Tuesday, 16 November 2004 - 8:48 AM

Impact of variable nitrogen fertilization of transgenic maize on corn earworm, fall armyworm, and southwestern corn borer development

Craig A. Abel, cabel@ars.usda.gov, USDA-ARS, Southern Insect Management Research Unit, P. O. Box 346, Stoneville, MS

Nitrogen fertilization of field maize is important for achieving high grain yield. Nitrogen deficiencies can occur in the plant during the growing season for multiple reasons. How these deficiencies impact concentrations of Cry1Ab and Cry1Ac in transgenic maize and how changes in the concentration of Cry1Ab or Cry1Ac affect insect control were studied in this paper. Three transgenic maize hybrids and their near-isolines were grown at Stoneville, MS, USA in 2002 and 2003 with nitrogen fertility rates of 0, 112, 224, and 336 kg /ha. Tissue samples of developing leaf blades on young maize plants and leaf sheaths, outer ear husks and silks on mature plants were harvested, analyzed for Cry1A concentration and fed to neonatal corn earworm, fall armyworm, and southwestern corn borer. Correlations between nitrogen fertilization and Cry1A concentrations in maize tissue will be presented. Correlations between variable Cry1A concentration of maize tissue and larval development will also be presented. The impact of growing transgenic maize in nitrogen deficient soils and how this may affect insect control will be discussed.

Species 1: Lepidoptera Noctuidae Spodoptera frugiperda (fall armyworm)
Species 2: Lepidoptera Crambidae Diatraea grandiosella (southwestern corn borer)
Species 3: Lepidoptera Noctuidae Helicoverpa zea (corn earworm)
Keywords: Bacillus thuringiensis, corn

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