European Corn Borer (Lepidoptera: Pyralidae) Leaf-feeding Resistance and DIMBOA Content in Inbred Lines of Dent Maize Grown Under Field Versus Greenhouse Conditions

Leaf-feeding ratings (infestations with ca. 450 European corn borers [ECB], Ostrinia nubilalis</it> (Hübner), eggs per plant) were made during midwhorl stage of plant development, and DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) contents of midwhorl leaf tissue were determined for four inbred lines of dent maize, Zea mays</it> L., grown under field and greenhouse conditions. CI31A, B75, and B85 (grown in the field) were almost immune to leaf feeding by first-generation ECB larvae, but were susceptible when grown in a greenhouse. WF9 was susceptible under both field and greenhouse conditions, but the leaf-feeding damage was more intense in the greenhouse. In general, DIM BOA concentrations in leaf tissue were the same or were higher for the four inbred lines grown under greenhouse conditions compared with the lines grown under field conditions. Thus, high DIMBOA content in resistant inbred lines grown in a greenhouse did not prevent severe leaf-feeding damage by ECB larvae.