Dynamics of tick populations (acari: Ixodidae) in the Eastern Cape Province of South Africa.

Abstract

A survey of ixodid ticks collected from livestock and from vegetation in the Eastern Cape Province of South Africa was carried out over a 5-year period. Five species, Rhipicephalus appendicidatus, Amblyomma hebraeum, Boophilus decoloratus, R. evertsi evertsi and Haemaphysalis silacea , were relatively abundant and 3 other species, R. s. simus, R. glabroscutatum , and Ixodes pilosus , were much less frequently encountered. R. appendicidatus showed a definitely seasonal pattern of activity. Larvae were present mainly during the early winter (April to June) and nymphs were active mainly during winter (July/August). Adult numbers increased sharply beginning in November, reached a peak in the late summer months (January/February), then decreased and finally disappeared in May. This tick was more common in bushy habitats than in open areas. A. hebraeum demonstrated a similar pattern of seasonal activity and like R. appendiculatus was abundant in humid habitats. B. decoloratus, R. e. evertsi and H. silacea were present throughout most of the year, and although they did not show a definite pattern of occurrence, they were more abundant during midsummer and midwinter. Seasonal activity, population size and dynamics of tick populations for each species from various habitats are presented. Patterns of activity are shown to be regulated by photoperiod and/or temperature, while population sizes are generally governed by humidity.