| parasites of domestic and wild animals in south africa. xxxi. adult ixodid ticks on sheep in the cape province and in the orange free state. | four to 10 dorper sheep on each of 12 farms in the cape province and 3 farms in the orange free state were examined for adult ixodid ticks at approximately 2- to 4-weekly intervals over periods varying from 4 to 18 months, commencing during january, february or april 1989. the farms in the cape province were located in the north-west, south-west and south of the province. those in the orange free state were situated in the north-east and in the south. the sheep in the cape province harboured 10 ... | 1992 | 1297957 |
| 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 ... | 1995 | 7634969 |
| 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 ... | 1990 | 2316179 |
| 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 ... | 1996 | 9173361 |
| 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 ... | 1996 | 9173358 |
| control of karoo paralysis ticks through vegetation management. | karoo paralysis, caused by feeding ixodes rubicundus females, is a major disease of small stock in south africa. control methods currently practised are almost exclusively chemical based. to limit overdependance on chemicals, vegetation management was investigated as a possible method for control, to be incorporated in an integrated tick management system. laboratory and field experiments were conducted to determine, firstly, the extent of vertical migration and survival of ticks on long and sho ... | 1996 | 8834741 |
| 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 ... | 1996 | 8792585 |
| improvement of field sampling methods for adult karoo paralysis ticks, ixodes rubicundus (acari: ixodidae), through addition of host odour. | the responsiveness of ixodes rubicundus ticks on questing substrates and the success of their attachment to non-living substrates were investigated. the purpose of this study was to relate responsiveness to conditions of temperature and humidity, to compare the efficacy of flagging and dragging methods to estimate the size of populations of adult i. rubicundus in the field, and to determine the possible influence of host odour on the efficacy of these methods. responsiveness was tested under var ... | 1995 | 7656732 |
| 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 ... | 1996 | 8856964 |
| the effect of the pattern of attachment weights of female ixodes rubicundus on karoo paralysis in a naturally infested flock of sheep. | the weights of feeding female ixodes rubicundus attaching to sheep was studied in a natural focus of karoo paralysis. the studies showed fewer females in the middle weight ranges and more in the heavier and lighter categories than would be expected if the distribution was normal. weights were also strongly skewed towards the lighter females between 0 and 400 mg. no differences in the pattern of attachment weights occurred over the four experimental groups used, suggesting that previous contact o ... | 1989 | 2800303 |
| 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 ... | 1989 | 2726194 |
| the seasonal abundance of adult ixodid ticks on merino sheep in the south-western orange free state. | with the exception of october, when no collections were made, adult ticks were collected at weekly intervals from february 1986 to january 1987 from 20 randomly selected sheep out of a flock of 60. ixodes rubicundus was the most abundant tick and was present from april to september with a peak during may. hyalomma marginatum rufipes was the next most numerous tick. it was recovered throughout the year with peak burdens being recorded from november to april. small numbers of a rhipicephalus sp. ( ... | 1988 | 3210216 |
| seasonal incidence of karoo paralysis in relation to the infestation density of female ixodes rubicundus. | the epidemiology of karoo paralysis, induced by the tick ixodes rubicundus, was investigated in a paralysis-enzootic area of the southwestern orange free state, republic of south africa. sheep became paralysed during the last week of april and the first week of may during the 1985 and 1986 seasons, respectively. paralysis cases were recorded up until july, but most paralysis cases occurred during the first week of may with a second but smaller peak occurring during june. tick numbers on paralyse ... | 1989 | 2815541 |
| a survey of karoo tick paralysis in south africa. | recent research interest in karoo tick paralysis and its vector. ixodes rubicundus, prompted this survey to determine the economic implications of this disease. the survey indicated relatively high losses caused by the condition, identified the stock involved and provided data on the incidence of paralysis and on the control methods employed. recommendations are made to institute chemical control earlier in the season to attempt better containment of the problem. | 1988 | 3393373 |