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Performance and field host range of the life stages of Cornops aquaticum, a biological control agent of water hyacinth
Get PDFHost specificity determination of weed biocontrol agents has historically relied on evidence generated through quarantine trials in the region of introduction. These trials could give ‘false positive’ results due to a maximum type I error probability, and where possible, more research under field conditions should be conducted in the region of origin. The oligophagous, semiaquatic grasshopper, Cornops aquaticum Bruner (Orthoptera: Acrididae, Tetrataeniini), was released in South Africa for the biological control of Pontederia crassipes Pellegrini and Horn (Pontederiaceae). The aim of this study was to assess how the performance and field host range of C. aquaticum varies according to its stages of development, and how this contributes to the understanding of the relationship between the fundamental (laboratory-based) and the ecological (field-based) host range of this grasshopper, and its implications for water hyacinth biocontrol. We conducted post-release laboratory no-choice trials, confining early instars (instars 1 and 2), later instars (instars 3–6), and adult females and males in mesh cages, to determine insect performance on wetland plants growing in sympatry with P. crassipes. Also, gut analysis from field-collected C. aquaticum was done to determine the ecological host range of this insect, identifying epidermal tissue of consumed plants. In no-choice trials, survival rates of the later instars and adult C. aquaticum were similar on Pistia stratiotes L. (Araceae), Oxycaryum cubense (Poepp. and Kunth) Lye (Cyperaceae), and P. crassipes. However, under field conditions, P. crassipes and the congeneric Pontederia azurea Sw. were the only plant contents in the guts of early instars and the most abundant species in later instars and adults. The results support the hypothesis that C. aquaticum is an oligophagous insect on the genus Pontederia, and that different life stages should be considered when conducting host-specificity trials in externally feeding mobile herbivore species. Diet composition of field-collected insects thus could help detect false positives in laboratory trials, being an additional and realistic approach in understanding and predicting the selection processes of the insect in the new environment. Retrospective analysis of potential agents that were rejected due to lack of host-specificity, using the methods from this study, could add a suite of additional agents to programs where invasive weeds remain unmanaged
Impact of Access and Benefit Sharing implementation on biological control genetic resources
Get PDFThe third objective of the Convention on Biological Diversity, the fair and equitable sharing of benefits arising out of the use of genetic resources was further developed when the Nagoya Protocol on Access and Benefit Sharing came into effect in 2014. Interpretation of how this agreement is being implemented is wide-ranging and there are implications for biological control. A survey of biological control workers indicated that while some countries have facilitated access to biological control genetic resources, requirements in other countries have impeded biological control implementation. There was consensus that benefits to provider countries should be in the form of supporting local research communities. There was also agreement that the free use and exchange of biological control genetic resources has provided benefits to the global community, including to both providers and recipients of the agents. It is recommended that consideration of the free use and exchange principal should be a key element of Access and Benefit Sharing measures for the future
faces, disappearing
Get PDFMy thesis explores township life through the eyes of a young boy, Sengwayo, whose life changes when a strange man arrives unexpectedly to stay with his family. The man is introduced as his uncle but nothing further is said about him. Sengwayo soon begins to experience visions and decides to find out who this man really is. His search for truth soon becomes obsessive and culminates in tragedy. As we follow Sengwayo in his quest of uncovering the truth it becomes difficult to differentiate between Sengwayo’s imagination and reality. This thesis collapses the distance between what is and what could be. It does this by alternating short sentences mostly used in the poetry of maskanda lyrics, and in the stream of consciousness found in jazz improvisation. In literary terms, the thesis draws influence from the rants and rhyme schemes of Lesego Rampolokeng, the tone and pace of Sony Labou Tansi and the surrealism in Mangaliso Buzani’s work.Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 202
Investigating teachers’ perceptions on translanguaging pedagogy in a multilingual intermediate ESL classroom: a comparative study of two primary schools in Namibia
Get PDFInternational literature has tested the effectiveness of translanguaging as a pedagogic tool to enhance learning in a bilingual classroom; however, with the recent curriculum reform and education sector policy, there is no direct claim in the National policy frameworks on the prominence of translanguaging as an effective tool in classroom pedagogy in Namibian schools. This research attempted to investigate the role of translanguaging as a pedagogic tool to enhance learning in the multilingual intermediate English Second Language (ESL) phase as the Language of Learning and Teaching (LoLT) for the intermediate phase, Grades 4-7, in the Erongo Region, Namibia. The study is within the interpretive paradigm and adopts a qualitative methodology using a qualitative multi-case study approach of exploring and understanding differences and similarities between cases. Data collection consisted mainly of open-ended interviews and observations (purposive sampling) of the participating teachers. The research sites and study participants were purposely selected as both schools, diversely located in urban and rural contexts of the region, are enacting the National Language Policy as proposed. This entails using Mother Tongue Instruction (MTI) from Grades 0-3 and then transitioning to English-monolingual instruction from Grades 4 onwards. The study was designed to investigate the role of translanguaging pedagogy in enhancing learning in the Second Language (L2) classroom, without prejudice of social classes - the elite and marginalized communities. It investigated the extent to which teachers’ use of translanguaging pedagogy enhances ESL learning as the LoLT to intermediate phase learners transitioning from MTI to English-only instruction. The main theories underpinning this study are the Vygotskian and Translanguaging theories supported by Krashen and Cummins’ Cognitive Underlying Proficiency (CUP) Model. The outcomes of the study reveal that in both schools translanguaging was supported by content subject teachers and English LoLT teachers and that it positively contributed to improving learner understanding of important concepts in several subjects. However, Mother Tongue (MT) teachers did not support the use of translanguaging and believed that it slowed down the learning of English.Thesis (MEd) -- Faculty of Education, Institute for the Study of Englishes in Africa, 202
Fabrication of nanocatalysts as nanozymes-based biosensors for the detection of glucose and ascorbic acid
No full textEmbargoed. Expected release in 2025.Thesis (MSc) -- Faculty of Science, Chemistry, 202
Mineral paragenesis of olmiite/poldevaartite and rhodochrosite/shigaite occurrences in the Kalahari Manganese Field, and their relation to the formation of high-grade manganese ore of Nchwaning II mine, Black Rock, South Africa
Get PDFAccess restricted. Access embargoed until 2025.Thesis (MSc) -- Faculty of Science, Geology, 202
A grounded theory study of the identity and career decisions of artistic creative entrepreneurs
Get PDFThis research, in the field of creative careers, identity and entrepreneurship, aims to develop a grounded theory to explain the interaction between the phenomena of identity and career decision-making, focusing on Artistic Creative entrepreneurs in the creative industries. Artistic Creatives have unique characteristics and creative identities, presenting unique career opportunities. This research is interested in the different values of Artistic Creatives compared to those of Artistic Creative Entrepreneurs, who often experience a tension between their creative identity and their entrepreneurial identities The methodology used is the Straussian Grounded Theory. A Qualitative Research Approach used interviews to collect data on the careers and identity of Artistic Creative entrepreneurs in an area in the Eastern Cape Province of South Africa. Creative entrepreneurs work in the fields of fine art, design and crafts. The research procedure was recorded in detail, which enhances dependability. Ethics approval was obtained prior to the data collection. The data was analysed through open coding, axial coding and using a Straussian paradigm model. The findings present the values and identity of the Artistic Creative with Artistic Creative Archetypes and the entrepreneurial identities as Artistic Creative Entrepreneur Profiles. The Thesis by JC Gibson-Tessendorf effects of identity and contextual factors on their career patterns, especially as entrepreneurs, are analysed. The contribution that this study makes towards the creation of new knowledge is through, firstly, presenting aspiring creatives with career opportunities that relate to individual values. Secondly, it provides a model of Career Stage Options and Strategies that Artistic Creative Entrepreneurs may follow to either become part-time creative entrepreneurs or use the model as a guide for career planning. The study also developed a substantial theory proposing that the identities of Artistic Creative Entrepreneurs are 1) firstly multiple, 2) flexible and open to change, 2) driven by their values, 3) enacting across the tripartite identity framework, being personal identity, role identity and social identity. The concept of a tripartite of identities was taken from Brewer and Gardner (1996).Thesis (PhD) -- Faculty of Commerce, Rhodes Business School, 202
A case study of role conflict experienced by middle management during organizational change
Get PDFThis research investigation is based on continuous improvement changes arising from - and related to - ISO 9001 implementation at Sundays River Citrus Company (SRCC), which is one of the biggest packers, marketers, and exporters of citrus fruit in South Africa. The Board of SRCC adopted ISO 9001 to ensure organizational efficiency and sustainability while improving quality control, customer service, teamwork and leadership. However, research indicates not all organizations that have Implemented ISO 9001 realize the intended benefits. While no research was available on the citrus agriculture industry, research in the tourism industry indicates that not only did some companies not realize the expected benefits, but also incurred substantial investment costs. It is estimated that approximately thirty to ninety percent of change initiatives fail to meet their objectives, and research studies also indicate that middle managers play a critical role that can influence the outcomes of a change project. However, Balogun (2003) indicates that middle managers play a complex role and are exposed to role conflict, which can influence the outcomes of change initiatives. In this context, this research study aimed to investigate the role conflicts experienced by middle managers during the process of an ISO 9001 continuous improvement change. The study draws on role theory, applying it to their management of change. The following role conflict types were investigated: (1) intra-sender conflict, (2) inter-sender role conflict, (3) inter-role conflict, (4) role ambiguity and (5) role strain. The research approach is qualitative, and has adopted a post-positivist paradigm, utilizing a deductive qualitative method. The study adopted a case study approach. Data was gathered mainly from interviews and supported by organizational documents. Semi structured interviews were conducted with questions formulated through the use of the coding manual (See Appendix C) to ensure alignment of data collection with the research propositions derived from literature. A deductive thematic analysis method was used to analyze the interview data. The research findings confirmed that during continuous improvement change, as middle managers strived to satisfy the incompatible expectations of role senders (mainly senior and junior managers), they experienced the five role conflict types. The study findings also indicate that middle managers experience conflicts due to the incompatible expectations of other role senders such as quality and marketing departments. The findings suggest that middle managers are managing these conflicts, but notes that they do require some assistance and support from senior management. The study concludes with managerial and research recommendations.Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 202
Wildlife-vehicle collisions mitigation measures using road ecological data and deep learning
Get PDFAccess restricted. Expected release in 2025.Thesis (PhD) -- Faculty of Science, Mathematics, 202
Arbuscular mycorrhizal fungi associated with wheat under conventional and conservation agricultural cultivation
No full textAccess restricted. Expected release date in 2024.Thesis (PhD) -- Faculty of Science, Chemistry, 202