Abstract
We examined 17 pairs of near-isogenic hybrids of Bacillus thuringiensis (Bt) (176, Mon810, and Bt11) and non-Bt corn, Zea mays L., to examine the effects of Bt on larval densities of Helicoverpa zea (Boddie) and Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) during 2 yr. During ear formation, instar densities of H. zea and S. frugiperda were recorded for each hybrid. We found that H. zea first, second, and fifth instar densities were each affected by Mon810 and Bt11 Bt corn but not by 176 corn. Surprisingly, first and second instars were found in higher numbers on ears of Mon810 and Bt11 corn than on non-Bt corn. Densities of third and fourth instars were equal on Bt and non-Bt hybrids, whereas densities of fifth instars were lower on Bt plants. S. frugiperda larval densities were only affected during 1 yr when second, and fourth to sixth instars were lower on ears of Mon810 and Bt11 hybrids compared with their non-Bt counterparts. Two likely explanations for early instar H. zea densities being higher on Bt corn than non-Bt corn are that (1) Bt toxins delay development, creating a greater abundance of early instars that eventually die, and (2) reduced survival of H. zea to later instars on Bt corn decreased the normal asymmetric cannibalism or H. zea-S. frugiperda intraguild predation of late instars on early instars. Either explanation could explain why differences between Bt and non-Bt plants were greater for H. zea than S. frugiperda, because H. zea is more strongly affected by Bt toxins and more cannibalistic.
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Claims 5
Claim · model-written summary
Mon810 and Bt11 affected first, second and fifth instar H. zea densities, whereas 176 did not.
- Treatment
- Mon810 and Bt11 Bt corne0
- Interactor
- H. zea
.jpg?width=60)
Helicoverpa zeae0pest - Outcome
- H. zea first, second, and fifth instar densitiese0
- Comparator
- 176 corne0
Zea maysNot reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“H. zea first, second, and fifth instar densities were each affected by Mon810 and Bt11 Bt corn but not by 176 corn”
e1“corn, Zea mays L.”
Claim · model-written summary
H. zea first and second instars were more numerous on Mon810 and Bt11 corn than non-Bt corn.
- Treatment
- Mon810 and Bt11 corne0
- Interactor
- H. zeaHelicoverpa zeae1pest
- Outcome
- first and second instarse0
- Direction
- highere0
- Comparator
- non-Bt corne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“first and second instars were found in higher numbers on ears of Mon810 and Bt11 corn than on non-Bt corn”
e1“H. zea first, second, and fifth instar densities”
e2“corn, Zea mays L.”
Claim · model-written summary
Third and fourth instar densities were equal on Bt and non-Bt hybrids.
- Treatment
- Bte0
- Interactor
- H. zeaHelicoverpa zeae1pest
- Outcome
- Densities of third and fourth instarse0
- Direction
- equale0
- Comparator
- non-Bt hybridse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Densities of third and fourth instars were equal on Bt and non-Bt hybrids”
e1“H. zea first, second, and fifth instar densities”
e2“corn, Zea mays L.”
Claim · model-written summary
Fifth instar H. zea density was lower on Bt plants.
- Treatment
- Bt plantse0
- Interactor
- H. zeaHelicoverpa zeae1pest
- Outcome
- densities of fifth instarse0
- Direction
- lowere0
- Comparator
- non-Bt hybridse3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“densities of fifth instars were lower on Bt plants”
e1“H. zea first, second, and fifth instar densities”
e2“corn, Zea mays L.”
e3“Bt and non-Bt hybrids”
Claim · model-written summary
Second and fourth to sixth instar S. frugiperda densities were lower on Mon810 and Bt11 ears during one year.
- Treatment
- Mon810 and Bt11 hybridse0
- Interactor
- S. frugiperda
.jpg?width=60)
Spodoptera frugiperdae0pest - Outcome
- S. frugiperda larval densitiese0
- Direction
- lowere0
- Qualifier
- during 1 yre0
- Comparator
- non-Bt counterpartse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“S. frugiperda larval densities were only affected during 1 yr when second, and fourth to sixth instars were lower on ears of Mon810 and Bt11 hybrids compared with their non-Bt counterparts”
e1“corn, Zea mays L.”
The same questions in other papers
Zea mays subsp. mays · Helicoverpa zea · Zea mays (maize)Positive and negative results
5 papers in the same direction as this paper · 11 in the opposite direction
- positive
- positive
- no effect
13 papers more in this group
See all 17 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.