New Records of Elm Leaf Beetle, Xanthogaleruca luteola, Parasitoids in Colorado, with Notes on Predators

Abstract

Elm leaf beetle, Xanthogaleruca luteola Müller (Coleoptera: Chrysomelidae), is an invasive pest of elm trees, Ulmus spp. L. Natural enemies are thought to be important in controlling elm leaf beetles, but their natural enemy community is poorly described in many areas of the invaded range. The aim of this research was to identify parasitoids and predators of elm leaf beetle in Colorado, an area with frequent pest outbreaks and where few natural enemies have been described. We present new state records of the egg parasitoid Oomyzus gallerucae Fonscolombe (Hymenoptera: Eulophidae) and the larval-adult parasitoid Erynniopsis antennata Rondani (Diptera: Tachinidae) in Colorado. Parasitism of elm leaf beetle eggs and larvae was <3% during the 2021 sampling season. Both parasitoid species were nearly absent early in the season, and parasitism peaked in late summer. We also identified six species of elm leaf beetle predators, several of which are newly documented to consume elm leaf beetle. Considering the low levels of parasitism and few predators observed in our study, it seems unlikely that natural enemies effectively control elm leaf beetles in Colorado. Additional research is needed to develop effective methods to control this invasive insect pest.