Náttúrufræðingurinn - 2021, Page 62

Náttúrufræðingurinn
62
inn samfelldu lagi af mítlum og mítla-
eggjum. Í þessu sambandi er athygl-
isvert að það er neikvætt samband á
milli smits snípuluddu á rjúpum og
smits kláðamítlanna M. borealis og M.
islandicus,14 og snípuluddur virðast
forðast kláðarjúpur.
Við fundum húðmítlana P. pari og
M. avus eingöngu á snípuluddum af
rjúpum. Hvorug þessara tegunda er
þekkt sníkjudýr á rjúpu10,29 og báðar eru
nýjar í fánu Íslands. P. pari er vel þekkt
sníkjudýr á fjölda fuglategunda víða
um heim, meðal annars á spörfuglum,
svo sem barrmeisu (Parus ater), flot-
meisu (P. major), söngþresti (Turdus
philomelos), mistilþresti (T. viscivorus)
og maríuerlu.20,30 M. avus sækir á spör-
fugla erlendis, svo sem gráspör (Passer
domesticus), svartþröst (T. merula) og
álmtittling (Emberizia cirlus) en einnig
á vaðfugla, svo sem hrossagauk.20 Það á
við um báðar þessar tegundir að líklega
hafa snípuluddurnar náð í þær af öðrum
tegundum fugla en rjúpu.
ÁLYKTANIR
Lúsflugur af ættkvíslinni Ornithomya
eru sérhæfð sníkjudýr með áhuga-
verðan lífsferil. Eini ílendi fulltrúi ætt-
kvíslarinnar á Íslandi er snípuludda (O.
chloropus). Snípuludda sníkir fyrst og
fremst á ýmsum tegundum mófugla og
er mjög algeng og útbreidd á Íslandi frá
miðju sumri og fram á haust. Lúsflugur
eru smitferjur fyrir ýmsar tegundir ytri
sníkjudýra en í þessari rannsókn fund-
ust eingöngu þrjár tegundir húðmítla
sem nýttu sér snípuluddu til dreifingar,
allt ósérhæfðar tegundir með tilliti
til hýsla.
SUMMARY
The hippoboschid Ornithomya
chloropus in Iceland: life cycle
and phoresy
Feather mites (Astigmata: Analgoidea)
and chewing lice (Phthiraptera) are
prevalent ectoparasites of birds. It is
important to know both transmissions
pathways and host specificity when
studying host-parasite interactions.
The life cycle of both feather mites and
chewing lice is simple and transmission
most often direct between conspecifics
but louse flies (Hippoboscidae) can also
function as vectors for ectoparasites.
This role of the louse fly was the impetus
for our study, and we wanted to answer
what parasites use the louse fly Orni-
thomya chloropus for transmission in
Iceland and to describe the life cycle of
the fly. We collected and examined 650
louse flies from 13 avian host species in
Iceland 1999–2011. The hosts included
six species of shorebirds (Golden Plover
Pluvialis apricaria, Ringed Plover Cha-
radrius hiaticula, Whimbrel Numenius
phaeopus, Black-tailed Godwit Limosa
limosa, Snipe Gallinago gallinago, and
Redshank Tringa totanus), two species
of passerines (Redwing Turdus iliacus
and Pied Wagtail Motacilla alba), two
falcon species (Gyrfalcon Falco rusti-
colus and Merlin Falco columbarius),
Rock Ptarmigan Lagopus muta, Grey-
lag Goose Anser anser and Arctic Tern
Sterna paradisaea. All fly specimens
were identified to Ornithomya chloro-
pus. The flies were collected between 16
June and 11 October, the active period is
thus at least four months. Sex ratio was
slightly female biased in June through
August (55.6–69.0% females) but in Sep-
tember and October females dominated
in the samples (92.7 and 96.3% females
respectively). Louse flies are larvipa-
rous and female flies „give birth“ to a
prepupae. Maturing larvae can be seen
through the skin of the abdomen of the
mother. We found no female flies car-
rying maturing larvae in June or July,
but 18.5–29.4% of female flies in August
through September. There is most likely
only one generation of O. chloropus per
year in Iceland and the over-wintering
stage is a pupa. We searched for pho-
ronts on all the specimens and found
three species of avian skin mites (Epi-
dermoptidae): Myialges borealis (prev-
alence 24.3%), Promyialges pari (4.3%)
and Microlichus avus (0.3%). The mites
were most prevalent in August and Sep-
tember. M. borealis was a hyperparasite
on O. chloropus with gravid females –
usually surrounded by eggs – attached
to the abdomen of the louse fly. Flies
infested with M. borealis were collected
from four species of hosts, Rock Ptarmi-
gan, Gyrfalcon, Merlin, and Redwing.
Mean intensity of M. borealis was 11.0
mites per infected fly (95% c.l. 9.7–12.5).
Adult females of P. pari – usually sur-
rounded by eggs and freshly hatched
larvae – were found loosely attached to
the underside of the wing of the louse
fly and apparently not a hyperparasite.
Mean intensity was 1.6 mites (95% c.l.
1.1–3.1). Two adult M. avus females were
found on louse flies. Both were loosely
attached to the flies; one was found on
the abdomen among M. borealis and the
other on the wing among P. pari. Both M.
avus and P. pari are new species records
for Iceland. However, their avian hosts
are not known. All flies carrying these
two mites were caught on Rock Ptarmi-
gan but neither species are known Rock
Ptarmigan parasites. We did not find
any chewing lice phoronts.