Duration: 03/01/2008 to 09/30/2012

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Soybean is a key crop in the U.S., which supplies 35% of the world's production. In 2006, more acres of soybean were harvested in the U.S. (74.6 million) than acres of any other crop, including corn (70.6 million). Soybeans are produced in 31 states and 3 provinces in the eastern, central, and southern U.S and Canada, from Quebec to Florida, and Delaware to Nebraska. Given this large acreage and wide distribution, it is not surprising that soybean continues to suffer from insect pests that impact plant growth, grain quality, and yield.


Whether it is a result of accumulated years in soybean production, changes in cropping practices, or global climate change, the distribution and impact of native and established pests is increasing in soybean. The populations of soil pests such as slugs, grubs, and millipedes, and foliar and pod feeders such as bean leaf beetle and stink bugs, are increasing in many regions. The distribution of other insects, such as Dectes stem borer and pyrethroid-resistant Lepidoptera (such as corn earworm), appears to be growing. Producers are encountering insect problems that they have never seen or managed. From a research standpoint, changes in pest distribution and status require greater understanding of pest biology and movement, as well as the development or modification of scouting and control methods. Although pesticides are often the easy first tools used to deal with new or growing insect problems, long-term sustainable solutions must include host plant resistance and biological control.


As in many other production systems, invasive species in particular are also an increasing issue in soybean production. The introduction of a single species can significantly and negatively impact the profitability of soybean production, and increase risks to human health and the environment. In the northern U.S. and eastern Canada, the discovery of the soybean aphid (SBA) in 2000 fundamentally changed soybean insect management. SBA feeding impacts all components of yield; under heavy aphid pressure, yield differences between treated and untreated research plots may reach 50%. On a landscape level, SBA outbreaks often correspond to potyvirus outbreaks in dry beans, snap beans, vine crops, and potato, broadening the impact of this invasive insect. From an economic standpoint, SBA infestation increases the cost of soybean production. In 1999, the year prior to discovery of SBA, the National Agricultural Statistics Service estimated that less than 1% of the soybean acres in Illinois, Indiana, Michigan, Minnesota, and Ohio were treated with insecticide (NASS 2000). In 2005, an outbreak year, estimated insecticide use in these same states ranged from 9% (IL) to 42% (MI) (NASS 2006); in 2006, when outbreaks were more sporadic, 56% of the acreage in Minnesota was treated (NASS 2007). At least 20 different foliar and seed-applied insecticides are now used for aphid control on millions of acres, adding $10-$20 per acre to production costs (Song et al. 2006). Although scouting methods and an economic threshold (ET) for aphid control were developed under the previous multi-state project, S-1010, these management practices are only applicable to soybeans in the R1 to R5 growth stages planted in 30-inch rows. The thresholds must be modified to account for plant maturity group and age, differences in planting systems (for example, varying row widths), and populations of biological control agents. Developing a dynamic threshold, however, requires a great deal more knowledge of aphid interactions with host plants, natural enemies, and the environment. By developing common research protocols implemented simultaneously in multiple states, we can rapidly modify the existing ET for SBA under different production practices, e.g., maturity groups, row spacing, planting date, etc.


Specialty soybean production is a growing, profitable market for producers, including production of seed, non-GMO, identity preserved (IP) and USDA-certified organic soybeans. IP soybeans are sought for traits such as high protein, high isoflavone, or improved flavor or texture in the case of tofu (bean curd) and edamame (vegetable soybean). University and private seed companies are breeding soybeans to deliver lower linolenic acid composition than conventional soybeans. Low lin soybeans produce oil that does not need to be hydrogenated, thus reducing the amount of trans fat in foods made with these IP soybeans. Since USDA implemented national organic standards in 2002, the U.S. organic industry has grown 20-percent or more annually (USDA 2007). By volume, soybeans make up the largest segment of organic legumes in the U.S. In 2005, 122,217 acres of certified organic soybeans were produced in the U.S., with Minnesota, Iowa, Michigan, Ohio and Wisconsin among the top five acres produced (USDA 2007). Canadian producers planted organic soybeans on 19,922 acres in 2005 (Macey 2006). Production practices and quality requirements of specialty beans differ from those of conventionally-produced roundup-ready beans, thus insect management practices (scouting, thresholds, and control measurements) are also likely to differ.


Chemical use has also changed dramatically in soybean production since the inception of the S1010 project. As mentioned previously, the introduction of soybean aphid resulted in an increase in pesticide use on soybeans in the Midwest. In most soybean production areas, the introduction of soybean rust will change soybean disease management; this will influence the entire production system, including insect management. For example, fungicide applications may actually increase insect pressure by reducing the impact of naturally occurring entomopathogenic fungi that control insects and mites. Since most fungicides cannot cure plant disease, they must be applied prophylactically. Preventative applications of fungicide made prior to infection may encourage growers to make unnecessary tank-mixes with insecticides. Industry recommendations to customers now routinely include tank mixes of insecticides and fungicides for plant health benefits, even in the absence of pest pressure. The recent registration of seed-applied insecticides also encourages growers to use products as insurance treatments rather than basing applications on scouting in an integrated pest management context. Besides violating the principles of IPM, prophylactic use of insecticide adds to the cost of production and increases the potential for insecticide resistance. From a research perspective, the efficacy and economic viability of insurance treatments need to be addressed in a concerted way. To move beyond chemical use, particularly to control bean leaf beetle, soybean aphid, stink bug, and other chronic pests, alternatives are critically needed. These alternatives include both biological control and host plant resistance, preventative tactics which form the foundation of IPM, and which must be integrated with therapeutic tactics such as insecticide use.

Related, Current and Previous Work

The regional project S1010, Dynamic Soybean Pest Management for Evolving Agricultural Technologies and Cropping Systems, not only involved entomologists from southern states, but also participants from northern (U.S. and Canadian) soybean production areas. The project had four major objectives.
The first objective broadly covered management strategies for important soybean pests. The soybean aphid, Aphis glycines, was discovered in 10 states in 2000 and is now found in 23 states and 3 Canadian provinces. During the last 5 years, many aspects of aphid life history, including reproductive capacity (McCornack et al. 2004) and overwintering hosts (Voegtlin et al. 2004, 2005) were determined. Numerous insecticide trials were conducted to measure yield loss and product efficacy. S-1010 members made great strides in soybean aphid sampling and management. A regional aphid suction trap network of 40 traps, coordinated by the Illinois Natural History Survey was set up across eight states (http://www.ncpmc.org/traps/). Traps were changed weekly, and soybean aphid numbers reported for each location. Based on fall aphid flights and egg counts on the overwintering host, common buckthorn,, the trapping network aided entomologists in predicting aphid outbreaks. Speed Scouting, a modified sequential sampling method (Hodgson et al 2007) was developed and validated to improve efficiency of aphid scouting. According to surveys conducted in Minnesota and Michigan (Olson and Badibanga 2005), at least 85% of soybean growers scouted fields for aphids in 2004 and 2005. An economic threshold of 250 SBA per plant (Ragsdale et al 2007) was developed and validated across multiple locations and years. The surveys in Minnesota and Michigan indicated that approximately 75% of producers were familiar with this threshold, and that over 60% of producers followed most or all university recommendations for SBA control. Based on a total of 9.2 million acres of soybean in Minnesota and Michigan, approximately 5.5 million acres were managed using recommended IPM practices, ensuring farm profitability. More recently, host plant resistance became a focus for long-term aphid management (Diaz-Montano et at. 2006, Hill et al 2004a, 2004 b, 2006a, 2006b, Mensah et al. 2005). Plant breeders at several universities, in conjunction with project entomologists, screened soybean germplasm for aphid resistance in the greenhouse and in field cages. Resistance genes such as the Rag1 gene were incorporated into soybean, and field-testing under natural populations of aphids is beginning.


Committee members also made progress managing native and established soybean pests. Corn earworm larvae attack soybeans in the eastern United States. Monitoring earworm moth activity and providing weekly updates encouraged growers to scout and use thresholds rather than simply spray when insects were observed. This led to a reduction in acres treated for earworm. Stink bugs were an increasing concern in southern states, shown to cause flat pod syndrome. Entomologists examined the impact of certain production practices on stink bug damage; they found that by using certain combinations of maturity-groups with later planting dates, stink bug damage was reduced.


Objective two focused on vector-virus relationships and management. Reductions in bean leaf beetle feeding and bean pod mottle virus infection in foliar-sprayed or seed treated soybean were inconsistent, differing from study to study. The introduction of soybean aphid into the Midwest added another potential vector to the landscape. S-1010 members documented transmission of soybean viruses, as well as transmission of potyviruses of potato, cucurbits, snap beans, and dry beans by this species. A new virus, soybean dwarf, was found in Wisconsin soybean. Thus soybean aphid impacts not only soybean production itself, but affects disease levels and yield potential in other crops in the landscape. S1010 members communicate and collaborate with the regional project, NCERA 200, Management Strategies to Control Major Soybean Virus Diseases in the North Central Region.


Objective three focused on the biological control of soybean aphid in North America, with the particular outcome of releasing one or more exotic parasitoids for soybean aphid. The search for exotic natural enemies of soybean aphid started in the summer of 2001, prior to formation of S-1010. Surveys of natural enemies in China included minute pirate bug, ladybird beetles, and parasitoids. By 2003, parasitoids from China, Japan, and Korea were being reared and evaluated in quarantine at the USDA Beneficial Insect Laboratory in Delaware and later at the Biosafety Level 2 quarantine facility located at the University of Minnesota. Environmental and non-target assessments were conducted on multiple aphid species. The most promising parasitoid species, Binodoxys communis, was released in several states in the summer of 2007, with federal and state approvals. This is the first classical biological control release against soybean aphid in North America. Risk assessments for several other parasitoid species are nearly complete, thus additional releases of additional species or strains are expected in the near future.


Another focus of the biocontrol objective was the conservation of native and naturalized natural enemies. Parasitoids of soybean aphid are not common, so in 2002, the established parasitoid Aphelinus albipodus, initially released in the western U.S. for Russian wheat aphid control, was reared by the USDA PPQ lab in Niles, Michigan and released by S-1010 members in Minnesota and Wisconsin. Life history and ecological studies were done on two key predators, Orius insidiosus and Harmonia axyridis, the Asian multicolored ladybeetle. This kind of research data is key to modifying existing aphid thresholds in soybean to account for natural enemies. . Progress in developing an ET that uses natural enemy abundance along with aphid density is a major effort of the current research project that will extend into the next funding cycle. Predators also played a role in reducing overwintering egg populations on common buckthorn. Six species of native entomopathogenic fungi were found to infect and kill aphids in soybean and on buckthorn. Project members from the University of Minnesota demonstrated that entomopathogen infection of aphids was significantly less on soybeans sprayed with fungicides labeled for soybean rust control, compared to untreated soybeans. This research demonstrated that control measures targeted for one pest could impact an entirely different pest, stressing the importance of using economic thresholds to make treatment decisions. To educate soybean producers about the impact of SBA biocontrol, extension materials and web sites were produced by S-1010 members. A regional distance education short course (Managing Soybean Aphid in 2007: How Will Biological Control Contribute?) was sponsored by University of Illinois in March 2007 and presented at over 160 remote locations in 17 states and provinces.


The goal of objective four was to determine if measurements taken using precision technologies correlated to insect damage and thus to soybean yield. Research in Louisiana confirmed that light measurements taken with a hand-held light meter were as accurate as a direct sampling method using drop-cloths to trigger insecticide applications for defoliating insects. Further, vegetation indices generated by remote sensing from fixed-wing aircraft correlated well with light interception measurements and leaf area indices in soybeans in both Louisiana and Virginia. In the future, precision technology may aid producers in managing damage from defoliating soybean pests.


Despite being planted in the U.S. for over 100 years, insect problems on soybeans are increasing. Many of our recent problems are regional, including new invasives spreading from one state into others, established pests increasing their range, native insect adapting to soybean, and finally insects (such as aphids) moving vast distances on weather fronts during the growing season. Because many insect problems cut across the landscape, they lend themselves to collaborative research that also cuts across state boundaries. In our previous project, S-1010, many of our activities included a multistate component. In some cases, we repeated studies in multiple locations under a range of local conditions, assuring that results were robust (ie. applicable in many locations). In one growing season, we could collect multiple data sets for immediate analysis and publication. Moreover, data were shared, and we use the S-1010 meeting as a venue to provide materials for extension activities among the member institutions. This data sharing was critical, for example, in the development of the threshold and rapid sampling methods for soybean aphid. Repeating studies in multiple locations also increased the likelihood that a range of insect pressure  low to heavy  was encountered during the season, an important consideration when evaluating efficacy or seed treatments or resistant varieties. Finally, in this time of reduced funding for research, collaborating among institutions made it possible to shorten the time between experimentation and publication. One state may only be able to afford a single location for a study; by working with five neighboring states, the study can be repeated at six locations rather than a single researcher needing to repeat the study for multiple years. We used the S-1010 committee (annual meetings and email list) as a means to coordinate research, develop multi-state grant proposals, to share preliminary data, and to avoid duplication of effort. For this new project, we will work in the same manner, using the regional project as a focal point to propose research ideas at annual meetings, to develop regional grant proposals and coordinate projects.


Soybean remains an important crop grown on millions of acres in the U.S., with uses as food, to make biodegradable industrial materials, and as an alternative fuel. The quantity and quality of soybean production is critical to these industries, as well as to the health of the local farm economy. The overarching goal of the project is to protect these soybean from pest insects, using environmentally and economically viable methods.

Objectives

1. Characterize insect-soybean interactions and their impact on plant growth, grain quality, and yield.
   
2. Develop and validate tactics for management of key soybean insects.
   

Methods

Participating states are listed after each sub-objective. If there is a lead state, it is indicated in (parentheses). Objective 1. Characterize insect-soybean interactions and their impact on plant growth, grain quality, and yield. Sub-objective 1a. Establish or modify thresholds of important regional pests to account for maturity group, planting systems, plant age, and natural enemy populations. BLB [NE, IA, IL, OH, ON]: The relationship between bean leaf beetle (BLB) and soybean phenology was exploited to develop beetle management strategies based primarily on a combination of planting date (Pedigo and Zeiss, 1996; Witkowski and Echtenkamp, 1996) and the use of foliar insecticides. However, recent changes in agronomic practices (most notably earlier planting) and the increase in organic soybean production limit the usefulness of current management strategies. A broader planting-date window results in less-distinct beetle generations. Conventional insecticides cannot be used in organic soybean production. Therefore, there is a need to re-examine the relationships between BLB and soybean phenology under new cropping paradigms, and to develop up-to-date region-specific management strategies for both conventional and organic soybeans. Initially, season-long BLB and soybean plant phenology surveys will be conducted in regions where current phenology-based management is proving inadequate (NE, OH, Ontario). General procedures will be developed, then optimized according to the specific cropping practices and environmental conditions of each region. Further procedures will depend on the findings of these studies and will focus on consistent relationships between BLB and soybean phenology. In general, relationships will be identified for each region and management programs will be developed that exploit these relationships. The region-specific management programs will then be field-tested using large plot or field level studies. SBA [(MN), IA, MI, ON, SD, QC]: The current soybean aphid (SBA) economic threshold (ET), readily adopted by growers across the North Central region, was developed based on 30-inch row spacing and a sampling unit of aphids per plant. It is applicable over a wide range of yield and price expectations, preventing yield loss and unnecessary insecticide use. However, there is a need for more dynamic thresholds that can account for variables such as other row spacings, plant populations, soybean varieties, natural enemy populations, and other factors that limit SBA population growth. With an improved understanding of these variables, future thresholds will better reduce yield loss and insecticide use. In Korea, soybean spacing influences SBA densities, but we do not know if SBA populations respond to variations in row spacing in the U.S. and how management strategies should be adjusted to this response. We will expand the current threshold research efforts to account for multiple row spacing by employing the same methodology used to create the 250 ET, that is, the use of a common set of experiments implemented across multiple states, with results analyzed and published as a whole. Further modifications to the ET will be considered as our understanding of key SBA mortality factors improve (e.g. incorporating abundance of natural enemies within the ET calculation). Stink bug [(VA), GA, MO, MS, TX]: Stink bugs are an increasing pest of soybean, reducing bean quality and yield. Adults and nymphs feed on developing pods, shriveling, staining, and killing seeds. Current economic thresholds were developed in the 1980s using different varieties and cultural systems. For example, double cropping with wheat, a practice adopted by many growers, increases the likelihood of stink bug damage early in the season. Stink bug populations build in early systems and move to later-maturing full-season fields, presenting a second period of risk. The recently implemented Early Soybean Production System, i.e. planting full-season soybeans in April instead of May-June, directly impacts seasonal incidence and damage potential of stink bugs. Stink bug species complexes also differ today. The brown marmorated stink bug (Halyomorpha halys), a known soybean pest, is now established in ornamental crops in the mid-Atlantic region. The red-banded stink bug (Piezodorus guildinii) is becoming a more prominent pest in the mid-south. Flat pod syndrome and delayed maturity are associated with P. guildinii and it is difficult to control with insecticides. Species surveys are critical to develop research and management programs. Research is needed to develop thresholds that are sensitive to different regions, cropping systems and growth stages, and that potentially include the impact of stinkbug parasitoids. Monitoring and sampling procedures need to be re-evaluated to complement new thresholds. Coordinated field surveys in Missouri, the mid-Atlantic and the mid-south will be used to track occurrence & spread of invasive stink bug species. A series of coordinated cage studies will be established in the mid-Atlantic states (VA, DE, MD) to evaluate the impact of stink bugs on plant maturity and soybean seed yield and quality. Data will be pooled across years and locations. In the mid-south, cage and insecticide exclusion techniques will be used to determine if pod feeding by P. guildinii affects development of other pods on the same plant, and to develop economic thresholds for P. guildinii and Nezara viridula (southern green stink bug). Also, surveys will be conducted in Texas to determine weed hosts responsible for P. guildinii build-up before immigration to susceptible soybeans. Standard sampling techniques (drop cloth and sweep net) will be compared across states and production systems to compare catch efficiency. Blacklight trap data will be analyzed to determine if numbers can serve to alert growers of high-risk periods. Sub-objective 1b. Characterize the unique relationships between insect pests and organic/ specialty beans. [(WI), IA, ON] Research will compare seasonal incidence, population dynamics, and damage potential of arthropods in organic and edamame soybeans to conventional beans; these are likely to differ. Under National Organic Standards, growers must first rely on cultural, physical, and biological methods to suppress insect pests before using approved insecticides (USDA 2005). In Ontario, agronomic, ecological and economic merits of intercropping organic beans with other marketable crops will be tested in the greenhouse and using cage and strip trials in the field. In Wisconsin, soil and plant tissue profiles will be compared in organic fertility regimes that include livestock manure, rotation with alfalfa, cover crop green manure, and calcium amendments. The quantity and diversity of natural enemies and insects pests, as well as yield and quality, will be compared among these systems. Lab bioassays and replicated field trials on organic farms and at university research stations will be developed and done in WI and Ontario to determine the effectiveness of approved botanical and biorational insecticides. Additional tests will determine non-target mortality and compatibility of the insecticides with key biocontrol agents. Optimal product choice, timing, application methods, and cost comparisons of insecticides, will be determined. In Iowa, research will focus on specialty beans for quality (such as oil) rather than yield alone, determining if insect management strategies in conventional beans are appropriate for specialty varieties. Sub-objective 1c. Understand the movement of pest Lepidoptera as it relates to pest management. [MN = Zea map), MS, VA] Helicoverpa zea (soybean podworm, cotton bollworm, corn earworm) is an important, mobile pest of soybean and many other crops in some regions. Previous efforts to describe the movements of this species had limited success. However, the recent development of techniques to determine an adults larval plant host, and the identification of DNA markers in H. zea, provide new tools to distinguish among populations. Further, some populations recently showed reduced mortality from pyrethroids. Insecticide resistance is both a concern for pest managers and an additional tool to distinguish among populations. Moths will be captured in pheromone traps by cooperators in multiple states over the entire flight period to evaluate the extent and nature of pyrethroid resistance, larval host, and genetic differences among populations. These studies will be conducted on the same moths; pooled data will enable us to better understand the large-scale movement of H. zea and to develop practical resistance management strategies. Data will feed into a common site, the Zea Map Network for monitoring H. zea resistance, at http://www.vegedge.umn.edu/ZeaMap/zeamap.htm. Sub-objective 1d. Maintain the Northcentral regional aphid suction trap network. [(IL), IA, IN, KS, KY, MI, MN, MO, SD, WI] Since 2001, suction traps monitor the summer and fall movement of the soybean aphid; currently there are 40 traps in 10 cooperating states. Cooperators maintain traps from May until mid-October, shipping samples weekly to the Illinois Natural History Survey for sorting and identification. Soybean aphid counts will be placed on a web site maintained by the Natural History Survey: http://www.ncpmc.org/traps/index.cfm. In general, summer trap catches reflect the populations in fields near each trap. On-going research is correlating trap catch to and summer field populations. Fall trap catches (September and October) help predict the general intensity of the following year's infestation. Few soybean aphids in the traps in fall predict a low population the following year; a high number of aphids in the trap indicates a potential for an aphid outbreak. Whether this actually happens is influenced by the abundance of predators and the success of egg deposition on the winter host. Research on egg deposition, survival, and predators will continue. Other aphids caught in the traps will also be sorted and identified, providing an indication of the aphid composition in the Midwest available as non-target hosts for released biological control agents. Objective 2. Develop and validate tactics for management of key soybean insects. Sub-objective 2a. Efficacy of seed treatments and foliar insecticides for key soybean insects. SBA [IA, MI, MN (Survey), NE, OH, ON, WI]: New and currently registered products will continue to be tested in the laboratory, replicated small-plots and on-farm trials to determine efficacy against SBA, and impacts on natural enemies (including those introduced for classical biological control). As the concern for soybean rust grows and companies market the benefits of fungicides, the efficacy and economics of tank mixes of insecticides and fungicides will also be investigated in replicated plots. Data for comparison will include pest density, rust infection, crop growth, yield, and gross margins for untreated, single-spray, or tank-mix applications. Replicated large-scale field trials will focus on developing effective nozzle configurations, volumes, and pressures to optimize insecticide spray coverage and SBA control. To determine insecticide use patterns, and measure grower knowledge and adoption of IPM practices for SBA control, a detailed "Management of Soybean Aphid" survey will be developed and mailed to roughly 1,000 producers randomly drawn from four state commodity lists; results will be tallied by Univ. of MN. As the use of neo-nicotinoid insecticides increases through seed and foliar-applied treatments, the risk of resistance increases as well; resistance monitoring is thus critical to SBA management, at least in the short term. Methods will be developed to determine the LD50 values for insecticides commonly used for SBA, and these methods will be used to assess field populations for resistance within and among soybean growing regions. If resistance is identified in field populations, appropriate recommendations on resistance management will be developed and distributed to producers, and resistance monitoring will continue. Dectes stem borer [IL, KS, MO]: Kansas recently identified that the systemic insecticide fipronil provides excellent stem borer, Dectes texanus texanus LeConte, control in small plots. Evaluation of fipronil will continue to measure its efficacy when it is applied in different ways and to varieties with differing tolerance of Dectes damage. It is important to know the extent of the Dectes problem in the U.S. Companies will not invest money to register products if the potential usage is not large enough to justify the expenses. To develop this information, KS will conduct a preliminary regional field survey of cooperating states to collect physical evidence of infestations in areas where the Dectes appears to reach pest status, particularly along the Mississippi, Ohio River and the East Coast. Stink bug [AR, GA, LA, MO, MS, TX, VA]: The red-banded stink bug (Piezodorus guildinii) is the most serious insect pest of the Early Soybean Production System in the south. Multiple applications of insecticides are required to effectively control this pod feeder; acephate is the only labeled insecticide that provides residual control. Other pest management tools are needed to improve control and delay development of resistance. Replicated soybean plots will be planted in mid-April to insure adequate populations of P. guildinii. Candidate insecticides (neo-nicotinoids and other novel chemistries) will be evaluated at varying rates. Pest and beneficial insects and spiders will be evaluated 1, 3, 7, and 10 days after treatment and yields will be taken. If appropriate, seed treatments will be evaluated in a similar manner as foliar sprays. Spray technology will be evaluated using over-the-top versus top-and-side applications. Electrostatic aircraft applications will be evaluated in commercial soybean fields. Sub-objective 2b. Enhance biological control of soybean aphid, using both conservation of natural enemies and classical biological control releases. [(IL, MN, USDA Beneficial Insect Intro Lab), IA, IN, MI, ON, QC, SD, VA, WI] Importation biological control efforts for the soybean aphid will include further exploration for new (Asian) natural enemies, quarantine evaluation of host-specificity, field and laboratory studies of potential non-target impacts, and release and evaluation of one or more Asian species. Collections will be made in China, Japan, and Korea. Natural enemies will be shipped to quarantine facilities at the USDA Beneficial Insect Unit in Delaware and the University of MN. In quarantine, the host specificity of select natural enemies will be evaluated against a suite of native and introduced aphid species. Non-target studies will include field sampling of native aphids to estimate population size and pre-release natural enemy load. We will develop a set of protocols to guide natural enemy releases and evaluate impact. In brief, we will use field cages to inoculate and increase natural enemy numbers, opening the cages to effect the release. SBA populations will be sampled to monitor the establishment of the natural enemies, and to measure their impact on aphid numbers and crop damage. Research will also focus on conserving and enhancing native and naturalized natural enemies. Work on generalist aphid predators (such as Syrphidae and Coccinellidae), fungal pathogens and parasitoids will continue in many states/provinces. Research will focus on how natural enemies delay or prevent aphid outbreaks, influence the growth of aphid populations between the economic threshold (currently 250 aphids/plant) and the economic injury level (ca. 660 SBA/plant), affect end-of-season dynamics, as well as impact production and survival of the overwintering aphid population. To conserve natural enemies, we will examine intercropping soybeans with other plants (e.g., annual rye), the effects of pesticide applications on the survival and efficacy of natural enemies, and the impact of host plant resistant on natural enemy-SBA dynamics. Sub-objective 2c. Screen, characterize, and incorporate host plant resistance to soybean aphid and other key insects. Soybean aphid [KS, IA, IL, MI, MN, OH, SD]: Although progress in SBA resistance screening was made in the past S-1010 project, there already appears to be an aphid isolate that is virulent to the Rag1 gene. Thus, the continuing search for sources of resistance is especially vital at this time. Kansas currently has several entries that are statistically more antibiotic than Rag1 varieties (Diaz-Montano et al. 2006), and thus may contain genes other than the Rag1. Michigan also has a novel form of multi-genic resistance (Mensah et al. 2005) that appears effective under field conditions. South Dakota is investigating the combination of the Rag1-based antibiosis with sources of antixenosis resistance, in some cases stacking both categories to provide more durable resistance. As part of the new project, we will continue to screen for resistance, evaluate resistance levels in lines under development, and look for new sources of resistance that will hold up against this new more virulent isolate. Multiple states will participate in a resistance project in which seed of the best entries from breeding programs will be planted in replicated plots under a common protocol. At least one susceptible variety will be included at each location as a positive check. Plots will be evaluated weekly for aphid numbers on whole plants. For the more intensive screening, the best resistant (R) line in each state will be compared to a known susceptible (S) variety planted in replicated strips. Half of each strip will be treated with insecticide as necessary to eliminate SBA. Whole plant aphid counts will be taken at regular intervals in all plots throughout the growing season, and interaction of natural enemies with host plant resistance will be assessed by comparing SBA numbers on caged and uncaged plants. Yield data (bu/acre) will be taken from the middle two rows of each R and S plot and treated versus untreated subplot. Comparison of yields from the treated and untreated areas will show how well the R line tolerated exposure to aphids. We will also examine how host plant resistance impacts soybean aphid thresholds, and how it interacts with natural enemies, since there are many examples of these two tactics synergizing each other. Finally, insect-vectored viruses are a perennial problem in soybean production. We will examine how insect-resistant varieties influence aphid behavior on plants and whether this alters the likelihood of virus transmission to soybeans to understand if host-plant resistance to insects as a management strategy is compatible with management of pathogens. Dectes stem borer [KS, MO]: To date there are no High Plains- or Midwest-adapted soybean varieties with confirmed resistance to soybean stem borers. Host plant resistance work was hampered by lack of effective evaluation tools. Kansas recently developed a protocol for evaluating soybean host plant resistance to soybean stem borers in field cages, and this protocol will be used to screen varieties. Large field cages (screen house tents) will be used to confine field-collected stem borer beetles over field-grown soybean entries. Egg laying scars are used to measure plant acceptability, and tunneling and/or living larvae will serve as an indicator of larval survival. These two sets of observations reveal different modes of host resistance (antixenosis and antibiosis, respectively). Damage to varieties exposed to insects will be compared to damage to an insecticide (fipronil) treated variety to demonstrate the level of antixenosis resistance.

Measurement of Progress and Results

Outputs

• Obj 1a. New or refined thresholds for soybean pests, appropriate for different regions, and cropping system, and growth stages.
• Obj 1b. Refined thresholds for arthropod pests of organic and vegetable soybeans. Assessment of the impact of cultural management practices on pest numbers, natural enemies, and plant nutrient profiles. Efficacy data for organic-compliant insecticides against soybean aphid and mortality impacts on natural enemies.
• Obj 1c. Increased understanding of Helicoverpa zea movement, host range, and genetic variability among populations, and development of resistance management strategies for H. zea.
• Obj 1d. Continuation of a multi-state suction trap network which predicts soybean aphid outbreaks the following season.
• Obj 2a. Identification of insecticides and spray technologies with improved activity and economic viability. Detection of insecticide resistance in soybean aphid.
• Obj 2b. Field releases of one or more species of exotic natural enemies of soybean aphid in participating states/province. Development of protocols to assess the risks and effectiveness of classical biocontrol releases for SBA. Increased understanding of the impacts of native natural enemies on soybean aphid, and how these impacts can be conserved and enhanced.
• Obj 2c. Incorporation of aphid resistance into commercially available soybean varieties. Increased understanding of the mechanisms of resistance to SBA and Dectes stem borer. Increased understanding of the interaction between aphid resistance and biocontrol.

Outcomes or Projected Impacts

• Obj 1a. Since 2000, millions of soybean acres have been treated for SBA. Sprays for bean leaf beetle and stink bug increased. Insecticides saved producers millions of dollars in crop loss, yet treatment costs alone, using a conservative $8 per acre chemical and application cost, exceeded $100 million. Understanding insect population dynamics with relation to soybean development will increase precision in sampling and increase treatment effectiveness. The recommendations that will result from better understanding of insect-soybean interactions and impacts on crop growth will significantly add to producer profitability by providing more precise decision-making tools and reducing unnecessary treatments. Refinement of economic thresholds for insect pests to account for resistant varieties and natural enemies can minimize both crop loss and unneeded input costs.
• Obj 1b. An improved scientific understanding of effects of organic management tactics (e.g., soil/ crop nutrient management, crop rotation, cover and inter-cropping) on soybean insect pest and natural enemy dynamics will allow producers to better chose and integrate control tactics, including approved insecticides. This will lead to a reduction in pest damage and yield loss, and thus more profitable production.
• Obj 1c. An improved understanding of Helicoverpa zea movement will help predict the spread of insecticide resistance and better maintain susceptible alleles in the population. As a result there will be reduced pest losses from ineffective treatments and fewer ineffective applications made. The economic benefits will be realized in the Mid-Atlantic and south where insecticide applications for control of Lepidoptera are common
• Obj 1d. The ability to predict SBA outbreaks reduces risk to growers, allowing decisions to be made in advance of the field season. Such decisions include variety, insecticide and equipment purchases, and crop insurance protection, not only for soybean growers, but also for vegetable growers impacted by aphid-transmitted viruses. Risk reduction allows growers to better allocate resources and in the end to save money.
• Obj 2a. Identifying new insecticides, and efficient use of current products, will save growers production costs. In the north, judicious use of insecticides for SBA, based on sampling and thresholds, will avoid unnecessary applications, saving $10-$15 per acre depending on the product type, rate, and application cost. In the south, an improved labeled insecticide for stinkbug could save Gulf Coast farmers one application a season, or about $12 per acre over 100,000 acres, equal to $1.2 million annually. Early identification of insecticide resistance in SBA will allow for changes in management guidelines to slow resistance development.
• Obj 2b. Success in classical biological control will reduce populations of, and yield loss from, SBA. A partial success could save producers tens of millions of dollars in control costs alone, with societal benefits of reduced human exposure, reduced non-target impacts from pesticide use, and slower formation of insecticide resistance. A better understanding of North American natural enemies and their conservation will have similar impacts as a partial success in importation biological control.
• Obj 2c. The introduction of resistant varieties will reduce grower inputs by protecting yield and reducing outputs for insecticides. As a further result of reducing insecticide use, resistant varieties will lessen human exposure and non-target impacts, and eliminate or slow the formation of insecticide resistance. Management of SBA through the use of aphid-resistant varieties may also manage plant viruses through changes in aphid behavior. Further, host plant resistance is highly compatible with biological, cultural and chemical control of pests, and as such is a key component of soybean IPM programs.

Milestones

(2008): (Obj. 1a) Print and distribute a new soybean aphid management bulletin. Print extension fact sheets on managing soybean insects in organic production systems. Complete "Management of Soybean Aphid" survey. (Obj 2b) Initial report on success of exotic natural enemy releases for soybean aphid control made in 2007.

(2009): (Obj 1a) Publish Photo ID Guide for Agronomic Stink Bug Pests of the Mid-Atlantic Region. (Obj 1b) Develop and publish an edamame crop budget, including crop protection and crop production inputs, for the southern region.

(2010): (Obj 1b) Develop and print extension fact sheets on the impact of soybean aphids and other pest on IP soybean grain quality. (Obj 2a) Provide improved information on the economics of seed treatments and tank mixes. Publish baseline information on SBA susceptibility to insecticides. (Obj 2b) Complete the required regulatory review of additional exotic natural enemies of soybean aphid from Asia.

(2011): (Obj 1a) Promote new thresholds for stink bugs in the mid-Atlantic and mid-south regions. Revision of soybean aphid threshold based on row spacing, plant population, and natural enemies. Develop user friendly software (Soybean Aphid Growth Estimator, SAGE) that accurately predicts soybean aphid growth using grower supplied data on temperature, rainfall, crop growth stage and variety. (Obj 1b) Refine and promote strategies for managing insect pests in specialty and organic soybean. (1c) Refine and promote management strategies for managing pyrethroid resistance in Helicoverpa zea.

(2012): (Obj 2b) Conduct and monitor releases of additional exotic natural enemies of soybean aphid from Asia. (Obj 2c) Introduction of commercially available varieties exhibiting resistance to soybean aphids

Projected Participation

View Appendix E: Participation

Outreach Plan

Members of this new project come from a wide area, and cover virtually all soybean production acres in the U.S. and Canada. The members have a great deal of experience and success providing knowledge and advice, in multiple forms, to clientele. Thus information from this project will reach not only large, technologically advanced producers in major production areas, but also those in under-represented or resource-poor regions. To meet the differing learning styles and technology levels of producers across the country, information from this project will be distributed using a variety of techniques. At the local and state level, members will contribute to extension meetings, printed extension bulletins, weekly crop production newsletters, field days, and Farm Radio interviews. At the broader level, members will travel among states to provide expertise at regional extension meetings, and coordinate the development of multi-state bulletins that pool data collected across a wider area. For wired users, internet sites are currently available to provide information on insect scouting and management; these will continue to be updated during the life of the project. New combinations of current technology, such as a teleconferences using slide sets downloaded from a web site plus a telephone (such as the March 2007 Soybean Aphid Biocontrol teleconference hosted by University of Illinois), will allow members to reach regional audiences at a low cost. We will continue our productive partnerships with regional commodity groups such as the Northcentral Soybean Research Program (NCSRP) to provide bulletins, magazine inserts, and web-site content. Finally, at the national level, members will provide data and commentary for the USDA Pest Information Platform for Extension and Education (PIPE) which currently maps soybean aphid observations during the field season.

Organization/Governance

The Technical Committee is made up of voting members from each state or province. The Executive Committee is made up of the Past-Chair, the Chair, and the Secretary (Chair-Elect), with the Administrative Advisor and the CSREES representative serving as ex-officio members. The Secretary in a given year assumes the Chair position the following year. Elections for a new Secretary are held at each annual meeting. A separate individual will handle local arrangements for annual meetings.

Literature Cited

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Hill, C. B., Y. Li, and G. L. Hartman. 2004a. Resistance of Glycine species and various cultivated legumes to the soybean aphid (Homoptera: Aphididae). J. Econ. Entomol. 97: 1071-1077.


Hill, C. B., Y. Li, and G. L. Hartman. 2004b. Resistance to the soybean aphid in soybean germplasm. Crop Sci. 44: 98-106.


Hill, C.B., Y. Li, and G.L. Hartman. 2006a. A single dominant gene for resistance to the soybean aphid in the soybean cultivar Dowling. Crop Sci. 46: 1601-1605.


Hill, C.B., Y. Li, and G.L. Hartman. 2006b. Soybean aphid resistance in soybean Jackson is controlled by a single dominant gene. Crop Sci. 46: 1601-1605.


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Olson, K. and T. Badibanga. 2005. Farmers awareness and use of IPM for soybean aphid control: results from the 2005 survey. St. Paul, MN: University of Minnesota, Department of Applied Economics, 2005. (Staff paper P05-13) 16p.


Pedigo, L. P., and Zeiss, M. R. 1996. Effect of soybean planting date on bean leaf beetle (Coleoptera: Chrysomelidae) abundance and pod injury. J. Econ. Entomol. 89:183-186.


Ragsdale, D. W., B. P. McCornack, R. C. Venette, B. D. Potter, I. V. MacRae, E. W. Hodgson, M. E. O'Neal, K. D. Johnson, R. J. O'Neil, C. D. DiFonzo, T. E. Hunt, P. A. Glogoza, and E. M. Cullen. 2007. Economic threshold for soybean aphid (Homoptera: Aphididae). J. Econ. Entomol. 100: 1258-1267.


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Voegtlin, D.J., R.J. ONeil, W.R. Graves, D. Lagos, and H.J.S. Yoo. 2005. Potential winter hosts of soybean aphid. Ann. Entomol. Soc. Am. 98(5): 690-693.


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Attachments

Land Grant Participating States/Institutions

AR, GA, IA, IL, IN, KS, KY, LA, MI, MN, MO, NC, ND, NE, OH, PA, TX, VA, WI

Non Land Grant Participating States/Institutions

South Dakota