Diurnal and seasonal activity of unfed adults of Rhipicephalus Appendiculatus, Neumann 1901 inrelation to some factors in the micro-environment
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A study was conducted on the activity response of unfed adults of Rhipicephalus appendiculatus to some of the environmental changes during the three main seasons here in East Africa. Ticks of two different ages were subjected to various treatments in the laboratory to vary their physiological (hydration) states and thereafter exposed in the field. Observations were made on the activity responses in relation to changes in temperature and relative humidity within the micro-habitat at two different sites. The results obtained showed that fully hydrated ticks were more active than the dehydrated ones. Similarly, six months old ticks were more active than the two months old ones. The fully hydrated ticks became active immediately after release into the field plots, while the dehydrated ticks needed to replenish the water lost during the dehydration process before they showed any sign of activity. They, therefore, remained inactive for 1-2 days after release. Although the dehydrated ticks were taking up water more rapidly during the wet season, the fully hydrated did not show any significant changes in their degree of water uptake. The ticks were generally losing more water during the day than they were able to replenish at night during the hot dry season, hence, progressive loss of water. The vertical distribution of ticks in the habitat was very much related to season, 'with most ticks found in the upper part of the during the rainy season while most of them were found at the so el during the hot dry season. Temperaturs between 2D°C 30°C seemed to be the optimal range for activity of the fully hydrated tick, below or above which activity will be markedly reduced. Temperature, therefore, seemed to be the triggering factor for activity. Ticks appeared to be indifferent to changes of darkness and light, but with the right hydration state, probably near full hydration, temperature and relative humidity of the microhabitat appear to be the cues for the daily pattern of tick activity which is also reflected in the seasonal pattern of activity. There was no significant difference in activity between the sexes, and also between the two sites. Probably due to the small number of ticks active, the seasons also did not differ significantly.
Faculty of Agriculture, University of Nairobi