Abstract
BACKGROUND: Using natural populations of Helicoverpa zea from Arizona, we tested the hypotheses that gene flow between Bacillus thuringiensis (Bt) plants 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 to 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. © 2020 Society of Chemical Industry.
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Claims 10
Claim · model-written summary
Gene flow was extensive in seed mixtures but undetected in separate blocks.
- Taxon
- corn
Zea mays subsp. mayse0 - Outcome
- Gene flowe0
- Setting
- seed mixturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Gene flow was not detected in blocks of non-Bt or Bt corn but was extensive in seed mixtures.”
Claim · model-written summary
Gene flow showed no consistent effect on corn earworm development rate or survival.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- gene flowe0
- Interactor
- corn earworm
.jpg?width=60)
Helicoverpa zeat1pest - Outcome
- development rate and survivale0
- Qualifier
- over a period of 3 to 4 weekse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Analyses of larval weight and abundance over a period of 3 to 4 weeks did not indicate consistent effects of gene flow on development rate and survival.”
t0“Cry1A.105 + Cry2Ab corn”
t1“corn earworm”
Claim · model-written summary
Non-Bt corn had significantly less ear area damaged in mixtures than blocks.
- Taxon
- cornZea mays subsp. mayst0
- Material
- non-Bt plantse0
- Interactor
- corn earwormHelicoverpa zeat1pest
- Outcome
- ear area damagede0
- Direction
- lowere0
- Comparator
- blockse0
- Setting
- seed mixturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks.”
t0“Cry1A.105 + Cry2Ab corn”
t1“corn earworm”
Claim · model-written summary
Non-Bt corn had a significantly lower percentage of ears with exit holes in mixtures than blocks.
- Taxon
- cornZea mays subsp. mayst0
- Material
- non-Bt plantse0
- Interactor
- corn earwormHelicoverpa zeat0pest
- Outcome
- percentage of ears with exit holese0
- Direction
- lowere0
- Comparator
- blockse0
- Setting
- seed mixturese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“for non-Bt plants, the ear area damaged and percentage of ears with exit holes were significantly lower in the seed mixtures than blocks.”
t0“corn earworm”
Claim · model-written summary
For Bt corn, ear exit holes and damage did not differ significantly between mixtures and blocks.
- Taxon
- cornZea mays subsp. mayst0
- Material
- Bt plantse0
- Interactor
- corn earwormHelicoverpa zeat0pest
- Outcome
- percentage of ears with exit holes and ear damagee0
- Comparator
- blockse0
- Setting
- seed mixturese0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the percentage of ears with exit holes and ear damage did not differ significantly between the seed mixtures and blocks for Bt plants.”
t0“corn earworm”
Claim · model-written summary
Nearly all corn ears were damaged, with substantial damaged area.
- Taxon
- cornZea mays subsp. mayst0
- Interactor
- corn earwormHelicoverpa zeat0pest
- Outcome
- ears were damagede0
- Value
- Nearly 100%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nearly 100% of the ears were damaged and the damaged area was substantial”
t0“corn earworm”
Claim · model-written summary
Bt corn did not significantly reduce the percentage of damaged ears relative to non-Bt corn.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- pyramided Bt corne0
- Interactor
- corn earwormHelicoverpa zeat0pest
- Outcome
- percentage of damaged earse0
- Direction
- reducee0
- Comparator
- non-Bt corne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Relative to non-Bt corn, the pyramided Bt corn did not significantly reduce the percentage of damaged ears”
t0“corn earworm”
Claim · model-written summary
Bt corn reduced damaged ear area by 21 to 39% relative to non-Bt corn.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- pyramided Bt corne0
- Interactor
- corn earwormHelicoverpa zeat0pest
- Outcome
- ear area damagede0
- Direction
- reducede0
- Value
- 21 to 39%e0
- Comparator
- non-Bt corne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“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%”
t0“corn earworm”
Claim · model-written summary
Gene flow in mixtures reduced effective refuge size.
- Taxon
- cornZea mays subsp. mayst0
- Treatment
- gene flow between Bt and non-Bt plantse0
- Outcome
- effective refuge sizee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gene flow between Bt and non-Bt plants in seed mixtures reduced effective refuge size”
t0“Cry1A.105 + Cry2Ab corn”
Claim · model-written summary
Block refuges may be needed to manage corn earworm resistance evolution.
- Taxon
- cornZea mays subsp. mayse0
- Interactor
- H. zeaHelicoverpa zeae0pest
- Outcome
- block refugese0
- Setting
- Arizonae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“block refuges may be needed to manage the evolution of H. zea resistance to Bt corn in Arizona”
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See all 22 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.