Invasive alien species in Switzerland - Schweizer ...

An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 114
The family Milacidae with two native species, has been supplemented in Switzerland
with two more, i.e. Milax gagates (Draparnaud) and Tandonia budapestensis (Hazay),
both from other parts of Europe. M. gagates has been found only in gardens, where it
probably arrived with plant material, so it is not known whether it is established in
Switzerland. T. budapestensis is an anthropochorous (disperses as a result of human
activity) species that is widely distributed within Europe. It is regarded as a pest,
especially in winter crops (Fischer and Reischütz, 1998), but is rather difficult to
observe because of its cryptic, nocturnal habits.
Another synanthropic species (in addition to members of the Milacidae) is Limacus
flavus (L.) (Limacidae), which is only rarely encountered in Switzerland. It is likely
that this species will be introduced with plant material in the future, but it is probably
not adapted to the Swiss environment, so that it is less likely to become established.
The slugs Deroceras sturanyi (Simroth) and D. panormitanum (Lessona & Pollonera)
belong to the Agriolimacidae. This family is taxonomically challenging and new
species have recently been described (Kerney et al., 1983). These slugs prefer fresh
green plant material and therefore some are recognized as pests. The former species has
been considered a pest in gardens, while the latter species is only rarely found in
Switzerland. However, D. panormitanum is expanding its range in Europe and is
increasingly reported as damaging plants of economic importance. This is a species
that should be monitored, since it is likely to establish populations in agricultural areas,
with the potential to cause economic damage in the near future.
The origin of the slug Boettgerilla pallens Simroth (Boettgerillidae) is assumed to be
the Caucasus, although Jungbluth (1996) argued that it might be a native species in
Central Europe which had not been reported earlier. Most collections of slugs are fairly
recent and the lack of a shell makes it difficult to find species as subfossils. This species
is a predator of slug eggs and young slugs (Reischütz, 2002), so it is a beneficial
organism in agricultural settings rather than a pest, as sometimes stated. However, in
natural localities, it may have a negative impact on native slugs through predation.
Arion lusitanicus Mabille (Arionidae) (see Fact Sheet) is rapidly expanding its range,
and is the most serious invader amongst the snails and slugs. It is not only a pest in
agriculture and gardens, but also displaces a native congeneric species in the lowland
parts of Switzerland (Turner et al., 1998).
The snail Hygromia cinctella (Draparnaud) (Hygromiidae) has been accidentally
introduced into the northern parts of Switzerland, but could be native around Genève or
in the Ticino. It was introduced prior to the start of malacological recording and is
mostly found in gardens and other anthropogenic settings (Kerney et al., 1983).
The only introduced species of Helicidae is Cryptomphalus aspersus (O.F. Müller),
which was introduced prior to the start of malacological recording. It is mostly found in
gardens and other anthropogenic habitats, although it is recorded from natural habitats,
e.g. in the Valais. Its environmental impact is not known, but it is regarded as a pest in
gardens.