Progress 01/03/11 to 09/30/15
Outputs
Progress Report Objectives (from AD-416): Objective 1: Clarify how grasshoppers influence interactions between exotic and native grassland plants and the sustainability of grazing systems. Objective 2: Define factors that influence grasshopper outbreaks and Mormon cricket migration to enhance predictions of when outbreaks and migration occur, and identify management techniques that impact population densities. Subobjective 2a: Define the impact climate conditions have on grasshopper and Mormon cricket egg survival to further understand population dynamics and outbreaks. Subobjective 2b: Examine the effectiveness and underlying mechanisms of grassland management practices, such as fire and livestock grazing, to sustainably manage grasshopper populations. Objective 3: Identify ecological factors underlying variability in populations of key crop insect pests and their natural enemies, and identify factors and/or management approaches that augment natural enemies and maximize control of key insect pests. Subobjective 3a: Quantify the effects of semi-natural habitat (grasslands) on grass feeding herbivore-parasitoid food web dynamics and pest pressure in small grains. Subobjective 3b: Determine the effects of landscape structure on the diversity and abundance of natural enemy communities associated with alfalfa pests and how this ultimately influences key interaction-based ecosystem services (i.e. biological control of pests by parasitoids, predators and pathogens). Objective 4: Define biological factors and mechanisms that regulate locomotion, reproduction, and immunity to enhance grasshopper and Mormon cricket management. Subobjective 4a: Identify intake target of Mormon crickets in last nymphal instar and first 8 days of adult life, during which reproductive and immune systems are maturing, and determine if dietary deficiencies alter the efficacy of fungal control. Subobjective 4b: Determine if dietary deficiencies exhibited by migratory Mormon crickets in the field alter their ability to escalate their immune responses. Objective 5: Develop commercializable microbial control agents and methods for their use in managing pest insects such as grasshoppers and Mormon crickets. Objective 6: Assess the suitability and potential effectiveness of classical biocontrol agents against wheat stem sawfly. Approach (from AD-416): Insects are key constraints in crops and rangelands. Rangeland is a fundamental resource for the beef industry, with grasshoppers frequently affecting food security on all inhabited continents. Wheat and alfalfa rank as the third and fourth most important crops grown in the U.S. ARS stakeholders have identified grasshoppers and Mormon crickets in rangeland, and wheat stem sawfly and alfalfa weevil in cropping systems as high priority pests. Current control strategies for these pests are inadequate, costly and result in unacceptable environmental impacts. Pest management in the modern era has generally focused on suppressive tactics, primarily via chemical means. However, the increasing reliance on agrochemical inputs in modern agriculture has led to public concerns over safety and environmental impacts. Ecologically based pest management approaches attempt to address these concerns by moving beyond the chemical paradigm, to develop safer and more sustainable control. This project focuses on generating the biological and ecological knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that maintain pest populations at sub-economic levels via biological and cultural means. A sound understanding of insect pest ecology will form the basis for predicting when an insect will be a pest, understanding pest impacts, and determining whether prevention or intervention will be necessary and/or effective. Long-term sustainable solutions to pest problems will only be achieved by restructuring and managing agricultural and rangeland systems in innovative and novel ways that maximize built-in preventive strengths or negatively affect pest population dynamics. In situations where preventive strategies are overcome or consistently ineffective, developing novel biological intervention tools becomes paramount to provide critically needed alternatives to pesticide-based control. In order to increase predictability of grasshopper and Mormon cricket outbreaks and assess their ecological impacts, we will investigate responses to changing climate conditions, and evaluate the effects of grasshoppers on competition between exotic and native rangeland plants. We will also develop novel, preventive strategies that either work against pest fitness in rangeland or render cropping systems less vulnerable to pest problems via the augmentation of natural enemies. Finally, we will develop innovative ways to intervene and control pests when preventive barriers are overcome, including investigations of Mormon cricket and grasshopper susceptibility to pathogens to enhance the efficacy of these natural enemies, and to identify new biocontrol agents to expand the biological arsenal to disrupt growth of wheat stem sawfly, grasshopper, and Mormon cricket populations. This research will fundamentally expand the knowledge base necessary to develop effective, ecologically-based pest management solutions, promoting food security while decreasing energy inputs and environmental impacts. Objective 2, Subobjective 2a. Grasshopper Ecology: A manipulative drought experiment designed to improve our ability to predict grasshopper population changes following drought was initiated. Both grasshopper density and drought (75% spring, 75% summer, 50% season long drought, no drought) are being manipulated. The results will inform rangeland management decisions under future climate scenarios. Research was completed in a related study examining how drought affects competition between an outbreaking late season grasshopper species and an earlier developing pest grasshopper species. The results were presented at a national meeting, with relatively weak effects of drought and competition found during the study conducted with well above average precipitation. Objective 4, Subobjective 4b. Mormon crickets: ARS researchers at Sidney, MT investigated how Mormon crickets, which can create severe crop damage, use hormones to access lipids from their body, alter metabolic rate, and then stimulate their large group migrations. Lipid mobilization did not differ between Mormon crickets and the desert locust. An experiment showed that lipids peaked 1-2 hours after injection of hormones in both males and females. Resting metabolic rate did not differ between hormone injected crickets and non-injected controls, and migration activity in laboratory arenas did not differ between hormone injected and control Mormon crickets. Objective 6. Wheat stem sawfly: ARS researchers at Sidney, MT have completed processing samples from a 2014 wheat stem sawfly survey examining how climate alters sawfly performance and infestation. Also completed the first year of processing of samples from a manipulative common garden experiment to assess the performance of wheat stem sawfly larvae on common native and introduced grass species. Now analyzing results on a project designed to look at wheat resistance effects on biological control. Established a large precipitation manipulation experiment to assess drought and rainfall effects on wheat stem sawfly infestations and the efficacy of their native parasitoids. Wrote up results concluding the classical biological control program for wheat stem sawfly, accepted for publication. Objective 3, Subobjective 3b. Alfalfa weevil: Completed processing 2014 alfalfa weevil/natural enemy survey samples, and recently completed 7th year of monitoring for weevils and quantifying parasitism in 2015 (10 sites). Larval and adult weevils from 10 sites were assessed for the presence of fungal pathogens; no fungi were found. Objective 5. Microbial Control of Grasshoppers: Second year of field tests of candidate fungi for grasshopper control completed. Efficacy of all except two commercial, nonindigenous fungi was strongly inhibited by grasshopper thermoregulation. Laboratory bioassays of several candidate fungi with selected butterfly and beetle species were completed and indicate good potential for several of the candidates. Overwintering nonpersistence of two nonindigenous fungi verified in second year of testing. Preliminary UV-protectant formulation for fungi developed. Accomplishments 01 Fire, grazing, and grasshopper control. Experiments have been lacking in the northern Great Plains that examine effects of fire and grazing utilization on grasshoppers. As part of a larger study examining vegetation responses to late summer fire and post-fire grazing utilization in eastern Montana to aid in post-fire management decisions, researchers at ARS in Sidney, MT examined grasshopper responses to fire and post-fire grazing. Fire reduced grasshopper density 36 to 53% across experiments, with the two most abundant grasshopper species reduced 80 and 84% the first year after a fire event. Late season fire can have complementary positive effects on both grass production and grasshopper control. While widespread burning of rangeland to deal with a current outbreak is unlikely to be practical for the control of grasshoppers, incorporating a system of rotating fire among pastures and years to dampen the potential for outbreaks in the first place may be an option. 02 Potential Microbial Control of Wheat stem sawfly: Wheat stem sawfly is the most important pest of wheat in the Great Plains with no fully effective control measures available. ARS researchers at Sidney, MT collected isolates of Beauveria fungus from overwintering wheat stem sawfly larvae during a multistate survey. Three isolates were effective in attacking and damaging the wheat stem sawfly larvae in lab bioassays. By just spraying the fungus on wheat, the fungal isolates successfully entered and established within the wheat plant, where they can then potentially attack wheat stem sawfly within the plant. This research, supported by two grants from the Montana Wheat and Barley Committee, indicates a potential, novel microbial control approach � via establishment of insect pathogenic fungus inside the wheat � may be possible.
Impacts
(N/A)
Publications
- Shaohui, W., Reddy, G.P., Jaronski, S. 2014. Advances in microbial insect control in horticultural ecosystems. In: Nandwani, D., editor, Sustainable Horticultural Systems: Sustainable Development and Biodiversity. Switzerland: Springer International Publishing. 2:223-252.
- Frost, C., Didham, R.K., Rand, T.A., Peralta, G., Tylianakis, J.M. 2015. Community-level net spillover of natural enemies from managed to natural forest. Ecology. 96(1):193-202. DOI: 10.1890/14-0696.1.
- Alves, O.C., Srygley, R.B., Riveros, A.J., Barbosa, M.A., Esquivel, D.M., Wajnberg, E. 2014. Magnetic anisotropy and organization of nanoparticles in heads and antennae of neotropical leaf-cutter ants, Atta colombica. Journal of Physics D. 47(43):435401. DOI: 10.1088/0022-3727/47/43/435401.
- Rand, T.A., Louda, S.M., Bradley, K., Crider, K. 2015. Effects of invasive knapweed (Centaurea stoebe subsp. micranthos) on a threatened native thistle (Cirsium pitcheri) vary with environment and life stage. Botany. 93:1-16. DOI: 10.1139/cjb-2015-0032.
- Clifton, E., Gassman, A., Hodgson, E., Jaronski, S. 2015. Abundance of soil-borne entomopathogenic fungi in organic and conventional fields in the Midwestern USA with an emphasis on the effect of herbicides and fungicides on fungal persistence. PLoS One. 10(7):e0133613. DOI: 10.1371/ journal.pone.0133613.
|
Progress 10/01/13 to 09/30/14
Outputs
Progress Report Objectives (from AD-416): Objective 1: Clarify how grasshoppers influence interactions between exotic and native grassland plants and the sustainability of grazing systems. Objective 2: Define factors that influence grasshopper outbreaks and Mormon cricket migration to enhance predictions of when outbreaks and migration occur, and identify management techniques that impact population densities. Subobjective 2a: Define the impact climate conditions have on grasshopper and Mormon cricket egg survival to further understand population dynamics and outbreaks. Subobjective 2b: Examine the effectiveness and underlying mechanisms of grassland management practices, such as fire and livestock grazing, to sustainably manage grasshopper populations. Objective 3: Identify ecological factors underlying variability in populations of key crop insect pests and their natural enemies, and identify factors and/or management approaches that augment natural enemies and maximize control of key insect pests. Subobjective 3a: Quantify the effects of semi-natural habitat (grasslands) on grass feeding herbivore-parasitoid food web dynamics and pest pressure in small grains. Subobjective 3b: Determine the effects of landscape structure on the diversity and abundance of natural enemy communities associated with alfalfa pests and how this ultimately influences key interaction-based ecosystem services (i.e. biological control of pests by parasitoids, predators and pathogens). Objective 4: Define biological factors and mechanisms that regulate locomotion, reproduction, and immunity to enhance grasshopper and Mormon cricket management. Subobjective 4a: Identify intake target of Mormon crickets in last nymphal instar and first 8 days of adult life, during which reproductive and immune systems are maturing, and determine if dietary deficiencies alter the efficacy of fungal control. Subobjective 4b: Determine if dietary deficiencies exhibited by migratory Mormon crickets in the field alter their ability to escalate their immune responses. Objective 5: Develop commercializable microbial control agents and methods for their use in managing pest insects such as grasshoppers and Mormon crickets. Objective 6: Assess the suitability and potential effectiveness of classical biocontrol agents against wheat stem sawfly. Approach (from AD-416): Insects are key constraints in crops and rangelands. Rangeland is a fundamental resource for the beef industry, with grasshoppers frequently affecting food security on all inhabited continents. Wheat and alfalfa rank as the third and fourth most important crops grown in the U.S. ARS stakeholders have identified grasshoppers and Mormon crickets in rangeland, and wheat stem sawfly and alfalfa weevil in cropping systems as high priority pests. Current control strategies for these pests are inadequate, costly and result in unacceptable environmental impacts. Pest management in the modern era has generally focused on suppressive tactics, primarily via chemical means. However, the increasing reliance on agrochemical inputs in modern agriculture has led to public concerns over safety and environmental impacts. Ecologically based pest management approaches attempt to address these concerns by moving beyond the chemical paradigm, to develop safer and more sustainable control. This project focuses on generating the biological and ecological knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that maintain pest populations at sub-economic levels via biological and cultural means. A sound understanding of insect pest ecology will form the basis for predicting when an insect will be a pest, understanding pest impacts, and determining whether prevention or intervention will be necessary and/or effective. Long-term sustainable solutions to pest problems will only be achieved by restructuring and managing agricultural and rangeland systems in innovative and novel ways that maximize built-in preventive strengths or negatively affect pest population dynamics. In situations where preventive strategies are overcome or consistently ineffective, developing novel biological intervention tools becomes paramount to provide critically needed alternatives to pesticide-based control. In order to increase predictability of grasshopper and Mormon cricket outbreaks and assess their ecological impacts, we will investigate responses to changing climate conditions, and evaluate the effects of grasshoppers on competition between exotic and native rangeland plants. We will also develop novel, preventive strategies that either work against pest fitness in rangeland or render cropping systems less vulnerable to pest problems via the augmentation of natural enemies. Finally, we will develop innovative ways to intervene and control pests when preventive barriers are overcome, including investigations of Mormon cricket and grasshopper susceptibility to pathogens to enhance the efficacy of these natural enemies, and to identify new biocontrol agents to expand the biological arsenal to disrupt growth of wheat stem sawfly, grasshopper, and Mormon cricket populations. This research will fundamentally expand the knowledge base necessary to develop effective, ecologically-based pest management solutions, promoting food security while decreasing energy inputs and environmental impacts. Grasshopper Ecology: Based on previous ARS research in Sidney, a long term experiment examining the impact of sustained grasshopper outbreaks on rangeland function, plant composition, and the sustainability of livestock grazing is wrapping up in its fourth year. The results from the experiment will allow managers to better understand how grasshopper outbreaks negatively or positively impact rangeland, and has relevance to chemical control decision making. To better understand the role of climate fluctuations on grasshopper population dynamics and outbreaks, new research was initiated using custom fabricated passive drought frames covering caged grasshopper populations. Research was completed examining how often grasshopper predators reduce rangeland forage damage and grasshopper outbreaks through direct and indirect effects on pest grasshoppers, with the results presented at two national meetings. Wheat stem sawfly: We have completed processing samples from a 2012 wheat stem sawfly survey (40 sites) examining the effects of agricultural intensification on wheat stem sawfly infestation and parasitism. Additionally, we have completed sample collection and processing from a large scale survey examining the use of native and introduced grasses of rangeland and CRP by the wheat stem sawfly. We have also initiated a manipulative common garden experiment to assess the survival of wheat stem sawfly larvae on common native and introduced grass species. Alfalfa weevil: We have processed 80% of our 2013 alfalfa weevil/natural enemy survey samples, and recently completed our 6th year of monitoring for weevils and rearing parasitoids in 2014 (14 sites). We completed an additional early spring collection of adult parasitoid wasps across 12 sites, to look at the frequency of sugar feeding in these key parasitoids and how this relates to local resource availability (aphid densities and floral resources). The insect pathogenic fungus Beauveria was recovered from adult weevils in several of the 15 survey sites, and observed to be epidemic at one site. All Beauveria isolated from weevils has been DNA- characterized to provide initial picture of its population genetics. Mormon crickets: In the Bighorn Mountains of Wyoming, Mormon crickets are reported to have outbreak populations every other year. A 1940s transfer experiment concluded that Mormon crickets in the Bighorns are obligately biannual, requiring two summers to complete embryonic development and hatching in the spring following the second winter. However mating pairs set up from Mormon crickets that we collected in the Bighorns in the summer of 2013 laid eggs that developed directly and hatched the following spring. Thus we conclude that the Mormon crickets in the Bighorns are facultatively biannual. We plan to test whether mothers use photoperiod as a cue to delay egg development. Grasshopper biological control using fungi: Eight promising fungus isolates, from the 450 originally under consideration, were subjected to outdoor cage tests to determine their tolerance to grasshopper behavior when they heat their bodies up in the sun to kill disease, and to outdoor exposure on sprayed foliage to evaluate UV tolerance of spores. A 10- acre field trial in Wyoming of one commercial and one experimental fungus was completed. Accomplishments 01 Novel potential microbial control of wheat stem sawfly was discovered. Wheat stem sawfly is the most important pest of wheat in the Great Plains; only a few inadequate control tools exist. Scientists at ARS Sidney, MT and Montana State University discovered 10 strains of the insect-attacking fungi Beauveria and Metarhizium in over-wintering wheat stem sawfly larvae. After the initial discovery, wheat stem sawfly larvae were sampled from two randomly chosen fields and a very high prevalence of fungi in the larvae was discovered in both fields. These are the first Beauveria or Metarhizium recorded from this insect. This insect spends its entire egg to adult cycle within the wheat stem, isolated from fungus spores in the environment, so that infections were most likely acquired from fungi growing harmlessly through the wheat tissue, a phenomenon described in a number of other plants but never in wheat. Artificial introduction of Beauveria into other plants has been demonstrated, so one or more of these isolates could provide successful management of this important wheat pest. 02 Climatic effects on Mormon crickets. Mormon crickets are a pest insect species across most western American rangelands. ARS researchers at Sidney, MT discovered that female Mormon crickets maximize their reproductive output when their body temperature reaches a maximum of 35�C. A higher maximum body temperature of 37-39�C or a lower one of 30�C resulted in a significant decline in the laying of eggs that developed. Hence a change in ambient temperature on the order of that predicted to occur in the U.S. Great Basin in the next 30 years is sufficient to reduce reproduction, particularly at lower elevations. This information will help in predicting future outbreaks of this pest species, as well as regions most susceptible to damage in the near future. 03 Severe grasshopper outbreaks can rapidly end with strong competition from insects and livestock grazing. Grasshopper outbreaks have plagued humans throughout recorded history worldwide, but few experiments have examined how competition between livestock and grasshoppers impact outbreaks. ARS researchers from Sidney and Miles City, MT manipulated both grasshopper densities and sheep grazing inside large cages during a grasshopper outbreak where grasshopper densities reached 130 per square meter. This novel experiment provides insights into how competition between insect and livestock herbivores influences grasshopper outbreaks. An earlier study by ARS Sidney, MT demonstrated that a large late summer rainfall event led to a severe grasshopper outbreak, caused by a link between precipitation and food availability. These results indicate that severe and extreme grasshopper outbreaks can rapidly end when competition from livestock and insect herbivores is strong, which may reduce the justification for large scale grasshopper pesticide control programs on western U.S. rangeland.
Impacts
(N/A)
Publications
- Rudeen, M.L., Jaronski, S., Petzold-Maxwell, J.L., Gassman, A.J. 2013. Entomopathogenic fungi in cornfields and their potential to manage larval western corn rootworm Diabrotica virgifera virgifera. Journal of Invertebrate Pathology. 114(3):329�332.
- Riveros, A.J., Esquivel, D.M., Wajnberg, E., Srygley, R.B. 2014. Do leaf- cutter ants Atta colombica obtain their magnetic sensors from soil? Behavioral Ecology and Sociobiology. 68(1):55-62.
- Srygley, R.B., Dudley, R., Oliveira, E.G., Riveros, A.J. 2014. El Ni�o, host plant growth, and migratory butterfly abundance in a changing climate. Biotropica. 46(1):90-97.
- Srygley, R.B., Lorch, P.D. 2013. Coping with uncertainty: Nutrient deficiencies motivate insect migration at a cost to immunity. Integrative & Comparative Biology. 53(6):1002-1013.
- Rand, T.A., Waters, D.K., Blodgett, S.L., Knodel, J.J., Harris, M.O. 2014. Increased area of a highly suitable host crop increases herbivore pressure in intensified agricultural landscapes. Agriculture, Ecosystems and Environment. 186:135-143. DOI: 10.1016/j.agee.2014.01.022.
- Guadalupe, P., Frost, C.M., Rand, T.A., Didham, R.K., Tylianakis, J.M. 2014. Complementarity and redundancy of interactions enhance attack rates and spatial stability in host-parasitoid food webs. Ecology. 95(7) :1888�1896. DOI: 10.1890/13-1569.1.
- Jaronski, S. 2013. Mycosis inhibits cannibalism by Melanoplus sanguinipes, M. differentialis, Schistocerca americana, and Anabrus simplex. Journal of Insect Science. 13(122):1-9.
- Vencl, F.V., Plata, C.A., Srygley, R.B. 2013. Proximate effects of maternal oviposition preferences on defense efficacy and larval survival in a diet-specialized tortoise beetle. Who knows best: mothers or their progeny? Ecological Entomology. 38(6):596-607.
- Jaronski, S. 2013. Mass production of entomopathogenic fungi: state of the art. In: Morales-Ramos, J.A., Rjoas, M.G, Shaprio-Ilan, D.I., editors. Mass Production of Beneficial Organisms. USA: Academic Press. p. 357-415.
- Branson, D.H., Haferkamp, M.R. 2014. Insect herbivory and vertebrate grazing impact food limitation and grasshopper populations during a severe outbreak. Ecological Entomology. 39(1):371�381.
- Srygley, R.B. 2014. Effects of temperature and moisture on Mormon cricket reproduction with implications for responses to climate change. Journal of Insect Physiology. 65:57-62. DOI: 10.1016/j.jinsphys.2014.05.005.
- Reddy, G.P., Tangtrakulwanish, K., Wu, S., Miller, J.H., Ophus, V., Prewett, J., Jaronski, S. 2014. Evaluation of the effectiveness of the entomopathogens for the management of wireworms (Coleoptera: Elateridae) on spring wheat. Journal of Invertebrate Pathology. 120:43�49. DOI 10.1016/ j.jip.2014.05.005.
|
Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): Objective 1: Clarify how grasshoppers influence interactions between exotic and native grassland plants and the sustainability of grazing systems. Objective 2: Define factors that influence grasshopper outbreaks and Mormon cricket migration to enhance predictions of when outbreaks and migration occur, and identify management techniques that impact population densities. Subobjective 2a: Define the impact climate conditions have on grasshopper and Mormon cricket egg survival to further understand population dynamics and outbreaks. Subobjective 2b: Examine the effectiveness and underlying mechanisms of grassland management practices, such as fire and livestock grazing, to sustainably manage grasshopper populations. Objective 3: Identify ecological factors underlying variability in populations of key crop insect pests and their natural enemies, and identify factors and/or management approaches that augment natural enemies and maximize control of key insect pests. Subobjective 3a: Quantify the effects of semi-natural habitat (grasslands) on grass feeding herbivore-parasitoid food web dynamics and pest pressure in small grains. Subobjective 3b: Determine the effects of landscape structure on the diversity and abundance of natural enemy communities associated with alfalfa pests and how this ultimately influences key interaction-based ecosystem services (i.e. biological control of pests by parasitoids, predators and pathogens). Objective 4: Define biological factors and mechanisms that regulate locomotion, reproduction, and immunity to enhance grasshopper and Mormon cricket management. Subobjective 4a: Identify intake target of Mormon crickets in last nymphal instar and first 8 days of adult life, during which reproductive and immune systems are maturing, and determine if dietary deficiencies alter the efficacy of fungal control. Subobjective 4b: Determine if dietary deficiencies exhibited by migratory Mormon crickets in the field alter their ability to escalate their immune responses. Objective 5: Develop commercializable microbial control agents and methods for their use in managing pest insects such as grasshoppers and Mormon crickets. Objective 6: Assess the suitability and potential effectiveness of classical biocontrol agents against wheat stem sawfly. Approach (from AD-416): Insects are key constraints in crops and rangelands. Rangeland is a fundamental resource for the beef industry, with grasshoppers frequently affecting food security on all inhabited continents. Wheat and alfalfa rank as the third and fourth most important crops grown in the U.S. ARS stakeholders have identified grasshoppers and Mormon crickets in rangeland, and wheat stem sawfly and alfalfa weevil in cropping systems as high priority pests. Current control strategies for these pests are inadequate, costly and result in unacceptable environmental impacts. Pest management in the modern era has generally focused on suppressive tactics, primarily via chemical means. However, the increasing reliance on agrochemical inputs in modern agriculture has led to public concerns over safety and environmental impacts. Ecologically based pest management approaches attempt to address these concerns by moving beyond the chemical paradigm, to develop safer and more sustainable control. This project focuses on generating the biological and ecological knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that maintain pest populations at sub-economic levels via biological and cultural means. A sound understanding of insect pest ecology will form the basis for predicting when an insect will be a pest, understanding pest impacts, and determining whether prevention or intervention will be necessary and/or effective. Long-term sustainable solutions to pest problems will only be achieved by restructuring and managing agricultural and rangeland systems in innovative and novel ways that maximize built-in preventive strengths or negatively affect pest population dynamics. In situations where preventive strategies are overcome or consistently ineffective, developing novel biological intervention tools becomes paramount to provide critically needed alternatives to pesticide-based control. In order to increase predictability of grasshopper and Mormon cricket outbreaks and assess their ecological impacts, we will investigate responses to changing climate conditions, and evaluate the effects of grasshoppers on competition between exotic and native rangeland plants. We will also develop novel, preventive strategies that either work against pest fitness in rangeland or render cropping systems less vulnerable to pest problems via the augmentation of natural enemies. Finally, we will develop innovative ways to intervene and control pests when preventive barriers are overcome, including investigations of Mormon cricket and grasshopper susceptibility to pathogens to enhance the efficacy of these natural enemies, and to identify new biocontrol agents to expand the biological arsenal to disrupt growth of wheat stem sawfly, grasshopper, and Mormon cricket populations. This research will fundamentally expand the knowledge base necessary to develop effective, ecologically-based pest management solutions, promoting food security while decreasing energy inputs and environmental impacts. BSL-2, 11/12/ 2010. Grasshopper ecology: Collaborations with six universities were developed leading to three NSF and NIFA grant proposals. To understand the impact of grasshopper outbreaks on grassland ecosystems, data from collaborative research in three grassland ecosystems examining the effects of geography and grasshopper diversity on grassland ecosystem processes was analyzed and results presented at a national meeting. Initiated new research examining how often grasshopper predators can reduce rangeland forage damage and grasshopper outbreaks through effects on grasshoppers. Research was completed examining how severe drought affects overwintering egg survival. Mormon crickets: Migrating Mormon crickets can be deficient in either protein or carbohydrates, depending on the population. ARS scientists showed that these two nutritional deficiencies have distinct effects on enzymatic immunities that might lead to susceptibility to fungus or bacteria for population control. We produced protein-deprived Mormon crickets in the laboratory and tested their susceptibility to insect- killing fungi. Following inoculation by the fungus Beauveria bassiana, a registered microbial agent for grasshopper and Mormon cricket control, adults with limited access to protein but adequate carbohydrates were more likely to be killed and died more quickly than those with a balanced diet or those with limited access to carbohydrates. Wheat stem sawfly: We are processing wheat and grass stem samples from a 2012 wheat stem sawfly survey (40 sites) to examine the effects of agricultural intensification on wheat stem sawfly infestation and parasitism. We additionally determined rates of sawfly overwintering mortality for a demographic modeling study. We have completed our containment experiments assessing the suitability of Collyria catoptron as a potential biological control agent for wheat stem sawfly. Our results indicate it will not be an effective agent against sawfly due host incompatibility, difficulty in rearing the parasitoid in a contained environment, and relatively low levels of attack even on its native host in China. Alfalfa weevil: We have completed data analysis and published the first manuscript on environmental influences on the effectiveness of alfalfa weevil natural enemies (2009-2010 samples). We have completed processing our 2011-2012 alfalfa weevil/natural enemy survey samples, and recently completed our 5th year of monitoring for weevils/ parasitoids in 2013 (15 sties). Grasshopper biological control using fungi: Assessment of complete thermal profiles completed for 131 ARS Beauveria isolates from grasshoppers and 150 Metarhizium isolates from Utah State. Few isolates withstood effect of transient heat that mimicks grasshopper behavioral fever; the African/Australian Metarhizium acridum was superior to all domestic isolates. Forty Beauveria isolates were bioassayed, with several being as virulent as the M. acridum. Preliminary evaluation of spore production on grasshoppers was completed; about two-thirds of the isolates are not commercially practical. In bioassays, Yersinia entomophaga showed some promise as a grasshopper pathogen. Accomplishments 01 Agricultural intensification magnifies pest pressure in wheat. The domination of agricultural landscapes by one or two crops is a major component of agricultural intensification with potentially important, yet seldom quantified, effects on insect pests. Researchers at ARS Sidney, MT have documented significant increases in levels of infestation by the wheat stem sawfly, Cephus cinctus, in response to increasing wheat acreage in surrounding landscapes across MT, ND and SD. The results indicate that reducing the area of a highly suitable host crop, wheat, for example by planting non-host crops such as peas or lentils or putting land into CRP grasslands, is a potentially useful tool for managing wheat stem sawfly. This information will help growers making decisions about cropping system diversification/planting design, as well as informing more general agricultural landscape management and incentive programs. 02 Laboratory rearing of Mormon crickets now possible. ARS researchers at Sidney, MT successfully reared Mormon crickets in the laboratory through a second generation for the first time and are currently preparing a third generation for hatching. This result will enhance our ability to perform research on these pest insect year round at our location, rather than just on field populations during summer months. A citizen interested in constructing a rearing facility to harvest Mormon crickets as a low protein food source requested information from ARS on collecting, handling and rearing. Mormon crickets make valuable fish bait with frozen adults selling at $3-5 per dozen. A second citizen indicated an annual demand of 100,000 crickets for bait.
Impacts
(N/A)
Publications
- Jaronski, S. 2012. Microbial Control of Invertebrate Pests-Chapter 7. In : Sundh, I., Wilcks, A., and Goettel, M.S. Beneficial Microorganisms in Agriculture, Food and the Environment: Safety Assessment and Regulation. Oxfordshire, United Kingdom: CAB International. p. 72-95.
- Branson, D.H., Vermeire, L.T. 2013. Heat dosage and oviposition depth influence egg mortality of two common rangeland grasshopper species. Rangeland Ecology and Management. 66(1):110-113.
- Boetel, M.A., Majumdar, A., Jaronski, S., Horsly, R.D. 2012. Cover crop and conidia delivery system impacts on soil persistence of Metarhizium anisopliae (Hypocreales:Clavicipitaceae) in sugarbeet. Biocontrol Science and Technology. 22(11): 1284-1304.
- Grez, A.A., Rand, T.A., Zaviezo, T., Castillo-Serey, F. 2013. Land use intensification differentially benefits alien over native predators in agricultural landscape mosaics. Diversity and Distributions. 19(7): 749- 759; DOI: 10.1111/ddi.12027.
- Vencl, F.V., Srygley, R.B. 2013. Enemy targeting, trade-offs, and the evolutionary assembly of a tortoise beetle defense arsenal. Evolutionary Ecology. 27(2): 237-252. Available: DOI 10.1007/s10682-012-9603-1.
- Petzold-Maxwell, J., Jaronski, S., Clifton, E.H., Dunbar, M.W., Jackson, M. A., Gassman, A.J. 2013. Interactions among Bt maize, entomopathogens, and rootworm species (Coleoptera: Chrysomelidae) in the field: effects on survival, yield and root injury. Journal of Economic Entomology. 106(2): 622-632.
- Rand, T.A. 2013. Host density drives spatial variation in parasitism of the alfalfa weevil, Hypera postica, across dryland and irrigated alfalfa cropping systems. Environmental Entomology. 42(1):116-122.
- Bitshadze, N., Jaronski, S., Khasdan, V., Abashidze, E., Abashidze, M., Latchininsky, A., Samasdashvili, D., Sokhadze, I., Rippa, M., Ishaaya, I., Horowitz, R. 2013. Joint action of Beauveria bassiana and the insect growth regulators diflubenzuron and novaluron, on the migratory locust, Locusta migratoria. Journal of Pest Science. 86(2):293�300. DOI: 10.1007/ s10340-012-0476-4.
- Meikle, W.G., Bon, M., Cook, S.C., Gracia, C.G., Jaronski, S. 2013. Two strains of Pseudomonas fluorscens bacteria differentially affect survivorship of waxworm (Galleria mellonella) larvae exposed to an arthropod fungal pathogen, Beauveria bassiana. Biocontrol Science and Technology. 23(2): 220-233.
- Jackson, M.A., Jaronski, S. 2012. Development of pilot-scale fermentation and stabilization processes for the production of microsclerotia of the entomopathogenic fungus Metarhizium brunneun strain F52. Biocontrol Science and Technology. 22(8):915-930.
- Jaronski, S., Jackson, M.A. 2012. Mass production of entomopathogenic hypocreales. In: Lacey, L.A., editor. Manual of Techniques in Invertebrate Pathology. 2nd edition. New York, NY: Academic Press. p. 255-284.
- Kim, S., Srygley, R.B., Lee, J.Y., Lee, S.I., Choe, J.C. 2012. Urban and natural components of Korean magpie (Pica pica sericea) territories and their effects on prey density. Polish Journal of Ecology. 60: 407-417.
- Petzold-Maxwell, J.L., Jaronski, S., Gassman, A.J. 2012. Tritrophic interactions among Bt maize, an insect pest and entomopathogens: effects on development and survival of western corn rootworm. Annals of Applied Biology. 160(1): 43-55.
|
Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Objective 1: Clarify how grasshoppers influence interactions between exotic and native grassland plants and the sustainability of grazing systems. Objective 2: Define factors that influence grasshopper outbreaks and Mormon cricket migration to enhance predictions of when outbreaks and migration occur, and identify management techniques that impact population densities. Subobjective 2a: Define the impact climate conditions have on grasshopper and Mormon cricket egg survival to further understand population dynamics and outbreaks. Subobjective 2b: Examine the effectiveness and underlying mechanisms of grassland management practices, such as fire and livestock grazing, to sustainably manage grasshopper populations. Objective 3: Identify ecological factors underlying variability in populations of key crop insect pests and their natural enemies, and identify factors and/or management approaches that augment natural enemies and maximize control of key insect pests. Subobjective 3a: Quantify the effects of semi-natural habitat (grasslands) on grass feeding herbivore-parasitoid food web dynamics and pest pressure in small grains. Subobjective 3b: Determine the effects of landscape structure on the diversity and abundance of natural enemy communities associated with alfalfa pests and how this ultimately influences key interaction-based ecosystem services (i.e. biological control of pests by parasitoids, predators and pathogens). Objective 4: Define biological factors and mechanisms that regulate locomotion, reproduction, and immunity to enhance grasshopper and Mormon cricket management. Subobjective 4a: Identify intake target of Mormon crickets in last nymphal instar and first 8 days of adult life, during which reproductive and immune systems are maturing, and determine if dietary deficiencies alter the efficacy of fungal control. Subobjective 4b: Determine if dietary deficiencies exhibited by migratory Mormon crickets in the field alter their ability to escalate their immune responses. Objective 5: Develop commercializable microbial control agents and methods for their use in managing pest insects such as grasshoppers and Mormon crickets. Objective 6: Assess the suitability and potential effectiveness of classical biocontrol agents against wheat stem sawfly. Approach (from AD-416): Insects are key constraints in crops and rangelands. Rangeland is a fundamental resource for the beef industry, with grasshoppers frequently affecting food security on all inhabited continents. Wheat and alfalfa rank as the third and fourth most important crops grown in the U.S. ARS stakeholders have identified grasshoppers and Mormon crickets in rangeland, and wheat stem sawfly and alfalfa weevil in cropping systems as high priority pests. Current control strategies for these pests are inadequate, costly and result in unacceptable environmental impacts. Pest management in the modern era has generally focused on suppressive tactics, primarily via chemical means. However, the increasing reliance on agrochemical inputs in modern agriculture has led to public concerns over safety and environmental impacts. Ecologically based pest management approaches attempt to address these concerns by moving beyond the chemical paradigm, to develop safer and more sustainable control. This project focuses on generating the biological and ecological knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that maintain pest populations at sub-economic levels via biological and cultural means. A sound understanding of insect pest ecology will form the basis for predicting when an insect will be a pest, understanding pest impacts, and determining whether prevention or intervention will be necessary and/or effective. Long-term sustainable solutions to pest problems will only be achieved by restructuring and managing agricultural and rangeland systems in innovative and novel ways that maximize built-in preventive strengths or negatively affect pest population dynamics. In situations where preventive strategies are overcome or consistently ineffective, developing novel biological intervention tools becomes paramount to provide critically needed alternatives to pesticide-based control. In order to increase predictability of grasshopper and Mormon cricket outbreaks and assess their ecological impacts, we will investigate responses to changing climate conditions, and evaluate the effects of grasshoppers on competition between exotic and native rangeland plants. We will also develop novel, preventive strategies that either work against pest fitness in rangeland or render cropping systems less vulnerable to pest problems via the augmentation of natural enemies. Finally, we will develop innovative ways to intervene and control pests when preventive barriers are overcome, including investigations of Mormon cricket and grasshopper susceptibility to pathogens to enhance the efficacy of these natural enemies, and to identify new biocontrol agents to expand the biological arsenal to disrupt growth of wheat stem sawfly, grasshopper, and Mormon cricket populations. This research will fundamentally expand the knowledge base necessary to develop effective, ecologically-based pest management solutions, promoting food security while decreasing energy inputs and environmental impacts. ARS researchers in Sidney, MT examined the impact of patch burning and grazing on grasshopper populations in multi-year experiments in shortgrass and mixed grass prairie. We initiated new research examining how predators (ex. spiders) can reduce rangeland forage damage and grasshopper outbreaks through negative direct and indirect impacts on pest grasshopper species. To better understand the impact of grasshopper outbreaks, new collaborative research was initiated in three grassland ecosystems (TX, KS, MT) examining the effects of geography and grasshopper diversity on grassland ecosystem processes. Additional research was initiated examining how severe drought affects overwintering egg survival and grasshopper outbreaks. We continued evaluating domestic fungi and five commercial fungi for controlling grasshoppers. We assessed heat tolerances of 393 fungal strains. We tested 20 candidate fungal strains for ability to kill grasshoppers in the lab, finding several potential candidates. An ARS- APHIS team conducted a grasshopper field trial of four of these fungi, plus two commercial ones; results pending. ARS completed two outdoor persistence tests of Green Muscle, a fungus used to control grasshoppers in Africa. The fungus failed to survive more than two months in the fall and one month in late spring, indicating that it may be useful as a short term, localized control method, which is our objective. Mormon crickets are pests in the western USA and can be deficient in either protein or carbohydrates when they migrate, depending on the population. These two nutritional deficiencies have distinct effects on immune systems that might lead to susceptibility to fungi or bacteria used for population control. By limiting access to proteins or carbohydrates in the last nymphal and early adult stages in the lab, we were able to produce adults with similar weaknesses in immunities to those we observe in migrating populations in the field. The next step is to test these nutrient-deprived adults for susceptibility to fungi and bacteria as potential control agents. We completed sample processing from a large scale effort in MT aimed at examining grassland influences and regional variation in wheat stem sawfly infestation and parasitism. The results suggest that nearby grasslands (rangeland and Conservation Reserve Program (CRP)) are not important sources of either the wheat stem sawfly or its native parasitoids moving into wheat. We performed predator exclusion experiments to characterize the important natural enemies (parasitoids, pathogens and predators) of alfalfa weevil in the MT/ND region. Results indicate that neither ground dwelling nor aerial predators significantly impact weevil survivorship. In larger scale surveys, carried out in 2010 and 2011, two larval parasitoids have been identified as potentially important (with parasitism rates often exceeding 50%). Weevil surveys were competed again in 2012, an outbreak year for this pest. Initial results suggest lower parasitism, compared with previous years, but the same two parasitoids predominate as the most important enemies. Accomplishments 01 Effects of climate change on agricultural insect pests. ARS researchers Sidney, MT summarized the literature on climate change effects on insect pests for the National Climate Assessment for Agriculture. Rising air temperatures affect all aspects of the insect life cycle and generally result in larger insect populations as a result of earlier emergence wit advancing spring, range expansion, and more generations per year. Under elevated CO2, plants shift their defenses from toxins to tougher, less digestible leaves. Beetles and aphids generally perform better under elevated CO2 to the detriment of plants. Information will be used in a status report on the impacts of climate on sectors of the United States for the U.S. Congress and the President of the United States. 02 Egg depth and vegetation abundance determine when pest grasshoppers can controlled by rangeland fire. Although fire has potential for use as a preventative pest management tool, little information exists on how rangeland fire can be used by land managers to reduce population outbrea of economically important pest grasshoppers. ARS researchers in Sidney, demonstrated that a major pest grasshopper species that lays egg pods deeper below ground than other grasshopper species whose egg pods are vulnerable to fire, is also vulnerable to egg mortality during rangeland fires. Rangeland fire is a common naturally occurring event and is a useful range management tool. This information will help rangeland managers make effective decisions regarding fire and grasshopper control 03 Development of microbial control agents for Mormon cricket and grasshopp control. USDA ARS and APHIS are jointly searching for environmentally sa effective microbial agents to manage outbreaks of Mormon crickets and grasshoppers in the Western United States. These would replace existing insecticides, the future of which is uncertain. ARS researchers in Sidne MT evaluated the spore production and thermal tolerances of 185 Beauveri isolates (new, collected from dead grasshoppers) and 108 Metarhizium isolates (obtained from Utah State University), and initiated bioassays these fungi, with completion for 20 isolates. ARS, with APHIS, also evaluated several commercial fungi in 10-acre grasshopper field trials. As a result USDA is closer to developing a satisfactory microbial contro agent to substitute for the broad-spectrum chemical insecticides current in use on rangelands.
Impacts
(N/A)
Publications
- Foster, N.R., Jaronski, S., Reuter, K.C., Harper, J.D., Schlothauer, R.J., Black, L.R. 2011. Simulated aerial sprays for field cage evaluation of Beauveria bassiana and Metarhizium brunneum (Ascomycetes: Hypocreales) against Anabrus simplex (Orthoptera: Tettigoniidae) in Montana. Biocontrol Science and Technology. 21(11): 1331-1350.
- Cossentine, J., Jaronski, S., Thistlewood, H., Yee, W.L. 2011. Impact of Metarhizium brunneum (Hypocreales: Clavicipitaceae) on pre-imaginal Rhagoletis indifferens (Diptera: Tephritidae) within and on the surface of orchard soil. Biocontrol Science and Technology. 21(2): 1501-1505.
- Srygley, R.B. 2012. Ontogenetic changes in immunity and susceptibility to fungal infection in Mormon crickets Anabrus simplex. Journal of Insect Physiology. 58: 342-347.
- Rand, T.A., Waters, D.K., Shanower, T.G., Berzonsky, W.A. 2012. Effects of genotypic variation in stem solidity on parasitism of a grass-mining insect. Basic and Applied Ecology. 13(3):250�259.
- Cossentine, J., Jaronski, S., Thistlewood, H., Yee, W.L. 2011. Impact of metarhizium brunneum petch clavicipitaceae (Hypocreales) on pre-imaginal Rhagoletis indifferens (Diptera: Tephritidae) within and on the surface of orchard soil. Biocontrol Science and Technology. 21:1501-1505.
- Rand, T.A., Waters, D.K., Shanower, T.G. 2011. Unexpectedly high levels of parasitism of wheat stem sawfly larvae in post-cutting diapause chambers. The Canadian Entomologist. 143(5): 455-459.
- Tscharntke, T., Tylianakis, J.M., Rand, T.A., Didham, R.K., Fahrig, L., Batary, P., Bengtsson, J., Clough, Y., Crist, T.O., Dormann, C.F. 2012. Landscape moderation of biodiversity patterns and processes - eight hypotheses. Biological Reviews. 87(3): 661-685. DOI: 10.1111/j.1469-185X. 2011.00216.x.
- Branson, D.H. 2011. Effects of nymph-overwintering grasshopper density on Ageneotettix deorum survival in a northern mixed grassland. Journal of Orthoptera Research. 20(2): 137-139.
- Blitzer, E.J., Dorman, C.F., Holzschuh, A., Klein, A., Rand, T.A., Tscharntke, T. 2012. Spillover of functionally important organisms between managed and natural habitats. Agriculture, Ecosystems and Environment. 146: 34-43.
- Srygley, R.B. 2012. Age- and density-dependent prophylaxis in the migratory Mormon cricket Anabrus simplex (Orthoptera: Tettigoniidae). Environmental Entomology. 41(1): 166-171.
|
Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Objective 1: Clarify how grasshoppers influence interactions between exotic and native grassland plants and the sustainability of grazing systems. Objective 2: Define factors that influence grasshopper outbreaks and Mormon cricket migration to enhance predictions of when outbreaks and migration occur, and identify management techniques that impact population densities. Subobjective 2a: Define the impact climate conditions have on grasshopper and Mormon cricket egg survival to further understand population dynamics and outbreaks. Subobjective 2b: Examine the effectiveness and underlying mechanisms of grassland management practices, such as fire and livestock grazing, to sustainably manage grasshopper populations. Objective 3: Identify ecological factors underlying variability in populations of key crop insect pests and their natural enemies, and identify factors and/or management approaches that augment natural enemies and maximize control of key insect pests. Subobjective 3a: Quantify the effects of semi-natural habitat (grasslands) on grass feeding herbivore-parasitoid food web dynamics and pest pressure in small grains. Subobjective 3b: Determine the effects of landscape structure on the diversity and abundance of natural enemy communities associated with alfalfa pests and how this ultimately influences key interaction-based ecosystem services (i.e. biological control of pests by parasitoids, predators and pathogens). Objective 4: Define biological factors and mechanisms that regulate locomotion, reproduction, and immunity to enhance grasshopper and Mormon cricket management. Subobjective 4a: Identify intake target of Mormon crickets in last nymphal instar and first 8 days of adult life, during which reproductive and immune systems are maturing, and determine if dietary deficiencies alter the efficacy of fungal control. Subobjective 4b: Determine if dietary deficiencies exhibited by migratory Mormon crickets in the field alter their ability to escalate their immune responses. Objective 5: Develop commercializable microbial control agents and methods for their use in managing pest insects such as grasshoppers and Mormon crickets. Objective 6: Assess the suitability and potential effectiveness of classical biocontrol agents against wheat stem sawfly. Approach (from AD-416) Insects are key constraints in crops and rangelands. Rangeland is a fundamental resource for the beef industry, with grasshoppers frequently affecting food security on all inhabited continents. Wheat and alfalfa rank as the third and fourth most important crops grown in the U.S. ARS stakeholders have identified grasshoppers and Mormon crickets in rangeland, and wheat stem sawfly and alfalfa weevil in cropping systems as high priority pests. Current control strategies for these pests are inadequate, costly and result in unacceptable environmental impacts. Pest management in the modern era has generally focused on suppressive tactics, primarily via chemical means. However, the increasing reliance on agrochemical inputs in modern agriculture has led to public concerns over safety and environmental impacts. Ecologically based pest management approaches attempt to address these concerns by moving beyond the chemical paradigm, to develop safer and more sustainable control. This project focuses on generating the biological and ecological knowledge necessary to achieve the ultimate goal of developing ecologically-based and economically practical management strategies that maintain pest populations at sub-economic levels via biological and cultural means. A sound understanding of insect pest ecology will form the basis for predicting when an insect will be a pest, understanding pest impacts, and determining whether prevention or intervention will be necessary and/or effective. Long-term sustainable solutions to pest problems will only be achieved by restructuring and managing agricultural and rangeland systems in innovative and novel ways that maximize built-in preventive strengths or negatively affect pest population dynamics. In situations where preventive strategies are overcome or consistently ineffective, developing novel biological intervention tools becomes paramount to provide critically needed alternatives to pesticide-based control. In order to increase predictability of grasshopper and Mormon cricket outbreaks and assess their ecological impacts, we will investigate responses to changing climate conditions, and evaluate the effects of grasshoppers on competition between exotic and native rangeland plants. We will also develop novel, preventive strategies that either work against pest fitness in rangeland or render cropping systems less vulnerable to pest problems via the augmentation of natural enemies. Finally, we will develop innovative ways to intervene and control pests when preventive barriers are overcome, including investigations of Mormon cricket and grasshopper susceptibility to pathogens to enhance the efficacy of these natural enemies, and to identify new biocontrol agents to expand the biological arsenal to disrupt growth of wheat stem sawfly, grasshopper, and Mormon cricket populations. This research will fundamentally expand the knowledge base necessary to develop effective, ecologically-based pest management solutions, promoting food security while decreasing energy inputs and environmental impacts. This is the first report for the new project #5436-22000-016-00D, started on January 3, 2011 and replaced bridging project #5436-22000-014-00D �Ecology and Management of Grasshoppers and Other Insect Pests in the Northern Great Plains�, terminated on January 2, 2011. Additional information relevant to the ongoing work associated with this current project is recorded in the old project 5436-22000-014-00D, including thirteen published works. Accomplishments are listed in the new project 5436-22000-016-00D. Grasshopper biological control: ARS researchers at Sidney, MT, along with collaborators, continue to evaluate domestic insect pathogens (fungi) and two commercial pathogens as insecticides for grasshoppers. We acquired 250 fungus specimens for evaluation and started preliminary bioassays. The USDA-APHIS conducted a field trial of four fungi against grasshoppers; we also tested a combination of one commercial fungus with two chemicals that stress the insects to enhance efficacy. One fungus continues to show excellent potential; it has been given to other ARS locations for evaluation against other insects. Mormon cricket ecology: To investigate environmental effects on the survivorship of crop damaging Mormon crickets, we conducted experiments on the effect of soil moisture during summer development. Although soil moisture had significant effects on the probability of eggs developing into embryos, we were surprised to find that many eggs showed normal development with 0% moisture. We also found that 70 days of autumn cooling significantly shortened the time that the embryos required in winter diapause (similar to hibernation). Wheat stem sawfly: We completed quarantine trials to assess the suitability of wheat stem sawfly as a host for a potential biocontrol imported from China in the spring of 2010. Only one parasitoid completed development on the native Chinese host, and none on wheat stem sawfly. A second set of trials with improved methodology is being evaluated. A large scale sampling effort (MT, ND, and SD) is close to completion to look at regional variation in wheat stem sawfly infestation and parasitism. Alfalfa weevil: Initial surveys and predator exclusion experiments have been completed to characterize the important natural enemies of alfalfa weevil in the region. Two larval parasitoids and a fungal pathogen have been identified as potentially important. Grasshopper ecology: Research continued with range ecologists from Oklahoma State University to examine the impact of long term grazing exclusion and fire on grasshopper population dynamics during a period with high grasshopper densities. We also continued examining how winter soil temperatures and fall soil moisture affect grasshopper outbreaks. We planned and initiated collaborative experiments examining the impact of grasshopper herbivory on restoration of exotic grass dominated landscapes, and initiated new research examining how predators influence rangeland forage damage through their impact on economically important grasshopper species. Accomplishments 01 Grasshopper coloration and disease. Grasshoppers are huge problems for producers, eating not only crops, but more forage than cattle eat in the western USA. At higher temperatures, grasshoppers develop lighter coloration to reflect more sunlight and keep their bodies cooler. Becau phenoloxidase is a key enzyme affecting both color and disease immunity, ARS researchers at Sidney, MT, explored whether grasshoppers reared at higher temperatures had less disease immunity and were more susceptible fungal attack. They discovered that phenoloxidase enzyme concentrations in the blood of grasshoppers reared in a hot environment were lower than those reared at a more normal temperature. Consistent with this difference in immunity, grasshoppers reared in the hot environment had greater mortality and shorter survival time following application of a pathogenic fungus. Thus, although the change in body coloration is generally considered beneficial for regulating body temperature, it is also harmful to the grasshopper from the standpoint of combating disease This research result helps us determine when grasshoppers are easiest to kill with chemical or biological treatments. 02 Wheat stem sawflies more susceptible to attack than previously believed. Wheat stem sawflies attack wheat stems in the northern Great Plains, living inside the stem, lowering seed production and quality, and eventually cutting the stem so that the wheat falls over and is difficul to harvest. It was previously thought that after the stem was cut, few o the sawflies were attacked by parasitic wasps that lay eggs through the wheat stem wall. ARS researchers at Sidney, MT, examined rates of late season parasitism by native species of wasps and found that rates of parasitism in wheat stubble chambers reached a maximum of 46%, exceeding the previously reported maximum of 2.5%. In contrast with previous work our results demonstrate that larvae of wheat stem sawfly are suitable hosts for parasitic wasps, even after the formation of overwintering chambers in wheat stubble, and suggest that parasitism rates have likely been seriously underestimated when sampling stems prior to harvest, as typically done. This research will help us determine how to improve the efficacy of native wasps in controlling wheat stem sawfly. 03 Plant diversity not a good predictor of grasshopper population density o diversity. Grasshoppers cause significant economic damage during outbrea periods, but not all species are economic problems. ARS researchers in Sidney, MT, demonstrated that in a northern mixed grass prairie with relatively low plant diversity, the number of plant species at a site cannot be used to accurately predict the number of grasshopper species o grasshopper abundance. In a number of grassland ecosystems, grassland insect diversity and abundance has often been linked to plant species composition and habitat structure. However, plant species richness appea to be too variable to lead to accurate predictions of grasshopper abundance or species richness in the northern Great Plains. This researc shows how we need to change our outlook to better predict grasshopper population densities and locations of outbreaks that threaten producers and range managers.
Impacts
(N/A)
Publications
|
|