Thesis (Ph. D.)--University of Adelaide, Dept. of Plant Pathology, 1987. / Includes bibliographical references.

Thesis (M. Tech.(Biomedical Technology)) - Central University of Technology, Free State, 2010 / Introduction: Geophagia, generally referred to as earth-eating, occurs in many countries of the world, including African countries such as South Africa. A need was identified to characterize human geophagic habits and the microbiological content of geophagic clayey soil, including the presence of potentially pathogenic nematodes (geohelminths), in South Africa. Materials and methods: Questionnaires were developed to generate data on human geophagia and included demography, socio-economics, indigenous knowledge, business aspects, mining and hygiene practices of vendors/geophagists. A total of 52 soil samples (n = 52) were collected from the district of Thabo Mofutsanyane (Free State, South Africa), which comprised of vendor, topsoil, excavated and control soil sample groups. Nematode content were isolated using the Ammonium bicarbonate protocol, thereafter the nematodes were classified and population sizes determined for each sample. Soil colour classification was completed using the Munsell Soil Color Charts. Results and discussion: The questionnaire revealed that geophagia in this region was practised mainly by women of child-bearing age because of the taste of the soil. Vendors sell geophagic clayey soil (known as mobu) collected from the mountain- and riversides for subsistence, generally costing one to two rand per bag. Hygiene and environmental conditions are considered when mining geophagic clayey soils. Whitish-perceived clayey soils are preferred by most of the geophagists. According to the Munsell Soil Color classification, Thabo Mofutsanyane geophagic soils ranged from brownish, to greyish, to yellowish in colour. Vendor soils were mostly greyish, while topsoils, excavated soils and control soils were mostly brownish. No human pathogenic nematode ova or larvae were isolated from any of the samples, however 34 nonpathogenic nematode taxa representing five trophic levels were identified. These included mainly herbivores, but also fungivores, bacteriovores, omnivores and predators. Taxon richness (number of taxa) greatly varied in the soil sample groups with vendor soil n = 9, topsoil n = 24, excavated soil n = 16 and control soil n = 14. Tylenchus sp., Criconemoides sphaerocephalus and Ditylenchus sp. were the only nematode taxa identified in all the different sample groups, with Tylenchus sp. notably more abundant overall. When the median nematode population sizes were compared between the geophagic soil samples, no significant difference (p ≥ 0.05) could be identified. In contrast, the median nematode population sizes for all samples differed significantly (p < 0.05) from the control soil sample group. Conclusion: This study revealed that geophagia is probably not a vector for geohelminth infection in the district of Thabo Mofutsanyane, South Africa. However, the rich presence of non-pathogenic soil nematode communities in these brownish, greyish and yellowish geophagic soils may be useful as biological indicators of general soil health.

Includes bibliography / ii, 84 leaves, [7] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1987

The tundra ecosystem, with its frost-molded landscape and large peat reserves, is vulnerable to climate change. Thus, any increase in temperature due to global warming will cause changes in above-and belowground biota. Understanding the linkage between these biotas will help make prediction of the biodiversity and ecosystem functioning when global change phenomena occur, and consequently aid in making management strategies. The role of nematodes in nutrient cycling and decomposition, among many other attributes, make them useful organisms to study soil processes. Associations between plant and nematode communities, from six sites (Berm Face, Berm Crest, Tundra Heath, Polygon, Hummock and Forest) and from within a young, visually homogeneous tundra heath field site, were examined in the subarctic environment of Churchill, Manitoba. The study also provided nematofaunal information, which is very limited in this region. Multivariate analyses of nematode taxa abundance revealed four distinct groupings: Berm Face, Berm Crest, heaths (Tundra Heath, Polygon and Hummock) and Forest. The result showed a parallel relationship between nematode and vegetation assemblages, and thus, a seeming interdependency between above-ground and below-ground biota. Conversely, association between nematode and plant assemblages within a visually homogeneous tundra site was not as obvious. At this fine scale, the heterogeneous nature of edaphic factors and not plant assemblages is hypothesized to influence within-site nematode communities. The thesis also provided results to improve nematofaunal analysis to enhance their utility as bioindicators of soil food webs.

The tundra ecosystem, with its frost-molded landscape and large peat reserves, is vulnerable to climate change. Thus, any increase in temperature due to global warming will cause changes in above-and belowground biota. Understanding the linkage between these biotas will help make prediction of the biodiversity and ecosystem functioning when global change phenomena occur, and consequently aid in making management strategies. The role of nematodes in nutrient cycling and decomposition, among many other attributes, make them useful organisms to study soil processes. Associations between plant and nematode communities, from six sites (Berm Face, Berm Crest, Tundra Heath, Polygon, Hummock and Forest) and from within a young, visually homogeneous tundra heath field site, were examined in the subarctic environment of Churchill, Manitoba. The study also provided nematofaunal information, which is very limited in this region. Multivariate analyses of nematode taxa abundance revealed four distinct groupings: Berm Face, Berm Crest, heaths (Tundra Heath, Polygon and Hummock) and Forest. The result showed a parallel relationship between nematode and vegetation assemblages, and thus, a seeming interdependency between above-ground and below-ground biota. Conversely, association between nematode and plant assemblages within a visually homogeneous tundra site was not as obvious. At this fine scale, the heterogeneous nature of edaphic factors and not plant assemblages is hypothesized to influence within-site nematode communities. The thesis also provided results to improve nematofaunal analysis to enhance their utility as bioindicators of soil food webs.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 140-151).

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 176-190). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 176-190). Also available on the Internet.

Please read the abstract provided for each separate chapter and the General Summary (Chapter 9) added to the section 00front / Thesis (PhD (Entomology))--University of Pretoria, 2005. / Zoology and Entomology / unrestricted

Thesis (M.A. (Horticulture)) --University of Limpopo, 2010 / Refer to document / University of Namibia