Utilization of non-native wood by saproxylic insects
Whether intentionally or accidentally introduced, non-native woody plants now feature prominently in many ecosystems throughout the world. The dying and deadwood produced by these plants represent novel resources for saproxylic insects, but their suitability to these organisms remains poorly understood. We herein review existing knowledge about the utilization of non-native wood species by saproxylic insect communities and also provide several previously unpublished case studies from the USA, Germany, Portugal/Spain, and New Zealand. The first case study suggests that the relative number of beetle species utilizing non-native vs. native wood varies greatly among wood species, with some non-native species (e.g., Albizia julibrissin) supporting a high beetle diversity. A decomposition experiment found that termites did not readily attack three non-native wood species and did not contribute significantly to their decomposition in contrast to what has been shown for a native pine species. The second case study found two species of non-native wood to support a lower richness of beetles compared to two native wood species in Germany, with Pseudotsuga menziesii supporting particularly few species which formed just a small subset of the community collected from native Picea abies. The third case study, from Iberia, found Eucalyptus to support a relatively small number of insect species with generalist host preferences. The fourthcase study provides a list of insects reported from non-native pine and Eucalyptus in New Zealand. Based on our literature review and these new case studies, we conclude that non-native wood species can support diverse insect assemblages but that their suitability varies greatly depending on host species as well as the host specificity of the insect(s) under consideration. Although many generalist species appear capable of using non-native woody resources, more research is needed to determine whether non-native wood species have any value in promoting the conservation of the most threatened taxa.