EVALUATION OF THE UNITED-STATES-NATIONAL-GERMPLASM-SYSTEM POPCORN COLLECTION FOR RESISTANCE TO CORN-EARWORM (LEPIDOPTERA, NOCTUIDAE) AND EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE)

The U.S. National Germplasm System's active collection of popcorn, Zea mays L., is maintained at the North Central Regional Plant Introducti on Station at Ames, IA. From 1983 to 1989 and from 1982 to 1990, 299 a ccessions of this collection were evaluated for sources of resistance to com earworm, Helicoverpa zea (Boddie), and European com borer, Ostr inia nubilalis (Hubner), respectively. During 1990, 32 accessions prev iously rated as resistant to com earworm, and in 1991, 39 accessions p reviously rated as resistant to leaf feeding by first-generation Europ ean com borer were retested for resistance. Coin earworm larval weight s, when grown on silks from 21 of the 32 accessions retested for resis tance, were not significantly different from the weights of larvae gro wn on the resistant control but were significantly smaller than larvae grown on the susceptible control. Fourteen of the 39 accessions retes ted for first-generation feeding resistance to European corn borer ret ained their resistance. Genetic studies will be necessary to determine if these new sources of resistance are governed by genes different fr om those in previously identified sources.