Suitability and feeding preference of selected North American, European, and Asian elm (Ulmus spp.) biotypes to elm leaf beetle (Coleoptera: Chrysomelidae).
Recently introduced North American elm cultivars, simple and complex elm hybrids of European and Asian parentage, and simple Asian hybrids of U. pumila and U. japonica [Ulmus davidiana] parentage growing at The Morton Arboretum, Lisle, Illinois, USA, were evaluated in laboratory bioassays for ovipositional response, and feeding preference and suitability for larvae and adults of the elm leaf beetle, Xanthogaleruca luteola [Pyrrhalta luteola] (Müller). Larval and adult no-choice and adult multiple-choice feeding studies revealed that the North American cultivars of U. americana 'Jefferson' and U. americana 'Valley Forge', U. americana (diploid form), and U. americana were the least preferred for feeding and reproduction by the elm leaf beetle. Among simple and complex European hybrids, 'Homestead', 'Patriot', and 'Prospector' were least preferred and least suitable for larval development, feeding, and reproduction by adult elm leaf beetles. Hybrids of 'Frontier', 'Pioneer', and 'Regal'; the simple Asian hybrids of 'Cathedral' and 'New Horizon'; and U. pumila were more highly preferred for feeding and suitable for reproduction. The least preferred and least suitable North American biotypes of U. × americana 'Jefferson', U. americana 'Valley Forge', and U. americana (diploid form), simple and complex European hybrids of 'Homestead', 'Patriot', and 'Prospector', show promise for use in areas where the elm leaf beetle is persistent and for future elm breeding programmes.