Fróðskaparrit - 01.01.1992, Síða 47

THE EXOTIC LAND PLANARIAN . . .
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2) Garden in Kaldbak
The village of Kaldbak lies about 12 km to
the north of Tórshavn. Specimens of A. tri-
angulata were first observed here in
Autumn 1992 in a well-established, private
garden containing several non-native
plants. This plant material had been trans-
planted over the years from different
Faroese locations, including local gardens
and shops, a garden centre near Kirkjubøur
(in 1991 and 1992) and the arboretum in
Tórshavn (about 20 years ago, only Danish
material being distributed at that time).
Apparently, the land planarian has not yet
been sighted in any of the other local gar-
dens involved in the exchange of plants (B.
Nysted, pers.comm).
Examination of the garden in November
1992 indicated that specimens of A. trian-
gulata were present under many of the
omamentally arranged stones (each stone
roughly 10x10 cm), with up to six coiled,
inactive adults/juveniles per stone.
Although flatworms were abundant, very
few egg capsules were seen. Earthworms
and other invertebrates (carabid larvae, ear-
wigs and slugs) were also found under the
garden stones.
3) Potato fields in Kvívík
Kvívík lies 30 km to the north-west of
Tórshavn. This coastal village is surround-
ed by intensively managed infields used
mainly for growing potatoes and hay har-
vest, sheep being allowed to graze the
fields after the growing season. A local
farmer had observed specimens of A. trian-
gulata in numbers of hundreds in his pota-
to field in May 1990, though none had been
seen during potato planting in the same
field the previous year (J.B. Jákobsen,
pers.comm.). The farmer has since noted a
lack of earthworms in his field and - well
aware of the beneficial effects of earth-
worms on soils and their habit of aggregat-
ing in manure - has attempted to attract
earthworms back to the area by putting out
heaps of cow dung.
This particular field was examined in
November 1992, over two years since the
first sightings of A. triangulata. The field,
now under grass (in 1991 and 1992), gave
no sign of the land planarian. Furthermore,
no earthworms nor their cocoons could be
found, not even in or under the dung heaps.
However, approximately 100 m away
from the field previously infested with A.
triangulata, another field had been used for
growing potatoes during 1992. This field,
now at post-harvest stage, was examined
by lifting the grass turves (see Fig. 1). Here,
the land planarian was found in high densi-
ties, e.g. under a 50 x 30 cm turf the num-
ber was often as high as 10 adults/large
juveniles and 30 egg capsules, half of these
capsules having already hatched. Both
active and coiled, inactive individuals were
found, along with many mucus-lined rest-
ing sites. No earthworms nor their cocoons
were evident, though other invertebrates
were observed.
For comparison, two other potato fields
(also post-harvest stage) on the outskirts of
the village were studied, one of these
belonging to the above farmer. These two
fields contrasted greatly to the ones already
examined in that many earthworms were
immediately visible on the grass surface