Pest categorisation of Saperda tridentata

Abstract

The EFSA Panel on Plant Health (PLHP) performed a pest categorisation of Saperda tridentata (Coleoptera: Cerambycidae) for the EU. S. tridentata (elm borer) occurs in eastern North America. Ulmus americana and U. rubra are almost exclusively reported as hosts, apart from two 19^th century records from the USA of larvae from Acer sp. and Populus sp. The Panel does not exclude the possibility of a post-entry shift in host range to European Ulmus or Acer and Populus. S. tridentata infests trees that are already weakened, and severe infestations can result in tree death. S. tridentata occurs across a range of climate types in North America that occur also in Europe. Between 2016 and 2019, S. tridentata larvae were intercepted with North American Ulmus logs imported into the EU. In the EU, American Ulmus species are mainly found in arboreta and as ornamental specimen trees. If only North American Ulmus are hosts, establishment is unlikely. However, if European Ulmus, Populus or Acer species become hosts, establishment is much more likely, with impact confined to already weakened trees. The information currently available on geographical distribution, biology, impact and potential entry pathways of S. tridentata has been evaluated against the criteria for it to qualify as potential Union quarantine pest or as Union regulated non-quarantine pest (RNQP). Since the pest is not reported in EU, it does not meet the criteria assessed by EFSA to qualify as potential Union RNQP. S. tridentata satisfies the criterion for quarantine pest regarding entry into the EU territory. Due to the scarcity of data, the Panel is unable to conclude if S. tridentata meets the post-entry criteria of establishment, spread and potential impact.

Keywords: Elm borer; host range uncertainty; longhorn beetle; pest risk; plant health; plant pest; quarantine.