Invasive alien species in Switzerland - Schweizer ...

An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 74
actually be native to Central Europe. Thus the inclusion of some species in the list is
questionable.
Some of the stored product pests are of tropical origin and are strictly domestic in
Switzerland, whereas others can also survive and reproduce under outdoor conditions.
Many more species than those listed in this study are found associated with stored
products in Switzerland. However, it is not always clear whether these species are
established, or regularly introduced with imported goods. Our list includes only the
species thought to be established, although, in several cases, the decision on whether to
include them or not was rather subjective. For example, we did not include the coffee
bean beetle, Araecerus fasciculatus De Geer, a species often found in imported coffee
and cocoa beans in Swiss food factories, but not clearly established in the country.
Hoppe (1981) surveyed stored commodities in Switzerland and found the most destructive
beetles to be the curculionids Sitophilus granarius and S. orizae, the silvanid
Oryzaephilus surinamensis and the tenebrionids Tribolium castaneum and T. confusum,
all considered to be of exotic origin.
Apart from stored product pests, few exotic beetles are recorded as agricultural pests in
Switzerland. However, two important chrysomelid beetles are worth mentioning. The
infamous Colorado potato beetle, Leptinotarsa decemlineata invaded Europe from
North America in the 1920s and reached Switzerland in 1937. It is a major pest of
potato in Europe and North America (see Fact Sheet). More recently, the western corn
rootworm, Diabrotica virgifera ssp. virgifera, a Nearctic species, took the same road
and arrived in Belgrade in 1992. Twelve years on, it has spread to more than 12 European
countries, including Switzerland (see Fact Sheet). D. virgifera virgifera is considered
the major pest of maize in North America and substantial economic damage has
already been observed in Central and eastern Europe.
Some exotic beetles are damaging to forest and ornamental trees. Xylophagous insects
are notorious for being easily introduced into new regions through the importation of
timber or solid wood packing material. At least six Scolytidae in Switzerland are of
alien origin. In particular, the Asian Xylosandrus germanus and the North American
Gnathotrichus materiarius damage freshly cut logs and reduce timber quality. They
both arrived in Switzerland in the 1980s (see Fact Sheet for X. germanus; Hirschheydt
(1992) for G. materiarius). Other wood boring scolytids arrived in Switzerland very
recently: Tripodendron laeve from East Asia or Scandinavia, Xyleborinus alni from
East Asia, and Xyleborus punctulatus from Siberia (C. Besuchet, pers. comm.). Similarly,
the cerambycids Neoclytus acuminatus and Xylotrechus stebbingi, xylophagous
beetles from North America and the Himalayas, respectively, have recently been found
in the Ticino (C. Besuchet, pers. comm.). Although these species have not yet caused
economic or environmental damage in Switzerland, their introductions show that
international movement of timber and timber products is an important introduction
pathway for bark and wood boring beetles that may eventually lead to the establishment
of serious forest pests. Among these potential introductions are the two Asian
cerambycids Anoplophora glabripennis (Motschulsky) and A. chinensis (Forster). Both
species are important pests in Asia, attacking and killing a whole range of tree species