Abstract
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.
Repellent, antifeedant and insecticidal effects of neem oil on Microtheca punctigera
