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Managing Insecticide-Resistant Soybean Aphids: A New Multi-State Extension Publication

By Robert Koch (Assistant Professor & Extension Entomologist)

Insecticide-resistant soybean aphids have emerged as a new challenge to growers in Minnesota and neighboring states. In a new Extension publication, we suggest strategies for managing soybean aphids resistant to pyrethroid insecticides. A few key points for managing insecticide-resistant aphids are:
  1. Apply insecticides only when needed (i.e., scout soybean fields and use the economic threshold of 250 aphids/plant to determine when to apply insecticides), 
  2. Apply insecticides correctly (i.e., proper rates, good coverage, etc.) and check efficacy of insecticide 3-5 days after application, and 
  3. Alternate insecticide groups if fields need to be retreated. 

To assist with alternation (rotation) of insecticides, we summarize the different insecticides (and their corresponding insecticide groups) available for soybean aphid management. This new publication, entitled “Management of Insecticide-Resistant Soybean Aphids,” is available here:

Management of soybean aphid since 2000 has relied primarily on the use of foliar-applied insecticides.  In a recent scientific paper (, we documented the first occurrence of insecticide-resistant soybean aphids in North America.  This problem with pyrethroid-resistant soybean aphids has now been observed over three years and from much of Minnesota and parts of Iowa, South Dakota, North Dakota and Manitoba. Insecticide resistance in this highly mobile pest with a complicated life-cycle, will likely continue to pose a challenge to soybean production in coming years. Growers and agricultural professionals should carefully evaluate their soybean aphid management practices.
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