Updated February 4, 2022:
Program I. Extension/Outreach and Farmer Feedback
1.1 Extension coordination and project deliverables
Participants: Kelley Tilmon* (Ohio State University), with contributions all team members *Project leader
Team members on this project created a number of information deliverables informed by our NCSRP results, past and current. These are detailed in the Project Outputs document (attached), but in summary: between 2019 and 2021 we produced 114 extension publications or other products (e.g., factsheets, podcasts, scouting videos, etc.); 185 extension presentations directly to stakeholders; 58 peer-reviewed journal papers; and 42 scientific meeting presentations. Our team-members were given 7 awards for work related to this project. In addition, we trained 14 graduate students and 2 postdocs, and employed 44 undergraduates on soybean research experiences. We received 35 leveraged grants related to this project, totaling $2.5 million. Several of the region-wide extension outputs planned for this project had to be deferred due to Year 3 budget cuts. However, we had enough cost recovery from canceled conference travel that we were able to print a new second edition of the popular field guide Stink Bugs of the North Central Region, and produce an ID/scouting/threshold quick-card on Defoliators of the North Central Region, with 15,000 hard copies for distribution in North Central states, and available for free online. Work on other planned Year 3 deliverables will resume as part of the new NCSRP entomology project which began in October 2021.
1.2 Determining farmer needs and priorities
Participants: Tom Hunt* (University of Nebraska), Kevin Rice* (University of Missouri) *Project leaders
This objective was focused on farmer participation and feedback to assess needs and thoughts, to help guide future efforts and investments. The findings of this report are intended guide future research and to improve current and create new pest management information, tools, and delivery methods. In early 2021, four focus group interviews were conducted with soybean growers among 11 North Central Region states who were currently or recently members of state soybean associations or boards, plus one focus group interview with crop consultants. The basic purpose of the study was to find about farmers thoughts and feelings regarding soybean insect pests and what they desire from public entomologists to aid in management. Twenty-five participants were recruited, with 22 participating, for a participation rate of 88% (considered excellent for focus groups). Groups in the North Central Region were 1) southeast (IL, MO, OH), 2) southwest (MO, NE, IA), 3) northwest (ND, SD, MN, IA), 4) northeast (WI, MI, IL), and 5) consultants (NE, MI, IL, IN, MN). There were four to five participants in each group.
Dr. Mary Anne Casey, a focus group specialist, conducted the 90-minute Zoom interviews, with Drs. Tom Hunt and Kevin Rice facilitating. Each call was recorded, transcribed, and analyzed using constant comparative methodology. A Final Report (Farmers’ Needs Related to Soybean Insect Pests, 2021, Casey, M.A, K.B. Rice, T.E. Hunt) and Executive Summary were produced and sent to all focus group participants, the NCSRP Board, and other interested parties. Both documents are posted on the NCSRP website. These documents can be considered a Needs Assessment—identifying what types of research, tools, and information are needed by farmers.
https://www.soybeanresearchdata.com/download.aspx?file=Progress2File&name=54114_NCSRP_Focus_Summary.pdf
https://www.soybeanresearchdata.com/download.aspx?file=Progress2File2&name=54114_Farmers_Needs_Related_to_Soybean_Insect_Pests_Report_Final.pdf
For a very brief capsule summary: farmers and crop consultants would like 1) real-time “alerts” about current pest pressure, dispersal direction, and management options, and 2) help from Land Grant Universities and Extension to increase adoption of IPM recommendations because of concerns about the overapplication of pesticides that is leading to resistance.
Program II. Insect Management and Profitability
2.1 Management guidelines for defoliating insects
Participants: Nick Seiter* (University of Illinois), Erin Hodgson (Iowa State), Brian McCornack (Kansas State), Chris DiFonzo (Michigan State), Christian Krupke (Purdue), Kelley Tilmon (Ohio State). *Project leader
We conducted a survey of soybean fields across 7 states (IA, IL, IN, KS, MI, ND) to (1) determine how extensive insect defoliation of soybean is within the North Central region and (2) to compare methods to quickly and effectively estimate these defoliation levels. Where possible, fields were chosen that were identified as having above-average levels of defoliation. Out of 65 fields sampled a total of 90 times in 2019 and 2020, most had negligible defoliation, and only 1 field reached a level of defoliation that would be considered economically damaging under current recommendations. This survey confirms previous Extension recommendations indicating that, while defoliating insects are commonly found in soybean fields, yield-limiting levels of soybean defoliation caused by insects are rare in the North Central U.S. During our survey, we estimated defoliation using two different methods: collecting individual leaflets and estimating levels of defoliation based on a visual guide (as currently recommended in most extension literature) and taking a visual assessment of the total soybean canopy (a potentially quicker way to sample and compatible with remote sensing approaches). We found that the results obtained using these two methods were similar, though there was variability among samplers. A quick canopy assessment is a viable method for estimating whether a soybean field has reached an economic threshold; however, scout training is still needed to ensure an accurate assessment. Outputs will include better training materials for soybean scouts, including images of soybean canopies with insect defoliation approaching economically relevant levels to show scouts what to look for.
2.2 Cover crops: pest and beneficial insects in cereal rye to soybean transition systems
Participants: Justin McMechan* (University of Nebraska), Shawn Conley (University of Wisconsin), Louis Hesler and Shannon Osborne (USDA ARS South Dakota), Thomas Hunt (University of Nebraska), Bruce Potter (University of Minnesota), Kevin Rice (University of Missouri), Nick Seiter (University of Illinois); Kelley Tilmon (Ohio State University), and Robert Wright (University of Nebraska). *Project leader
The purpose of this study was to evaluate how rye cover crop transitioning to soybean affects insect pest pressure – is pest pressure better, worse, or neutral with regard to the presence of the cover crop and three different termination dates. With 30 site/years of cover crop data spanning seven states (NE, WI, SD, MN, MO, IL, OH), there is sufficient evidence to show that a cereal rye cover crop does not increase the risk of pest pressure when transitioning to soybean. In this study, treatment combinations lead to low as well as exceptionally high amounts of cover crop biomass. This wide variation in biomass is important for representing the wide range of responses that can occur in a rye cover crop to soybean system. Of the insects collected from pitfall traps, none appear to pose a threat to soybean yield. The arthropods collected in the study were placed in broad classification; most are considered to be generalist predators or decomposers which could provide ecosystems services to soybean. However, the value of these arthropods is difficult to determine and was not evaluated in the study.
No significant defoliation of soybean was observed at any of the sites, regardless of the presence or absence of a cover crop. In general, soybean yields were not impacted by the presence of the cover crop. Soybean biomass was measured at a few sites during the V2 stage and in some situations the presence of cover crop significantly reduced total soybean biomass, however, it did not impact final yield.
2.3 Pollinators to improve soybean yield
Participants: Reed Johnson*, Chia Lin, and Kelley Tilmon (Ohio State University) *Project leader
Although soybeans do not require insect pollination to produce a crop, pollination by bees can potentially improve soybean yield while the immense acreage of flowering soybeans can produce substantial nectar flow for honey bees and other pollinators. Our results clearly demonstrate that soybean is an important foraging resource for bees in the agricultural region of Ohio.
We found that honey bee colonies surrounded by more soybeans also gained more weight during soybean bloom. Pollen analysis of honey samples further confirmed that soybean was the predominant nectar source for colonies in large soybean fields. Positive effects of honey bee pollination on soybean yield was only apparent in two fields that were larger than 100 acres. There was no observable effect of honey bee colonies on soybean yield in the smaller fields. The yield benefit could be difficult to detect in small fields due to honey bees’ ability to forage over a long distance (a forager bee can travel over 1 – 2 miles for food). In walk-n cage studies, plants that were caged with honey bees produced up to 7 % more full pods compared to plants in without bees pollination, although the yield difference was not greater in the more attractive varieties.
We find that different soybean varieties can exhibit different levels of attractiveness to bees. Honey bees are more attracted to varieties that produced more nectar whereas sugar concentration, flower size, and flower color have little effect. Nectar production in the bee-attractive varieties was comparable to the values reported for clovers, which are very common forage plant for bees.
Taken together, our findings suggest that soybean is an important nectar source for honey bees. Some varieties are particularly attractive to bees can produce substantial nectar flow to improve honey bee productivity while supporting wild pollinators in the surrounding landscape. Although yield benefits from bee pollination alone was difficult to assess in the field, our controlled experiment showed that honey bee pollination could improve soybean production. Including pollinator management in the soybean cropping system could be the win-win strategy to improve the soybean and honey bee productivity while supporting local pollinators.
2.4 Insecticide-resistant soybean aphids
Participants: Robert Koch* (University of Minnesota), Ana Vélez (University of Nebraska), Janet Knodel (North Dakota State University); with contributions from other NCSRP participants including Andy Michel (Ohio State University), Erin Hodgson (Iowa State University), Adam Varenhorst (South Dakota State University), Louis Hesler (USDA ARS South Dakota), and Tom Hunt (University of Nebraska) *Project leader
This project addressed emerging problems related to insecticide resistance in soybean aphid. Since 2015 we have observed field failures of pryrethroids (such as Warrior) in some locations. This objective was to document the level of insecticide resistance in soybean aphids to pyrethroids, and also to examine associated biological characteristics in the aphids. We performed both laboratory and field trials. Field trials performed over multiple years and states confirmed decreased efficacy of field applications of pyrethroids. However, we found that other classes of insecticides still show promising levels of control. Through laboratory research we found that the development of insecticide resistance in soybean aphid is not associated with negative impacts on aphid biology (size, survival, reproduction, etc.). When insecticide resistance is accompanied by fitness costs for the aphids, the aphid lines are more likely to revert back to the insecticide-susceptible state over time if they are not exposed to the insecticide. However, these aphids lacked these fitness costs, making it more likely that they will retain the insecticide resistance into the future. Additional research focused on screening populations of soybean aphid for resistance to neonicotinoid insecticides. The results of our research are being shared with farmers and scientists.
2.5 Soybean stem borer (Dectes)
Participants: Kevin Rice* (University of Missouri), Robert Wright (University of Nebraska), Raul Villanueva (University of Kentucky) *Project leader
This objective was to look at the potential of sunflower to serve as a trap crop for soybean stem borer (Dectes). It was to be performed in 2020 and 2021. Several grower-cooperators with historic Dectes infestations eventually opted out of this study due to Covid-19 or because they rotated out of soybean. However, in Kentucky we discovered a novel, previously undocumented interaction between sunflower, red cocklebur weevil, and Dectes. The weevil interferes with successful development of Dectes inside the plant by preventing Dectes from reaching the root to build its overwintering chamber. Both Dectes and the red cocklebur weevil are attracted to sunflower, but the weevil gets there first, thus interfering with the Dectes life cycle and causing mortality which might eventually decrease populations. Further research is needed to see how this could play into management. In addition, we were fortunate to have a volunteer participant in this study, Dr. David Owens at the University of Delaware. In Delaware, 52-96% of sunflower stems planted near soybean fields showed signs of Dectes infestation, demonstrating the attractiveness of this plant to the pest.
Program III. Aphid Resistant Varieties and Aphid Virulence Management
3.1 Advancing aphid resistant soybeans through a public-private partnership
Participants: Matt O’Neal* (Iowa State University), Andy Michel* (Ohio State University), Mauricio Urrutia* (Corteva), David Onstad* (Corteva), Kelley Tilmon (Ohio State University), Thomas Hunt (University of Nebraska), Deirdre Prischmann (North Dakota State University), Adam Varenhorst (South Dakota State University), Louis Hesler (USDA ARS South Dakota). *Project leaders
The work in this objective will help predict how long aphid-resistant soybeans will remain durable, and also lead to strategies that can delay the increase in virulence (aphids overcoming resistant varieties). Dr. Onstad (Corteva) has developed and fine-tuned a mathematical model to explore the durability of aphid resistance. Dr. Onstad included parameters such as reproductive rate, dispersal to other soybean fields and buckthorn, and fitness differences among virulent and avirulent aphids. This model is in the final stages of development, with a manuscript to be submitted in spring or summer of 2022. During the course of this project, both Dr. O’Neal and Dr. Michel generated additional data for use in the model. One study explored how virulent and avirulent aphids interact on aphid-resistant soybeans and was submitted to the Journal of Economic Entomology. Another study investigated the impact of insecticidal seed treatments on the differential survival and growth of virulent and avirulent aphids. Other data generated included a new assay to identify virulent aphids, which will be further validated in the new NCSRP project.
3.2 Soybean breeding for aphid resistance
Participants: Brian Diers* (University of Illinois), Glen Hartman* and Doris Lago-Kutz (USDA-ARS) *Project leaders
Registration of 64 soybean germplasm lines with all combinations of five soybean aphid resistance genes in two genetic backgrounds, and agronomic and phenotyping was completed during this project by Brian Diers, et al.: Registration of 64 soybean germplasm lines with all combinations of five soybean aphid resistance genes in two genetic backgrounds. In addition, aphid resistance backcross lines were developed earlier in the project and used in the current time period of this report. A release notice for announcing these isolines has been drafted.
Additionally, through the support of this project we maintained colonies of four known soybean aphid biotypes that overcome resistant varieties. These colonies are critical resources for current and future research. We also tested isogenic lines for resistance to soybean aphid and conducted phenotyping for pyramiding resistant lines. We also evaluated the virulence of soybean aphid clones by using detached leaves and whole plants. Most notably, we found that Rag6 gene alone or in any combination with other genes provides high levels of resistance to the biotypes in our collection, showing good promise for this resistance gene. In adjacent work, we found survivorship of soybean aphid biotypes on winter hosts, common and glossy buckthorn, showing that these virulent biotypes are capable of using the same winter host plants as the non-virulent biotype (and won’t be eliminated from the population by interrupted overwintering).
Program IV. Insect Monitoring
4.1 Biological control of soybean aphid
Participants: George Heimpel*, with contributions from other project team members *Project leader
Biological control of an invasive species (soybean aphid) often occurs through the action of parasitoids, which are stingless wasps that tend to be very specific in the species they target. After much study we released two parasitoid species but neither established locally surviving populations. The parasitoid Aphelinus certus appeared in 2005 and spread rapidly across the soybean growing region of North America, and we have been studying this wasp, trying to determine its effectiveness at controlling soybean aphid. One concern is that, if aphid numbers are low, the parasitoid might go locally extinct, so even with very basic sampling we hope to be able to show that the parasitoid is found where we find the aphid. In the North Central region we found A. certus tends to track the soybean aphid generally, though in 2021 we had 5 states report aphids with no reports of the parasitoid. From our studies in Minnesota, which were much more intensive, we found that even at very low aphid densities the parasitoid was generally active. The low aphid numbers in the years 2019 to 2021 might be a result of parasitism, though other factors have to be considered such as widespread drought (2021) or severe winter cold with no snow cover and delayed planting from a wet spring (2020, Minnesota).
4.2 Monitoring soybean aphids and other soybean insect pests in suction traps
Participants: Glen Hartman* and Doris Lagos-Kutz (USDA-ARS/ University of Illinois) and Nick Seiter (University of Illinois), with contributions from other project team members *Project leader
The Suction Trap Network maintains insect sampling locations throughout the North Central Region through combined funding from NCSRP, state soybean checkoffs, and private industry. 34 monitoring stations collectively are located in IL, IN, KS, MI, MN, MO, NE, WI, and an un-funded cooperator in Louisiana. This network has allowed us to identify long term trends in soybean aphid biology and can provide a broader idea of where and when outbreaks are likely to occur. In addition, we have a much better understanding of what other pests can be tracked in the monitoring traps, including soybean thrips, and pests of corn, hemp, and wheat. Now we know how rainfall and temperature can affect aerial aphid populations, and how aphids with complex overwintering biology may vary with climate. Besides aphids, we have used the network to monitor soybean thrips which vector several viruses. These findings have implication for understanding microbe diversity in insect pests and their potential use in controlling insect pests. Each summer, trapping data is publicly available at https://suctiontrapnetwork.org/data/ and https://www.eddmaps.org
View uploaded report 
Program I. Extension/Outreach and Farmer Feedback
1.1 Extension coordination and project deliverables
Team members on this project created a number of information deliverables informed by our NCSRP results, past and current. These are detailed in the Project Outputs document (attached), but in summary: between 2019 and 2021 we produced 114 extension publications or other products (e.g., factsheets, podcasts, scouting videos, etc.); 185 extension presentations directly to stakeholders; 58 peer-reviewed journal papers; and 42 scientific meeting presentations. Our team-members were given 7 awards for work related to this project. In addition, we trained 14 graduate students and 2 postdocs, and employed 44 undergraduates on soybean research experiences. We received 35 leveraged grants related to this project, totaling $2.5 million. Several of the region-wide extension outputs planned for this project had to be deferred due to Year 3 budget cuts. However, we had enough cost recovery from canceled conference travel that we were able to print a new second edition of the popular field guide Stink Bugs of the North Central Region, and produce an ID/scouting/threshold quick-card on Defoliators of the North Central Region, with 15,000 hard copies for distribution in North Central states, and available for free online. Work on other planned Year 3 deliverables will resume as part of the new NCSRP entomology project which began in October 2021.
1.2 Determining farmer needs and priorities
We worked with farmers and crop consultants from throughout the North Central Region to conduct focus groups to assess their needs and thoughts, to help guide future efforts and investments. The findings of this report are intended guide future research and to improve current and create new pest management information, tools, and delivery methods. For a very brief capsule summary: farmers and crop consultants would like 1) real-time “alerts” about current pest pressure, dispersal direction, and management options, and 2) help from Land Grant Universities and Extension to increase adoption of IPM recommendations because of concerns about the overapplication of pesticides that is leading to resistance. A report on the outcomes of these focus groups was submitted to the NCSRP for inclusion in the checkoff database, and has also been made available to all focus group participants and other interested parties.
https://www.soybeanresearchdata.com/download.aspx?file=Progress2File&name=54114_NCSRP_Focus_Summary.pdf
https://www.soybeanresearchdata.com/download.aspx?file=Progress2File2&name=54114_Farmers_Needs_Related_to_Soybean_Insect_Pests_Report_Final.pdf
Program II. Insect Management and Profitability
2.1 Management guidelines for defoliating insects
We conducted study of soybean fields in 7 states (1) determine how extensive insect defoliation of soybean is within the North Central region and (2) to compare methods to quickly and effectively estimate these defoliation levels. This survey confirms previous Extension recommendations indicating that, while defoliating insects are commonly found in soybean fields, yield-limiting levels of soybean defoliation caused by insects are rare in the North Central U.S. We tested different methods to assess soybean defoliation. A quick canopy assessment is a viable method for estimating whether a soybean field has reached an economic threshold; however, scout training is still needed to ensure an accurate assessment. Outputs will include better training materials for soybean scouts, including images of soybean canopies with insect defoliation approaching economically relevant levels to show scouts what to look for.
2.2 Cover crops: pest and beneficial insects in cereal rye to soybean transition systems
The purpose of this study was to evaluate how rye cover crop transitioning to soybean affects insect pest pressure – is pest pressure better, worse, or neutral with regard to the presence of the cover crop and three different termination dates. With 30 site/years of cover crop data spanning seven states (NE, WI, SD, MN, MO, IL, OH), there is sufficient evidence to show that a cereal rye cover crop does not increase the risk of pest pressure when transitioning to soybean.
2.3 Pollinators to improve soybean yield
Although soybeans do not require insect pollination to produce a crop, pollination by bees can potentially improve soybean yield while the immense acreage of flowering soybeans can produce substantial nectar flow for honey bees and other pollinators. Our results clearly demonstrate that soybean is an important foraging resource for bees in the agricultural region of Ohio. Taken together, our findings suggest that soybean is an important nectar source for honey bees. Some varieties are particularly attractive to bees can produce substantial nectar flow to improve honey bee productivity while supporting wild pollinators in the surrounding landscape. Although yield benefits from bee pollination alone was difficult to assess in the field, our controlled experiment showed that honey bee pollination could improve soybean production. Including pollinator management in the soybean cropping system could be the win-win strategy to improve the soybean and honey bee productivity while supporting local pollinators.
2.4 Insecticide-resistant soybean aphids
This project addressed emerging problems related to insecticide resistance in soybean aphid. Since 2015 we have observed field failures of pryrethroids (such as Warrior) in some locations. This objective was to document the level of insecticide resistance in soybean aphids to pyrethroids, and also to examine associated biological characteristics in the aphids. In summary, we have documented substantial insecticide resistance to pyrethroids in some aphid populations, which has been contributing to spray failures. However, we found that other classes of insecticides still show promising levels of control.
2.5 Soybean stem borer (Dectes)
This objective was to look at the potential of sunflower to serve as a trap crop for soybean stem borer (Dectes). It was to be performed in 2020 and 2021. Several grower-cooperators with historic Dectes infestations eventually opted out of this study due to Covid-19 or because they rotated out of soybean. However, in Kentucky we discovered a novel, previously undocumented interaction between sunflower, red cocklebur weevil, and Dectes. In short, the cocklebur weevil contributes to Dectes mortality in sunflower, and may prove to be a useful partner in sunflowers as a trap-crop for soybean stem borer.
Program III. Aphid Resistant Varieties and Aphid Virulence Management
3.1 Advancing aphid resistant soybeans through a public-private partnership
The work in this objective will help predict how long aphid-resistant soybeans will remain durable, and also lead to strategies that can delay the increase in virulence (aphids overcoming resistant varieties). Dr. Onstad (Corteva) has developed and fine-tuned a mathematical model to explore the durability of aphid resistance. In addition, we collected additional biological information to be used in the model, which is in the final stages of development. One study explored how virulent and avirulent aphids interact on aphid-resistant soybeans and was submitted to the Journal of Economic Entomology. Another study investigated the impact of insecticidal seed treatments on the differential survival and growth of virulent and avirulent aphids. Other data generated included a new assay to identify virulent aphids, which will be further validated in the new NCSRP project.
3.2 Soybean breeding for aphid resistance
Registration of 64 soybean germplasm lines with all combinations of five soybean aphid resistance genes in two genetic backgrounds, and agronomic and phenotyping was completed during this project by Brian Diers, et al.: Registration of 64 soybean germplasm lines with all combinations of five soybean aphid resistance genes in two genetic backgrounds. In addition, aphid resistance backcross lines were developed earlier in the project and used in the current time period of this report. A release notice for announcing these isolines has been drafted.
Additionally, through the support of this project we maintained colonies of four known soybean aphid biotypes that overcome resistant varieties. These colonies are critical resources for current and future research. We also tested isogenic lines for resistance to soybean aphid and conducted phenotyping for pyramiding resistant lines. A key finding is that the Rag6 gene alone or in any combination with other genes provides high levels of resistance to the biotypes in our collection, showing good promise for this resistance gene.
Program IV. Insect Monitoring
4.1 Biological control of soybean aphid
Biological control of an invasive species (soybean aphid) often occurs through the action of parasitoids, which are stingless wasps that tend to be very specific in the species they target. After much study we released two parasitoid species but neither established locally surviving populations. The parasitoid Aphelinus certus appeared in 2005 and we have documented its rapid spread across the soybean growing region of North America. From our studies in Minnesota, which were much more intensive, we found that even at very low aphid densities the parasitoid was generally active. The low aphid numbers in the years 2019 to 2021 might be a result of parasitism, though other factors have to be considered such as widespread drought (2021) or severe winter cold with no snow cover and delayed planting from a wet spring (2020, Minnesota).
4.2 Monitoring soybean aphids and other soybean insect pests in suction traps
The Suction Trap Network maintains insect sampling locations throughout the North Central Region through combined funding from NCSRP, state soybean checkoffs, and private industry. 34 monitoring stations collectively are located in IL, IN, KS, MI, MN, MO, NE, WI, and an un-funded cooperator in Louisiana. This network has allowed us to identify long term trends in soybean aphid biology and can provide a broader idea of where and when outbreaks are likely to occur. In addition, we have a much better understanding of what other pests can be tracked in the monitoring traps, including soybean thrips, and pests of corn, hemp, and wheat. Besides aphids, we have used the network to monitor soybean thrips which vector several viruses. These findings have implication for understanding microbe diversity in insect pests and their potential use in controlling insect pests. Each summer, trapping data is publicly available at https://suctiontrapnetwork.org/data/ and https://www.eddmaps.org