Taxonomy and ecology of parasitic chigger mites (Acari: Trombiculidae) on small mammals in South Africa

Malan, Karlien (2015-03)

Thesis (MSc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Within South Africa (SA) parasites have received variable attention with limited research conducted on mites within the family Trombiculidae. They are regarded as temporary parasites with only the larval stage or “chigger” being parasitic. The present study investigated the diversity, ecology and distribution of chiggers associated with small mammal hosts (rodents and insectivores) across SA, with a focus on the Cape Floristic Region (CFR). The study supports the existence of seasonal occurrence of chiggers in a temperate region. Chiggers that occurred on a generalist rodent host were most prevalent during the warm dry months of the year as opposed to wet cold months. Total counts conducted on the bodies of several co-occurring rodent species in the CFR recorded a diverse assemblage of chigger species. The findings support previous studies in that chiggers are host generalist, though there does appear to be a preference for the most abundant host species, Rhabdomys pumilio, in the biotype. Host species were parasitized by multiple chigger species of which Leptotrombidium muridium was the most abundant species. The study recorded and described three new chigger species (Austracarus n. sp., Microtrombicula n. sp. and Schöngastiella n. sp.). Chigger abundances were found to be higher on reproductively active as opposed to non-active hosts. Twelve chigger species were recorded across SA and the individual species showed variation in extent of their geographic range. On-host distribution of chigger species recorded a preference for the tail area of the host, which was shared by the three most abundant chigger species. This pattern may explain the higher co-occurrence of chigger species than expected by chance that was recorded on R. pumilio. It is evident that chiggers of small mammals are a diverse group that vary spatially and temporary across the landscape.

AFRIKAANSE OPSOMMING: Die verskeie parasiet taksa wat in Suid Afrika (SA) voorkom het ongelyke aandag ontvang tydens parasitologie studies tot dusver. Trombiculidae myte is een van die parasiet groepe wat baie min aandag ontvang het. Die groep myte word beskou as tydelike parasiete, weens die feit dat slegs die larf stadium (ook verwys as “chigger”) van die myt parasities is. Die studie het die diversiteit, ekologie en geografiese verspreiding van chiggers bestudeer wat geassosieer word met klein soogdiere binne SA, met ‘n fokus op die Kaapse Floristiese Ryk (KFR). Die studie het bevind dat chiggers ‘n seisoenale voorkoms het, hul was meer volop tydens die warm droë maande in vergelyking met nat en koel winter maande, soortgelyke resultate is aangeteken in ander dele van die wêreld. Die studie het ook gevind dat die myte wat in die KFR nie gasheer spesifiek was nie, maar dat hul wel ‘n voorkeur getoon het vir die gasheer wat die volopste was, Rhabdomys pumilio. Die verskeie gasheer spesies wat ondersoek was was deur verskillende chigger spesies geparasiteer waarvan Leptotrombidium muridium die mees volopste was. Drie nuwe chigger spesies is beskryf tydens die studie (Austracarus n. sp., Microtrombicula n. sp. and Schöngastiella n. sp.). Die resultate van die studie het ook gedui dat gashere wat reproduktief was hoër getalle myte gehad het wat op hul geparasiteer het in vergelyking met gashere wat nog nie reproduktief aktief was nie. Twaalf chigger spesies was tydens die studie aangeteken, hul het verskil in terme van hul geografiese verspreidings. Die verspreiding van die myte op die gasheer se lyf was ook bestudeer en daar was bevind dat die myte ‘n voorkeur toon vir die stert area van die gasheer. Die verskillende chigger spesies het ook saam voorgekom op ‘n spesifieke aanhegtings plek op die muis se lyf en geen uitsluitings-kompetisie was gevind nie. Die gevolgtrekking van die studie is dat chiggers wat klein soogdiere parasiteer in SA ‘n baie diverse groep is wat verskil ten opsigte van hul geografiese verspreiding asook in terme van in hul seisoenale teenwoordigheid binne die landskap.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96617
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