Impacts of the brown spruce longhorn beetle, Tetropium fuscum (Fabricius) (Coleoptera: Cerambycidae), on insect community structure in its invaded habitat of Nova Scotia, Canada

Abstract

Tetropium fuscum (Coleoptera: Cerambycidae), a wood boring beetle native to Europe, was accidentally introduced to Halifax, Nova Scotia, likely in wood packaging in shipping containers. Non-indigenous species can change insect community diversity, or displace native species. I tested whether the invasive Tetropium fuscum or Tetropium cinnamopterum a native congener, had a significant impact on insect community structure (Simpson’s Diversity, richness, and evenness) in spruce logs, and if impact was greater on closely related species by comparing emerged insects from red and Norway spruce bolts colonized with Tetropium fuscum and Tetropium cinnamopterum to control bolts. Tetropium egg treatments generally reduced community diversity, although the combination of significantly affected indices varied somewhat among Tetropium species and host. In Norway spruce, both Tetropium spp. significantly reduced Simpson’s diversity and richness; evenness was significantly lower only for T. fuscum. In red spruce, both Tetropium spp. significantly reduced richness; only T. fuscum reduced Simpson’s diversity and evenness. Impact of Tetropium on presumed competitors was not simply related to phylogenetic distance: the closest relative was not impacted, although the next closest relative, Evodinus monticola, was significantly reduced in both red and Norway spruce.