Tick (Acarina: Ixodidae) infestations on zebu cattle in northern Uganda

Tick populations were observed on zebu cattle (Bos indicus) over an 18 month period at Patiko in northern Uganda. Monthly collections were made of all stages of ticks from five cattle and six sheep (Ovis aries). Collections of adults of Rhipicephalus appendiculatus Neumann were also made from the ears of about 30 cattle on several occasions. The species recorded on cattle, in order of decreasing abundance, were R. appendiculatus, Amblyomma variegatum (Fabricius), Boophilus decoloratus (Koch) and R. evertsi evertsi Neumann. Far fewer ticks were collected from the sheep. The adults of R. appendiculatus were randomly distributed over the herd. There was a distinct seasonal incidence of R. appendiculatus and A. variegatum on their hosts, which could be related to rainfall and to the emergence of new cohorts during the long rainy season. In addition, adult females of R. appendiculatus were collected daily off the ears of cattle at Entebbe following an infestation with 200 adult males and females. Measurements of the growth of the ticks were used to define the sizes of 'standard' ticks which would complete engorgement in the following 24 h. Such ticks provide a means of sampling to estimate the number of ticks engorging daily. Comparison of the frequency distributions of each stage and species in the Patiko collections were then used to infer the sizes of standard ticks for other species