The prevalence of itchmite, Psorergates ovis, among sheep flocks with a history of fleece derangement.
An investigation of sheep flocks in the main sheep raising areas of New South Wales showed that the itchmite Psorergates ovis was frequently associated with fleece derangement. In 26 of the 41 flocks examined, P. ovis was the only ectoparasite detected. P. ovis and the sheep body louse Damalinia ovis, were found in 5 flocks. No external parasites were found on sheep examined from the 10 remaining flocks. The type of fleece derangement most frequently recorded was rubbing which in some cases was combined with areas of chewed fleece. Among flocks, there were positive relations between the prevalence of fleece derangement and prevalence of itchmite or scurf and between itchmite count and mean scurf score. Within flocks, itchmite infested sheep or sheep with scurf had higher prevalences of fleece derangement than sheep on which no mites or no scurf were found. Itchmite infested sheep had a higher prevalence of scurf than those with no detectable mite infestation. There were no significant differences in itchmite populations or fleece derangement between untreated flocks and flocks treated with synthetic pyrethroids, organophosphates or arsenic and rotenone.
Johnson
P W
PW
NSW Agriculture and Fisheries, Central Veterinary Laboratory, Glenfield.
Plant
J W
JW
Boray
J C
JC
Blunt
S C
SC
Nicholls
P J
PJ
D000818:Animals; D008924:Mite Infestations / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D009517:New South Wales / Q000453:epidemiology; D015995:Prevalence; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology* / Q000473:pathology; D014935:Wool / Q000473:pathology*