Ecology and host-relationships of ticks (Ixodoidea) infesting domestic animals in Kassala Province, Sudan, with special reference to Amblyomma lepidum Dönitz.

Abstract

Amblyomma lepidum Dön., previously incriminated as a vector of heartwater (caused by Rickettsia ruminantium) among sheep and goats, and possibly camels, in southern Kassala Province, Sudan, is apparently the only Amblyomma species in this area. Systematic collections of all ticks infesting domestic animals were carried out in November 1959, just after the rains, in five ecologically differing areas in the region most severely infected with heartwater. Though rare in desert scrub (north of 16°N. latitude) and only moderately numerous in semidesert grassland (Butana area), incidence of A. lepidum is high in wooded savannah (River Atbara) and in the cultivated Gash Delta, and highest (15·5 per host) in the Acacia seyal savannah of the River Gash. Chief hosts of adults are cattle. Sheep are secondary hosts, and camels, donkeys, and goats are less heavily infested. Two males were taken feeding on humans. Mating (breeding) activity is only slight following the rains (November). Few larvae and nymphs were found during this period; those present were mainly on sheep and goats, with a few on cattle, and these were usually feeding on the hoofs of their hosts.Rhipicephalus s. sanguineus (Latr.), the most numerous and widely distributed tick here, infests chiefly sheep and goats, is common on cattle, and also occurs on camels and donkeys. Mating activity of this species is high in November. Hyalomma dromedarii Koch is equally widely distributed and follows R. s. sanguineus in numbers, but is most frequent on camels, common on cattle, and rare on donkeys and sheep; goats were uninfested. Mating is moderately active at this season. The incidence of H. impeltatum Schulze & Schlottke, which occurs in each zone, equalled that of A. lepidum. Cattle are the chief hosts and camels are secondary hosts; donkeys, sheep, and goats are less frequently infested. Mating activity is moderate in November.Other more or less common tick species on these domestic animals are Boophilus decoloratus (Koch), R. e. evertsi Neum., R. simus Koch, H. anatolicum excavatum Koch, H. truncatum Koch and H. marginatum rufipes Koch, evidence for the status of which as a subspecies of H. marginatum Koch is to be presented in a subsequent paper. Several other rare species are also recorded.