Invasive alien species in Switzerland - Schweizer ...

An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 118
clude the use of nematodes and runner ducks (a special breed of the mallard) as biological
control agents, as well as hand-picking. The latter approach, although very
laborious, was successfully used to eradicate the giant African snail (Achatina fulica
Bowdich) in Florida, USA (Simberloff, 1996). This was a remarkable achievement.
Slug fences and beer traps are often used in gardens. However, these methods are
usually used to protect plants at a specific location and are not designed to reduce
numbers of snails and slugs of environmental concern on a large scale.
In conclusion, the freshwater ecosystems need to receive more attention and the potential
impacts of alien invaders should not be underrated. It is generally very difficult to
give conclusive proof of the impacts of invasive species on native biodiversity. However,
many of the freshwater invaders reach remarkable densities and will have impacts
on natural ecosystems. These invaders are not only molluscs, but often crustaceans and
fish (see respective chapters). The boom-and-bust phenomenon (Williamson, 1996)
that is frequently observed with many invading species seems often to be caused in
European freshwater systems by the arrival of yet another invader. Thus, this does not
solve the problem, but simply shifts it to another invader and its impacts. In a terrestrial
context, the slug Arion lusitanicus is probably of greatest concern in Switzerland (and
Central Europe).
Tab. 6.2 > Established alien molluscs in Switzerland.
Scientific name Family Year Origin Pathway Impact Note
Terrestrial snails
Solatopupa similis Chondrinidae 19th Genoa, Italy Released to enrich Probably harmless Only one location near Lo-
(Bruguière) century fauna carno, Ticino
Milax gagates (Drapar- Milacidae 1968 Western and Accidental with vegeta- Pest in crops and gardens Not clear whether established
naud) southern
Europe
bles shipment? or only repeatedly introduced
Tandonia budapesten- Milacidae 1935 South-eastern Accidental with vegeta- Pest, in particular in winter crops, Anthropochorous – introduced
sis (Hazay) Europe bles shipment? when abundant widely by human-mediated
transport
Limacus flavus (L.) Limacidae 1927 Mediterranean Accidental Harmless Very rare in Switzerland, mostly
synanthropic
Deroceras sturanyi Agriolimacidae 1963 South-eastern Accidental Damage to plants in gardens Mostly secondary habitats
(Simroth) Europe
Deroceras panormita- Agriolimacidae 1982 South-western Accidental Future damage anticipated Very rare in Switzerland, only in
num (Lessona &
Pollonera)
Europe gardens and parks
Boettgerilla pallens Boetgerillidae 1960 Caucasus? Accidental Predator of native slugs? Impact not known, but a
Simroth predator of slugs
Arion lusitanicus Mabille Arionidae 1950s Western Accidental Most serious pest in gardens and Most problematic terrestrial
Europe agriculture
Displaces native Arion rufus (L.)
snail