Currently, Great Britain regulates Agrilus planipennis, emerald ash borer (“EAB”) (Insecta, Coleoptera, Buprestidae), within the Implementing Regulation (EU) 2019/20721 (“the Phytosanitary Conditions Regulation”) as retained and made operable in GB. EAB is a Quarantine Pest (“QP”) in Annex 2, with associated special requirements which apply to the import of plants and wood of specified hosts in Annex 7. The EU has similar requirements, but the list of hosts to which the special requirements apply to is starting to diverge. This document examines the evidence for the hosts currently listed in GB and the EU and considers whether the current GB host lists should be updated, and if so, what changes are appropriate.

Summary of recommendations
Add Chionanthus virginicus to the GB regulation for Annex 7 hosts requiring special measures for EAB, for both plants and wood. Natural infestation of this host is seen in North America, and EAB is able to complete its development to adult on this plant, though it is a less suitable host than many North American Fraxinus species.
Remove Juglans ailantifolia, J. mandshurica and Pterocarya rhoifolia from the GB regulation for Annex 7 measures for EAB, for both plants and wood. Papers written over the last ten years or so regard these host records as unreliable, and recommend that, at a minimum, they require review. As EAB is an Annex 2 QP, action would be taken on findings of EAB associated with any plant, including these three species, irrespective of their inclusion or exclusion from the Annex 7 host list for special requirements.

Maintain Ulmus davidiana, but keep under review. While the historical literature for this as a host is regarded as unreliable, recent host testing suggests some Ulmus cultivars allow some larval development in freshly cut wood. This evidence would not be enough to newly list U. davidiana as a host. However, given it is already listed, it is proposed to maintain the EAB Annex 7 measures on U. davidiana, but to keep an active watch for any new information and review this listing in response.