BACKGROUND: Using natural populations of Helicoverpa zea from Arizona, we tested the hypotheses that gene flow between Bt and non-Bt plants in a seed mixture of 10% non-Bt corn and 90% Bt corn producing Cry1A.105 and Cry2Ab reduces larval performance on ears from non-Bt plants, or increases performance on ears from Bt plants. RESULTS: Gene flow was not detected in blocks of non-Bt or Bt corn but was extensive in seed mixtures. Analyses of larval weight and abundance over a period of 3-4 weeks did not indicate consistent effects of gene flow on development rate and survival. However for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks. By contrast, the percentage of ears with exit holes and ear damage did not differ significantly between the seed mixtures and blocks for Bt plants. Nearly 100% of the ears were damaged and the damaged area was substantial, showing that H. zea is a major ear-feeding pest in Arizona. Relative to non-Bt corn, the pyramided Bt corn did not significantly reduce the percentage of damaged ears and only reduced the ear area damaged by 21 to 39 %, indicating that H. zea may have evolved resistance to Cry1A.105, Cry2Ab, or both. CONCLUSIONS: Our results indicate that gene flow between Bt and non-Bt plants in seed mixtures reduced effective refuge size, and that block refuges may be needed to manage the evolution of H. zea resistance to Bt corn in Arizona. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
BACKGROUND: Using natural populations of Helicoverpa zea from Arizona, we tested the hypotheses that gene flow between Bt and non-Bt plants in a seed mixture of 10% non-Bt corn and 90% Bt corn producing Cry1A.105 and Cry2Ab reduces larval performance on ears from non-Bt plants, or increases performance on ears from Bt plants. RESULTS: Gene flow was not detected in blocks of non-Bt or Bt corn but was extensive in seed mixtures. Analyses of larval weight and abundance over a period of 3-4 weeks did not indicate consistent effects of gene flow on development rate and survival. However for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks. By contrast, the percentage of ears with exit holes and ear damage did not differ significantly between the seed mixtures and blocks for Bt plants. Nearly 100% of the ears were damaged and the damaged area was substantial, showing that H. zea is a major ear-feeding pest in Arizona. Relative to non-Bt corn, the pyramided Bt corn did not significantly reduce the percentage of damaged ears and only reduced the ear area damaged by 21 to 39 %, indicating that H. zea may have evolved resistance to Cry1A.105, Cry2Ab, or both. CONCLUSIONS: Our results indicate that gene flow between Bt and non-Bt plants in seed mixtures reduced effective refuge size, and that block refuges may be needed to manage the evolution of H. zea resistance to Bt corn in Arizona. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Entities:
Keywords:
Bt corn; Helicoverpa zea; cross‐pollination; refuge in a bag; refuge mandates; seed blend
Authors: Kyle M Benowitz; Carson W Allan; Benjamin A Degain; Xianchun Li; Jeffrey A Fabrick; Bruce E Tabashnik; Yves Carrière; Luciano M Matzkin Journal: Genetics Date: 2022-05-05 Impact factor: 4.402
Authors: Benjamin R Arends; Dominic D Reisig; Shawnee Gundry; Jeremy K Greene; George G Kennedy; Francis P F Reay-Jones; Anders S Huseth Journal: Pest Manag Sci Date: 2022-03-22 Impact factor: 4.462
Authors: Jeffrey A Fabrick; Chan C Heu; Dannialle M LeRoy; Ben A DeGain; Alex J Yelich; Gopalan C Unnithan; Yidong Wu; Xianchun Li; Yves Carrière; Bruce E Tabashnik Journal: Sci Rep Date: 2022-10-06 Impact factor: 4.996