Adult tick burdens and habitat use of sympatric wild and domestic ungulates in a mixed ranch in Zimbabwe : no evidence of a direct relationship
2002
De Garine-Wichatitsky, Michel
Ticks do not usually infest sympatric hosts species according to their availability in a given environment, and it has been suggested that habitat use by hosts is a major determinant of tick burdens. The knowledge of such infestation patterns and their relationship with host habitat use is important for the control of the vectors of some major stock diseases in Africa, particularly in the context of mixed game/cattle ranching. In a ranch of Zimbabwe, we monitored the number of adult ticks found on cattle and wild ungulates. Tick bur-dens were measured weekly during one year on 12 heifers of an experimental herd (no acaricide used), and on wild ungulates occasionally shot for meat. Adult ticks were not evenly distributed among wild hosts, and infestation patterns corresponded to observations made by several authors in similar conditions. However, these infestation patterns could not be related to habitat use by ungulates, which had been previously monitored by road transect at the scale of the ranch, as these authors found a high niche overlap and no habitat segregation between ungulate species. In an attempt to relate habitat use by Brahman and Simmental heifers with the number of adult ticks collected during one day of grazing, we followed the heifers and recorded their position and activity (one or two days per week; each recording session was 7h30 min on average, for a total of 940 hours of survey). No correlation was found between the number of ticks collected and the distance (or time spent) traveled in each vegetation type or the number of grooming episodes. The possible role of other behavioral and physiological parameters is discussed, and the results are compared with those found for other tick-host associations. (Résumé d'auteur)
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