Ear Resistance of Sweet Corn Populations to Sesamia nonagrioides (Lepidoptera: Noctuidae) and Ostrinia nubilalis (Lepidoptera: Pyralidae)

Abstract

Corn borers are the main pests of maize, Zea mays L., in temperate areas. In Spain and other Mediterranean countries, the principal corn borer is Sesamia nonagrioides Lefebvre, although the European corn borer, Ostrinia nubilalis (Hubner), is also an important pest in sweet corn. The objectives of this work were to study resistance to attack of both species in sweet corn populations and to compare the mechanisms of resistance. Twenty sweet corn populations and 1 field corn population were evaluated for ear resistance under artificial infestation, with eggs of S. nonagrioides and O. nubilalis, under natural conditions, and protected with an insecticide, in 1996 and 1997. There were significant differences between years and the interactions genotype × year and treatment × year were significant for most traits. In 1996, damage produced by S. nonagrioides was greater than damage produced by O. nubilalis. In 1997, attack of O. nubilalis was most important. The insecticide did not protect the crop in 1996, and protection was low in 1997. The field corn synthetic cultivar ‘BSCB1(R)C11’, and the sweet corn synthetic cultivars ‘NE-HY-13A(S)C1’, ‘NE-HY-13B(S)C1’, and ‘AS11’ were resistant to attack by both species in both years. Stowell’s ‘W. Evergreen’ and ‘EPS11’ were resistant to O. nubilalis and showed some resistance to S. nonagrioides. All resistant populations have field corn in their pedigree. Field corn seemed to be more resistant than sweet corn, and mechanisms of resistance to both pests were not entirely independent.