This proposal is a request for a Year 2 renewal on the three-year project plan first submitted in May 2021. Funding on Year 1 began in October 2021, and we are currently starting the first field season of the Year 1 plan. This proposal has programs related to several insect pest problems of emerging importance in the North Central Region. In early 2021 we conducted a series professionally organized focus group sessions with farmers and crop consultants to assess farmer needs and priorities for pest management research and extension communication. Our objectives are based on the needs assessment report resulting from this effort [this report is being made available to all soybean checkoff groups]. Farmers identified several concerns. Among these were (1) the emerging threat of soybean gall midge, (2) lack of threshold use for several reasons, but in part because of the time and effort needed to scout, (3) soybean aphid insecticide resistance, (4) the need for pest monitoring and alerts, (5) and the importance of communicating unbiased, research-based pest management information to farmers and their consultants. Other concerns were identified as well, but these are the issues we focused on this this proposal.

Soybean gall midge is an emerging pest which can cause significant damage and which appears to be spreading further each year. When this pest became prominent a few short years ago nothing was known about its biology or management. With NCSRP and state checkoff support, entomologists on our team were able to rapidly respond to this new threat by learning its life cycle, some basic facts about its biology, and some preliminary information about possible routes of control. Much work remains. In this proposal we have objectives to run a gall midge emergence monitoring program with rapid real-time alerts, which will help farmers know when to scout and when to attempt management. There is an objective to screen landrace germplasm for midge resistance traits to help jump-start breeding efforts for midge-resistant varieties. We are examining both tillage and mowing as cultural controls for gall midge based on promising preliminary data that these approaches can reduce midge damage. Finally, we will perform survey work in new areas to determine the current extent of the gall midges’ range.

Regarding farmers’ concerns that scouting difficulty deters threshold use, we have an objective targeting one of the most difficult scouting problems of all – scouting for stink bugs in later-season soybeans. Stink bugs are a stealthy pest that can be managed with insecticide, but which usually go unnoticed because the damage (piercing into seeds with straw-like mouthparts) is hard to detect visually. Scouting involves sweeping dense vegetation throughout the field, which is both difficult and time consuming; few people do it. We will develop a method to monitor stink bugs from the field edge using sticky cards and pheromone lures. Preliminary data suggests this may be a good alternative to sweeping vegetation, and detection and thresholds based on this method will be easy to employ.

This proposal also contains objectives on aphid insecticide resistance, and aphid-resistant varieties. Insecticide resistance is an alarming problem which has been growing since its first detection in 2015. We will determine baseline susceptibility of soybean aphids to newer chemistries, which is the first step in resistance monitoring. We will also screen populations in several states for resistance. Aphid-resistant soybean varieties will become increasingly important as a tool to combat insecticide resistance. As a result of our team’s public-private partnership with Corteva, resistant varieties will soon be available from this major retailer. Our objectives are a new partnership with Corteva, to monitor resistance-breaking virulent aphid biotypes, model the increase of virulence, and to determine the consequences of growing resistant soybeans without supplemental insecticide. In addition, we will continue running regional aphid monitoring system. Finally, we have a dedicated objective to turn project results into extension deliverables to communicate state-of-the-art pest management advice to farmers. All of these objectives will contribute to best-practice pest management in soybean, and contribute positively to farmers’ bottom lines.

Program I. Soybean Gall Midge
1.1 Soybean Gall Midge Alert Network
1.2 Midge-Resistant Soybean Germplasm
1.3 Tillage and Mowing as Control Strategies for Soybean Gall Midge
1.4 New Detection/Injury Survey

Program II. Easier Scouting Methods
2.1 Pheromone-Baited Traps for Stink Bug Monitoring and Thresholds

Program III. Soybean Aphid
3.1 Insecticide Resistance
3.2 Aphid-Resistant Varieties
3.2.1 Impact of growing resistant varieties without insecticide
3.2.2 Frequency and modeling of virulent aphid biotypes
3.3 Suction Trap Network for Monitoring Aphids and Thrips

Program IV. Extension and Outreach
4.1 Extension Deliverables

• Soybean gall midge alert network
• Identify gall midge resistant germplasm
• Evaluate tillage and mowing as control strategies for gall midge
• Updated gall midge distribution information (including new locations)
• Bait+trap-based stink bug monitoring tool (2nd year of data)
• Assessment of new soybean aphid insecticide resistance (2nd year of data)
• Data for a summary on frequency of soybean aphid virulence in NC region
• Seasonal soybean aphid monitoring via suction trap network
• Extension products based on project results

Updated April 6, 2023:
Layman’s Summary

The Soybean Gall Midge Alert Network is an important tool to help farmers stay on top of gall midge levels in their area during the growing season. During this reporting period we identified sites for monitoring in each participating state – we expect to monitor 20 sites this season. We performed routine maintenance in preparation for the season such as emergence cage repair. We also presented emergence data from last season in several in-person extension events and in a soybean gall midge webinar. In the quest for midge-resistant soybean germplasm we analyzed evaluation data from 2022 and decided upon 110 accession lines for further testing in 2023. In the objective looking at how useful tillage and mowing might be for soybean gall midge management, we are planning the experiments for the 2023 growing season. Mowing studies are planned for MN and NE. In NE we will also have a hilling treatment (hilling soil at the base of the plant being an agronomically difficult, but potentially effective, control measure). Regarding tillage, populations of gall midge were low in 2022 and experiments on the value of tillage for management were inconclusive. In the objective to record new detections (range expansion) of gall midge, we have a likely new record from ND (new state) which was inconclusive because of poor sample quality. This will need to be validated in 2023. CropScape data from the 2022 season was available in February 2023 and is being collected to add to the plant injury survey. Monitoring sites are being selected throughout the region for 2023. In addition, we are planning an experts’ tour through KS and MO during the season to meet with farmers and provide additional insights into scouting and surveying in these states.

In the objective to adapt stink bug pheromone lures and sticky traps into an easier scouting method, during 2022 there were 12 states participating in the experiment. During the reporting period we analyzed data from 2022, made minor changes to our protocol, and began preparing for experiments in the 2023 field season.

Regarding the objective on soybean aphid resistance to insecticide, we finished developing the methods to perform bioassays with the insecticides Warrior, Transform, Sefina and Sivanto. We are planning to screen field-collected soybean aphid populations in the summer of 2023. Results to date will be presented at the upcoming Entomological Society of America North Central Branch meeting in Oklahoma City. In addition we have published an updated multistate factsheet on managing insecticide-resistant soybean aphids: https://www.ndsu.edu/agriculture/sites/default/files/2022-04/e1878.pdf (which has also been supplied to SRIN).

In the objective for aphid tolerant soybean varieties, during the reporting period we analyzed data from the 2022 field season [results still pending], consisting of aphids sampled in IA, SD, ND, and OH. Phenotyping indicated a low frequency of virulent aphids. Confirmation of virulence with a few aphid colonies is ongoing and preparations are underway for the 2023 season.

In the soybean pest suction trap monitoring network, suction trap data from the 2022 field season have been entered up to October 2022 to online database https://suctiontrapnetwork.org/data/ and are available to the public. Easter flower thrips, soybean thrips, hover flies and pirate minute bugs data will be analyzed to correlate prey and predator activity patterns. Coordination with collaborators/co-authors for the 2023 monitoring season is in progress.

Finally, in the Outreach objective, the new, second edition of Stink Bugs of the North Central Region has been distributed for winter extension events. We also developed a new exercise for helping farmers determine defoliation levels in soybean, utilizing 3D printed leaves. This skill is important for scouting/management of leaf-feeding insects. We beta-tested the exercise in Ohio this winter and found an average of 35% improvement in the accuracy of assessing defoliation using the leaf tool. SRIN has used our design program to print over 10,000 copies of the soybean defoliation leaf guide, showing the leveraging effect of this investment. The exercise will now be packaged for distribution to extension educators throughout the North Central Region.



Detailed Report

Program I. Soybean Gall Midge

1.1 Soybean Gall Midge Alert Network
Participants: Justin McMechan,* Thomas Hunt, Robert Wright (University of Nebraska); Erin Hodgson (Iowa State University); Bruce Potter, Bob Koch (University of Minnesota); Adam Varenhorst (South Dakota State University). *Project leader

• Adult emergence sites for 2023 are currently being identified in each state
• We anticipate approximately 20 sites for adult monitoring this coming season
• Emergence cages were repaired, and jars were cleaned for the 2023 season.
• Data on adult emergence was presented at local, regional, and national in-person and webinar-based events.
• 43 new subscribers since October 2022 were added to the Soybean Gall Midge Alert Network

1.2 Midge-Resistant Soybean Germplasm
Participants: George Graef,* Justin McMechan (University of Nebraska); Erin Hodgson (Iowa State University); Adam Varenhorst (South Dakota State University) *Project leader

• Data from the 2022 season was reviewed to determine the number of entries and type of experiments for the 2023 season.
• Three germplasm field experiments will be conducted during 2023 with two of the experiments occurring in NE, IA, and SD.
• A validation experiment will test 110 accession lines for larval presence and plant injury at two locations in NE and one location in Iowa and South Dakota, with three replications per location. The selection of accession lines for the validation experiment will be based on information collected from previous years. Detailed data collection on a small number of entries (10-15 accession lines) will occur at the same locations as the validation experiment, where a total larval count will be collected on a subsample of plants from each plot. Approximately 50 elite germplasm lines will be tested in Nebraska for larval presence and plant injury.
• Plant injury data will be collected on all experiments at 10-14 internals to calculate an area under the severity progress curve.


1.3 Tillage and Mowing as Control Strategies for Soybean Gall Midge
Participants: Justin McMechan,* Tom Hunt (University of Nebraska); Erin Hodgson (Iowa State University); Bruce Potter, Bob Koch (University of Minnesota); Adam Varenhorst (South Dakota State University) *Project leader

• Mowing studies are planned for MN and NE.
• The mowing study in Nebraska will have hilling treatment added to a portion of the assessment area after the overwintering population emergence to isolate the impact of mowing for that generation.
• Due to the low and sporadic adult emergence, data has been inconclusive on tillage as a viable suppression tactic for overwintering populations.
• This year, an infested stem burial study will be conducted to see if cocoons and adult emergence can be increased. If successful, tillage studies will be implemented in the fall to evaluate this effect.
• The benefits of the stem burial study extend beyond just tillage and allow for a better understanding of other management studies that focus on the soil-dwelling stages of soybean gall midge


1.4 New Detection/Injury Survey
Participants: Justin McMechan* (University of Nebraska); Janet Knodel (North Dakota State University); Brian McCornack (Kansas State University); Kevin Rice (University of Missouri), Bryan Jensen (University of Wisconsin); Nicholas Seiter (University of Illinois) *Project leader

• Continue to validate the potential new state detection of orange larvae from ND
• Genetics from samples collected across NE and an adjustment of primer concentrations submitted with sequences indicate a strong likelihood that the samples from ND are soybean gall midge.
• GPS points are being generated for KS, MO, IL, WI, and ND for fields at high risk for the presence of SGM for the 2023 season
• Drs. Hodgson and McMechan are planning to tour through KS and MO during the season to provide additional insights into scouting and surveying some fields in these states using their experience from surveys in their respective states.
• CropScape data from the 2022 season was available in February 2023 and is being collected to add to the plant injury survey

Program II. Easier Scouting Methods

2.1 Pheromone-Baited Traps for Stink Bug Monitoring and Thresholds
Participants: Kevin Rice* (University of Missouri); Kelley Tilmon (Ohio State University); Robert Wright (University of Nebraska); Janet Knodel, Deirdre Prischmann-Voldseth (North Dakota State University); Matt O’Neal (Iowa State University); Robert Koch (University of Minnesota); Brian McCornack (Kansas State University); Nicholas Seiter (University of Illinois); Shawn Conley (University of Wisconsin); Raul Villanueva (University of Kentucky); Christina DiFonzo (Michigan State University); John Tooker (Penn State University) *Project leader

• During 2022, 12 states participated in this objective totaling 184 weekly comparisons between stink bugs captured on clear sticky traps and in field sweep net samples.
• Total trap captures were not significantly correlated with total field sweep net samples.
• We are currently analyzing the dataset to determine if distance from trap relates to stronger correlations for sweep net captures.
• We are also currently comparing stink bug species that are captured on clear stinky traps among 11 states.
• We will have additional the statistical analysis completed by May.


Program III. Soybean Aphid

3.1 Insecticide Resistance
Participants: Robert Koch* (University), with contributions from all team members *Project leader

• Methods for dose-response bioassays were developed and implemented with the insecticides Warrior, Transform, Sefina and Sivanto for an laboratory population of soybean aphid.
• In summer of 2023, several field-collected populations of soybean aphid will be screened against the three new insecticides using this methodology.
• Results from this NCSRP-funded work focused on insecticide resistance in soybean aphid will be presented at the upcoming meeting of the North Central Branch of the Entomological Society of America in Oklahoma City. In addition, the multistate factsheet on managing insecticide resistant soybean aphid was updated ( https://www.ndsu.edu/agriculture/sites/default/files/2022-04/e1878.pdf ).


3.2 Aphid-Resistant Varieties
Participants: Andy Michel* (Ohio State University); Matt O’Neal* (Iowa State university); Louis Hesler (USDA-ARS South Dakota); Deirdre Prischmann-Voldseth (North Dakota State University) *Project leaders

• Data was collected for defoliation, aphid infestations and sweep nets samples and pod feeding. Sweep net sample identification is ongoing
• Yield was collected at all locations and is currently being analyzed
• Preparation for year 2 is underway
• Aphid samples were collected from IA, SD, ND, and OH. Phenotyping indicated a low frequency of virulent aphids. Confirmation of virulence with a few aphid colonies is ongoing.

3.3 Suction Trap Network for Monitoring Aphids and Thrips
Participants: Nick Seiter* and Doris Lagos-Kutz (University of Illinois); Glen Hartman (USDA-ARS Illinois); with cooperation from other team members *Project leader

• The suction trap season for 2023 will start on 12 May and end on 20 October. This represents 23 weeks of suction trap sampling from each of 32 locations. Most of the suction trap supplies have been ordered and currently preparing for packaging and shipping in April. Two undergrad students from University of Illinois have been hired to help with this process, Wesley Hall and Nethra Yuvaraj with majors in Natural Resources and Environmental Sciences, and Biology respectively.
• Aphids suction trap data have been entered up to October 2022 to online database https://suctiontrapnetwork.org/data/ and available to the public.
• Eastern flower thrips, soybean thrips, hover flies and pirate minute bugs data will be analyzed to correlate prey and predator activity patterns. Coordination with collaborators/co-authors is in progress.
• A draft of manuscript about monitoring potato leafhopper is in progress.


Program IV. Extension and Outreach

5.1 Extension Deliverables
Participants: Kelley Tilmon* (Ohio State University), with contributions from all team members *Project leader

• The new, second edition of Stink Bugs of the North Central Region has been distributed for winter extension events.
• We developed a new exercise for helping farmers determine defoliation levels in soybean, utilizing 3D printed leaves. This skill is important for scouting/management of leaf-feeding insects. We beta-tested the exercise in Ohio this winter and found an average of 35% improvement in the accuracy of assessing defoliation using the leaf tool. SRIN has used our design program to print over 10,000 copies of the soybean defoliation leaf guide, showing the leveraging effect of this investment.

The objectives in this proposal are designed around a formal needs assessment conducted prior to the project, where we worked with farmers to identify top priorities for pest management. Farmers identified several concerns. Among these were (1) the emerging threat of soybean gall midge, (2) lack of threshold use for several reasons, but in part because of the time and effort needed to scout, (3) soybean aphid insecticide resistance, (4) the need for pest monitoring and alerts, (5) and the importance of communicating unbiased, research-based pest management information to farmers and their consultants. Addressing these objectives will help farmers to be better informed about the pest problems in their fields and the best way to monitor and manage them most profitably.

Each project objective has a well-defined set of metrics and milestones that included research, surveys, data collection and analysis, and the communication of results and information, especially targeted at increasing knowledge sets and providing soybean farmers with useful insights for short- and long-term insect pest management.