Distribution and ecology of economically important ticks on cattle, with special reference to the Eastern Cape Province, South Africa and Namibia

Nyangiwe, Nkululeko (2017-12)

Thesis (PhDAgric)--Stellenbosch University, 2017.

Thesis

ENGLISH SUMMARY: Ticks (Acari: Ixodidae) are parasites of major economic and medical importance that transmit a multitude of pathogenic organisms affecting domestic animals globally and in South Africa. High tick infestations are associated with skin damage, tick worry, reduced growth and milk production, transmission of tick-borne pathogens and mortalities. The aims of the study were to: (1) investigate the effect of vegetation type (Albany Coastal Belt, Amathole Montane Grassland, Bhisho Thornveld and Great Fish Thicket) on the tick species composition and diversity on cattle and on the vegetation on communal farms in the south-west region of the Eastern Cape Province (ECP), (2) obtain baseline data on the perceptions of cattle farmers with regard to ticks, tick-borne diseases (TBDs) and the management practices being used on communal farms in the ECP and (3) record the geographic distribution of an alien invasive tick, Rhipicephalus microplus and the closely related endemic species Rhipicephalus decolaratus in the environmentally less optimal south-western and north-western regions of South Africa and in Namibia. The study was conducted at two scales: local (ECP) and regional (South Africa and Namibia). At a local scale, ticks were collected from cattle (adult and calves) and from the vegetation from five localities in each of four vegetation types. Ticks were removed from one-side of each animal (n = 1000) and replicated drag-sampling was performed at each locality, to record the ticks on vegetation. In addition, at each locality five cattle owners were randomly selected to participate in a questionnaire study. Face-to face interviews were carried. A total of 100 individual questionnaires were completed (25 in each of the four vegetation types). At a regional scale, ticks were collected through active tick removal from cattle and by passive citizen-science approach where tick samples were provided by private cattle farmers solicited via social media. Cattle (n = 415) were examined in the Western-, Eastern- and Northern Cape and Free State Province in South Africa and in Namibia (n = 18). About 20 212 ticks belonging to 12 species were collected from adult cattle, calves and on vegetation at the 20 communal localities. Vegetation type did not consistently affect tick abundance, species richness or species composition, though there were differences in the abundance of individual tick species. The abundance of R. e. evertsi was significantly higher on cattle in Thornveld and Thicket compared to Coastal belt and Grassland, while A. hebreaum was significantly more abundant on the vegetation in Coastal belt compared to Thornveld and absent in Grassland. The effect of individual villages on tick infestations was more important than vegetation types. Tick abundance and species richness was higher on adult cattle compared to calves. In terms of farmer perceptions, significantly more respondents confirmed that adult animals were more affected by ticks compared to calves. All of the respondents identified redwater as the commonest TBDs, followed by gallsickness (90%) and heartwater (43%). For the geographic distribution of R. microplus, a total of 8 408 Rhipicephalus (Boophilus) spp. ticks were recovered from cattle in SA. R. microplus extended its range to new areas for the first time in the Northern Cape Province and the western regions of the Eastern- and Western Cape Provinces. In Namibia, R. microplus was recorded for the first time with 142 adult R. microplus collected from 20 cattle on four farms, whereas R. decoloratus was present on all 18 of the survey farms in Namibia. Evident from the study is that the concern of communal cattle farmers in the ECP about ticks and TBDs is supported with field-based studies. The patterns of tick infestation observed in the present study seems to be the result of a combination of factors that include amongst others the uncontrolled movement of cattle within SA and between SA and Namibia, the development of acariside resistance and the highly adaptable nature of the invasive Asiatic tick.

AFRIKAANS OPSOMMING: Bosluise (Acari: Ixodidae) is parasiete van groot ekonomiese en mediese belang wat verskei patogene aan huis- en plaasdiere oor dra. Hoë bosluis besmetting hou verband met vel beskadiging, verminderde groei van diere en melkproduksie, oordrag van bosluis-oordraagbare patogene en sterftes. Die doelwitte van die studie was om: (1) die effek van plantegroei tipe (Albany kusstrook, Amathole berggrasveld, Bhisho Doringveld en Groot Vis- bos) op die bosluisspesies samestelling en diversiteit op beeste en op die plantegroei op kommunale plase in die suidweste streek van die Oos-Kaap (OK) te bepaal, (2) basislyndata op die persepsies en kennis van beesboere met betrekking tot bosluise, bosluisoorgedraagde siektes (BOSs) en die bestuurspraktyke wat gebruik word op kommunale plase in die OK te verkry en (3) die geografiese verspreiding van 'n uitheemse bosluisspesie, Rhipicephalus microplus en die naverwante endemiese spesies Rhipicephalus decolaratus in minder optimale suidwestelike en noordwestelike streke van Suid-Afrika en in Namibië aan te teken. Die studie is uitgevoer op twee skale: plaaslik (OK) en streeks (Suid-Afrika en Namibië). Op 'n plaaslike skaal, is bosluise van beeste (volwasse en kalwers) en van die plantegroei van vyf lokaliteite in elk van vier plantegroeitipes versamel. Bosluise is van die een kant van elke dier (n = 1000) versamel en herhaalde sleep-opnames is uitgevoer by elke lokaliteit, om die bosluise op die plantegroei aan te teken. Daarbenewens, by elke lokaliteit is vyf bees-eienaars ewekansig gekies om deel te neem in 'n vraelys-studie. Aangesig tot aangesig onderhoude is gevoer. 'n Totaal van 100 vraelyste is voltooi (25 in elk van die vier tipes plantegroei). Op 'n streeks skaal is bosluise ingesamel deur middel van aktiewe bosluis verwydering van beeste en deur passiewe burger-wetenskap benadering waar bosluise verskaf is deur private beesboere. Beeste (n = 415) was geondersoekte in die Wes-, Oos- en Noord-Kaap en Vrystaat in Suid-Afrika en in Namibië (n = 18). Die resultate is soos volg, sowat 20 212 bosluise wat deel uitmaak van 12 spesies is versamel van volwasse beeste, kalwers en op plantegroei by die 20 kommunale lokaliteite. Plantegroei tipe het nie deurgans ‘n invloed op spesierykheid of spesiesamestelling gehad nie. Daar was egter verskille tussen individuele bosluisspesies. Rhipicephalus evertsi evertsi was aansienlik hoër op beeste in Bhisho Doringveld en Groot Vis-bos in vergelyking met Albany kusstrook en Amathole berggrasveld, terwyl Ablyomma hebraeum aansienlik meer volop was op Albany kusstrook in vergelyking met Bhisho Doringveld en afwesig in Amathole berggrasveld. Die effek van individuele dorpe op bosluis besmetting was belangriker as plantegroeitipes. Bosluis getalle en spesierykheid was hoër op volwasse beeste in vergelyking met kalwers. In terme van die persepsies en kennis van kommunale beesboerer het aansienlik meer respondente bevestig dat volwasse diere meer geraak word deur bosluise in vergelyking met kalwers. Al die respondente het gemerk dat rooiwater die algemeenste BOSs is, gevolg deur galsiekte (90%) en hartwater (43%). Die studie wat gefokus het op die geografiese verspreiding van R. microplus het 'n totaal van 8 408 Rhipicephalus spp. bosluise van beeste in SA verhaal. Daar is gevind dat R. microplus se verspreiding uitgebrei het en die spesie kom vir die eerste keer in die Noord-Kaap Provinsie en die westelike streke van die Oos- en Wes-Kaap voor. In Namibië is R. microplus vir die eerste keer aangeteken. Meer as 100 volwasse R. microplus is versamel van 20 beeste op vier plase, terwyl R. decoloratus teenwoordig was op al 18 van die plase in Namibië. Uit die studie blyk dit dat die kommer van kommunale veeboere in die OK oor bosluise en BOSs ondersteun word deur veld-studies. Die patrone van bosluis besmetting wat waargeneem is in die huidige studie blyk die gevolg te wees van 'n kombinasie van faktore. Dit sluit onder andere die onbeheerde beweging van vee in SA en tussen SA en Namibië, die ontwikkeling van weerstand, teen bosluis-beheer middels, en die hoogs aanpasbaar aard van die indringer Asiatiese bosluis in.

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