1. Department of Plant Biology (E.H.D., P.D.N.) and Department of Entomology (M.R.B.), University of Illinois, Urbana, Illinois 61801; and Catedra de Bioquimica/Instituto de Investigacion en Biociencias Agricolas y Ambientales, Facultad de Agronomia, University of Buenos Aires, Buenos Aires C1417DSE, Argentina (J.A.Z.)