Identifying ticks in livestock: Part 2

Prof Maxime Madder, Prof Ivan Horak and Dr Hein Stoltsz look at the African and Asian blue ticks, as well as the Karoo paralysis tick, and explain how farmers can spot the differences between these dangerous parasites.

There are probably three different tick species within the sourveld tick group (Ixodes pilosus), of which only one has been described. The female is similar in appearance to the Karoo paralysis tick (Ixodes rubicundus), but the auriculae protrude laterally on the ventral side of the basis capituli, and there are spurs on the first pair of coxae. The alloscutum bears four longitudinal rows of long, stout setae dorsally. The posterior alignment of the anal groove is short and converging. In the male, the genital aperture is present in an inverted U-shaped area formed by the ventral shields.

The sourveld tick is present in the southeastern sourveld coastal regions of the Western and Eastern Cape, around Nelspruit, and near Polokwane. It is a three-host tick, with adults present in summer, larvae in autumn and nymphs in spring. This species is not known to transmit diseases.

All stages of development of I. pilosus infest cattle, sheep, dogs, grey rhebok, bushbuck, caracal, and scrub hare. It attaches around the head.

KAROO PARALYSIS TICK

I. rubicundus is a strictly South African tick and has a reddish-brown colour. It can be found in the Karoo, southern Free State, and in small areas near Bronkhorstspruit, Belfast, and Heidelberg.

The presence of hilly or mountainous veld and of the wild olive tree (Olea europaea subsp africana), the besembos shrub (Searsia erosa), and wire lemongrass (Elionurus muticus, or suurpol) all support the existence of the tick. The ticks also prefer the southern slopes of hills to the northern slopes, as the former are cooler.

Adults feed on sheep, goats, dogs, caracals, and mountain reedbuck. Immatures are found on rock elephant shrews, red rock rabbits, and caracals. Females are present in the wool line on the limbs and bellies of sheep. Males rarely attach to host animals but are frequently found attached to females.