Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/1996
Publication Date: N/A
Interpretive Summary: Fall armyworm and southwestern corn borer are major pests of corn in the southern United States. Feeding by the larvae on corn can substantially reduce yields. Techniques for moving genes into crop plants from other organisms have been developed, and these techniques have been used to move genes from the bacterium, Bacillus thuringiensis, into corn. Proteins produced by these genes have effectively controlled insect pests of some crops. This research was undertaken to determine whether the addition of genes from Bacillus thuringiensis into corn would be effective in controlling southwestern corn borer and fall armyworm. We found that southwestern corn borer larvae did not survive when placed on the Bt corn plants and, therefore, caused no damage. Survival and growth of fall armyworm larvae ws reduced in comparison to that on standard commercial hybrids. Plant damage was also significantly reduced. The Bt corn plants also sustained significantly less damage than resistant hybrids developed by conventional plant breeding methods. Growing Bt corn should be an effective way of reducing losses to southwestern corn borer and fall armyworm.
Technical Abstract: Fall armyworm, Spodoptera frugiperda (J.E. Smith), and southwestern corn borer, Diatraea grandiosella Dyar, are important pests of corn, Zea mays L., in the southern United States. Germplasm lines with moderate levels of resistance to leaf feeding by these pests have been developed and released. Techniques for transforming corn have expanded opportunities for developing corn with higher levels of resistance and additional mechanisms of resistance to various insect pests. In this investigation, transgenic corn hybrids with insecticidal protein from Bacillus thuringiensis var. kurstaki were evaluated for resistance to fall armyworm and southwestern corn borer in field tests and laboratory bioassays. The transgenic hybrids sustained significantly less leaf-feeding damage than the resistant check hybrids. Both survival and larval growth were reduced. Growth was also reduced when larvae were fed laboratory diets comprised primarily of lyophilized leaf or husk tissue. Southwestern corn borer larval survival on the transgenic corn hybrids was very low in both the field tests and laboratory bioassays. The high levels of resistance to fall armyworm and near immunity to southwestern corn borer of these transgenic corn hybrids provide the highest levels of resistance documented for fall armyworm and southwestern corn borer.