Evaluation of Peruvian Maize for Resistance to European Corn Borer (Lepidoptera: Pyralidae) Leaf Feeding and Ovipositional Preference

Abstract

Partial control of the European corn borer, Ostrinia nubilalis (Hubner), in maize, Zea mays L., has been achieved through germplasm resistant to leaf feeding that was incorporated into breeding populations. Leaf-feeding resistance to European corn borer in maize had generally been attributed to presence of the chemical 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). New sources of resistance, other than that mediated by DIMBOA, are desirable for developing new resistant cultivars. From 1990 to 1992, 1,601 accessions of Peruvian maize maintained in the U.S. National Plant Germplasm System were evaluated for leaf-feeding resistance to European corn borer. Eleven resistant accessions were identified, all of which originated from Peru's north coast. The 11 resistant accessions were then analyzed for 6-methoxybenzoxazolinone (MBOA), the degradation product of DIMBOA and an indicator of DIMBOA levels present in the plant. All 11 resistant accessions contained low MBOA concentrations, equivalent to that found in the susceptible inbred WF9, indicating that DIMBOA is not the basis of this resistance. The factor(s) underlying this source of host plant resistance remains to be determined. Six morphologically diverse Peruvian maize races were evaluated in the greenhouse for ovipositional nonpreference by the European corn borer. Some differences were noted, but morphological factors could not be confirmed as causing the differences.