Biotic resistance towards Hydrellia egeriae, a biological control agent for the aquatic weed Egeria densa, in South Africa

Egeria densa is a submerged aquatic weed that can grow into dense monocultures in rivers and dams in South Africa, which negatively affects ecosystem functioning and services. The biological control agent Hydrellia egeriae Rodrigues-Júnior (Diptera: Ephydridae) was first released against Egeria densa Planchon (Hydrocharitaceae) in South Africa in 2018. Biotic resistance in an introduced range can have negative impacts on the ability of a biological control agent to establish and exert top-down pressure. Dipteran and lepidopteran species that are used as biological control agents are often susceptible to higher levels of parasitism in their introduced range than biological control agents from other insect orders. In addition, ecological analogues that are present in South Africa, make H. egeriae particularly vulnerable to biotic resistance. Considering this, post-release surveys were conducted to investigate if native parasitoids will extend their host range to include H. egeriae. Chaenusa seminervata van Achterberg, C. anervata van Achterberg (Braconidae: Alysiinae: Dacnusini) and Ademon lagarosiphonae van Achterberg (Braconidae: Opiinae) were reared from field-collected H. egeriae pupae, within a year of its release. These braconid parasitoids were previously recorded from a native herbivore, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae)

The demographic-specific prey preferences of lions and cheetahs, and potential impacts on prey populations

Understanding prey selection offers predictive insights into predator-prey interactions, which can be extended to explore the impacts of predators on prey populations. Prey availability and vulnerability vary across species, demographic classes, body sizes, and seasons. Traditional prey selection models for large carnivores, based on estimates of prey body size, assume uniform vulnerability across prey demographic classes and seasons, failing to account for these variations. This study aims to contrast seasonal shifts in demographic-specific prey preferences between lions and cheetahs and examine the potential impact of their demographic-specific predation patterns on a range of prey species across a body size spectrum. It was predicted that cheetahs would shift their selection from adults and juveniles of smaller prey species in the dry season to neonates and juveniles of both smaller and larger prey species in the wet season, while lions would select adults irrespective of the season. Additionally, predation focusing on adults would have a greater impact on prey populations compared to predation focusing on non-adults. Furthermore, it was predicted that prey populations experiencing demographic-specific selection from both lions and cheetahs would be impacted more than species selected by only one predator. Degrees of preference (DOP) were estimated based on prey availability (camera traps) and prey use (GPS clusters) for lion and cheetah populations in Lapalala Wilderness Reserve. Generalized Additive Models for Location, Scale, and Shape (GAMLSS) were used to determine seasonal shifts in demographic-specific prey preferences. The seasonal-demographic specific predation patterns of lion and cheetah, along with prey vital rates extracted from the literature, were then used to model potential predation impacts on prey populations using both Leslie-Usher and Lefkovitch matrix models. Lions preferred larger adult prey such as blue wildebeest, eland, and buffalo, while cheetahs preferred smaller prey, particularly juveniles of small to intermediate-sized species like impala, kudu, blue wildebeest, and zebra. Both predators showed seasonal shifts in demographic-specific prey preferences, with lions selecting adult buffalo during the dry season and juvenile buffalo in the wet season, and cheetahs selecting juveniles in the dry season and neonates and juveniles during the wet season. Lions and cheetahs exerted the highest degree of top-down limitations on their preferred prey. Predation on adult prey had a greater effect on prey population growth rates than predation on non-adults, especially in the dry season. Intermediate-sized prey species experienced the highest predation pressures, while larger prey species were more affected than smaller ones, contrary to the size-nested predation hypothesis. My study represents a first effort in the southern hemisphere to model the demographic impacts of multiple predators on diverse prey species, incorporating seasonal and demographic-specific prey preferences. The findings emphasise the importance of incorporating prey demographics and seasonality in predator-prey studies as these refined studies have implications for the management and conservation of both predator and prey populations.Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 202

Learners’ understanding of their linguistic resources as a basis for learning natural sciences

With eleven official languages, South Africa is known for its multilingual environment. Despite this, the country's educational system heavily favours English and Afrikaans. Despite the varied linguistic backgrounds of learners, English continues to be used as the Language of Learning and Teaching (LoLT), which raises questions regarding fair access to education. Within the context of South Africa's constitution and policy frameworks, particularly the Language in Education Policy (LiEP), this study aims to investigate how group work activities in a Natural Sciences classroom can give learners an opportunity to mobilise their multilingual repertoires. Three formerly Afrikaans-medium high schools in the Northern Areas of Gqeberha, were the sites for this research which focuses on Grade Nine Natural Sciences learners. Through the use of both quantitative and qualitative methods such as questionnaires, classroom observations, and focus groups, the study explores how learners make use of their language resources to navigate science instruction in English. The results contest the idea that languages are distinct entities and show that learners use language interchangeably as a learning tool, a practice known as translanguaging. Group work becomes an important space in which learners exercise agency in language selection, enabling the link of dialogical, multilingual, and cultural responses. Sociocultural theory offers insights into group work relationships and provides the theoretical foundation for understanding how learners use language to understand scientific topics. Building on Gibbons' mode continuum (2003), which maps the shifts in discourse in classroom contexts from every day talk at the “here and now” to more specialized talk, the study also explored an expanded continuum which aimed at clarifying the nuances of language and cognitive progression among learners working in collaborative groups. This study adds to the conversation about language ideologies by recognising the ideologies of inclusion, access and identity which informed learners’ thinking and attitudes to language choice in education. Thus, the study emphasises the importance of a sophisticated comprehension of multilingual repertoires in the classroom. In order to better accommodate the changing linguistic patterns of multilingual learners, the study recommends re-evaluating language policies and encouraging educators to exploit the potential of group work to develop understanding of scientific concepts.Thesis (DPhil) -- Faculty of Education, School of Post Graduate Education, 202

Preparation and Investigation of coumarin-based chemosensors towards sensing of ions using UV studies in aqueous systems

Humanity's unrelenting expansion has shown little regard for the environment, and this has resulted in tons of toxic heavy metal cations and anions being released into the environment through industrial, agricultural, electronic, and mining dumping. The release of these toxic heavy metals can cause diseases and sometimes lead to death, especially in third-world countries with low-income that reside in informal settlements, who suffer the most. Furthermore, the release of these toxins eventually finds their way back into the environment through bioaccumulation in fish, plants and animals. Although there is an ever need for the growth of these industries; low-cost, sensitive, selective, and organic-based sensors is a positive step forward in highlighting the need for environmental restoration and remediation, whilst striving to avoid unnecessary disease and death through this development. In this project, coumarin-based chemosensors for the detection of cationic and anionic species in aqueous and organic media are described. This project involves the synthesis of six different coumarin-based ether derivatives (E2-E5) and coumarin-based ester derivatives (H1-H2). FT-IR, 1H NMR and 13C NMR were used to confirm the structures of all sensors. The abilities of these novel compounds as chemosensors for detection of cations and anions were investigated using UV-vis analysis. These compounds displayed a favourable interaction with Fe2+ and Fe3+ ions with an increase in absorbance. Ether derivatives E2-E5 did not display any degree of selectivity or sensitivity towards the chosen anions. It was found that in the presence of FeCl2, sensors H1 and H2 displayed a degree of selectivities and further investigations were therefore carried out. From the titration experiments, the limit of detection, limit of quantification and association constants were determined. Job’s plot analyses were performed to determine the binding ratios, which was supported by Benesi-Hildebrand studies. The binding ratio between the sensors and metal cations during complexation was found to be 1:1. Reversibility studies were carried out using EDTA to determine whether the sensors could be reused. Molecular Modelling studies were used to determine the most preferred binding sites. Lastly, real-life application screenings were also run to determine if the sensors will be able to be used in real-life scenarios.Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 202

Investigating playing-related musculoskeletal disorders in South African instrumental musicians

This study, one of the first studies in SA to investigate PRMD in a wideranging sample of instrumental musicians using a validated self-report tool, shows that PRMDs are highly prevalent among a range of SA musicians and have a considerably negative effect on musicians’ performance ability and quality of life. However, making inferences about most affected genre or instrumental group was challenging due to the small sample sizes in some categories. The results from this study confirm that the nature of PRMD development is indeed multi-factorial, with factors numerous individual and playing-related factors playing a role in the development of PRMDs in SA musicians. Better support and education on health promotion for musicians, including awareness of and prevention strategies for PRMDs in the SA context are needed which may reduce the prevalence of PRMDs.Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 202

A social realist account of the way academic managers exercise agency in monitoring students’ academic success in South African higher education

The roots of this thesis lie in discourses which promote the use of academic monitoring strategies for student success in South African higher education. Although access to higher education widened for black South Africans following the first democratic election, this ‘formal’ access (Morrow, 1993) has not been matched by success with annual cohort studies showing that, regardless of the university at which they are registered, the subjects they are studying and the qualifications they hope to attain, black South Africans fare less well than their white peers. Monitoring performance and referring students on to academic support and development structures thus became a strategy identified as having the potential to address patterns in performance data. The study reports on an attempt to introduce a strategy for Academic Monitoring for Integrated Academic Development at a historically black university in South Africa’s Eastern Cape province. It draws on a metatheoretical framework developed from Bhaskar’s (1978, 1998) critical realism and Archer’s (1995, 1996) social realism to do this. More specifically, it focuses on the way managers at the institution exercised their agency in relation to the strategy and identifies the way social and structural conditions, developed from the time colonial settlers first arrived on the continent, worked to constrain the exercise of this agency. Although the focus of the study was on agency, the study revealed a system of necessary contradictions (Archer, 1995, 1996), a system of conflicting beliefs exacerbated by a lack of resources, that led to the implementation of the strategy not being as successful as intended. The study not only illuminates the conditions at one South African university but also adds to the body of work on management in higher education and to critiques of ‘managerialism’.Eyona ngxam yale thisisi kukuphendla iindlela zokukhuthaza ukusetyenziswa kwamaqhinga ezemfundo okuqwalasela impumelelo yabafundi kumaziko emfundo ephakamileyo aseMzantsi Afrika. Nangona emva konyulo lokuqala lwedemokhrasi abemi abantsundu baseMzantsi Afrika bethe bavuleleka ukuba bafikelele kwimfundo ephakamileyo, olu fikelelo 'lusesikweni' (Morrow, 1993) khange luhambelane nempumelelo yaba bafundi, nanjengoko uphando olujolise kwimpumelelo yabafundi ngonyaka ngamnye lubonisa ukuba aba bafundi bathi nokuba bafunda kweyiphi iyunivesithi, befunda ziphi iikhosi bekwafundela waphi amakhono, abafundi abantsundu basoloko berhuqeka emva xa bethelekiswa nabo bamhlophe. Ukuqwalaselwa kwenkqubela nokudluliselwa kwabafundi kumacandelo enkxaso nophuhliso kwimiba yemfundo kube liqhinga elithe lachongwa njengelunokukwazi ukujongana neepateni zendlela abaqhuba ngayo abafundi. Olu phando lunika ingxelo malunga nenzame yokuza neqhinga lokuQwalaselwa kwemiba yeMfundo ukwenzela uPhuhliso kwiyunivesithi eyayisakuba yeyabantsundu kwiphondo leMpuma Koloni laseMzantsi Afrika. Luqamele ngesakhelo semethathiyori esakhelwe kwi-critical realism kaBhaskar (1978, 1979) kunye ne-social realism kaArcher (1995, 1996). Eyona nto lugxile kuyo yindlela abalawuli neenkokeli zeli zikomfundo eziwasebenzisa ngayo amagunya azo ngokunxulumene neli qhinga, lukwachonga indlela iimeko zentlalo nezeziko, ezamana ziphuhliswa ukususela oko kwathi kwafika abarhwaphilizi kweli lizwekazi, ezasebenza ngayo ekunqandeni ukusetyenziswa kwala magunya. Nangona ugxiliso lolu phando belusemagunyeni, luthe lwaveza uluhlu lwemiba echaseneyo eyimfuneko (Archer, 1995, 1996), uluhlu lweenkolelo ezingqubanayo ezihlutshezwa kukushokoxeka kwezixhobo, nolukhokelele ekubeni ukufezekiswa kweli qhinga kungabiyiyo le mpumelelo ibilindelekile. Olu phando aluphelelanga nje ekugqamiseni iimeko zale yunivesithi yaseMzantsi Afrika, koko lukongeza kumsebenzi osele wenziwe kwimfundo ephakamileyo lukwaphendla ‘ezolawulo’.Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 202

IL-4/ IL-13 directed microglial activation and differentiation in response to LPS-induced neuroinflammation

Microglia activation is a common hallmark of neuroinflammation that occurs during pathogen invasion or lipopolysaccharide (LPS)-induced inflammation. A neuroinflammatory response is elicited by the release of proinflammatory cytokines which stimulates microglia in an autocrine manner to be polarized into classically activated, pro-inflammatory M1 cells. Prolonged exposure to the inflammatory response can have disastrous effects on the central nervous system (CNS). However, microglia can alternatively be polarized into the activated M2 anti-inflammatory phenotype, but the exact molecular mechanism mediating this phenotypic switch remains poorly understood. Studies have shown that interleukin (IL)-4 can induce the M2 phenotype and activate the signal transducer and activator of the transcription 6 (STAT6) signalling pathway that in turn provokes a beneficial Th2 immune response. Since IL-4 and IL-13 share a common IL-4 receptor alpha (IL-4Rα) chain, it is possible that alternative microglia differentiation and its anti-inflammatory action also involve IL-13. This study aimed to investigate how IL-13 and STAT6 signalling orchestrates the microglial response and differentiation associated with LPS-induced inflammation. Furthermore, the molecular mechanisms that relieve LPS-induced neuroinflammation and neural protection through IL-13-enhanced BDNF signalling were also investigated. C8-B4 microglial cells were induced with LPS to exhibit an M1 pro-inflammatory phenotype or stimulated with IL-4 and/or IL-13 to exhibit an M2 anti-inflammatory microglial phenotype. The cell viability following LPS, IL-4, and/ or IL-13 exposure was determined. The LPS-induced neuroinflammatory response and the anti-inflammatory response induced by IL-4 and IL-13 which promotes STAT-6 signalling were determined by measuring TNFα, IL-1β, and BDNF protein concentrations using ELISA assays. The polarising effects of LPS and IL-4/IL-13 cytokines were also examined via changes in the expression of Iba-1, CD206, CD86, and STAT-6 determined by immunofluorescence analysis. These changes were further investigated by quantifying the mRNA transcripts of TNFα, IL-1 β, Arg-1, CD206, IL-4R, and STAT-6 and BDNF using qRT-PCR.Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 202

A leadership model for South Africa’s infrastructure-related State-owned Enterprises

The objective of this research was to create a leadership model designed specifically to address the challenges faced by South Africa's infrastructure-related, state-owned enterprises. Both Eskom and Transnet are currently experiencing leadership crises, which might be further exacerbated by the global economic difficulties. Through an initial literature review it became evident that there was a knowledge gap regarding leadership within South Africa's state-owned enterprises. Consequently, it was crucial to conduct an extensive analysis of leadership styles to ensure effective infrastructure management for these state-owned enterprises. The primary aim of this study was to propose a leadership model that would be suitable for South Africa's infrastructure-related, state-owned enterprises. To achieve this objective, the relationship between effective leadership and perceived success in infrastructure development was explored, as well as the relationship between effective planning and perceived success in infrastructure development within these enterprises. Additionally, the connection between leadership training and perceived success in infrastructure development was investigated in the study. Quantitative research methods were employed to address these research objectives. The data for this study were collected through an online survey, with a total of 335 respondents from South Africa. Descriptive statistics and structural equation modelling (SEM) were used for analysis, using SPSS AMOS 29 Software. The findings of the study indicated a significant positive relationship between effective management and perceived success in infrastructure development for state-owned enterprises. However, the results regarding the relationship between effective planning and perceived success were not statistically significant, as the p-value exceeded 0.05. Based on the outcomes of the study, appropriate and meaningful recommendations have been provided regarding the leadership model necessary for effective infrastructure management in South Africa's infrastructure-related, state-owned enterprises.Thesis (PhD) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 202

A case study of code-switching in English First Additional Language Foundation Phase classrooms

Access restricted. Expected release in 2026.Thesis (MEd) -- Faculty of Education, Secondary and Post School Education, 202

“COVID-19 made me a single parent”: an interpretative phenomenological analysis of a woman’s perinatal experiences during the COVID-19 pandemic

The COVID-19 pandemic resulted in unprecedented challenges across various aspects of life. In particular, pregnant women encountered unique challenges and circumstances that necessitated adaptation to the experience of the perinatal period1 Satyanarayana et al., (2011). A considerable amount of research has been conducted regarding women's experience of the perinatal period during COVID-19, especially in first world countries. However, inadequate research has been done in the South African context and specifically, there is a lack of qualitative research providing thick descriptions of experience. The analysis describes three master themes supported by subordinate themes. The main themes are (1) A sense of loss and change, (2) Managing COVID-19 and its regulations during the perinatal period, and (3) Glimmers of hope and desirable aftermaths. The study’s findings expand and support the growing literature of women’s experiences on the perinatal period during the COVID-19 pandemic.Thesis (MA) -- Faculty of Humanities, Psychology, 202