Íslenskar landbúnaðarrannsóknir - 01.09.1981, Síða 64

62 ÍSLENZKAR LANDBÚNAÐARRANNSÓKNIR
The hay samples originated from the
following farms: Laugardælir in
Hraungerðishreppur, Arnessýsla (sample
L1—L7), Keldur in Reykjavík (K1—K7),
Hvanneyri in Andakílshreppur, Borgar-
fjarðarsýsla (H1—H5), Björg in Arnar-
neshreppur, Eyjafjörður (A1—A5), Stóri
Dunhagi in Skriðuhreppur, Eyjafjörður
(A6—AIO), Eyrarteigur in Skriðdalur,
Suður Múlasýsla (El), Brennistaðir in
Eiðahreppur, S.M. (E2), Kolstaðagerði in
Egilsstaðahreppur, S.M. (E3), Geitdalur
RESULTS
Concentration of mites
The calculated number of mites in one kg
of hay (Table 1) varied from 64 to
1,234,119. These figures are estimated
from the number of live, active specimens
and therefore the actual concentration.of
mites must have been somewhat higher
than this.
In a single barn the concentrations of
mites may vary from one sample site to
another. These variations appeared to be
much more pronounced than between
barns despite differences in harvesting
and storage of the hay and the geographic
position within Iceland as well.
Only a few comparable estimates are
available as sampling was not standardiz-
ed.
If a sample is taken close to the outside
wall it may contain more mites/kg than a
sample of the same lot taken in the centre
of the barn. In the samples A7/A6 taken in
this way there are 955 times more mites/
kg by the outside wall. For the samples
A9/A8 this factor is 50, but in the samples
K2/K1 the concentrations are almost eq-
in Skriðdalur, S.M. (E4), Dagverðargerði
in Tunguhreppur, Norður-Múlasýsla
(E5), Höfði in Vallahreppur, S.M. (E6),
Gilsárteigur in Eiðahreppur, S.M. (E7).
The author collected sample series L
(May 17, 1981), K (May 7, 1981), and H
(May 19—20, 1981). Þórarinn Lárusson
collected series A (May 13, 1981) and Páll
Sigbjörnsson collected series E (May 12,
1981). The harvest year for each sample is
indicated in Table 1.
ual. A closer look at the stage distribution
in K1 and K2 shows, however, signs of
more activity in K2 (by the outside wall)
which is dominated by active, feeding
specimens of Acarus farris, while the K1
sample is dominated by its second nym-
phal stage which is able to walk but
cannot feed (it has no mouth).
Hay damaged by water (H4) may con-
tain 8192 times the number of mites in its
corresponding dry part (H2). There are
also pronounced differences in a single
bale of hay: The hay on top, exposed to
air, (Ll) contained few mites. If a test
corer was used in the same position (L2) it
was found that the number of mites in-
creased downwards, the highest concentra-
tion being in the bottom layer (L7), resting
on the floor of the barn.
The mite species
Tarsonemus sp. belongs to a probably
undescribed species (E.E. Lindquist det.)
and its function in the hay ecosystem is
unknown. Lepidoglyphus destructor and Acar-
us farris are fungivorous species. Tydeus