1. Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108
2. Corn Insects and Crop Genetics Research Unit, United States Department of Agriculture-Agricultural Research Service, Ames, Iowa 50011
3. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108
4. Plant Science Research Unit, United States Department of Agriculture-Agricultural Research Service, St. Paul, Minnesota 55108