Íslenskar landbúnaðarrannsóknir - 01.09.1981, Blaðsíða 67

MITES OF STORED HAY 65
Staphylinidae spp. were seen. They were
not identiíied to species as most of the
larvae of Icelandic Staphylinidae still
await description (Larsson & Gigja,
1959). Members of the Staphylinidae are
predators. With the above exceptions all
other beetles of the samples wer eLathridius
minutus (L.), a fungus-eating beetle, which
is common in stored products and also in
English hay (Griffiths, 1960, under the
synonym of Enicmus minutus).
DISCUSSION
Concentration of mites
The present work illustrates how difficult
it is to characterize a lot of stored hay by
its concentration of mites as the number of
mites seems to depend upon local humi-
dity gradients.
In stored hay from the Orkney Islands,
Ingram et al. (1979) and Cuthbert et al.
(1980) have reported 8—1700 mites/g of
hay. When differences in assessment
method and the time of sampling are ac-
counted for, these figures resemble the
present estimates from Iceland. Several
Icelandic samples contained less than
8000 mites/kg, however, but it should be
taken into consideration that four of the
five farms in the investigations on the
Orkney Islands were chosen because the
farmers already showed allergic sympt-
oms connected with the handling of hay.
According to Cuthbert et al. (1980)
the peak number of mites occurs shortly
after the harvest and from that time on the
number of mites stabilizes at an inter-
mediate level. This might be so in Ice-
landic hay but we cannot be sure because
As most hay includes some moss, a part
of the animal community of moss is also
represented in hay: the tardigrade Macro-
biotus hufelandii Schultze confined to the
upper green part of moss stems (Hallas,
1978) is commonly encountered and so
are testate amoebae, rotifers and ne-
matodes. These animals are inactive when
not covered by a water film and are thus
unable to multiply in stored hay.
the species composition of mites is differ-
ent.
Species composition
The presence of large concentrations of
Tarsonemus sp. in stored hay is unique to
Iceland. Griffiths (1960) does not
mention Tarsonemus among the 52 species
he found in hay, straw and grain in Eng-
land and I found no other records for hay.
Acarus farris was one of the most prevalent
species in hay from the Orkney Islands
(78.7% occurrence) (Ingram et al., 1979)
and in the Icelandic samples it was also
frequent (81%). Lepidoglyphus destructor
and the two predator mites Cheyletus erudi-
tus and Tydeus interruptus seem to be present
in English hay (Griffiths, 1960) too, but
comparable quantitative estimates are not
available. In the Icelandic samples C. er-
uditus is confined to older hay.
A dominant species in English
(Griffiths, 1960) and Orcadian (Orkn-
ey) hay (Ingram et al. 1979 and Cuth-
bert et al. 1980) is Tyrophagus longior
Gervais. This species has not been found
5