Project Details:

Title:
Soybean Entomology in the North Central Region: Management and Outreach for New and Existing Pests

Parent Project: Soybean entomology in the North Central region: Management and outreach for new and existing pests
Checkoff Organization:North Central Soybean Research Program
Categories:Insects and pests, Nematodes
Organization Project Code:NCSRP
Project Year:2019
Lead Principal Investigator:Kelley Tilmon (The Ohio State University)
Co-Principal Investigators:
Erin Hodgson (Iowa State University)
Matthew O'Neal (Iowa State University)
Brian McCornack (Kansas State University)
Christina DiFonzo (Michigan State University )
Janet Knodel (North Dakota State University)
Deirdre Prischmann-Voldseth (North Dakota State University)
Robert Koch (Northwest Research and Outreach Center, University of Minnesota)
Christian Krupke (Purdue University)
Louis Hesler (South Dakota State University)
Adam Varenhorst (South Dakota State University)
Andy Michel (The Ohio State University)
Brian Diers (University of Illinois at Urbana-Champaign)
George Heimpel (University of Minnesota)
Bruce Potter (University of Minnesota)
Kevin Rice (University of Missouri)
Thomas E Hunt (University of Nebraska)
Justin McMechan (University of Nebraska)
Robert Wright (University of Nebraska)
Ana Velez Arango (University of Nebraska at Lincoln)
Shawn Conley (University of Wisconsin)
Glen Hartman (USDA/ARS-University of Illinois)
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Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

The subject of this proposal is research and outreach on soybean entomology in the North Central Region. Soybean insect pests not only reduce yield, but can also reduce grain quality, altering oil and protein content (Rupe and Luttrell 2008). Thus insect pests can affect soybean value by affecting composition, in addition to reducing revenue by reducing yield. In addition, inefficient pest management adds to the expense of farm production, cutting into farmers’ bottom lines. This proposal involves24 researchers in all 12 states of the North Central Region in collaborative research in four main program areas encompassing
I.Extension/outreach and farmer feedback, II. Insect management and profitability, III. Aphid resistant varieties and virulence management, and IV. Insect monitoring. The objectives within these programs address the efficient, cost-effective management of defoliating (chewing) insects; the role of cover crops relative to insects in soybean production; aphid resistance to insecticides (a documented and growing problem in the region); the ability of honey bees to improve soybean yield; a public-private partnership with Pioneer Hi-Bred International to advance aphid resistant soybean varieties for wide scale commercialization; advances in soybean breeding for aphid resistant varieties; regional monitoring programs for pest and beneficial insects; and a survey program to assess farmer priorities and needs to inform future research and extension. In addition, we have an extension objective with a dedicated budget line to produce deliverables and disseminate project results.
This project builds on past NCSRP research and investment in several important ways. Previous work on the potential for insecticide resistance in aphids and tools to measure this resistance are now being used because the insecticide-resistant soybean aphids have been found in four states, with the problem spreading each year. NCSRP research to develop aphid resistant soybean lines is nearing fruition as a major seed distributor (Pioneer) is moving towards commercialization; the collaborative work with industry described in the current proposal will advance this effort. NCSRP research on pollinators in soybean has advanced to the point where we are ready to assess the value that honey bees may provide in soybean production (with some preliminary studies documenting the potential for substantial yield improvement). This proposal also incorporates new objectives including the role of cover crops in pest management (whether for good or for ill); maximizing the efficiency of scouting and management of defoliating insects (such as Japanese beetle, loopers and clover worm, bean leaf beetle); and the potential use of remote-sensing technology (e.g., satellite imagery or drones) to spot defoliation damage.
The soybean team in this proposal is multi-disciplinary, with researchers in the fields of entomology, agronomy, and plant breeding. Several of our objectives are coordinated multi-state efforts making our results applicable to a broad geographic area and creating greater research efficiencies through collaboration. Finally, this proposal incorporates several new researchers in the region (new faculty at the University of Nebraska, University of Illinois, University of Missouri) and also includes established researchers who are new to the project from the University of Wisconsin and Michigan State University – all of which increases our collaborative power and the reach of our results. The benefit for soybean farmers is that coordinated, collaborative research and outreach is the most efficient way to address insect pest problems that affect their production and profitability.

Project Objectives

Program I. Extension/Outreach and Farmer Feedback
1.1 Extension coordination and deliverables
1.2 Determining farmer needs and priorities

Program II. Insect Management and Profitability
2.1 Management guidelines for defoliating insects
2.2 Cover crops: insects in cereal rye to soybean transition systems
2.3 Pollinators to improve soybean yield
2.4 Insecticide-resistant soybean aphids

Program III. Aphid Resistant Varieties and Aphid Virulence Management
3.1 Advancing aphid resistant soybeans through a public-private partnership
3.2 Soybean breeding for aphid resistance

Program IV. Insect Monitoring
4.1 Biological control of soybean aphid
4.2 Monitoring soybean aphids and other soybean insect pests in suction traps

Project Deliverables

Progress of Work

Updated May 24, 2019:
Program I. Extension/Outreach and Farmer Feedback

1.1 Extension coordination and deliverables
Participants: Kelley Tilmon* (Ohio State University), with contributions all team members *Project leader
Progress. We are in the process of updating our multistate soybean aphid insecticide resistance factsheet with a goal to have this completed before the end of project Year 1. We have completed a draft of an extension publication detailing the pollinators found in North Central soybeans (a multistate research project in the previous proposal), and expect to publish it in summer 2019. In addition, we have completed a second print run of the popular field guide Stink Bugs of the North Central Region.

1.2 Determining farmer needs and priorities
Participants: Tom Hunt* (University of Nebraska), Kevin Rice* (University of Missouri) *Project leaders
Progress. During the first six months of the project we wrote a first draft of farmer/consultant focus group discussion questions, initiated the Institutional Review Board (IRB) process with the University of Nebraska [the process to obtain approval to conduct a Human Subjects study, which falls into a special category of research even for focus groups and survey] and made a first draft of a farmer/consultant focus group contact list. Our next steps are to send our draft of farmer/consultant focus group discussion questions to soybean commodity board members for comment and additional questions; finalize the IRB process at the lead institution (UNL) and expand to other participating institutions as necessary.

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

Progress. We have developed a defoliation sampling protocol for use during our first field season on this project (summer 2019). Sampling will be conducted on commercial fields or large production areas on research farms; fields with insect defoliation will be identified during the season in six states.

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

Progress. In the fall of 2018, 14 locations in 7 states were planted to wheat or rye cover crops. Cover crops were planted between mid-June and mid-November at a seeding rate of 58 to 113 lb./acre. Herbicide applications to terminate cover crops began in April. Inclement weather through much of the growing region interfered with our ability in some locations to stick to the termination and soybean planting schedule. Data collection on insect damage will begin in early summer. This study will be repeated in Year 2 and 3 of the project.

2.3 Pollinators to improve soybean yield
Participants: Reed Johnson*, Chia Lin, and Kelley Tilmon (Ohio State University) *Project leader

Progress. From October to May we have ordered hive equipment and honey bee colonies to be installed in April and May for the experiment. We have identified at least two growers who are willing to assist with the honey bee pollination experiment. We are communicating with soybean growers and researchers to select soybean varieties that will be used for evaluating floral attractiveness in 2019. Experiments will begin in the summer of 2019.

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), and Tom Hunt (University of Nebraska) *Project leader

Progress. From October to April we developed a standardized protocol for a diagnostic-concentration, glass-vial bioassay that will be performed by collaborators in six states. In each of the six collaborating states, sites are being identified for field experiments that will include application of pyrethroid insecticides to soybean plots, which will allow assessment of in-field efficacy of pyrethroid insecticides. This field work will be conducted in Summer 2019.


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). *Project leaders

Progress. From October to May we developed the protocol for the field experiments to be performed in the summer of 2019 in six confirmed locations. We encountered and obstacle with the transformation of Pioneer into Corteva, at which point we had to re-negotiate prior understandings and agreements. New material transfer agreements have been negotiated institution by institution and seed is being shipped for 2019 planting. The modeling work will require a separate MTA which is under negotiation. For this objective we have performed a small, microcosm experiment mixing soybean aphid biotypes and insecticide seed treated Rag plants. Aphids have been collected and are undergoing genotyping to monitor for biotype frequency change.

3.2 Soybean breeding for aphid resistance
Participants: Brian Diers* (University of Illinois), Glen Hartman* and Doris Lago-Kutz (USDA-ARS) *Project leaders

Progress. During the past 6 months, we have continued to develop experimental lines in a maturity group (MG) I and a MG II background that have all 32 combinations of homozygotes for resistance and susceptible alleles at Rag1, Rag2, Rag3, Rag4, and Rag6. All five genes were backcrossed into both backgrounds and combined into an F1 that was heterozygous for the five genes. From October to January, F2 plants segregating for the five genes were grown in a greenhouse and plants were selected that contained different combinations of the genes. Because of the large number of genes segregating, we selected plants with markers linked to each gene that were homozygous for some genes and heterozygous for others. In January, F3 progeny from each selected F2 plant were grown and among the F3 progeny, plants homozygous for all five gene were selected. We were successful in selecting all 32 combinations of homozygous plants for both backgrounds except in one case the selected plant was still heterozygous for one gene. During the summer, F3:4 lines from each combination will be grown in the field to increase seed that can be used for genetic studies. In the one case that homozygosity for all five genes was not achieved, we will select homozygous plants for the line. When plants are harvested in the fall, we should be able to provide seed of lines with these combinations to researchers.
The breeding program is continuing to develop high yielding lines that have the resistance genes Rag1 and Rag2 stacked together. The program recently licensed a variety with this two gene stack to a seed company located in Iowa and there is interest from other companies to license additional lines with this stack.
Program IV. Insect Monitoring

4.1 Biological control of soybean aphid
Participants: George Heimpel*, with contributions from other project team members *Project leader

Progress. We have contacted collaborators to prepare for 2019 sampling for Aphelinus mummies in soybean. Materials have been shipped to collaborators to sample 3 times, in late June, July, and August, and mail those samples to Saint Paul, MN. Last year we found aphids in all states but Missouri and Nebraska, and we found Aphelinus in the Dakotas, Minnesota, Wisconsin, Michigan and Ohio. We are also tracking 7 hyperparasitoids from 4 genera.

4.2 Monitoring soybean aphids and other soybean insect pests in suction traps
Participants: Glen Hartmant* and Doris Lagos-Kutz (USDA-ARS/ University of Illinois) and Nick Seiter (University of Illinois), with contributions from other project team members *Project leader

Progress. There were 33 suction traps that operated until October 19th, 2018. We received samples on a weekly basis and provided weekly aphid data to our collaborators. The suction trap data were also posted to https://suctiontrapnetwork.org/data/ through https://www.eddmaps.org/user/projects.cfm. This site allows users to select any suction trap location and see a graph of the seasonal abundance for the eight most abundant aphid species. This website is publicly available. A feature manuscript about the Suction Trap Network was submitted to American Entomologist in December 2018. Suction trap supplies were ordered by the end of December 2018, except postage and mailing services. We expect to ship all the supply packages to our collaborators by the end of April. The plan for this coming season is to operate the Suction Trap Network from May 17 through October 18, 2019 (23 weeks).

Final Project Results

Updated February 4, 2020:
Progress Report (Year 1 through December 2019)

Note: Year 1 funds were extended until December 31, 2019

Program I. Extension/Outreach and Farmer Feedback
1.1 Extension coordination and deliverables
Participants: Kelley Tilmon* (Ohio State University), with contributions all team members *Project leader
During the reporting period we published an updated soybean aphid insecticide resistance factsheet including an updated distribution map of the problem and new insecticide products registered for soybean aphid. Partering with the Ohio Soybean Council, NCSRP results were used to publish a Pollinators of Soybean fact-card for specimens found in Ohio. Copies from the new print run of Stink Bugs of the North Central Region were sent to 12 states for distribution to farmers at various extension programs.
1.2 Determining farmer needs and priorities
Participants: Tom Hunt* (University of Nebraska), Kevin Rice* (University of Missouri) *Project leaders
Progress. A professional facilitator, Dr. Mary Anne Casey, was contracted to advise on and conduct the farmer needs assessment focus groups. Question development was initiated. These will not be simple questions with short answers, but questions intended to initiate group discussion. An information-rich participant pool was initiated – farmers/consultants that are likely to enter in discussion.

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
Progress. 27 soybean fields in 6 states were sampled following a common protocol to (1) estimate the extent and spatial distribution of soybean defoliation, (2) compare those estimates to measurements taken with a smartphone app, and (3) collect images of canopy defoliation with known levels of defoliation. We are still seeking a graduate student to coordinate data analysis and publication of these results; however, the project remains on schedule. Insect defoliation throughout most of the sampled region was relatively low in 2019 (far less than established economic thresholds in every field we sampled). Defoliators collected through sweep net sampling included bean leaf beetles, Japanese beetles, green cloverworm, thistle caterpillars, and flea beetles. Data for 2019 are currently being compiled. Defoliation estimates will be conducted again in 2020, with the sampling procedure modified based on our 2019 experience. Additional efforts will focus on verifying that typical levels of defoliation are not reducing yields.

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
Progress. Arthropod collection from pitfall traps and injury estimates on soybean were completed at all sites. Identification of arthropods is currently in progress or completed. Soybean harvest is in progress. So far there is no indication of significant of arthropod injury to soybean with cover crop treatment. Beneficial insect activity was reported at a number of sites. Cereal rye cover crop have already been planted in a few states in late September, however, some sites are experiencing delays due to wet weather.

2.3 Pollinators to improve soybean yield
Participants: Reed Johnson*, Chia Lin, and Kelley Tilmon (Ohio State University) *Project leader
Progress. We placed honey bee colonies in three large soybean fields during soybean bloom, and are currently hand-harvesting plants at three distances in relation to the hive location, as three “pollination treatments” in each field:(1) Pollination by honey bees (near bee hives, far from field edges); (2) Pollination by local bees (near field edge, where wild bees have easy access to field); (3) Minimal pollination (mid-point between bee hive and field edges, which is the farthest point to either pollinator groups. The number of pods and seeds per plant will be counted in October and November to evaluate any treatment effect on soybean yield. A second experiment where pollinator-exclusion cages were placed in a field where three soybean varieties (AG34X6, AG39X7, and 38A98X) were planted side-by-side and 10 honey bee colonies were placed to boost pollination. The three varieties differ in sugar concentrations in nectar (16 - 30%) and show different attractiveness to honey bees according to the grower’s previous observation. The plants have been harvested and the effects of pollinator boosting vs. exclusion on seed production in these varieties will be evaluated. We measured nectar during peak bloom in approximately 160 soybean varieties planted by Laura Lindsey’s team. Preliminary results indicate significant variation in nectar quantity and sugar concentration among varieties. Up to 0.5 microliter of nectar produced by single flowers and sugar concentration 39% have been observed, while many varieties produced very little or no nectar. We will analyze the data to evaluate correlations with pollinator visitation and seed quality parameters when the data become available after harvest.

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
Progress. Clonal lines of soybean aphid are being established for on-plant assessment of resistance to thiamethoxam. To assess the magnitude and scale of pyrethroid resistance in soybean aphid, the standardized protocol for coupled field efficacy trials and glass-vial bioassays was implemented in Minnesota, South Dakota and Iowa, at 3, 1 and 1 sites, respectively. Aphid populations in other cooperating states (and at the South Dakota site) were extremely low. In preparation for the efforts to assess potential fitness costs of pyrethroid resistance in soybean aphid, several insecticide-resistant populations were identified and laboratory colonies were established for upcoming research. These were detected in a broader effort that assessed at least 23 aphid populations (approximately 18 in MN, 2 in IA, 1 in ND and 1 in SD). This work has been the source of four new extension publications.

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
Progress. For the project on field testing aphid resistant soybean varieties for commercialization: we obtained and executed legal agreements with Corteva Agriscience, and planted full experimental design in 6 locations (5 states). We collected aphid population data at least 2 times per month throughout the growing season. We provided aphids for insect resistance management study (sub-objective 3.1.2), and provided field efficacy data and aphids for insecticide resistance study (Objective 2.4). For the project on insect resistance management for aphid-resistant soybeans: aphids collected from sub-objective 3.1.1 fields are undergoing screening/phenotyping for virulence; individual clonal lineages have been established. The legal agreement for IRM modeling is still in the works.

3.2 Soybean breeding for aphid resistance
Participants: Brian Diers* (University of Illinois), Glen Hartman* and Doris Lago-Kutz (USDA-ARS) *Project leaders
Progress. In the soybean aphid resistance breeding objective we completed the development of the isolines with all five resistance genes and we will have seed available of them soon. The University of Illinois completed the development of isogenic lines that have all 32 combinations of Rag1, Rag2, Rag3, Rag4, and Rag6 in the backgrounds of a MG I and a MG II cultivar. A few pounds of seed will be harvested this fall from each line, which includes lines that have all five resistance genes. Seed of these lines will be made available to the research community. We have continued to develop cultivars with Rag1 and Rag2 and the stack of the two genes. Several experimental lines with the Rag1 and Rag2 stack are being increased this year by seed companies. Assuming the lines continue to perform well, the companies plan to commercialize them. The phenotyping test of five lines with Rag genes 1 and 2 (Rag1/2): LD14-4098a, LD16-4429a, LD16-4471a, LD15-5170a and LD16-5724a, and three checks: LD14-8033 (R,S,S), LD14-8034 (S,S,S) and LD14-8037 (S,R,S) is in progress. The phenotype information is being generated to compare to with the marker-assisted selection.

Program IV. Insect Monitoring
4.1 Biological control of soybean aphid
Participants: George Heimpel*, with contributions from other project team members *Project leader
Progress. Aphelinus parasitoid numbers were low this year (as were soybean aphid numbers), with most states reporting no mummies found. In August Aphelinus were at moderate densities of 0.5 to 1.5 per plant in Minnesota, Wisconsin, and Illinois, and lower numbers were detected in North Dakota, Iowa, and Michigan. Despite low aphid numbers, we found a surprisingly high number of tan braconid mummies, which are Lysiphlebus testaceipes. In late June an aphid-infested plant on the Saint Paul, Minnesota, campus produced more than 40 tan mummies. In early July, Michigan sent 118 tan mummies. Iowa sent 141 tan mummies in late August, Wisconsin sent 5, and Indiana sent 24. Hyperparasitism was undetected in most sites. From Indiana we received black mummies from which emerged 3 Syrphophagus aphidivorus. Within Minnesota we sampled more extensively and found dozens of Alloxysta as well as 2 or 3 Asaphes sp. and S. aphidivorus. No hyperparasitoids were observed emerging from L. testaceipes mummies.

4.2 Monitoring soybean aphids and other soybean insect pests in suction traps
Participants: Glen Hartmant* and Doris Lagos-Kutz (USDA-ARS/ University of Illinois) and Nick Seiter (University of Illinois), with contributions from other project team members *Project leader
Progress. Our collaborators (33 located in 10 states with one new location in Nebraska, UNL Haskell Ag Lab led by Thomas Hunt) have been sending suction trap samples to the USDA Laboratory in Urbana weekly starting from May 17th, 2019. The samples have been processed (drain the antifreeze and water, and store the samples in ethanol at -20 C) up to September 20, 2019. The sampling will continue until October 18th. Data has been entered in excel files up to September 13 and shared with our collaborators and extension personnel. Also, the suction trap data have been shared through https://suctiontrapnetwork.org/data/.

1.1 Extension coordination and deliverables
During the reporting period we published an updated soybean aphid insecticide resistance factsheet including an updated distribution map of the problem and new insecticide products registered for soybean aphid. Partering with the Ohio Soybean Council, NCSRP results were used to publish a Pollinators of Soybean fact-card for specimens found in Ohio. Copies from the new print run of Stink Bugs of the North Central Region were sent to 12 states for distribution to farmers at various extension programs.

1.2 Determining farmer needs and priorities
A professional facilitator, Dr. Mary Anne Casey, was contracted to advise on and conduct the farmer needs assessment focus groups. Question development was initiated. These will not be simple questions with short answers, but questions intended to initiate group discussion. An information-rich participant pool was initiated – farmers/consultants that are likely to enter in discussion.

2.1 Management guidelines for defoliating insects
27 soybean fields in 6 states were sampled following a common protocol to (1) estimate the extent and spatial distribution of soybean defoliation, (2) compare those estimates to measurements taken with a smartphone app, and (3) collect images of canopy defoliation with known levels of defoliation. We are still seeking a graduate student to coordinate data analysis and publication of these results; however, the project remains on schedule. Insect defoliation throughout most of the sampled region was relatively low in 2019 (far less than established economic thresholds in every field we sampled). Defoliators collected through sweep net sampling included bean leaf beetles, Japanese beetles, green cloverworm, thistle caterpillars, and flea beetles. Data for 2019 are currently being compiled. Defoliation estimates will be conducted again in 2020, with the sampling procedure modified based on our 2019 experience. Additional efforts will focus on verifying that typical levels of defoliation are not reducing yields.

2.2 Cover crops: pest and beneficial insects in cereal rye to soybean transition systems
Arthropod collection from pitfall traps and injury estimates on soybean were completed at all sites. Identification of arthropods is currently in progress or completed. Soybean harvest is in progress. So far there is no indication of significant of arthropod injury to soybean with cover crop treatment. Beneficial insect activity was reported at a number of sites. Cereal rye cover crop have already been planted in a few states in late September, however, some sites are experiencing delays due to wet weather.

2.3 Pollinators to improve soybean yield
We placed honey bee colonies in three large soybean fields during soybean bloom, and are currently hand-harvesting plants at three distances in relation to the hive location, as three “pollination treatments” in each field:(1) Pollination by honey bees (near bee hives, far from field edges); (2) Pollination by local bees (near field edge, where wild bees have easy access to field); (3) Minimal pollination (mid-point between bee hive and field edges, which is the farthest point to either pollinator groups. The number of pods and seeds per plant will be counted in October and November to evaluate any treatment effect on soybean yield. A second experiment where pollinator-exclusion cages were placed in a field where three soybean varieties (AG34X6, AG39X7, and 38A98X) were planted side-by-side and 10 honey bee colonies were placed to boost pollination. The three varieties differ in sugar concentrations in nectar (16 - 30%) and show different attractiveness to honey bees according to the grower’s previous observation. The plants have been harvested and the effects of pollinator boosting vs. exclusion on seed production in these varieties will be evaluated. We measured nectar during peak bloom in approximately 160 soybean varieties planted by Laura Lindsey’s team. Preliminary results indicate significant variation in nectar quantity and sugar concentration among varieties. Up to 0.5 microliter of nectar produced by single flowers and sugar concentration 39% have been observed, while many varieties produced very little or no nectar. We will analyze the data to evaluate correlations with pollinator visitation and seed quality parameters when the data become available after harvest.

2.4 Insecticide-resistant soybean aphids
Clonal lines of soybean aphid are being established for on-plant assessment of resistance to thiamethoxam. To assess the magnitude and scale of pyrethroid resistance in soybean aphid, the standardized protocol for coupled field efficacy trials and glass-vial bioassays was implemented in Minnesota, South Dakota and Iowa, at 3, 1 and 1 sites, respectively. Aphid populations in other cooperating states (and at the South Dakota site) were extremely low. In preparation for the efforts to assess potential fitness costs of pyrethroid resistance in soybean aphid, several insecticide-resistant populations were identified and laboratory colonies were established for upcoming research. These were detected in a broader effort that assessed at least 23 aphid populations (approximately 18 in MN, 2 in IA, 1 in ND and 1 in SD). This work has been the source of four new extension publications.

3.1 Advancing aphid resistant soybeans through a public-private partnership
For the project on field testing aphid resistant soybean varieties for commercialization: we obtained and executed legal agreements with Corteva Agriscience, and planted full experimental design in 6 locations (5 states). We collected aphid population data at least 2 times per month throughout the growing season. We provided aphids for insect resistance management study (sub-objective 3.1.2), and provided field efficacy data and aphids for insecticide resistance study (Objective 2.4). For the project on insect resistance management for aphid-resistant soybeans: aphids collected from sub-objective 3.1.1 fields are undergoing screening/phenotyping for virulence; individual clonal lineages have been established. The legal agreement for IRM modeling is still in the works.

3.2 Soybean breeding for aphid resistance
In the soybean aphid resistance breeding objective we completed the development of the isolines with all five resistance genes and we will have seed available of them soon. The University of Illinois completed the development of isogenic lines that have all 32 combinations of Rag1, Rag2, Rag3, Rag4, and Rag6 in the backgrounds of a MG I and a MG II cultivar. A few pounds of seed will be harvested this fall from each line, which includes lines that have all five resistance genes. Seed of these lines will be made available to the research community. We have continued to develop cultivars with Rag1 and Rag2 and the stack of the two genes. Several experimental lines with the Rag1 and Rag2 stack are being increased this year by seed companies. Assuming the lines continue to perform well, the companies plan to commercialize them. The phenotyping test of five lines with Rag genes 1 and 2 (Rag1/2): LD14-4098a, LD16-4429a, LD16-4471a, LD15-5170a and LD16-5724a, and three checks: LD14-8033 (R,S,S), LD14-8034 (S,S,S) and LD14-8037 (S,R,S) is in progress. The phenotype information is being generated to compare to with the marker-assisted selection.

4.1 Biological control of soybean aphid
Aphelinus parasitoid numbers were low this year (as were soybean aphid numbers), with most states reporting no mummies found. In August Aphelinus were at moderate densities of 0.5 to 1.5 per plant in Minnesota, Wisconsin, and Illinois, and lower numbers were detected in North Dakota, Iowa, and Michigan. Despite low aphid numbers, we found a surprisingly high number of tan braconid mummies, which are Lysiphlebus testaceipes. In late June an aphid-infested plant on the Saint Paul, Minnesota, campus produced more than 40 tan mummies. In early July, Michigan sent 118 tan mummies. Iowa sent 141 tan mummies in late August, Wisconsin sent 5, and Indiana sent 24. Hyperparasitism was undetected in most sites. From Indiana we received black mummies from which emerged 3 Syrphophagus aphidivorus. Within Minnesota we sampled more extensively and found dozens of Alloxysta as well as 2 or 3 Asaphes sp. and S. aphidivorus. No hyperparasitoids were observed emerging from L. testaceipes mummies.

4.2 Monitoring soybean aphids and other soybean insect pests in suction traps
Our collaborators (33 located in 10 states with one new location in Nebraska, UNL Haskell Ag Lab led by Thomas Hunt) have been sending suction trap samples to the USDA Laboratory in Urbana weekly starting from May 17th, 2019. The samples have been processed (drain the antifreeze and water, and store the samples in ethanol at -20 C) up to September 20, 2019. The sampling will continue until October 18th. Data has been entered in excel files up to September 13 and shared with our collaborators and extension personnel. Also, the suction trap data have been shared through https://suctiontrapnetwork.org/data/.

Benefit to Soybean Farmers

Performance Metrics

Project Years