Pre-invasion assessment of potential invasive wood borers on North American tree species in Chinese sentinel gardens

Sentinel gardens are vital tool for detecting potential insect or pathogen invasions on plants from other regions. Limited knowledge exists on wood borers' potential impact on non-coevolved plants and their influence on future invasions due to potential host stress levels. Here, we surveyed wood borers colonizing 11 North American tree species planted in two sentinel gardens in China. detecting 38 woodboring insect species from 9 families including Curculionidae, Cerambycidae, and Cossidae. <i>Quercus texana</i> Buckley (Fagales: Fagaceae) was the most targeted species. Wood borers typically infest unhealthy or dead tissues, irrespective of the tree's overall vitality. We identified several species capable of colonizing healthy trees: <i>Anoplophora chinensis</i> Forster (Coleoptera: Cerambycidae), <i>Sinoxylon</i> sp., and <i>Zeuzera coffeae</i> Nietner (Lepidoptera: Cossidae). Several species colonized unhealthy tissues in living stressed trees: <i>Xylosandrus crassiusculus </i>Motschulsky (Coleoptera: Curculionidae), <i>Chlorophorus</i> sp., <i>Xyleborus affinis</i> Eichhoff<i> </i>(Coleoptera: Curculionidae), and <i>Xylosandrus germanus </i>Blandford (Coleoptera: Curculionidae). Some of these are well-known invasives established overseas, but <i>A. chinensis</i> and <i>Z. coffeae</i> represent under-documented potential pests with considerable regulatory importance. Most species recorded are already recognized as pest of live trees or invasive elsewhere, indicating a limited number of potentially invasive wood borers, rather than an inexhaustible pool. This suggests that pre-invasion assessment via sentinel garden can help in pest prevention prioritization. In future pre-invasion assessments, we recommend documenting the vitality of colonized tissues, rather than that of the entire tree, in order to avoid misrepresentation of secondary colonizers as primary pests.