Abstract
Bt crops are able to produce Cry proteins, which were originally present in Bacillus thuringiensis bacteria. Although Bt maize is very efficient against corn borers, Spanish crops are also attacked by the earworm H. armigera, which is less susceptible to Bt maize. Many mechanisms could be involved in this low susceptibility to the toxin, including the insect's metabolic resistance to toxins due to cytochrome P450 monooxygenases. This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves in larval development and in the gene expression of three P450 cytochromes: CYP6AE14, CYP6B2 and CYP9A12. Larvae fed on sublethal amounts of the Bt toxin showed reduced food ingestion and reduced growth and weight, preventing most of them from achieving the critical weight and pupating; additionally, after feeding for one day on the Bt diet the larvae showed a slight increase in juvenile hormone II in the hemolymp. Larvae fed on the non-Bt diet showed the highest CYP6AE14, CYP6B2 and CYP9A12 expression one day after feeding on the non-Bt diet, and just two days later the expression decreased abruptly, a finding probably related to the developmental programme of the last instar. Moreover, although the response of P450 genes to plant allelochemicals and xenobiotics has been related in general to overexpression in the resistant insect, or induction of the genes when feeding takes place, the expression of the three genes studied was suppressed in the larvae feeding on the Bt toxin. The unexpected inhibitory effect of the Cry1Ab toxin in the P450 genes of H. armigera larvae should be thoroughly studied to determine whether this response is somehow related to the low susceptibility of the species to the Bt toxin.
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Claims 7
Claim · model-written summary
Larvae fed sublethal Bt toxin showed reduced food ingestion relative to non-Bt maize leaves.
- Treatment
- sublethal amounts of the Bt toxine2
- Interactor
- H. armigera
_gusano_cogollero.png?width=60)
Helicoverpa armigerae1pest - Outcome
- food ingestione2
- Direction
- reducede2
- Comparator
- non-Bt maize leavese1
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
_gusano_cogollero.png?width=500)
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e2“Larvae fed on sublethal amounts of the Bt toxin showed reduced food ingestion and reduced growth and weight, preventing most of them from achieving the critical weight and pupating”
Claim · model-written summary
Larvae fed sublethal Bt toxin showed reduced growth and weight relative to non-Bt maize leaves.
- Treatment
- sublethal amounts of the Bt toxine2
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Outcome
- growth and weighte2
- Direction
- reducede2
- Comparator
- non-Bt maize leavese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e2“Larvae fed on sublethal amounts of the Bt toxin showed reduced food ingestion and reduced growth and weight, preventing most of them from achieving the critical weight and pupating”
Claim · model-written summary
Bt toxin prevented most larvae from achieving the critical weight and pupating.
- Treatment
- sublethal amounts of the Bt toxine2
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Outcome
- achieving the critical weight and pupatinge2
- Direction
- preventinge2
- Comparator
- non-Bt maize leavese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e2“Larvae fed on sublethal amounts of the Bt toxin showed reduced food ingestion and reduced growth and weight, preventing most of them from achieving the critical weight and pupating”
Claim · model-written summary
After one day on the Bt diet, larvae showed a slight increase in juvenile hormone II in the hemolymph.
- Treatment
- Bt diete3
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Outcome
- juvenile hormone II in the hemolympe3
- Direction
- increasee3
- Qualifier
- slighte3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e3“after feeding for one day on the Bt diet the larvae showed a slight increase in juvenile hormone II in the hemolymp”
Claim · model-written summary
Larvae fed the non-Bt diet showed the highest CYP6AE14, CYP6B2 and CYP9A12 expression one day after feeding.
- Treatment
- non-Bt diete4
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Gene
- CYP6AE14, CYP6B2 and CYP9A12e4
- Outcome
- expressione4
- Direction
- higheste4
- Qualifier
- one day after feeding on the non-Bt diete4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e4“Larvae fed on the non-Bt diet showed the highest CYP6AE14, CYP6B2 and CYP9A12 expression one day after feeding on the non-Bt diet”
Claim · model-written summary
Gene expression of CYP6AE14, CYP6B2 and CYP9A12 decreased abruptly two days after feeding on the non-Bt diet.
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Gene
- CYP6AE14, CYP6B2 and CYP9A12e4
- Outcome
- expressione5
- Direction
- decreased abruptlye5
- Qualifier
- just two days latere5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e4“Larvae fed on the non-Bt diet showed the highest CYP6AE14, CYP6B2 and CYP9A12 expression one day after feeding on the non-Bt diet”
e5“just two days later the expression decreased abruptly”
Claim · model-written summary
Bt toxin suppressed the expression of CYP6AE14, CYP6B2 and CYP9A12 in larvae relative to non-Bt maize leaves.
- Treatment
- Bt toxine6
- Interactor
- H. armigeraHelicoverpa armigerae1pest
- Gene
- CYP6AE14, CYP6B2 and CYP9A12e4
- Outcome
- expression of the three genes studiede6
- Direction
- suppressede6
- Comparator
- non-Bt maize leavese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“This paper examines the response of last instar H. armigera larvae to feeding on a diet with Bt and non-Bt maize leaves”
e4“Larvae fed on the non-Bt diet showed the highest CYP6AE14, CYP6B2 and CYP9A12 expression one day after feeding on the non-Bt diet”
e6“the expression of the three genes studied was suppressed in the larvae feeding on the Bt toxin”
The same questions in other papers
transgenic · Helicoverpa armigera · Zea mays (maize)Results agree
3 papers in the same direction as this paper
- positive
- positive
- positive
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.