Journal of Economic Entomology (2001) 94, 197-203

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Eric C. Burkness, W.D. Hutchison, Patricia C. Bolin, David W. Bartels, D.F. Warnock and D.W. Davis (2001)
Field efficacy of sweet corn hybrids expressing a Bacillus thuringiensis toxin for management of Ostrinia nubilalis (Lepidoptera: Crambidae) and Helicoverpa zea (Lepidoptera: Noctuidae)
Journal of Economic Entomology 94 (1), 197-203
Abstract: Field studies were done in 1995–1996 to assess the efficacy of three sweet corn hybrids that express the Bacillus thuringiensis (Bt) toxin, Cry1Ab, against two lepidopteran pests, Ostrinia nubilalis (Hübner) and Helicoverpa zea (Boddie). The Bt hybrids tested were developed by Novartis Seeds, using the event BT-11, which expresses Bt toxin in green tissue as well as reproductive tissues including the tassel, silk, and kernel. Bt hybrids were compared with a standard non-Bt control or the non-Bt isoline for each hybrid; none of the hybrids were treated with insecticides during the study. Hybrid efficacy was based on larval control of each pest, as well as plant or ear damage associated with each pest. In both years, control of O. nubilalis larvae in primary ears of all Bt hybrids was 99–100% compared with the appropriate non-Bt check. Plant damage was also significantly reduced in all Bt hybrids. In 1996, control of H. zea in Bt hybrids ranged from 85 to 88% when compared with the appropriate non-Bt control. In 1996, a University of Minnesota experimental non-Bt hybrid (MN2 x MN3) performed as well as the Bt hybrids for control of O. nubilalis. Also, in 1996, two additional University of Minnesota experimental non-Bt hybrids (A684su X MN94 and MN2 x MN3) performed as well as Bt hybrids for percent marketable ears (ears with no damage or larvae). In addition, compared with the non-Bt hybrids, percent marketable ears were significantly higher for all Bt hybrids and in most cases ranged from 98 to 100%. By comparison, percent marketable ears for the non-Bt hybrids averaged 45.5 and 37.4% in 1995 and 1996, respectively. Results from the 2-yr study strongly suggest that Bt sweet corn hybrids will provide high levels of larval control for growers in both fresh and processing markets. Specifically, Bt sweet corn hybrids, in the absence of conventional insecticide use, provided excellent control of O. nubilalis, and very good control of H. zea. However, depending on location of specific production regions, and the associated insect pests of sweet corn in each area, some insecticide applications may still be necessary.
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Database assignments for author(s): Eric C. Burkness, William (Bill) D. Hutchison

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
genetical engin./transgenic plants
evaluation - screening - selection


Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.


Ostrinia nubilalis Maize/corn (Zea mays) U.S.A. (mid N)
Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis genes in crops (entomopathogen) Ostrinia nubilalis Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis genes in crops (entomopathogen) Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Ostrinia nubilalis Maize/corn (Zea mays) U.S.A. (mid N)
Bacillus thuringiensis Cry1A-toxin (entomopathogen) Helicoverpa zea Maize/corn (Zea mays) U.S.A. (mid N)