Practical resistance to Cry toxins and efficacy of Vip3Aa in Bt cotton against Helicoverpa zea

Fei Yang, David L. Kerns, Nathan Little, Sebe A. Brown, Scott D. Stewart, Angus L. Catchot, Donald R. Cook, Jeffrey Gore, Whitney D. Crow, Gustav M. Lorenz, Tyler Towles, Bruce E. Tabashnik

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


BACKGROUND: Crops genetically engineered to make insect-killing proteins from Bacillus thuringiensis (Bt) have revolutionized management of some pests. However, the benefits of such transgenic crops are reduced when pests evolve resistance to Bt toxins. We evaluated resistance to Bt toxins and Bt cotton plants using laboratory bioassays and complementary field trials focusing on Helicoverpa zea, one of the most economically important pests of cotton and other crops in the United States. RESULTS: The data from 235 laboratory bioassays demonstrate resistance to Cry1Ac, Cry1Fa, and Cry2Ab occurred in most of the 95 strains of H. zea derived from Arkansas, Louisiana, Mississippi, Tennessee, and Texas during 2016 to 2021. Complementary field data show efficacy decreased for Bt cotton producing Cry1Ac + Cry1Fa or Cry1Ac + Cry2Ab, but not Cry1Ac + Cry1Fa + Vip3Aa. Moreover, analysis of data paired by field site and year shows higher survival in bioassays was generally associated with lower efficacy of Bt cotton. CONCLUSIONS: The results confirm and extend previous evidence showing widespread practical resistance of H. zea in the United States to the Cry toxins produced by Bt cotton and corn, but not to Vip3Aa. Despite deployment in combination with Cry toxins in Bt crops, Vip3Aa effectively acts as a single toxin against H. zea larvae that are highly resistant to Cry toxins. Furthermore, Vip3Aa adoption is increasing and previous work provided an early warning of field-evolved resistance. Thus, rigorous resistance management measures are needed to preserve the efficacy of Vip3Aa against this highly adaptable pest.

Original languageEnglish (US)
Pages (from-to)5234-5242
Number of pages9
JournalPest management science
Issue number12
StatePublished - Dec 2022
Externally publishedYes

Bibliographical note

Funding Information:
The authors are grateful to Kate Crumley, Danielle Sekula, Stephen Biles, John David Gonzales, Tyler Mays, Pat Porter, Suhas Vyavhare, and Danielle Sekula from Texas A&M AgriLife Extension Service for providing the authors with larvae they collected from the field. The authors thank G. V. P. Reddy for constructive comments on the manuscript. The authors thank Bayer Crop Science for providing Cry1Ac and Cry2Ab2 and Corteva Agriscience for providing Cry1Fa. This work was supported by the USDA National Institute of Food and Agriculture: Biotechnology Risk Assessment Research Grants Program 2017‐33522‐27090/project accession no. 1013740 and Agriculture and Food Research Initiative 2020‐67013‐31924; the Cotton Technical Subcommittee of the Agricultural Biotechnology Stewardship Technical Committee (ABSTC); and Cotton Incorporated. H. zea

Publisher Copyright:
© 2022 Society of Chemical Industry.


  • Bacillus thuringiensis
  • bollworm
  • corn earworm
  • genetically engineered crop
  • resistance management
  • sustainability

PubMed: MeSH publication types

  • Journal Article


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