Fróðskaparrit - 01.01.1992, Side 46

50
THE EXOTIC LAND PLANARIAN . . .
northem hemisphere countries appears to
have occurred by passive long-distance
migration facilitated by the transport of
plant material. For example, the most prob-
able immigration routes for Northem
Ireland and Scotland are via the import of
daffodil bulbs (Willis and Edwards, 1977)
or roses (Blackshaw and Stewart, 1992)
from New Zealand, whereas the most like-
ly route for the Faroes is via the import of
potatoes or other plant material from
Scotland (Bloch, 1992).
Initially the New Zealand flatworm was
regarded as a curiosity, but owing to its
apparent colonisation potential and preda-
tory habit on earthworms it is now consid-
ered to pose a threat to earthworm popula-
tions and thereby soil fertility (Blackshaw,
1990; Mather and Christensen, 1991;
Blackshaw and Stewart, 1992). At present,
there are no known commercial control
measures for the land planarian. The
British authorities are now taking the mat-
ter seriously and have recently classified A.
triangulata as a pest, adding it to the list of
non-native species not allowed to be intro-
duced into the wild. However, as the land
planarian has not yet been recorded in con-
tinental Europe, countries such as Denmark
have not considered any form of import
control.
The A. triangulata situation in the Faroe
Islands appears to be developing rapidly. In
order to evaluate the current status of the
land planarian, the authors conducted a
sampling survey of the main island of
Streymoy during the period 12th-17th
November 1992.
Site observations
Four main sites on the island of Streymoy
were investigated, the first three having
previous records of A. triangulata:
the Gundadalur plantation in the
centre of Tórshavn
a private garden in the village of
Kaldbak
potato fields in the village of
Kvívík
the arboretum in Tórshavn
1) Gundadalur plantation
The plantation in Tórshavn dates from
1885, and the planting of various non-
native species of trees and shrubs from
northem and southem hemisphere coun-
tries has taken place on several occasions
since with varying degrees of success.
Examination of the plantation during
November 1992 revealed specimens of A.
triangulata in an area west of the river.
Despite ground frost, adult and juvenile
individuals and egg capsules (non-hatched
and hatched) were readily found, but with
patchy distribution, under stones and logs,
and also beneath pieces of bark overlying
moss. Most individuals appeared inactive,
being in a coiled position and surrounded
by mucus. Three to four adults/juveniles
were usually found under logs or stones,
and an area of 20 x 20 cm in the mossy
habitat gave up to 15 non-hatched egg cap-
sules. Earthworms and slugs were also
observed in the same habitats as the land
planarians.