Host distributions do not limit the species ranges of most African ticks (Acari: Ixodida)

The factors that set broad-scale limits on the species ranges of ticks have not been clearly defined, despite their potential importance for the study and control of ticks. A database of 33,989 published collection records for African ticks is used to test the hypothesis that the outer limits to tick species ranges are determined by the distributions of their hosts. Distribution maps for many of the more economically important tick species are given. Direct comparisons of the known ranges of ticks and their hosts show that the hypothesis of a host-determined species range is supported for only one tick species, Amblyomma rhinocerotis (de Geer), which has been constrained by the near-eradication of its rhinoceros hosts. At least 97 other species are not host-limited; the quality of available host-use and distribution information is insufficient to draw strong conclusions about the (approximately) 132 remaining species, in general, the boundaries to tick species ranges are more likely to be set by factors such as vegetation and climate.