Pest categorisation of Saperda tridentata.

Area of Science:

• Entomology and Plant Pathology
• Pest Risk Assessment
• Forestry and Horticulture

Background:

• Saperda tridentata, the elm borer, is a pest native to eastern North America.
• Primary hosts are American elm species (Ulmus americana, U. rubra), with historical records from Acer and Populus.
• The pest targets already weakened trees, potentially causing mortality.

Purpose of the Study:

• To conduct a pest categorization of Saperda tridentata for the European Union (EU).
• To evaluate its potential as a Union quarantine pest or regulated non-quarantine pest (RNQP).
• To assess risks associated with its introduction and potential establishment in the EU.

Main Methods:

• Evaluation of available data on geographical distribution, biology, host range, and impact.
• Assessment against EU criteria for quarantine and regulated non-quarantine pests.
• Analysis of interception data from imported North American Ulmus logs (2016-2019).

Main Results:

• Saperda tridentata is not reported in the EU, thus not meeting RNQP criteria.
• The pest satisfies criteria for a quarantine pest due to its entry into the EU.
• Larvae have been intercepted in North American Ulmus logs imported into the EU.

Conclusions:

• The potential for Saperda tridentata to shift host range to European Ulmus, Acer, or Populus species is a concern.
• Establishment is unlikely if only North American elms are hosts, but more probable if European species are affected.
• Insufficient data prevents a definitive conclusion on post-entry establishment, spread, and impact, necessitating further research.