren, J.G. 2015. The effect of flowering calendula and cuphea plants on Orius insidiosus survival and predation of Aphis glycines. Biocontrol Science and Technology. 26: 12-22. doi: 10.1080/09583157.2015.1072130.
French, B.W., Hammack, L., Tallamy, D.W. Mating success, longevity, and fertility of Diabrotica virgifera virgifera LeConte (Chrysomelidae: Coleoptera) in relation to body size and Cry3Bb1 resistant and susceptible genotypes. Insects. 2015, 6, 943-960; doi:10.3390/insects6040943.
Schmid, R.B., Lehman, R.M., Volker, B., Lundgren, J.G. 2015. Gut bacterial symbiont diversity within beneficial insects linked to reductions in local biodiversity. Annals of the Entomological Society of America. 108(6):993-999, doi: 10.1093/aesa/sav081.
Oyediran, I., Matthews, P., Narendra, P., French, B.W., Conville, J., Burd, T. 2015. Susceptibility of northern corn rootworm Diabrotica barberi Smith & Lawrence (Coleoptera: Chrysomelidae) to mCry3A and eCry3.1Ab Bacillus thuringiensis proteins. Insect Science. doi: 10.1111/1744-7917.12249.
Anderson, R.L. 2015. Integrating a complex rotation with no-till improves weed management in organic farming. Agronomy for Sustainable Development. 35:967-974.
Pereira, A.E., Wang, H., Zukoff, S.N., Meinke, L.J., French, B.W., Siegfried, B.D. 2015. Evidence of field-evolved resistance to bifenthrin in western corn rootworm (Diabrotica virgifera virgifera LeConte) populations in western Nebraska and Kansas. PLoS One. 10(11): e0142299. doi:10.1371/journal.
Layman, M., Lundgren, J.G. 2015. Mutualistic and antagonistic trophic interactions in canola: the role of aphids in shaping pest and predator populations. Biological Control. 91:62-70.
Anderson, R.L. 2016. Converting perennial legumes to organic cropland without tillage. Renewable Agriculture and Food Systems. 31: 166-171.
Mogren, C.L., Rand, T.A., Lundgren, J.G. 2016. The effects of crop intensification on the diversity of native pollinator communities. Environmental Entomology, 45(4), 865–872. doi: 10.1093/ee/nvw066.
Anderson, R.L. 2016. Suppressing weed growth after wheat harvest with underseeded red clover in organic farming. Renewable Agriculture and Food Systems. 31: 185-190.
Erb, M., Marti, G., Robert, C., Lu, J., Doyen, G., Villard, N., Barriere, Y., French, B.W., Wolfender, J., Turlings, T.J. 2015. A physiological and behavioral mechanism for leaf-herbivore induced systemic root resistance. Plant Physiology. 169: 2884-2894.
Eberle, C.A., Thom, M.D., Nemec, K.T., Forcella, F., Lundgren, J.G., Gesch, R.W., Riedell, W.E., Papiernik, S.K., Wagner, A.K., Peterson, D.H., Eklund, J.J. 2015. Using pennycress, camelina, and canola cash crops to provision pollinators. Industrial Crops and Products. 75:20-25.
Robert, C.A., Schirmer, S., Barry, J.M., French, B.W., Hibbard, B.E., Gershenzon, J. 2015. Belowground herbivore tolerance involves delayed overcompensatory root regrowth in maize. Entomologia Experimentalis et Applicata. 157:113-120.
Thom, M.D., Eberle, C.A., Forcella, F., Gesch, R.W., Weyers, S.L., Lundgren, J.G. 2016. Nectar production in oilseeds: Food for pollinators in an agricultural landscape. Crop Science. 56:727-739.
Zukoff, S.N., Ostlie, K.R., Potter, B., Meihls, L.N., Zukoff, A.L., French, L., Ellersieck, M.R., French, B.W., Hibbard, B.E. 2016. Multiple assays indicate varying levels of cross resistance of Cry3Bb1-selected field populations of the western corn rootworm to mCry3A, eCry3.1Ab, and Cry34/35Ab1. Journal of Economic Entomology. 109(3):1387-1398.