Management of Pyrethroid-resistant Red Sunflower Seed Weevils

Written collaboratively by Adam Varenhorst, Patrick Wagner, Bradley McManus, Philip Rozeboom, Patrick Beauzay, and Janet Knodel.

Recent research from SDSU determined that the South Dakota red sunflower seed weevil populations are resistant to lambda-cyhalothrin, esfenvalerate, cypermethrin, deltamethrin, and beta-cyfluthrin. In 2025, entomologists at NDSU found evidence suggesting reduced susceptibility at one location in North Dakota. Due to the high level of resistance to pyrethroid insecticides, they are not recommended for red sunflower seed weevil management in South Dakota, and their use in North Dakota should be closely evaluated to gauge effectiveness and delay the development of pyrethroid resistance. This fact sheet covers different management strategies recommended for Pyrethroid-resistant Red Sunflower Seed Weevils. 

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