Invasive Gehölzinsekten: Bedrohung für den Schweizer Wald?

Abstract

Invasive tree insects: a menace to the Swiss forests? The rate of introduction of non-native insects and other arthropods to Europe has been exponentially increasing in recent decades, amounting to 20 species per year in the past ten years. By 2008, a total of 1590 species had been introduced since the discovery of America. The main causes are the intensification and globalization of international trade. The most important pathways are trade in ornamental plants and import of goods in infested wooden crates. Most often new species first establish in residential areas, where the normally mild climate favors the survival of exotic species. Three species recently introduced from East Asia to Switzerland are particularly relevant to forests: the box tree moth (Cydalima perspectalis) has infested box tree stands near Basel, the chestnut gall wasp (Dryocosmus kuriphilus) now covers almost all of southern Switzerland, with single infestations also on the Swiss Central Plateau, and two infestation spots of the Asian longhorned beetle (Anoplophora glabripennis) have been identified. Potential future species of invasive insects are discussed. The largescale introduction of foreign tree species in forests needs to be critically examined, as they may be hosts of current and future non-native insects.