Pyrethroid resistant soybean aphids were detected and confirmed in eastern North Dakota in 2017, and this issue continues to threaten effective pest management of soybean aphids. The first goal of this research is to provide soybean growers with the facts needed to successfully manage pyrethroid resistant soybean aphids in their fields, and to mitigate the development of resistance to other insecticides. By understanding which insecticide tools will manage pyrethroid resistant soybean aphids, soybean yields can be maximized. We will evaluate a broad range of registered insecticides with different modes of action to determine which are best for management of pyrethroid resistant soybean aphids. The second goal of this research is to survey for the invasive soybean gall midge, a new economic insect pest of soybeans. Soybean gall midge was recently discovered in neighboring states. In summary, this research will identify the best management practices for pyrethroid resistant soybean aphids and determine the pest status of soybean gall midge in ND. By understanding the producer's increasing risk of insecticide resistant soybean aphids, management of soybean aphids can be optimized through Integrated Pest Management (IPM) and maximize soybean profits. Survey work for the invasive and destructive soybean gall midge is crucial so that soybean producers are aware of its current distribution and pest density in ND and effective pest management strategies can be developed.

1) To determine which insecticides and mode of actions are the best tools for management of pyrethroid resistant soybean aphids.
2) To conduct survey work for the detection of the invasive soybean gall midge.
3) To develop extension outreach material on soybean insect pests for NSDC and growers.

• Results will be published in NDSC reports and trade magazines, NDSC podcasts and NDSU Extension's Crop & Pest Report.
• Results also will be posted on the NDSU Extension Entomology and IPM websites.
• Results will be presented at soybean extension and commodity meetings / field.
• New soybean insect outreach materials will be provided to NDSC for soybean growers. Benefit to ND Soybean Farmers: We propose to be proactive in detecting developing insecticide resistance in populations of soybean aphids in eastern North Dakota. Insecticide resistance in populations of soybean aphids will complicate control decisions for producers, and potentially increase costs and decrease net returns. Producers need to know which insecticide products will control pyrethroid resistant soybean aphids, since economic aphid populations are known to cause significant yield losses of over 50% if not managed.
For the 2nd objective, a survey will be conducted in eastern ND to determine if the soybean gall midge is present and at what level of infestation in ND. Currently, no pest management recommendation are available for control of this yield robbing gall midge in soybeans.
The 3rd objective will provide a 'new' soybean insect pest publication and banner for use by the NDSC, soybean growers and NDSU Extension.

Updated November 14, 2021:
Please see attached file.

View uploaded report

Updated July 18, 2022:

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View uploaded report 2

North Dakota Soybean Council
Executive Summary – June 30, 2022

Pyrethroid Resistant Soybean Aphids and Soybean Gall Midge Survey

Investigators:
Dr. Janet J. Knodel, Professor and Extension Entomologist
Dr. Veronica Calles-Torrez, Post-doctoral Scientist
Patrick Beauzay, State IPM Coordinator and Research Specialist

Cooperators:
Brian Otteson, Director, NDSU Agronomy Seed Farm, Casselton, ND
Grower cooperators – Jared Hagert, Dale Flesberg

Soybean aphid is a major insect pest of soybeans in North Dakota. The goal of this research was to develop the best pest management (BPM) practices for insecticide resistant soybean aphids. Grower complaints of pyrethroid insecticides not controlling soybean aphids were common and widespread in eastern North Dakota during 2017. Laboratory bioassays confirmed that about 70% of the soybean aphid populations tested were resistance to pyrethroid insecticides. In 2021, soybean aphid populations were low and present at non-economic levels, so no insecticide testing of new different modes of action could be done. Since soybean aphid were not present at economic population levels in 2021, we used our soybean insecticide plots to conduct a grasshopper insecticide efficacy study, and evaluated some newer products like Vantacor. Recently, grasshopper populations have been economic throughout the state due to the drought increasing population levels. This research is important for soybean growers, so they can wisely select which insecticide and mode of action to use against existing insect pests like grasshoppers and pyrethroid resistant soybean aphids.

Our second objective was to survey for the invasive soybean gall midge, a new insect pest of soybeans. Soybean gall midge is now established in five states (Iowa, Minnesota, Missouri, Nebraska and South Dakota) and has increased its distribution from a total of 67 counties in 2018 to 114 counties in 2021. As soybean gall midge continues to expand its distribution, it is important for North Dakota soybeans growers to know if soybean gall midge is present in North Dakota. A total of 588 soybean fields were inspected for soybean gall midge in 48 of the 53 counties in North Dakota (90% of the counties). Results of our 2021 soybean gall midge survey were negative for all soybean fields surveyed in North Dakota. Future survey work for detection of soybean gall midge will be crucial for soybean production in North Dakota.

Our last objective was to produce extension outreach materials including a large banner and a Soybean Insect Diagnostic Series (to be completed winter 2022-23) on economic insect pests of soybean.

An Integrated Pest Management (IPM) approach will benefit the ND soybean industry by minimizing pesticide costs, soybean pest damage, and risks of pests developing pesticide resistance, thereby increasing soybean productivity.