Records of unsuccessful attack byAnoplophora glabripennis(Coleoptera: Cerambycidae) on broadleaf trees of questionable suitability in Canada

Abstract

Discovery of the non-native Anoplophora glabripennis Motschulsky (Coleoptera: Cerambycidae) in Ontario, Canada, in 2003 led to the implementation of an eradication programme. The plan consisted of removing all infested trees and all trees belonging to a genus considered suitable for complete development of this wood-borer that were found within 400 m of an infested tree; however, many of the trees within that 400 m belonged to genera for which suitability for development of A. glabripennis was questionable or unknown. We visually inspected over 3000 such trees annually for the three years following removal of infested trees. All but one tree were unattacked: an ash (Fraxinus excelsior Linnaeus (Oleaceae)) tree had signs of oviposition and early-instar development, but not of adult emergence. Before that survey, we had found only one other species with questionable suitability, a little leaf linden (Tilia cordata Miller (Malvaceae)) that had many signs of oviposition, but no evidence of full development, suggesting resistance to A. glabripennis. Both of these trees were within 200 m of the most heavily infested maple (Acer platanoides Linnaeus (Sapindaceae)) tree found in that infestation, suggesting that colonisation of trees with questionable or unknown suitability might occur mostly where population pressure is high.

Canada’s response to invasion by Asian longhorned beetle (Coleoptera: Cerambycidae) in Ontario

“…7). Upon arrival at a tree, the data collector and specialist undertook the following steps (similar to those listed in Turgeon et al 2016;Fig. 8).…”

“…To mitigate against the possibility that these genera could be targeted by A. glabripennis in Toronto/Vaughan more frequently than they had been in other outbreaks or in the beetle's native rangeand thus escape detectionthe science subcommittee suggested that a host-confirmation survey of trees from these two categories be undertaken. A host-confirmation survey of more than 3000 trees, all within 400 m of a tree with an A. glabripennis emergence hole, was initiated on 1 April 2004 and lasted three years (Turgeon et al 2016). All that was found were signs of oviposition on a single ash (Fraxinus sp.)…”

“…Similar doubts existed for the genus Tilia. Anoplophora glabripennis was known to oviposit on Tilia mongolica Maximovich, and first-and second-instar larvae were observed successfully mining galleries at the cambium-bark interface of several Tilia species (Turgeon et al 2016), but no evidence could be found of larvae tunnelling into the xylem or developing beyond the third instar. Similar observations were reported by Morewood et al (2003Morewood et al ( , 2004.…”

“…These categories were "suitable," "questionable," and "unknown" (Ric et al 2007). A genus would be considered "suitable" if evidence suggested A. glabripennis had completed its entire development in tree species within that genus under field conditions in the United States of America or in its native range (Turgeon et al 2007(Turgeon et al , 2016. A genus would be considered of "questionable" suitability if laboratory or field evidence suggested that A. glabripennis oviposition and larval development were possible within tree species of that genus but no verifiable evidence yet existed indicating that the insect had completed development in any of those species under field conditions.…”

“…In January 2007, after a review of removal data by the science subcommittee, the CFIA shortened that list from 10 to four. The decision was based on evidence that no tree of the genus Albizia was present in the regulated area, that no trees from the genera Aesculus, Celtis, Platanus, and Sorbus had been affected (Turgeon et al 2022), that only three of the more than 10 000 available stems of Ulmus had been infested, and that only one stem each of two genera of questionable suitability (Fraxinus and Tilia) and no stems from genera deemed unsuitable within 400 m of trees with an emergence hole had been injured (Turgeon et al 2016). This evidence removed support for the argument that each of these suitable genera was at high risk of injury.…”