Media type: E-Article Title: Cross‐resistance and redundant killing of Vip3Aa resistant populations of Helicoverpa zea on purified Bt proteins and pyramided Bt crops Contributor: Kennedy, Haley; Kerns, David L; Head, Graham P; Yang, Fei imprint: Wiley, 2023 Published in: Pest Management Science Language: English DOI: 10.1002/ps.7720 ISSN: 1526-498X; 1526-4998 Keywords: Insect Science ; Agronomy and Crop Science ; General Medicine Origination: Footnote: Description: <jats:title>Abstract</jats:title><jats:sec><jats:title>BACKGROUND</jats:title><jats:p>Pyramiding Bt proteins is a key strategy to delay insect resistance development. However, the durability of pyramided Bt crops for controlling insect pests is threatened by cross‐resistance among Bt proteins, which can ultimately contribute to resistance development. The corn earworm, <jats:italic>Helicoverpa zea</jats:italic>, is a major agricultural pest of pyramided Bt crops. Previous studies have examined cross‐resistance and redundant killing of Cry resistance in <jats:italic>H. zea</jats:italic>, but such information is lacking for Vip3Aa resistance in this pest. Here, we evaluated cross‐resistance and redundant killing of Vip3Aa‐resistant <jats:italic>H. zea</jats:italic> to purified Bt proteins, as well as Bt corn and Bt cotton.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>Diet bioassays demonstrated high susceptibility of Vip3Aa‐resistant <jats:italic>H. zea</jats:italic> to Cry1Ac, Cry1A.105, and Cry2Ab2 purified proteins. No Vip3Aa‐susceptible, ‐heterozygous, or ‐resistant <jats:italic>H. zea</jats:italic> could survive on pyramided Bt corn containing Cry1 and/or Cry2 proteins. Complete redundant killing was observed in pyramided Bt corn containing Cry1 and/or Cry2 proteins against Vip3Aa resistance in <jats:italic>H. zea</jats:italic>. Vip3Aa‐susceptible, ‐heterozygous, and ‐resistant <jats:italic>H. zea</jats:italic> exhibited survival rates ranging from 0.0% to 22.5% on pyramided Bt cotton with Cry1 and/or Cry2 proteins. Incomplete to complete redundant killing was observed for Vip3Aa‐resistant <jats:italic>H. zea</jats:italic> on pyramided Bt cotton containing Cry1 and/or Cry2 proteins.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSION</jats:title><jats:p>Our findings indicate that Vip3Aa‐resistant <jats:italic>H. zea</jats:italic> does not exhibit positive cross‐resistance to Cry1 or Cry2 proteins. In addition, most pyramided Bt crops showed complete or nearly complete redundant killing of Vip3Aa‐resistant <jats:italic>H. zea</jats:italic>. These results indicate that a pyramiding strategy would often be effective for managing Vip3Aa resistance in regions of the United States where <jats:italic>H. zea</jats:italic> has not evolved resistance to Cry1 and Cry2 toxins. © 2023 Society of Chemical Industry.</jats:p></jats:sec>