European elms as potential hosts of Saperda tridentata (Coleoptera: Cerambycidae)

The elm borer, Saperda tridentata (Olivier, 1795) (Coleoptera: Cerambycidae), is a North American longhorn beetle that has been repeatedly intercepted in Europe on imported elm logs. Although climatic conditions are considered suitable for its establishment, uncertainty remains regarding the suitability of European tree species as hosts. We evaluated the potential host range of S. tridentata by testing 4 elm species (Ulmus glabra, Ulmus laevis, Ulmus minor, and Ulmus pumila), 3 maple species (Acer campestre, Acer platanoides, and Acer pseudoplatanus), and 3 poplar species (Populus alba, Populus nigra, and Populus tremula) that are widespread in Europe. No-choice and choice feeding bioassays were conducted to assess adult feeding preference, while no-choice development bioassays were performed to determine whether larvae could establish and develop within logs of the tested species. Adults fed on all elm species but showed no feeding activity on maples or poplars. Feeding levels on European elms did not differ significantly from those recorded on the primary North American host, U. americana. Larvae were recovered from logs of all 4 European elm species, confirming their suitability for larval establishment, whereas no larvae were found in maple or poplar logs. Adult emergence was limited, with only 3 individuals emerging from U. minor logs. Our results indicate that European elm species can support both adult feeding and larval development of S. tridentata, whereas the tested maple and poplar species appear to be unsuitable hosts. These findings suggest that host availability is unlikely to limit the establishment of S. tridentata in Europe if introductions occur.