Parasitism Rates in European Corn Borer (Lepidoptera: Crambidae) Larvae Collected from Six Maize Hybrids

The parasitoid complex and level of parasitism of European corn borer, Ostrinia nubilalis (Hübner), larvae in six maize, Zea mays L., hybrids was determined in Nebraska during 1995 and 1996. Three parasitoids, Eriborus terebrans (Gravenhorst), Macrocentrus grandii Goidanich, and Lixophaga sp., were reared from field-collected European corn borer larvae. Larvae collected from Hoegemeyer 2626 exhibited the highest percentage parasitism for the 1995 first generation in Lancaster (37.2%) and Dixon (28.6%) counties. No significant differences were identified for the 1995 second generation at both sites because of reduced sample size and high larval mortality caused by naturally-occurring entomopathogens. During 1996, there were several significant differences in percentage parasitism of larvae collected from the hybrids. Larvae collected from Northrup King N7070 exhibited the highest first-generation parasitism (23.8%), while larvae collected from Hoegemeyer 1125W exhibited the highest second-generation parasitism (46.0%) in Dixon Co. In Lancaster Co., parasitism of first-generation larvae collected from Hoegemeyer 1125W (10.3%) was only significantly greater than parasitism of larvae collected from Hoegemeyer 2626 (1.1%). Results indicate that European corn borer larval parasitism is significantly affected by the maize hybrid planted in the field; however, differences may vary among years and generations as environmental factors affect the maize phenology.