Entomologia Experimentalis et Applicata (2005) 115, 341-350

Fajun Chen, Gang Wu, Feng Ge, Megha N. Parajulee and Ram B. Shrestha (2005)
Effects of elevated CO₂ and transgenic Bt cotton on plant chemistry, performance, and feeding of an insect herbivore, the cotton bollworm
Entomologia Experimentalis et Applicata 115 (2), 341-350
Abstract: Effects of elevated atmospheric CO₂ (double-ambient CO₂) on the growth and metabolism of cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), fed on transgenic Bacillus thuringiensis (Berliner) (Bt) cotton [Cry1A(c)], grown in open-top chambers, were studied. Two levels of CO₂ (ambient and double-ambient) and two cotton cultivars (non-transgenic Simian-3 and transgenic GK-12) were deployed in a completely randomized design with four treatment combinations, and the cotton bollworm was reared on each treatment simultaneously. Plants of both cotton cultivars had lower nitrogen and higher total non-structural carbohydrates (TNC), TNC:Nitrogen ratio, condensed tannin, and gossypol under elevated CO₂. Elevated CO₂ further resulted in a significant decrease in Bt toxin level in GK-12. The changes in chemical components in the host plants due to increased CO₂ significantly affected the growth parameters of H. armigera. Both transgenic Bt cotton and elevated CO₂ resulted in a reduced body mass, lower fecundity, decreased relative growth rate (RGR), and decreased mean relative growth rate in the bollworms. Larval life-span was significantly longer for H. armigera fed transgenic Bt cotton. Significantly reduced larval, pupal, and adult moth weights were observed in the bollworms fed elevated CO₂-grown transgenic Bt cotton compared with those of bollworms reared on non-transgenic cotton, regardless of the CO₂ level. The efficiency of conversion of ingested food and of digested food of the bollworm were significantly reduced when fed transgenic Bt cotton, but there was no significant CO₂ or CO₂ x cotton cultivar interaction. Approximate digestibility of larvae reared on transgenic cotton grown in elevated CO₂ was higher compared to that of larvae fed non-transgenic cotton grown at ambient CO₂. The damage inflicted by cotton bollworm on cotton, regardless of the presence or absence of insecticidal genes, is predicted to be more serious under elevated CO₂ conditions because of individual compensatory feeding on host plants caused by nitrogen deficiency.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Feng Ge, Megha N. Parajulee

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa armigera	Cotton (Gossypium)
Bacillus thuringiensis genes in crops (entomopathogen)	Helicoverpa armigera	Cotton (Gossypium)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Helicoverpa armigera	Cotton (Gossypium)