Turnbull, Duncan Mc Diarmid

English

PART 1. THE ECOLOGY OF IXOCLES TRIANGULICEPS BIRULA, 1895.

Ixodes trianguliceps and its small mammal hosts have previously
been proposed as serving an occult reservoir role in the cycling of
Louping-ill virus. The tick was collected from three host species:
11. glareolusq M. agrestis and A. sylvaticus. The main study area
was at Balerno, Midlothian where it was the only species of 'tick
recovered. Regular collections were made from July 1974 until
August 1976.

C. glareolus had the greatest frequency of parasitised hosts and
the heaviest burdens; the males were more heavily burdened than the.
females. Such sex preference was not found for the other hosts.
Larvae infest the hostý throughout the year, burdens being max in
June and minimal in July, a second, much lower, peak occurs in October.
Females are active from early spring and nymphs from late spring until
autumn. The ear pinna is the area of the body most heavily infested
by larvae and nymphs, particularly the inner surface with voles and
the outer surface with the mouse. While larvae are overdispersed on
all three species of host, nymphs and females are overdispersed on
C. glareolus only, and this host alone of the three maintains the
instars in appropriate numbers and proportions to qualify it as an
independent maintenance host. While C. glareolus could maintain the
tick population, M. agrestis and A. sylvaticus could not and may even
be deleterious to the tick population.

Larvae have a pre-feeding diapause while attached to the host from
December until February. There is no evidence that larvae are active
during winter as reported by other workers. Diapause is abandoned
when infested hosts are brought into the laboratory and engorgement
to repletion is slower on all three hosts than it is during the rest
of the year. At any time of the year larvae take longer to feed on
A. sylvaticus than on the voles.

Only 9% of field captured larvae completed development and it is
proposed that the majority of engorged larvae enter a pre-developmental
diapause. Similar conclusions are reached for nymphs and females.
For larvae and nymphs which develop at constant temperature without
manifest diapause delays the relationship between incubation temperature
and developmental velocity is linear and direct.

PART 2. PREVALENCE OF LOUPING-ILL IN NORTHERN SCOTTISH CATTLE:

In a survey of cattle in the northern counties and inner islands
of the west coast of Scotland, 4529 sera were tested for immunoglobulin
G to Louping-ilI, using antigen derived from Louping-ill strain 31
The incidence of antisera in herds
decreases
from the west of the
country to the east. In a stable herd structure there is a significant,
steady increase in antibody with age. It is suggested, that cattle are
useful indicators of Louping-ill, but their role in maintenance of the
disease remains an unknown factor

Turnbull, Duncan McD.

Edinburgh Research Archive

Contributions to the epidemiology of louping-ill: 1. the ecology of Ixodes trianguliceps Birula, 1895, a potential vector; 2. prevalence of Louping-ill in northern Scottish cattle

https://era.ed.ac.uk/bitstream/1842/6934/1/502617.pdf

Contributions to the epidemiology of louping-ill

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