1. Department of Entomology, University of Minnesota, 1980 Folwell Ave., St. Paul, MN 55108.
2. These authors contributed equally to this publication
3. Department of Entomology, University of Nebraska, NEREC, Haskell Agriculture Laboratory, Concord, NE 68728.
4. Department of Entomology, University of Nebraska, Lincoln, NE 68583.
5. Dow AgroSciences, Indianapolis, IN 46268.
6. Pioneer Hi-Bred International, Johnston, IA 50131.