Reduced toxin binding associated with resistance to Vip3Aa in the corn earworm (Helicoverpa zea)

Dawson D. Kerns, Fei Yang, David L. Kerns, Scott D. Stewart, Juan Luis Jurat-Fuentes

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Transgenic corn and cotton that express Cry and Vip insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt), have been valuable tools for the management of lepidopteran pests. In 2019, a Vip3Aa-resistant strain of Helicoverpa zea (CEW-Vip-RR) was isolated from F2 screens of field populations in Texas. Characterizing the resistance mechanism in this strain is important for predicting the sustained efficacy of current commercial Bt traits and guiding the development of future transgenic traits. Resistance to insecticidal proteins in Bt traits is commonly associated with reduced toxin binding, with the exception of Vip3Aa resistance being associated to altered proteolytic processing in the insect host gut. Therefore, Vip3Aa protoxin processing was tested by incubation with midgut fluids from CEW-Vip-RR relative to a susceptible strain (CEW-SS). Finding no significant processing differences, alterations in Vip3Aa binding were tested by comparing binding of radiolabeled and biotinylated Vip3Aa toxin to midgut brush border membrane vesicles (BBMV) from CEW-Vip-RR and CEW-SS larvae. Specific Vip3Aa binding to CEW-Vip-RR BBMV in these experiments was consistently reduced when compared with CEW-SS BBMV. These results support that an altered Vip3Aa-receptor is associated with resistance in CEW-Vip-RR. Understanding this resistance mechanism could have important implications for resistance management decisions, considering widespread Cry1 and Cry2 resistance in H. zea populations.

Original languageEnglish (US)
Article numbere01644-23
JournalApplied and environmental microbiology
Volume89
Issue number12
DOIs
StatePublished - Dec 2023

Bibliographical note

Publisher Copyright:
© 2023 American Society for Microbiology. All rights reserved.

Keywords

  • altered binding
  • Bacillus thuringiensis
  • Helicoverpa zea
  • proteolytic processing
  • resistance
  • Vip3Aa

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.

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