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 OPM) 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.

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 days.
A new NDSU Extension publication will be developed on IPM of soybean gall midge including its distribution in ND.

Update:

View uploaded report

Update:

View uploaded report

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. Soybean aphids are very mobile and pyrethroid resistant soybean aphids could migrate from other resistant areas, such as south-central Minnesota where the resistance first occurred in 2015. Since populations of soybean aphid can vary by year and locations, screening for pyrethroid resistant soybean aphids is key to determine their presence or absence, and their resistance status in North Dakota. In 2020, soybean aphid populations were low and present at non-economic levels, so no insecticide testing of new different modes of action could be tested against these pyrethroid resistant soybean aphids. This research is important for soybean growers, so they can wisely select which insecticide and mode of action to use against pyrethroid resistant soybean aphids. Insecticide resistant soybean aphids will continue to complicate pest management of soybean aphids for growers.

Our last 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 2020. Since it’s populations and severity are increasing in our neighboring states of Minnesota and South Dakota, growers need to know if soybean gall midge is present in North Dakota. A total of 605 soybean fields were inspected for soybean gall midge in 47 counties of the 53 counties in North Dakota (89% of the counties). Result of our 2020 soybean gall midge survey were negative for all soybean fields surveyed in North Dakota. This is good news for North Dakota soybean growers. Future survey work for soybean gall midge will be crucial for soybean production in North Dakota.

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%.
For the second 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.
Overall, 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 and sustainability of the environment.