Mechanisms of Resistance in Corn to Leaf Feeding by Southwestern Corn Borer and European Corn Borer (Lepidoptera: Pyralidae)

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Abstract
No-choice and choice laboratory feeding experiments with excised corn (Zeamays L.) leaf tissue were conducted during two summers to determine the resistance mechanisms operating against southwestern corn borer, Diatraea grandiosella Dyar, and European corn borer, Ostrinia nubilalis (Hübner), larvae in selected hybrids. Two corn hybrids with leaf feeding resistance to the southwestern corn borer and two susceptible corn hybrids were used in the studies. Under no-choice conditions, southwestern corn borer larvae fed for 10 d on leaf tissue from the resistant hybrids weighed significantly less than larvae fed on tissue from one of the susceptible hybrids. In a similar test, European corn borer larvae fed on tissue of the same hybrids for the same time period weighed significantly less on the resistant hybrids than those fed on the susceptible hybrids. Significantly fewer European corn borer larvae survived on tissue from the resistant genotypes. When given a choice, significantly more larvae of both species were observed feeding on tissue from one of the susceptible hybrids than on the other hybrids. We conclude that antibiosis and nonpreference types of resistance mechanisms occur in these hybrids.