Importing deciduous wood chips from North America to northern Europe – the risk of introducing bark- and wood-boring insects

Abstract

Increasing inter-continental trade with wood chips represents a challenge for phytosanitary authorities as such trade may lead to pest introductions and invasions with huge impacts on forest ecosystems and economy. Predicting species invasions and their impacts in advance may be difficult, but improved information about potential invasive species ahead of any interceptions is an important precautionary step to reduce the probability of invasions. Here we identify bark- and wood-boring insects that have a potential to become invasive in northern Europe and that may be introduced by import of deciduous wood chips from North America. The potentially most damaging species belong to the beetle genus Agrilus (Buprestidae), which includes the highly damaging emerald ash borer A. planipennis. We give a brief presentation of this and seven other Agrilus species or subspecies and review factors of importance for the risk of establishment and potential economic and ecological impacts of these species. We also discuss one Scolytinae, Hylurgopinus rufipes. There are strong indications in the literature that some north European trees are highly susceptible to attack from the selected beetle species. We therefore conclude that because north European trees have not coevolved with these herbivores and thus may lack adequate defenses, most of the identified beetle species are likely to spread in “defense- and enemy-free space” if they are introduced to northern Europe, with considerable economic and ecological consequences.

Keywords:

• naïve hosts
• wood-boring insects
• Agrilus
• invasive species
• phytosanitary risk

Acknowledgements

We would like to thank Daniel A. Herms and Vanessa Muilenburg for valuable discussions and feedback and for help in providing literature, Robert A. Haack for reviewing our initial lists of wood-borers, the Canadian Food Inspection Agency for providing literature, and three reviewers for helpful input and suggestions that improved the manuscript.