Duration: 10/01/2002 to 09/30/2007

Administrative Advisor(s):

NIFA Reps:

Non-Technical Summary

Statement of Issues and Justification

Soybean pest management is challenged by simultaneous occurrence of biotic (e.g., various insects) and abiotic (e.g., drought) stresses. With new understandings about the physiological basis for yield loss from different stressors, we now have the opportunity to develop better strategies to address combined stressors, which are what most soybean growers experience (Higley 1992). Additionally, the emergence of new soybean production practices, transgenic genotypes, and new insect pests requires research to determine how best to manage insects and other stressors in these systems (Boethel 2002). The potential impact on soybean profitability makes it essential that we begin addressing current and future problems now.

Soybean growers have recently experienced increases in certain insect pest problems and the introduction of a new and potentially significant problem over the past few years. The first situation is the increase in population densities of the bean leaf beetle, Cerotoma trifurcata, and a corresponding rise in the incidence of bean pod mottle virus, a pathogen vectored by the beetle (Rice et al. 2000). This relationship between bean leaf beetle and bean pod mottle virus, previously more common in southern states, is a relative new occurrence in the central and northern United States. The second problem is the recent introduction of the soybean aphid, Aphis glycines (Marking 2001). Soybean growers now are facing widespread use of insecticide over potentially millions of acres of soybean in the upper Midwest and given the native range of this insect, soybeans throughout the United States are at risk of being invaded.

Over the past decade, bean leaf beetle populations have increased to routinely exceed economic thresholds (Rice et al. 2000). Increased soybean acres planted in the Midwest and earlier planting dates are most likely the major factors contributing to the general increase in beetle numbers. The spring colonizing population, which has in the past been a relatively minor concern, is regularly entering fields during seedling emergence and causing great concern to soybean growers. Concurrent with the population increase has been an increase in diseases transmitted by the beetle (particularly bean pod mottle virus) (unpublished data from numerous states). Bean leaf beetle populations have increased dramatically over the past decade, and perhaps is one reason for the increase in bean pod mottle virus. The occurrence of virus-caused symptoms, most notable green stem syndrome and mottled seeds, has caused growers great concern. This has been especially true for growers of food grade soybeans where seed appearance is of utmost importance.

Most recently, the discovery of the soybean aphid in the Upper Midwest presents a new challenge to United States soybean production (Marking 2001). The soybean aphid is a recent invader of North American soybean fields. The aphids native range is from northern China to Indonesia. In 2000, aphids were found in nine Midwestern states (WI, MI, MN, IL, IN, IA, MS, OH, KY) and by 2001 it expanded into the eastern states of PA, NY, VA, WV and south and west into MO, SD, ND and into Canada (Manitoba and Ontario). Soybean aphids can damage plants by reducing photosynthesis (Higley, personal communication) and reducing pod set by as much as 33% (Ostlie, unpublished data). They can also transmit a number of plant viruses and indirectly affect yield by promoting growth of sooty mold on leaf surfaces. Yield reductions in excess of 16 bu/A have been measured with an average loss in grower strip trials of over 6.2 bu/A (13.9%) in Minnesota in 2001 (Ostlie, unpublished data). In the 2000 field season, the highest reported yield reduction was 13% in one Wisconsin replicated experiment (D. Hogg, unpublished data). Given that the aphid has been in the U.S. for a few years, it probably is overwintering successfully on its primary host, buckthorn. However, it is not known which species of buckthorn or other plants could be serving as a primary host, or the potential range of its overwintering capabilities. We currently do not know the present or future extent of the infestation or whether natural enemies are capable of controlling the soybean aphid.

An additional concern with the soybean aphid, similar to the bean leaf beetle relates to aphid transmission of soybean mosaic virus (Boethel 2002). Aphids that do not colonize soybeans have in the past, transmitted this virus. Transmission of this non-persistent virus is from aphids passing through and probing soybeans in search of a suitable host. Symptoms of soybean mosaic virus are similar to those associated with bean pod mottle virus. Plants can also be infected simultaneously with both viruses that result in severely stunted plants. Soybean diseases caused by viruses are reaching near epiphytotic proportions in many parts of the United States. The two viruses of most concern are bean pod mottle, transmitted by the bean leaf beetle, and soybean mosaic, vectored by aphids. Symptoms are similar, and thus, correct identification is crucial. With the recent discovery of the soybean aphid, which is the first aphid able to colonize soybeans in North America, and one that can transmit soybean mosaic virus, the incidence and impact of this virus may increase substantially. Research is critically needed to understand how to manage soybean aphid to reduce spread of soybean mosaic virus, if this disease becomes more widespread due to the presence of the soybean aphid.

The proposed research on pest sampling and injury assessment by precision agriculture technologies is at the leading edge of IPM research. In the dynamic agricultural environment, diminishing resources (in terms of time and effort) must be directed at significant problems that arise quickly and do not respect property boundaries, county lines, and state or federal districts. Landscape ecology focuses on entire agroecosystems and has won favor in the scientific community because many of the large-scale problems cannot adequately be addressed in small plot experiments or even entire fields. Much scientific effort has focused on small scale and limited factor analyses of ecological communities generally associated with agroecosystems. However, this bottom-up approach has been much maligned in the ecological literature because of its limited scope, and because many of these small-scale factors may become insignificant when viewed at landscape scales. Recently, more support has been given to large-scale, landscape analysis of entire watersheds, ecological communities, and agroecosystems. In agriculture, we have seen tangible results from the landscape perspective including: area-wide management of such pests as boll weevil, Hessian fly, screwworm, and gypsy moth. Significant problems face producers and scouts in soybean in the future, and at least some of these problems could be addressed using remote sensing technologies. For instance, nutrient deficiencies, drought stress, insect damage, pathogen infestations, and delayed maturity are all significant problems over broad geographic areas. The solutions to these problems require an area-wide view. Under the auspices of previous soybean entomological regional projects, viz., S-255 and S-281, it has been demonstrated that Leaf Area Index (LAI), a measurement of the amount of leaf area per unit area, could be used as an indicator of problem or great-risk soybean fields (Hunt et al. 1999). Yield losses are likely to ensue when LAI values drop below critical levels because of poor stand, drought stress, soil problems, nutrient deficiencies, insect damage, or pathogens. It also has been demonstrated that infrared photography from a fixed-wing aircraft can detect variations in LAI within a field. The aim of this project is to conduct research on remote sensing of soybean fields to determine risks of yield loss, and in this manner, direct management strategies to those areas where yield losses are likely. This research will incorporate new technology including satellite imagery, digital orthographic images or quadrangles (DOQs), geographic information system (GIS) software, and global position systems (GPS) in current management practices and scouting techniques. Distribution of the information via the Internet also will be a component of this effort. There are no technical restraints to conducting the research although the GIS, GPS research proposed will require greater dependence on equipment.

In summary, the proposed research addresses new and evolving pest problems that demand attention by researchers in all soybean-growing regions. The potential impact of these concerns warrants that efforts begin now. Soybean producers, consumers, and other stakeholders will be the beneficiaries of the research. This group of scientists has collaborated in three multi-state projects, and some of the participants are second generation with their major professors being founding members of S-74. The group is comprised of scientists in virtually every soybean producing state. This is particularly important with the recent invasion of the soybean aphid in the Upper Midwest and Northeast United States. There is already a track record of productivity documented by numerous publications, edited books, southern region series bulletins, and stakeholder focused literature. Perhaps the most noteworthy publication is the Handbook of Soybean Insects (Higley and Boethel 1994) published by the Entomology Society of America, the first of a nationally known series. The addition of new states, regions, and researchers into this group truly gives this project a national scope. Joining all soybean workers will allow those new to the project to share in the long-term expertise that currently exists in S-281, along with bringing in new perspectives from areas outside the typical soybean entomology arena.

The research proposed for the replacement for S-281 addresses the following SAAESD priority areas; Goal 1-A,B,&C; Goal 2-A; Goal 4-F.

Related, Current and Previous Work

The previous soybean entomology regional project, S-281, addressed three objectives during the five year period it has been in existence. The first objective was to determine the effect of production systems with transgenic and other herbicide-resistant soybeans on insect pests and natural enemies. The research conducted over the first four years of the project revealed that the adoption of herbicide tolerant soybean would not significantly affect the soybean arthropod community (Buckelew et al. 2001; McPherson 2000). Thus, no specific changes in IPM approaches are necessary concerning the adoption of these new production practices. If and when transgenic soybeans resistant to arthropods, i.e., Bt-soybeans, are developed and enter the market, their impact on arthropod communities including non-target species will need to be determined.

The second objective was to determine the impact of early soybean production systems (ESPS) on the population dynamics of pest and beneficial arthropods on soybean. Research has defined which and when certain insect pests should be a problem, and hence the critical periods for monitoring their abundance. Adoption of ESPS can have positive and negative effects on insect management. The early planting dates and early maturing varieties associated with ESPS generally allow for escape from late season migrating lepidopterous pests, such as soybean looper, velvetbean caterpillar, and green cloverworm (Boyd et al. 1997). However, ESPS soybean may be at greater risk to attack by the stinkbug pest guild commonly found in the southern growing regions of the United States (McPherson et al. 2001). The incidence of bean pod mottle virus was higher in ESPS than conventional soybean, undoubtedly associated with larger numbers of the vector, bean leaf beetle, being found in ESPS (Baur et al. 2000).

The final objective of S-281 was to determine the influence of environmental variability, specifically water stress, as soybean responds to insect injury and to develop management tools that account for environmental considerations. Yield responses of soybean subjected to combined stresses from defoliation and drought indicated that the stresses are independent, within the context of a given canopy size (Haile et al. 1998). Economic injury levels and economic thresholds for defoliators on stressed and non-stressed soybeans were developed. Drought stressed soybeans were found to be more susceptible to spider mite problems (Hammond, unpublished data). Although more research is needed, preliminary data suggest that leaf area index (and reduction thereof) can be used to assess the need for management of defoliators (Hunt et al. 1999; Board and Boethel 2001).

Current research related to this proposal concerns the efforts already occurring towards understanding the relationships between the bean leaf beetle and soybean aphid and soybeans. A few states have begun examining the ability to control the overwintering population of bean leaf beetle to limit the occurrence of bean pod mottle virus. Early indications are that a spray following soybean emergence, plus an additional insecticide application in July against the first generation of the insect, offers promise (Krell and Pedigo, unpublished data). The possibility of using this approach by applying a systemic seed treatment is being discussed. This overall approach to management of bean leaf beetle and thus, reducing the incidence of bean leaf beetle is but one objective that needs a regional approach over multiple states.

With the introduction of the soybean aphid into the U.S., most researchers involved in this proposal have begun work towards management of this insect. This ranges from states in the northern soybean production areas where detailed biological studies are being done along with the development of management programs, to more central U.S. states where the aphid occurred for the first time in 2002, to the southern states where monitoring for the soybean aphid will be essential in the coming years. Although it is questionable whether the aphid will become established as a significant pest in the southern states, the potential nevertheless exists. Current efforts against the soybean aphid are under the auspices of NC-502 that was established in October 2000 following the discovery of the aphid in the Midwest. Although a North Central project, it nevertheless had membership and participation from most soybean producing states including those in the south. That project is scheduled to terminate in September 2002 (the same time as the current S-281), at which time regional efforts will be coordinated through this proposed project, the revision of S-281. There are also regional efforts towards biological control of the aphid through NC-125, Biological Control of Arthropods and Weeds, of which numerous participants belong to both groups. Collaborative efforts with this group are expected.

There is also research directed toward soybean viruses through the auspices of a new regional project, NCR-200, Management Strategies to Control Major Soybean Diseases in the North Central Region. That group, however, is a virus-disease oriented project. This proposal will focus on the role vectors play in spreading virus and develop management tactics that focus on proven cultural practices that can mitigate virus spread. Additionally, numerous members of this proposed project are members of that group, and strong collaborative efforts as well as with other plant virologists and pathologists are expected.

Objectives

1. Characterize the dynamics and impact of evolving insect pests and optimize insect management as an integral element of developing cropping systems.
   
2. Define insect-vector ecology and virus-disease relationships and develop management strategies.
   
3. Biological control of the soybean aphid in North America.
   
4. Apply geospatial and precision technologies to advance pest management in soybeans.
   
5. 
   

Methods

Participating states by sub-objectives are provided in an attachment.

Objective 1 (AR, GA, IA, IL, IN, KS, KY, LA, MI, MS, ND, NE, OH, TN, TX, VA, WI, and USDA (MO)).

Sub-objective 1a. Develop management strategies for the soybean aphid. .

Document distribution and develop standardized sampling protocols. -- Soybean fields throughout the Midwest will be sampled for soybean aphid from early vegetative stages through reproductive stages to improve soybean aphid sampling to produce quantitative estimates. Sampling protocols will be those as presented through the NC Pest Management Centers Website. Soybean fields elsewhere will be sampled to document continued spread of the soybean aphid. In areas with aphid build-up, sampling will intensify and as understanding of aphid biology and population dynamics increase, sampling protocols will be optimized for geographic surveys, research needs, and pest management. Suspected soybean aphid overwintering habitat (Rhamnus spp.) and other suspected overwintering hosts also will be sampled and data will be reported on the national database. Locations of Rhamnus populations will be marked with GPS coordinates and referenced to locations of nearby soybean fields. Selected populations of Rhamnus will be monitored to determine key phenological events (e.g., arrival and departure of aphids to/from overwintering, etc.) and aphid densities and survival. The relative risk of aphid invasion into soybean fields will be determined from the spatial relationships between the primary (Rhamnus) and secondary (soybean) host and the aphid dynamics-damage in monitored fields.

Determine soybean response to the soybean aphid. -- Research plots will be established in areas where soybean aphid infestation is expected and opportunistically where aphid populations develop. Plots will receive various insecticide treatments to establish different levels of infestation. Depending on location, physiological responses (e.g., photosynthetic rate, stomotal conductance, transpiration rate) of aphid infested and non-infested soybean will be measured at different infestation levels and plant stages. Preliminary research indicates that photosynthetic rate reductions occur at low aphid intensities and are not associated with chlorophyll loss. Plant growth parameters (e.g., plant growth stage, plant height, number of branches) and yield parameters (e.g., number of 0-, 1-, 2-, and 3-seeded pods, pod, seed, and stem dry weight) also will be taken. ANOVA procedures will be used to identify significant treatment effects and regression analyses will be used to identify significant relationships. Results of these studies identify the physiological basis of yield loss and will be used to develop economic injury levels. Use of similar or common procedures and common measurements will allow analysis of plant response data regionally (within appropriate groupings, such as soybean maturity groups).

Develop management strategies for soybean aphid. -- Preliminary studies indicate host plant resistance holds promise for managing soybean aphid. Illinois studies identified 18 cultivars that exhibited resistance to soybean aphid. Trials will continue to be conducted to identify and characterize soybean aphid resistant cultivars. Preliminary studies also indicate planting date plays a role in aphid population build-up and resultant feeding injury; late-planted soybeans appear more susceptible to large aphid population build-up and injury. Soybean aphid management must occur in the context of other soybean production and pest management practices. In particular, grower practices may significantly influence soybean aphid population buildup and natural enemies. Studies will be conducted to determine the effect of planting date and cropping system on soybean aphid establishment, build-up, biology, injury, and economic damage to soybean. Insecticide trials also will be conducted. Treatments will combine planting date, row spacing, cropping system, different compounds, and plant stage-specific insecticide application. Initial work on resistance management will focus on establishing baseline susceptibility of aphid populations regionally for comparison of susceptibility in later years. Depending on need over the life of the project, additional work on monitoring, discriminating dosages, and management plans may be undertaken.

Sub-objective 1b. Validate emerging management strategies for the bean leaf beetle.

Recent research from Iowa has resulted in a bean leaf beetle management strategy based on sweep-net sampling the F1 population, using the F1 population densities to predict if the F2 population will reach economically damaging populations, and if necessary, treating the F2 population early in its population growth period. Because overwintering habitat and other environmental factors vary, studies will be conducted to validate this strategy where it occurs. Potential fields will be identified and sweep-net sampling of F1 beetles will begin. Sampling will continue on a weekly basis through late reproductive stages to validate that F1 population densities are closely correlated to F2 population densities, and that F1-based predictions of F2 economic thresholds are valid.

Sub-objective 1c. Develop management strategies for insect pests of soybean under evolving cropping systems.

Threshold development for soybeans under multiple stresses. -- Research will be conducted to develop economic thresholds for soybeans under multiple stresses. General procedures will include insect/injury treatments combined with other stresses as appropriate to location. Experimental design will be a randomized complete block with 4 replications. Treatment design will be split-plot or split-split plot, depending on the combination of stresses. Depending on location and combination of stresses, physiological responses (e.g., photosynthetic rate, stomotal conductance, transpiration rate) will be measured at different plant stages. Plant growth parameters and yield parameters will be taken. ANOVA procedures will be used to identify significant treatment effects and regression analyses will be used to identify significant relationships.

Threshold development for value-added soybeans. -- Studies will be conducted to examine the effects of early season and mid-season defoliation on value-added soybean varieties including high sucrose and high protein varieties. Experimental design will be a randomized complete block with 4 replications. Treatment design will be a split-split plot consisting of soybean variety as main plots, insect injury as subplots. Plant growth parameters and yield parameters will be taken. ANOVA procedures will be used to identify significant treatment effects and regression analyses will be used to identify significant relationships.

Arthropod pest management in transgenic soybeans. -- Studies will be conducted to examine the arthropod complex in transgenic, Bt soybeans, with particular emphasis on secondary pests and beneficial organisms. Initial studies will include arthropod sampling, including sweep net, visual counting, sticky trap, and pit-fall trap. As insect resistant transgenic soybean production is in its infancy, research procedures will evolve as experience and understanding of these soybean varieties develop. Work on resistance management will initially focus on the development of baseline susceptibility data.

Objective 2 (GA, IA, IL, MI, MN, NE, OH, and WI)

Sub-objective 2a. Examine relationships between bean pod mottle virus and its primary vector, the bean leaf beetle.

Bean leaf beetle overwintering and initial transmission of bean pod mottle virus to soybean. -- Visits will be made in early spring to areas that had noticeable F2 generation bean leaf beetle populations the prior year. Bean leaf beetles will be collected from overwintering sites prior to spring emergence. Cages also will be used to confine fall-collected beetles throughout the winter. Beetles will be tested for the ability to transmit soybean mosaic virus. Earlier observations suggest that a positive ELISA finding for the virus does not reflect an ability to transmit the virus to newly emerged plants. Thus, individual bean leaf beetles will be placed on to potted greenhouse plants to determine their ability to transmit the virus. We will determine the ability of the overwintered beetle to transmit the virus throughout the soybean growing regions of the United States.

Soybean planting dates in relation to bean leaf beetle infestations and incidence of bean pod mottle virus. -- Soybean fields within a limited geographic area, planted at various planting dates in the spring, will be located. The various generations will be sampled from these fields to include representatives of the overwintered, F1, and F2 generation. Beetles will be assayed with ELISA to determine the presence of the virus. Observations will be recorded for viral symptoms during the growing season started on late vegetative stages and proceeding through the reproductive stages. This would include recording the presence of green stem syndrome and mottled seeds at harvest. In those cases where symptoms exist, leaves will be taken to plant virologists for virus detection by ELISA.

Insecticide control of bean leaf beetle and management of bean pod mottle virus. -- Preliminary data suggest that an insecticide application following crop emergence, followed by a second insecticide application in July at the beginning of the F1 generation is effective at reducing the incidence of bean pod mottle virus (Krell & Pedigo, personal comm.). Studies will be conducted using large, replicated plots. Plots will be arranged in a randomized complete block design with at least 2 treatments, plots with both spray applications and plots without any spray. The presence of bean leaf beetles will be monitored during the summer using sweep net sampling. Near plant maturity, plants will be examined for the presence of virus symptoms including green stem syndrome. At harvest, representative samples of seed will be collected for examination of mottled seeds. Analyses of variance will be used to determine whether the spray applications reduced the incidence of virus-symptoms.

ESPS in wide row and narrow row production in relation to bean leaf beetle populations and incidence of bean pod mottle disease. -- Insect population densities and disease levels (ELISA procedure) will be quantified for varieties of different maturity groups in different replicated, large plot early season production systems (ESPS) in narrow row and conventional plantings to determine dynamics of the bean leaf beetle and bean pod mottle disease for making decisions on the need for application of insecticide or other control measure for insect pest and disease management. Yield measurements and cost/benefit economic analysis of insect control, resulting in reduction of bean pod mottle disease, will determine the economic benefits obtained, if any, of insect pest management in the different soybean production systems.

Sub-objective 2b. Examine the potential for soybean aphid to be an effective vector of soybean mosaic virus, and whether the virus is increasing in incidence in the major soybean growing areas of the U.S.

Research has determined that the soybean aphid is able to transmit North American strains of soybean mosaic virus and alfalfa mosaic virus in controlled environment experiments. The question remains how effective of a vector the aphid is in the field, and whether the incidence and severity of aphid transmitted viruses will become greater. At this time, observations suggest that they are not on the increase. However, this project feels it is important to maintain vigilance towards that possibility. Throughout the soybean growing production areas, the incidence and severity of virus-like symptoms will be continuously observed. During any and all studies involving the soybean aphid, we will examine the plants within the various plots for differences in symptoms. In those cases where symptoms exist, leaves will be taken to plant virologists for virus detection by ELISA. If soybean viruses do become a greater problem, we anticipate working closely with virologists and the NCR-200 regional project to develop appropriate management tactics.

Objective 3 (AR, IL, KY, MI, MN, MS, OH, WI, and USDA (MO and MI))

Sub-objective 3a. Importation of exotic natural enemies for controlling soybean aphid.

Foreign exploration of natural enemies, including parasitoids and predators, began in the summer of 2001 with 2 expeditions, one to northeastern China (Drs. Heimpel, Wu and Ragsdale) and one to Japan (Drs. ONeil and Voegtlin). The aphidiine braconids, Lipolexis gracilis Foerster and Lysiphlebus fabarum (Marshall) were found attacking soybean aphid in China. An aphelinid, Aphelinus albipodus Hayat and Fatima, was found attacking soybean aphid in Japan. These parasitoids were shipped to the USDA Beneficial Insect Introduction Research Unit in Delaware and reared under quarantine. Only L. gracilis and Aphelinus albipodus are now in culture with L. fabarum being lost in a mixed culture.

Research thrusts to be considered will include the development of a set of protocols to guide decisions on natural enemy releases and evaluation of impact, continued exploration for SBA in Asia, collaborating with Asia scientists to define essential relationships among SBA its natural enemies and host plants, determination whether there are different strains of natural enemies adapted to conditions similar to U.S. soybean production areas, and monitor releases, and evaluation of the success of natural enemy establishment and impact on SBA populations and damage.

The effort will examine all types of natural enemies and is not limited to parasitoids. Appropriate permits from USDA/APHIS/PPQ and responsible state agencies will be facilitated by cooperating project members. This regional project will develop linkages to regional biological control groups (e.g., NCR-125 in the Midwest) to aid in research coordination and communication. The following objective will be an initial effort of this project:

Release of Aphelinus albipodus. -- A. albipodus has been released in the western U.S. against the Russian wheat aphid. This parasitoid has USDA APHIS approval for release in the U.S. but researchers will need approval from state regulatory authorities prior to release within any state where the soybean aphid now occurs. In late 2001, personnel from the USDA APHIS laboratory in Niles, MI were able to collect A. albipodus from Wyoming. This winter they demonstrated that the Wyoming strain of A. albipodus will parasitize soybean aphids under laboratory conditions. In 2001, this same parasitoid was found attacking soybean aphid in Japan. The Japanese strain of A. albipodus is currently being maintained in 2 separate laboratories awaiting further host testing prior to making an application to USDA APHIS for permission to release the Japanese strain of A. albipodus. USDA APHIS personnel are able to provide state cooperators with A. albipodus mummies (Wyoming strain) for the purposes of establishing their own colony. No special precautions are needed to prevent accidental release once state approval for release is obtained.

Releases will be made in 6 x 6 foot cages containing soybean with small soybean aphids colonies with plants that are in the early vegetative stages. Soybean aphids will be sampled twice weekly with adult aphids or mummies returned to the laboratory to confirm parasitization. When a high proportion of aphids are parasitized (>25%) cages will be removed and parasitoids will be allowed to move outside of the cage to adjacent soybean fields. Sampling at known distances from the release point will continue twice weekly until soybeans reach maturity. Soybeans will be planted in subsequent years either in adjacent fields or in the same field and monitored for presence of parasitoids to determine the success of this species to overwinter locally. As the Japanese strain of A. albipodus becomes available or other parasitoids are approved, releases of these natural enemies will be made. At least 2 locations will be selected for initial releases, with additional states participating as the project proceeds.

Sub-objective 3b. Conserving natural enemies.

Research will focus on native and naturalized natural enemies already present in North America. As the invasion front of the soybean aphid passes it appears that soybean aphids are not reaching as high a density (C. DiFonzo, personal comm.). Work on generalist predators, e.g., Nabidae, Anthocoridae, Chrysopidae, and Coccinellidae, is underway in many states. There is also a suite of pathogens that will infect soybean aphids and there may be cultural practices that will encourage earlier onset of epizootics of entomophthoraceous fungi. Research will focus on how to conserve natural enemies through management practices implemented by growers and how to account for natural enemies as economic thresholds are developed.

Objective 4 (LA, ND, NE, TX, and VA)

This objective is to develop criteria for insecticide application based on remote sensing technology (digital aerial photography) that is cheaper and more efficient than the method currently used. Currently, the decision to employ control measures is based on scouting fields and employing a control tactic when insect damage in terms of yield loss is equivalent to the cost of control. It would be more cost efficient to be able to scout fields from the air (either airplanes or satellites). Scouting by airplane would increase statewide yields, lower production costs to producers (thus increasing profit margins), and bolster the entire consulting/aerial applicator industry by increasing their efficiency and lowering their costs. Radiometers or digital cameras mounted on airplanes could quickly assess leaf area weekly during periods when defoliation is likely. We propose to develop models based on ground based collections reflectance spectra and canopy light attenuation curves from soybean fields using handheld radiometers and ceptometers. Models then will incorporate leaf angle distributions to arrive at estimates of leaf area based on the light penetration. New technology will be incorporated including satellite imagery, digital orthographic images or quadrangles (DOQs), geographic information (GIS) software, and global position systems (GPS) in current management practices and scouting techniques.

Explore the relationship of vegetative indices, leaf area index, and soybean yield. -- To link remote sensing data to the canopy light interception and leaf area, we will rely on procedures established on measuring the light interception of agricultural crops and generating remote sensing reflectance spectra associated with those agricultural crops (Board & Boethel 2001, Ma et al. 2001). A series of plots will be established to achieve different canopy sizes using 4 planting dates and 5 plant populations. Stand counts will be taken to determine plant population. LAI measurements and aerial color and infrared photos will be taken from a fixed wing aircraft every 2 weeks beginning at the V5-6 growth stage until flowering - and weekly after flowering. Vegetative indices will be developed from infrared photos using the ArcView GIS software. Yields will be taken using a small-plot research combine. Correlation and regression analyses will be used to determine the relationship of vegetation index (VI), leaf area index (LAI), and yield. Because of the focus of the project, the expertise of plant pathologists, geographers, agronomists, entomologists, and consultants may be needed.

Measurement of Progress and Results

Outputs

• Develop standard sampling protocols and multiple management strategies for the soybean aphid.
• Determine the overwintering survival ability of the bean leaf beetle and determine the correlation between the F1 and F2 generations.
• Develop thresholds for value-added soybeans and when the crop is under multiple stresses.
• Determine how bean pod mottle virus is transmitted by the bean leaf beetle in the field, and examine the ability to lesson the impact of the virus by insect management with multiple applications of an insecticide.
• Establish an incidence base line for aphid transmitted viruses (soybean mosaic virus and alfalfa mosaic virus) and monitor annually to determine trends in incidence associated with soybean aphid.
• The release and establishment of one or more natural enemies of the soybean aphid.
• Determine the correlation between VI, LAI, and soybean yield using new precision agricultural technologies.

Outcomes or Projected Impacts

• Standard sampling protocols for the soybean aphid will allow stakeholders to manage this new pest using multiple tactics, and thus, ensuring soybean profitability.
• F1 bean leaf beetle generation thresholds can be used to make treatment decisions for the F2 beetle generation, thus, providing more efficient management of the second generation and reducing pod injury.
• Development of new thresholds for value-added soybeans and when under multiple stresses will allow better decision-making by stakeholders and ensuring profitability.
• Disease management of bean pod mottle virus is accomplished by control of the bean leaf beetle with two, well-timed insecticide applications.
• Released natural enemies are effective in reducing soybean aphid densities and thus, reducing insecticide applications.
• Increased use of geospatial and precision technology in pest management in aiding stakeholders to more prescriptively manage existing pest problems.

Milestones

(2003): Development and evaluation of standard sampling protocols for soybean aphid. Begin evaluating multiple tactics for soybean aphid management. Begin management studies of bean leaf beetle and bean pod mottle virus. Begin threshold studies with value-added soybeans and when grown under various stresses. Release of available natural enemies. Establish plots to achieve different canopy sizes, and begin taking LAI measurements and aerial color and infrared photos.

(2004): Evaluation of standard sampling protocols for soybean aphid. Continued evaluation of multiple tactics for soybean aphid management. Continue management studies of bean leaf beetle and bean pod mottle virus. Continue threshold studies with value-added soybeans and when grown under various stresses. Determine the establishment of released natural enemies. Continue with plot work with LAI measurements and aerial color and infrared photos. Begin to develop vegetative indices from infrared photos using the ArcView GIS software.

(2005): Continued evaluation of standard sampling protocols for soybean aphid. Continued evaluation of multiple tactics for soybean aphid management. Continue management studies of bean leaf beetle and bean pod mottle virus. Continue threshold studies with value-added soybeans and when grown under various stresses. Evaluation of released natural enemies. Develop models based on ground based collections reflectance spectra and canopy light attenuation curves from soybean fields using handheld radiometers and ceptometers.

(2006): Grower acceptance of standard sampling protocols for soybean aphid. Grower acceptance and use of multiple tactics for soybean aphid management. Evaluate bean leaf beetle and virus management tactics under grower conditions. Being to evaluate potentially new thresholds under various environments. Continue threshold studies with value-added soybeans and when grown under various stresses. Evaluation of released natural enemies. Develop criteria for insecticide application based on remote sensing technology, and incorporate new precision technologies into management practices and scouting techniques.

(2007): Grower acceptance of standard sampling protocols for soybean aphid. Continued use of multiple tactics for soybean aphid management. Evaluate bean leaf beetle and virus management tactics under grower conditions. Being to evaluate potentially new thresholds under various environments. Evaluation of released natural enemies. Monitor and evaluate the use of new precision technologies into management practices and scouting techniques.

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Projected Participation

View Appendix E: Participation

Outreach Plan

Distribution of the information generated by the new project will be disseminated via the Internet and traditional outreach programs including the various extension programs that exist in all states. Numerous Internet sites concerning the soybean aphid are already established in many of the states, with a central source of information from the North Central IPM Center (http://www.pmcenters.org/Northcentral/Saphid/aphidindex.htm). Because the project will contain southern and north central participants, virtually all the soybean growing area of the United States will be represented and thus, growers in underserved and underrepresented areas should have access to the data generated in a timely manner.

Organization/Governance

The Technical Committee is comprised of the voting members from each state. The Executive Committee consists of the Chair, Chair-Elect/Secretary, and the Coordinators of the research objectives. The Administrative Advisor and the CSREES representative serve as ex-offico members of the Executive Committee. Each year a Chair-Elect/Secretary is elected and the following year ascends to the position of Chair. The current Chair of S-281 is Gary Lentz, Tennessee, with Ron Hammond, Ohio, serving as Chair-Elect/Secretary.

Literature Cited

Baur, M. E., D . J. Boethel, M. L. Boyd, G. R. Bowers, M. O. Way, L. G. Heatherly, J. Rabb, and L. Ashlock. 2000. Arthropod populations in early soybean production systems in the mid-south. Environ. Entomol. 29: 312-328.

Board, J.E., and D.J. Boethel, 2001. Light interception: a way for soybean farmers to determine when to spray for defoliating insects. Louisiana Agriculture 44: 810.

Boethel, D. J. 2002. Integrated management of soybean insects. In Soybeans: Improvement, Production, and Uses. 3rd Edition. Amer. Soc. Agron. Madison, WI. (to be published).

Boyd, L. D., D. J. Boethel, B. R. Leonard, R. J. Habetz, L. P. Brown, and W. B. Hallmark. 1997. Seasonal abundance of arthropod populations on selected soybean varieties grown in early season soybean production systems in Louisiana. La. Agric. Exp. Stn. Bull. 860. 27 pp.

Buckelew, L. D., L. P. Pedigo, H. M. Mero, D. K. Owen, and G. L. Tylka. 2001. Effects of weed management systems on canopy insects in herbicide-resistant soybeans. J. Econ. Entomol. 95: 1437-1443

Haile, F. J., L. G. Higley, and J. E. Specht. 1998. Soybean cultivars and insect defoliation: yield loss and economic injury levels. Agronomy J. 90: 344-352.

Higley, L. G. 1992. New understandings of soybean defoliation and their implications for pest management. pp. 56-66, In Pest Management in Soybean, L. G. Cropping, M. B. Green, and R. T. Rees, eds., Elsevier Applied Sci, New York, 367 pp.

Higley, L. G., and D. J. Boethel. 1994. Handbook of Soybean Insect Pests, Entomology Society of America, Lanham, MD, 136 pp.

Hunt, T. E., F. J. Haile, W. W. Hoback, and L. G. Higley. 1999. Indirect measurement of insect defoliation. Environ. Entomol. 28: 1136-1139.

Ma, B.L., M.D. Lianne, C. Costa, E.R. Cober, and M.J. Morrison, 2001. Early prediction of soybean yield from canopy reflectance measurements. Agron. J. 93:12271234.

Marking, S. 2001. Tiny Terrors. Soybean Digest 61:64-65.

McPherson, R. M. 2000. Georgia Annual Report. Dynamic Soybean Insect Pest Management for Emerging Agricultural Technologies and Variable Environments. CSREES Regional Research Project S-281. Washington, D.C., 59 pp.

McPherson, R. M., M. L. Wells, and C. S. Bundy. 2001. Impact of early soybean production system on arthropod pest populations in Georgia. J. Econ. Entomol. 30:76-81.

Rice, M. E., R. K. Krell, W. F. Lam, and L. P. Pedigo. 2000. New thresholds and strategies for management of bean leaf beetles in Iowa soybean, pp. 75-84, In Proceedings of the Integrated Crop Management Conf., Iowa State Univ. Ext. Serv.

Attachments

Land Grant Participating States/Institutions

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

Non Land Grant Participating States/Institutions

CPHST, South Dakota, USDA, ARS