Publications

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paralysis of laboratory rabbits by nymphae of ixodes rubicundus, neumann 1904 (acarina: ixodidae) and some effects on the life-cycle following feeding under different temperature conditions.feeding under constant cold conditions resulted in a marginal shortening of feeding period and a major shortening of the subsequent developmental phase of all stages of ixodes rubicundus neumann 1904, the karoo paralysis tick. paralysis occurred in laboratory rabbits when nymphae were fed on them under constant warm, constant cold and fluctuating ambient winter conditions. this paralysis was found to be dependent on infestation rate and feeding conditions. under constant cold conditions paralysi ...19892726194
an evaluation of strategic and threshold control measures against the karoo paralysis tick, ixodes rubicundus (acari: ixodidae) in south africa.paralysis caused by feeding female ixodes rubicundus ticks is a major problem in large areas of south africa. as the life cycle of the tick extends over a period of 2 years, it was hypothesized that strategic treatment of sheep with an acaricide over a 2 year period, timed to kill most engorging females, should markedly lower the biotic potential of the tick. two flocks of sheep grazing in separate paddocks known to be infested with i. rubicundus were treated either strategically or on a thresho ...19957634969
sex ratio characteristics in ixodes rubicundus (acari:ixodidae), the karoo paralysis tick.the sex ratio is an important parameter which characterizes the state and dynamics of natural populations of animals. although ixodid ticks are specialized ectoparasites, most species are bisexual and are characterized by a 1:1 sex ratio for their progeny. in natural populations and even in laboratory colonies, biased sex ratios are often observed. ixodes rubicundus, the karoo paralysis tick, parasitizes domestic stock and wild ungulates in south africa. adults quest from vegetation, can mate of ...19968856964
the dispersion of the karoo paralysis tick, ixodes rubicundus, within a naturally infested population of sheep in south africa.the ratio of variance to mean (s2/means) of numbers of ixodes rubicundus (males and females) per sheep was used as a measure of the dispersion pattern of this tick within a naturally infested population of sheep. sheep were divided into two groups, one with previous contact with i. rubicundus and the other with no previous contact. samples of 10 sheep from each group were searched for ticks on a weekly basis for 19 weeks during the winter of 1986. in each group, both male and female ticks had an ...19902316179
the role of host behaviour in tick-host interactions: a domestic host-paralysis tick model.the aim of this study was to quantify the infestation densities of karoo and brown paralysis ticks on sheep and goats and explain it in terms of the etho-ecology of these ticks and their domestic hosts. the karoo paralysis tick usually quests from a vantage point on the vegetation whereas the brown paralysis tick displays an appetence response from the ground and mainly engages hosts that are prostrate. both tick species are confined chiefly to hilly areas. temporal differences in the infestatio ...19921563303
seasonal dynamics of the karoo paralysis tick (ixodes rubicundus): a comparative study on merino and dorper sheep.karoo paralysis in south africa is induced in livestock by feeding female ixodes rubicundus ticks when infestation densities on hosts exceed certain critical levels. it has been shown previously that angora goats are at a higher risk of being paralysed than merino sheep, and such differences have been related to differences in feeding behaviour and spatial distribution of the two small-stock breeds. we hypothesized that differences in infestation densities with karoo paralysis ticks would also o ...19969173358
spatial and temporal variations in the commencement of seasonal activity in the karoo paralysis tick, ixodes rubicundis.successful prophylaxis of paralysis, induced in small stock by feeding female ixodes rubicundus, is dependent on the accurate determination of the commencement of seasonal activity by the tick. the commencement of this activity was recorded for 11 consecutive years on a farm in the south-western free state, south africa, and for shorter periods on other farms, some of these in regions with markedly colder climates. the colder the mean minimum atmospheric temperatures during the 2 months precedin ...19969173361
interbreed differences in the efficacy of 1% deltamethrin pour-on to protect small livestock against infestation with ixodes rubicundus (acari:ixodidae).synthetic pyrethroid pour-on compounds have been developed for use on cattle but many are now also registered for the control of ectoparasites on small ruminants. the breed of small livestock has been known to influence the efficacy of various pour-ons and we hypothesized that differences in the duration of protection afforded by a synthetic pyrethroid pour-on against ticks on small livestock, would be greatest between hairy and woolly breeds. angora goats with mohair, dorper sheep with hairy wo ...19968792585
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