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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Pest Management Research » Research » Research Project #429648

Research Project: Ecology and Management of Grasshoppers and Other Rangeland and Crop Insects in the Great Plains

Location: Pest Management Research

2020 Annual Report


Objectives
Objective 1: Determine the role of rangeland insects, particularly grasshoppers and Mormon crickets, on rangeland ecosystem function and production. [NP304, Component 3, Problem Statements 3B1, 3B2] Subobjective 1.A: Identify the impacts of grasshopper herbivory and drought on rangeland function and nutrient cycling. Subobjective 1.B: Identify the competitive and predatory interactions between Mormon crickets and grasshoppers, their impacts on plant community composition and nutrient cycling on rangeland, and the effect of grasshopper abundance on Mormon cricket immunity to disease. Objective 2: Identify climatic and biotic ecological drivers of pest population dynamics (such as wheat stem sawflies, grasshoppers, and Mormon crickets) in order to develop practical predictive models of when these key pests will exceed economic thresholds. [NP304, Component 3, Problem Statements 3A1, 3B1, 3B2] Subobjective 2.A: Using long-term monitoring data, identify climatic and vegetation/landscape components that are associated with population shifts and variability of individual grasshopper species and grasshopper species diversity. Subobjective 2.B: Determine whether Mormon crickets have annual, biennial, and plurennial populations, and identify cues that cause females to lay eggs that break diapause and hatch after one, two, or several winters. Subobjective 2.C: Identify the role of moisture stress in breaking diapause and triggering Mormon cricket embryonic development. Subobjective 2.D: Identify climatic correlates of wheat stem sawfly and parasitoid wasp abundance and quantify the effects of precipitation on pest pressure, biological control and crop yield. Objective 3: Design sustainable approaches (e.g. roadside and conservation plantings, landscape diversification, rangeland fire, and grazing management) to manage key crop and rangeland insects, such as wheat stem sawfly, grasshoppers, and their natural enemies. [NP304, Component 3, Problem Statements 3A2, 3B2] Subobjective 3.A: Identify components of native vegetation that provide sugar resources for beneficial natural enemies, and assess the potential influence of these resources on natural enemy longevity and biological control. Subobjective 3.B: Identify components of rangeland management practices that can be used to sustainably manage grasshopper populations. Objective 4: Develop microbial control agents as tools for control of key rangeland and wheat pests [NP304, Component 3, Problem Statement 3A2, 3B2] Subobjective 4.A: Develop microbial control agents for grasshoppers and Mormon crickets. Subobjective 4.B: Determine the biological significance of endophytic Beauveria affecting wheat stem sawfly.


Approach
Grasshoppers, Mormon crickets and wheat stem sawfly are key constraints on rangeland and crop productivity. Grasshoppers and Mormon crickets consume ~$1.5 billion of forage annually and wheat stem sawfly causes ~$250-350 million in crop damage annually. Current control strategies for these major pests are inadequate, costly and/or result in unacceptable environmental impacts due to the historical reliance on broad spectrum insecticides. The goal of this proposed project is to acquire the knowledge needed to develop innovative, environmentally sound and sustainable management alternatives for control of these pests which currently lack sustainable control measures. To achieve this end, we will pursue research to broaden our ecological foundation, enhance prevention of pest outbreaks, and develop microbial intervention tools. We will develop a sound understanding of pest impacts on rangeland function and determine climatic and biotic drivers that cause these pervasive Great Plains pests to exceed economic thresholds. We will design sustainable habitat and landscape approaches to manage these pests and their natural enemies. We will develop microbial control agents to provide critically needed alternatives to pesticide-based control. Pursuing research along these themes of ecology, prevention and intervention will provide the foundational knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that reduce economic impacts and promote food security, while decreasing environmental impacts of control measures. We will communicate our results through on-going relationships with land management agencies, farmers and ranchers, academic societies, industry and state extension services.


Progress Report
ARS scientists completed greenhouse studies examining floral resource use by wheat stem sawfly parasitoids, a manuscript was submitted and published. New experiments were initiated on examining the effects of various aphid honeydew sugars on wheat stem sawfly parasitoid performance. A manuscript on population model projecting the influence of crop resistance and biological control on sawfly population growth was revised and published. A second year of study was completed on examining effects of harvest timing and landscape structure on alfalfa weevil population dynamics and biological control. Many managers use degree day estimates of pest occurrence after spring thawing to plan surveying and control efforts. In order to understand hatching and growth of Mormon cricket nymphs, ARS scientists modeled near-surface soil and air temperatures and compared these to data collected in populations across a range of elevations from 200-9,000 feet above sea level. In combination with degree day models of hatching and nymphal growth developed by ARS scientists, modeled temperatures will be used to forecast hatching and growth across the broad elevational range occupied by Mormon crickets to improve the efficiency of pest surveying, forecasting, and management. At the request of the National Grasshopper Management Board, new research was initiated with the long-term goal of determining the role of plant micronutrients in grasshopper outbreaks, as grasshoppers remove over $1 billion in rangeland forage annually. New collaborative research with ARS researchers in Mandan, North Dakota, was initiated examining if a range of grazing and fire management treatments can reduce dominance of the exotic grass Kentucky bluegrass and simultaneously increase the abundance of dung beetles that can reduce livestock fly pest problems. Research continued examining how these management practices affect grasshopper populations. Data collection from a 5-year experiment examining interactions between the pest rangeland grasshoppers and Mormon crickets was completed. Long-term grasshopper sampling continued at 25 sites, with the goal of better predicting grasshopper outbreaks, since detailed long-term data is highly uncommon. Data analysis from this data is underway. In addition, vegetation and soil measurements were conducted at each site.


Accomplishments
1. Sugar resources enhance performance of wheat stem sawfly parasitoids. Despite almost a century of research, the wheat stem sawfly continues to be a major pest of wheat, with estimated regional losses to growers of >$350 million/year. While biological control has promise, efficacy is variable across the region. Providing sugar resources for parasitoids is an important component of habitat management approaches to bolster biological control, which could be leveraged to increase biocontrol against sawfly benefiting farmers in the region. Researchers at ARS in Sidney, Montana, screened three flowering cover crop species, and one aphid species, for their potential to increase the longevity of the parasitoid wasp that attacks wheat stem sawfly, the most important pest of wheat in the Northern Great Plains. Results demonstrate that buckwheat and honeydew from a common wheat aphid both substantially increased longevity of parasitoid females, by over threefold, while longevity on sunflower and coriander was not significantly different from controls on wheat. The results suggest that incorporating buckwheat into cover crop mixes could enhance parasitoid performance in adjacent wheat crops. However, the finding that honeydew associated with a common wheat aphid is a suitable resource suggests that future work assessing the varying quality, and spatial and temporal availability, of aphid honeydew will be a critical consideration in developing habitat management strategies for parasitoid conservation in this system.

2. Parental control over timing of egg development in Mormon crickets. Most insects lay eggs that hatch the following year. ARS scientists in Sidney, Montana, were first to determine that Mormon crickets in the Bighorn Mountains of Wyoming, where they compete with cattle for summer pasture, laid eggs with delayed embryonic development and hatching when the parents were exposed to a short-day photoperiod. Females in a short daylength, which is indicative of the end of the growing season, were more likely than those in long daylength, which occurs at mid-summer, to lay eggs that developed in later growing seasons, even though the conditions for egg development were identical. By delaying the development of their eggs in the soil, females create an egg bank that is analogous to a seed bank. An egg bank provides a refuge for their offspring to survive the harsh conditions of winter and persist at high altitudes where the growing season is short. State entomologists report that knowledge of egg bank longevity improves forecasting and reduces the cost and impact of management of this pest.

3. Grasshopper feeding on plants impacts belowground communities. Together with collaborators, ARS researchers in Sidney, Montana, found that grasshopper species composition and functional diversity (i.e. what they feed on) have strong but different effects on above- and belowground communities. Grasshopper diet shifted soil community composition and function, while grasshopper composition only changed belowground functions. The results demonstrate that grasshopper feeding patterns may be important for understanding how grasshoppers affect both plants and belowground organisms. In a novel finding, grasshopper presence increased carbon storage belowground, which is a previously underappreciated pathway of soil carbon sequestration. This study demonstrates that grasshoppers can affect belowground parts of rangeland systems which could influence the impacts of livestock grazing on rangeland during grasshopper outbreaks.


Review Publications
Srygley R., Jaronski, S., 2019. Mormon cricket, Anabrus simplex Haldeman, 1852 (Tettigoniidae). In: Lecoq M., Zhang L., editors. Encyclopedia of Pest Orthoptera of the World. Beijing: China Agricultural University Press. p. 219-223.
Srygley, R.B. 2020. Coping with drought: Diapause plasticity in katydid eggs at high, mid, and low elevations. Ecological Entomology. 45(3):485-492. https://doi.org/10.1111/een.12820.
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.
Rand, T.A., Richmond, C.E. 2020. Modeling the combined impacts of host plant resistance and biological control on the population dynamics of a major pest in wheat. Pest Management Science. https://doi.org/10.1002/ps.5830.
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.
Rand, T.A., Waters, D.K. 2020. Aphid honeydew enhances parasitoid longevity to the same extent as a high quality floral resource: implications for conservation biological control of the wheat stem sawfly (Hymenoptera: Cephidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toaa076.
Srygley, R.B. 2020. Parental photoperiod affects egg diapause in a montane population of Mormon crickets Anabrus simplex (Orthoptera: Tettigoniidae). Environmental Entomology. 49(4):895-901. https://doi.org/10.1093/ee/nvaa062.
Rand, T.A., Waters, D.K., Srygley, R.B., Branson, D.H. 2020. Tri-trophic interactions are resilient to large shifts in precipitation levels in a wheat agroecosystem. Agriculture, Ecosystems and Environment. 301:1-10. https://doi.org/10.1016/j.agee.2020.106981.
Cambraia Alves, O., Wajnberg, E., Esquivel, D.M., Srygley, R.B. 2020. Magnetic material in migratory and non-migratory Neotropical Lepidoptera: A magnetic resonance study. Journal of Magnetism and Magnetic Materials. 513:1-11. https://doi.org/10.1016/j.jmmm.2020.167053.
Sharma, A., Jaronski, S., Reddy, G.V. 2019. Impact of granular carriers to improve the efficacy of entomopathogenic fungi against wireworms in spring wheat. Journal of Pest Science. https://doi.org/10.1007/s10340-019-01161-1.
Chen, X., Johnson, D., Stark, J., Kawchuk, L., Jaronski, S. 2018. Toxicity of biopesticide candidate Metarhizium anisopliae var anisopliae S54, neonicotinoid imidacloprid, neem extract (Azatin), and agricultural adjuvant R-11 on the crustacean Ceriodaphnia dubia Richard. Biopesticides International. 14(2):71-77.
Branson, D.H. 2020. Grasshopper populations respond similarly to multiple moderate intensity livestock grazing treatments. Journal of Orthoptera Research. 29(1):67-69. https://doi.org/10.3897/jor.29.46966.
Branson, D.H. 2020. Influence of cold temperature and exposure time on egg overwintering survival in the white-whiskered grasshopper (Orthoptera: Acrididae). Journal of Orthoptera Research. 29(1):63-65. https://doi.org/10.3897/jor.29.46967.