Invasive alien species in Switzerland - Schweizer ...

An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 126
(2003) estimate that Germany incurs annual costs of about €5 million for the removal
and replacement of trees, the lost value of dead trees, and additional expenditure of
planting resistant varieties.
While Phytophthora quercina Jung et al. (see Fact Sheet) is a rather recent invader (or
at least attention has been drawn to it by its recent impact), P. ramorum Werres, de
Cock & Man in’t Veld (sudden oak death) (see Fact Sheet) is already well-known
from its devastating effect in North America. In Europe it is still only a problem in
nurseries, but it can be expected to infest native forests in the not-too-distant future.
Many woody hosts have been shown to be susceptible to sudden oak death and it has
been recorded from Switzerland (Heiniger and Stadler, 2003).
The crayfish plague (Aphanomyces astaci (Schikora)) (see Fact Sheet) is one of the
most devastating fungi attacking European wildlife. The fungus was introduced with
North American crayfish species, which are asymptomatic carriers of the disease, into
Europe. The European crayfish species are highly susceptible and almost 100 % die
within two weeks of infection. There are regular outbreaks in European populations
resulting in total collapse (Voglmayr and Krisai-Greilhuber, 2002).
The bacterium Erwinia amylovora (Burrill) Winslow et al. (see Fact Sheet) is the
causal agent of fire blight, which was first found on Cotoneaster species and is now
widely distributed in Switzerland (Hasler et al., 2002).
An interesting case of a mutual relationship between two invaders may be the association
between mycorrhizal fungi and plant species. There is some evidence that alien
mycorrhiza can help their alien host plant to become a weed in the introduced range
(e.g. Crawley, 1993; Harrington et al., 1998). In that way, an introduced mycorrhiza
might have an indirect detrimental effect on native biodiversity.
In can be concluded that although quarantine measures are successfully implemented in
Switzerland, non-crop plants need to get more attention, e.g. plants in the nursery
industry. The few examples described here indicate the enormous impacts diseases can
have. Some introduced diseases are completely changing entire ecosystems by eliminating
important key species. Moreover, there are human diseases not mentioned in
this report with global impact, such as AIDS (a viral disease).
The Fact Sheets are presented after the references, in alphabetical order for ease of
location of specific sheets.