TRANSGENIC CORN EVALUATED FOR RESISTANCE TO FALL ARMYWORM AND SOUTHWESTERN CORN-BORER

Fall armyworm, Spodoptera frugiperda (J.E. Smith), and southwestern co rn borer, Diatraea grandiosella Dyar, are important pests of corn, Zea mays L., in the southern USA. Germplasm lines with moderate levels of resistance to leaf feeding by these pests have been developed and rel eased. Techniques for transforming corn have expanded opportunities fo r developing corn with higher levels of resistance and additional mech anisms of resistance to various insect pests. In this investigation, t ransgenic corn hybrids with insecticidal protein from Bacillus thuring iensis var. kurstaki were evaluated for resistance to fall armyworm an d southwestern corn borer in field tests and laboratory bioassays. The transgenic hybrids sustained significantly less leaf feeding damage t han 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 bor er of these transgenic corn hybrids provide the highest levels of resi stance documented for fall armyworm and southwestern corn borer.