Influence of Elm Foliar Chemistry for the Host Suitability of the Japanese Beetle, Popillia japonica, and the Gypsy Moth, Lymantria dispar
The Asian elm trees that are closely associated with the David complex, Ulmus davidana (Planch), U. propinqua (Koidz), U. japonica (Rehd.), and U. wilsoniana (Schneid), show substantial levels of disease resistance and tolerance. Studies have shown that these species suffer moderate levels of injury from the adult Japanese beetle, Popillia japonica (Newman) (Coleoptera: Scarabaeidae). The research presented here reports the influence of elm leaf chemistry on the feeding activity of two generalist herbivores, the Japanese beetle and gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae). Elm leaf chemistry was surveyed for 19 species, 5 cultivars, and 2 varieties that are known to vary in susceptibility to Japanese beetle feeding damage. Extracts were analyzed for significant differences in lipid, phenolic, terpene, and alkaloid diversity; those data were then compared with previous findings in Japanese beetle laboratory and field studies, and a gypsy moth no-choice developmental study. Elms that belong to the U. davidiana complex were more suitable for gypsy moth development compared with other elms tested. These elms typically had greater levels of lipid and overall blend complexity in the leaf chemical extracts. Elm leaf lipid extractions were evaluated for deterrent effects on Japanese beetle feeding activity in a greenhouse study and only three (U. propinqua var suberosa, ‘Commendation’ and U. wilsoniana) deterred Japanese beetle feeding. Elm tree susceptibility to gypsy moth and Japanese beetle injury was correlated with the leaf chemistry surveyed in this study; more specifically elm leaf lipids influenced Japanese beetle and gypsy moth preference for the Asian elms tested.
This article is from Journal of the Agricultural and Urban Entomology, Oct 2006, 23(4); 209-223. Posted with permission.