Selected elms Ulmus spp. and their hybrids growing at the Morton Arboretum, Lisle, IL were evaluated in the laboratory for feeding preference by the elm leaf beetle, Pyrrhalta luteola (Muller). Results from the single-choice and multiple-choice feeding studies showed that U. szechuanica was the least suitable for feeding and reproduction by the adult elm leaf beetle. The hybrids U. pumila x U. parvifolia and U. pumila x U. americana, and U. pumila (control) appeared to be highly suitable for feeding and reproduction by the adult elm leaf beetle. Adult longevity and the pre-ovipositional period appeared to be a function of suitability as adults feeding on U. szechuanica had the shortest longevity and the longest pre-ovipositional period. The converse was also true. Results from multiple-choice studies were consistent with the single-choice studies. The intermediately suitable species/hybrids of U. japonicawilsoniana x U. pumila, U. Japonica, U. macrocarpa, and U. wilsoniana show promise for further elm breeding programs. Further studies are needed to evaluate hybrid crosses of the intermediately and least preferred elms as potential sources of shade trees resistant to Dutch elm disease and not preferred by the elm leaf beetle.
Special appreciation is extended to M. Raupp, C. Sadoff, R. Hall, and F. Swink for their helpful review of an earlier draft of the manuscript. The authors wish to express their thanks and appreciation to M. Spravka, D. Kuzwara, and other members of the arboretum research staff for their invaluable assistance in field location of the candidate elmslhybrids, collection of foliage specimens, and maintenance of leaf beetle colonies. A special thanks to K. von der Heide-Spravka, M. Miller, and J. Hammershaimb for their assistance in day-to-day evaluation of bioassay studies, data entry, and statistical analysis.
3Research Fellow, The Morton Arboretum 60532.