Tick (Acari: Ixodidae) infestations on Zebu cattle in western Kenya: seasonal dynamics of four species of ticks on traditionally managed cattle.

A study was conducted on the population dynamics of four tick species infesting livestock on Rusinga Island. Infestations of Rhipicephalus appendiculatus Neumann, Rhipicephalus evertsi evertsi Neumann, Amblyomma variegatum (F.)., and Boophilus decoloratus (Koch) were monitored on East African shorthorn Zebu cattle at monthly intervals for 2 yr. These cattle were of unimproved stock under traditional husbandry without any tick control practices. Most ticks were on cattle between September and March, with a peak in December-February. Following the onset of the rainy season in April, tick numbers on the cattle declined markedly; this decline continued until July or August, when numbers started to increase again. No significant correlation could be made between these population changes and any of the four climatic factors recorded. Instead, there was a notable relationship between tick population changes and local farming practice. The area and duration of cattle grazing activity were severely curtailed during the cropping season from April to September, which reduced tick-host contact and thus the tick burdens of the cattle at that time.