The effect of rainfall on tick challenge at Kyle Recreational Park, Zimbabwe

Abstract

The effect of rainfall pattern on tick challenge was investigated at Kyle Recreational Park, Zimbabwe, from 1991 to 1992 using drag and removal plot methods to sample environmental tick density. The abundance of adults and nymphs of the brown ear-tick Rhipicephalus appendiculatus and larvae of the bont tick Amblyomma hebraeum was positively correlated with monthly rainfall, whereas no relationship with rainfall was revealed for larval R. appendiculatus, adults of the red-legged tick R. evertsi, or larvae of the blue tick Boophilus decoloratus. A comparison between 1991 (490 mm rainfall) and the drought year of 1992 (161 mm) revealed significant differences in the abundance of R. appendiculatus, A. hebraeum, and B. decoloratus. During the wet season, R. appendiculatus adults were 2-3 times more numerous in the environment during the higher rainfall year of 1991. A. hebraeum larval abundance exhibited a similar pattern to that of R. appendiculatus adults, but B. decoloratus larvae were more abundant in the drought year of 1992 during both the wet and dry seasons. Comparable tick abundance data collected at Kyle during the above-average rainfall years of 1975-1977 (mean = 1029 mm) were compared with tick challenge during the below-average rainfall years of 1991-1992 (mean = 326 mm). In grassland sand habitat and all habitats combined R. appendiculatus adults, nymphs, and larvae were much more abundant during the high rainfall years. In contrast, larvae of B. decoloratus were more numerous during the drier years. A hebraeum larvae were also more abundant during the drier years. The strong positive correlation of adult R. appendiculatus abundance with rainfall and the coincidence of increased adult tick challenge with increased rainfall indicate that adult R. appendiculatus tick burden on hosts would be heaviest during the wet season and high rainfall years.

Identification of hard ticks (Acari: Ixodidae) and seroprevalence to Theileria parva in cattle raised in North Kivu Province, Democratic Republic of Congo

“…The species was not found at higher altitude which confirms previous studies carried out in Rwanda at altitudes comprised between 1,000 and 1,550 m (Bazarusanga et al 2007a) and in Uganda between 1,100 and 1,350 m (RubaireAkiiki et al 2004). It is well known that tick distribution and abundance are largely determined by different bio-climatic factors (Estrada-Peña 2003; Moorling et al 2004) including the availability of appropriate hosts (Cummings 2002;Olwoch et al 2003). During the present work, rainfalls were low at high altitude.…”

Scratch that itch: revisiting links between self-directed behaviour and parasitological, social and environmental factors in a free-ranging primate

“…Revisiting studies linking SDB changes to environmental or social changes taking into account ectoparasite loads could fill the gaps in our knowledge of mechanisms or functions that we are still unable to explain fully, for example considering the inconsistent results about the links between social grooming and scratching, or the so-far under-investigated difference between a stimulus and an idiopathic itch, or the inclusion of a broader range of ectoparasites such as ticks and fleas (e.g. [8,27,72,73]).…”

“…Increased frequency of body care has also been related to high ambient temperatures and humidity or rainfall [6][7][8][9]. Underlying mechanisms behind this environmental hypothesis are often linked to ectoparasite load because the life cycle of many ectoparasites is also influenced by environmental seasonality and their abundance thus fluctuates seasonally [8,27,28]. As the mammalian pelage constitutes the habitat of their ectoparasites, variation in its quality should greatly influence ectoparasite fitness and population dynamics [1], thereby creating the potential for pelage-associated variation in SDB frequency due to habitat-associated effects on ectoparasite loads.…”

Statistical modeling of annual highest monthly rainfall in Zimbabwe

“…However, there have been several papers focusing on rainfall (not maximum rainfall) in specific regions of Zimbabwe. For example, Mooring et al 2 examined the effect of rainfall on tick challenge at Kyle-Recreational-Park, Zimbabwe; Gargett et al 3 examined the influence of rainfall on Black Eagle breeding in the Matobo Hills, Zimbabwe; Bourgarel et al 4 studied the effects of annual rainfall and habitat types on the body mass of impala in the Zambezi Valley; Muchuru et al 5 assessed variability of rainfall over the Lake Kariba catchment area in the Zambezi river basin; Sibanda et al 6 studied long-term rainfall characteristics in the Mzingwane catchment of south-western Zimbabwe; and so on.…”