Host Suitability of Asiatic Elm Species and Hybrids for Larvae and Adults of the Elm Leaf Beetle (Coleoptera: Chrysomelidae)

Abstract

Selected elms (Ulmus spp.) and their hybrids growing at The Morton Arboretum in Lisle, Illinois, U.S., were evaluated in no-choice larval and adult suitability laboratory bioassays for the elm leaf beetle, Pyrrhalta luteola Miiller. No-choice larval suitability studies revealed that the elm biotypes of U. davidiana X U.japonica, U. elongata, U. parvifolia, U. szechuanica, and U. 'Morton'-Accolade™ were the least suitable for larval development and pupation. Ulmus davidiana X U. japonica-wilsoniana-pumila, U. pumila (reference), U. lamellosa, U. macrocarpa, U. szechuanica X U. japonica, U. 'Morton Plainsman'-Vanguard™, and U. 'Morton Red Tip'-Danada Charm™ were more suitable for larval development and pupation. Similar low and high suitability rankings were also observed for adult beetles in no-choice studies reared from the larval suitability study. Larval development time and proportion of larvae reaching pupation appear to be good predictors of adult emergence. Larvae feeding on less suitable biotypes took longer to develop with a lesser proportion of adults emerging. The reverse is also true. Preovipositional period was found, in part, to be a function of suitability. Female longevity reflected suitability for the elms tested in this study. Ulmus pumila appears to be a major influence on both larval and adult host suitability. The least suitable elm biotypes, listed above, show promise for future elm breeding programs and for use in localities with acute and chronic elm leaf beetle populations.