The impact of Fintech firms on bank performance: analysing the South African case (2009-2021)
- Authors: Runyowa, Simon Simbarashe
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/462812 , vital:76337
- Description: The growth of the Fintech Firm sector globally was inevitable, given the changes in consumer behaviour, expectations, and the ever-changing and evolving nature of technology. The sector saw a sharp increase during the 2008 Global Financial Crisis and was driven by digital payments, government policy, less stringent regulation, and technological innovation. Unsurprisingly, South Africa was home to a mature and developing Fintech sector primarily driven by money transfers and mobile payments putting Fintech firms in the same market segment as traditional banks but with a more extensive potential customer base through offering easily accessible and lower-cost services. The relationship between the growth of the Fintech firm sector and Bank performance was widely researched within the literature with varying results. The study aimed to add to the body of literature and determine the nature of this relationship in the South African context. The study primarily aimed to determine the relationship and impact of the growth of the Fintech firm payments segment on the performance of the South African Banking sector. Additionally, the study aimed to measure the sector's growth by creating a Fintech Growth Index. Using the Ordinary Least Squares, Fixed Effect and the Generalized Method of Moments estimation techniques, estimations between Bank performance variables and the Fintech growth Index were analysed between 2009 and 2021. Firstly, the study found the growth of the Fintech payments segment to be positive. Secondly, the study found that the growth of the payment segment had a negative relationship and impact on the financial performance of South African banks. The findings of this study have implications for the development and regulatory framework of the South African Fintech sector as well as its interaction with the South African banking sector. Furthermore, policymakers may find that the growth of the Fintech Firm sector has overall positive benefits for financial inclusion for South African consumers. The study recommended that future research be taken to address the gap in the literature regarding the growth of the South African Fintech sector. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
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- Date Issued: 2024-10-11
The role of popular and traditional music during the umgidi initiation ceremonies among the Amampondo: subtitle if needed. If no subtitle follow instructions in manual
- Authors: Gushu, Lindokuhle
- Date: 2024-04
- Subjects: Xhosa (African people) -- Music , Folk music -- Social aspects -- South Africa -- Eastern Cape , Xhosa (African people) -- Rites and ceremonies , Popular music -- South Africa -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62805 , vital:72962
- Description: This study investigates the intricate dynamics of music within the umgidi initiation ceremonies among the amaMpondo, focusing on the interplay between traditional and modern popular music. The study explores the cultural foundation of the umgidi ceremony, emphasising its transformative significance and the evolving influence of modern popular music, particularly among the youth. A comprehensive literature review follows, contextualising the amaMpondo, their cultural practices, and the complex relationship between traditional and popular music in the broader South African music scene. The study adopted a qualitative ethnographic approach, including participant observation and individual interviews, to explore the impact of modern popular music on traditional elements during umgidi initiation ceremonies. Thematic analysis was employed for data interpretation, ensuring a systematic exploration of patterns and meanings. Ethical considerations were meticulously addressed, emphasising protecting participants' rights and cultural sensitivity. The study's findings highlighted the multifaceted roles of music during umgidi initiation ceremonies. Music is a powerful medium for cultural expression, communication, and communal celebration. The call-and-response format, rhythm variations, and the influence of modern genres such as Gqom and Amapiano were explored. Community attitudes toward integrating modern popular music reveal diverse opinions, ranging from full embrace to resistance. In summary, this study contributes to understanding the evolving dynamics of music in umgidi initiation ceremonies among the amaMpondo. The study provides a nuanced exploration and a roadmap for future research, community engagement, and policy considerations by combining cultural insights, literature review, methodological rigour, and community perspectives. , Thesis (MMus) -- Faculty of Humanities, School of Visual and Performing Arts, 2023
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- Date Issued: 2024-04
Discovery and classification of compact radio sources in the MeerKAT Galactic Centre data
- Authors: Rammala, Isabella Dineo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432218 , vital:72852
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2023
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- Date Issued: 2023-10-13
Labour law and non-standard employment: case studies of selected workplaces in Makhanda
- Authors: Mini, Sifanelwa
- Date: 2023-10-13
- Subjects: Non-standard employment South Africa Makhanda , Job security , Labor market South Africa , Labor laws and legislation South Africa , Work-life balance South Africa , Temporary employment South Africa , Collective bargaining South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425171 , vital:72216
- Description: While precarious and poorly-regulated forms of employment are on the increase worldwide, the patterns vary significantly over time and space. This study sought to understand employees’ perceptions of non-standard employment (NSE), the reasons why employers resort to NSE and why they use particular types of NSE. In addition, the research explored how labour law protections for NSE are applied in particular workplaces. Drawing on the regulation approach, which provides a conceptual framework to explain changes in production and employment relationships under specific spatio-temporal conditions, this study focused on three companies in Makhanda. Furthermore, this study employed a qualitative research method to explore the employees’ perceptions on non-standard work. This was done by using an interpretive approach to explore how workers experience NSE and how Eastern Cape citizens in Makhanda navigate the scourge of unemployment and exploitation in the labour market. Moreover, the research investigated how employees experience the efficacy of their employment rights in the workplace. The employment rights observed in the study include (among others) leave, contract of employment and collective bargaining; all of which are provisions in the Labour Relations Act. The findings in the study do validate the use of NSE as a ‘tool’ to curb high unemployment. However, the study finds that the positive result of job creation does not signify job security for non-standard workers, instead beneath the rhetoric of job creation and investment, lies hidden the exploitation of vulnerable groups of citizens and extension of precarious forms of employment. This is because businesses engage in economic competition locally and globally. Therefore, in order to successfully compete against other, employer’s cut on labour expenses by adopting a “race to the bottom,” the effect of which is paying employees below the minimum wage. Moreover, this study opposes the argument that NSE is a stepping stone to permanent employment. The conditions which prevail in NSE are distinctly different from those in the Standard Employment Relationship (SER), making it difficult for employees to transition to a new labour market. The latter is more aligned with the heterodox approach than it is to the orthodox approach to labour market. , Thesis (MA) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2023-10-13
Investigating the determinants of economics growth in South Africa
- Authors: Dudumashe, Nomsindisi
- Date: 2023-00
- Subjects: Economic growth determinants in South Africa
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/9986 , vital:74931
- Description: Economic growth is regarded as one of the prime macroeconomic objectives of any economy. The study aimed to investigate the determinants of economic growth in South Africa for the period 1994 to 2021 using yearly data obtained from World Bank and IMF. The analysis of all the variables has been provided to show the relationship that the variables have with economic growth in the South African economy. The independent variables used were capital stock, financial development, employment and inflation. In achieving this aim, an Autoregressive Distributive Lag (ARDL) was used since it examines both the short-term and the long-term dynamics of the determinants of economic growth. In addition, Granger causality was used to determine whether the explored variables were causally related to one another. In the long run, the results point out that financial development was significant at 5%, while capital stock and employment were significant at 10%. In the short run, all variables were significant at 1%. The study recommends employment stimulation, investment in capital stock and financial development in order to boost economic growth. , Thesis (Masters) -- Faculty of Economics and Financial Sciences, 2023
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- Date Issued: 2023-00
Reforging Ockham’s Razor: an enquiry into the ontology of parsimony arguments
- Authors: Dichmont, Thomas
- Date: 2022-10-14
- Subjects: Logic , Metaphysics , Ontology , Knowledge, Theory of , Epistemology , Philosophy and science , Occam's razor
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/406736 , vital:70303
- Description: Nearly every philosopher in English-speaking world has heard of Ockham’s Razor, which is given in one of two ways, don’t multiply entities beyond necessity and all things being equal choose the simpler explanation. Yet it is unclear from the scholarship whether the use of Ockham’s Razor is justified in science and philosophy. However, if it can be shown to ‘get’ us truth, it would gain an unequivocal justification, as disputes that are continued after the parties to the substantive truth of one or the other are defined as frivolous. Alternative, one may contend that explanation could have other criteria of success. The implication of a direct connection between the razor and truth comes with ontological commitments, namely a commitment to realism (about universals) and philosophical theism. This is contrary to the razor’s use as a tool of nominalism and naturalism. I argue in this thesis there that the only possible non-circular justification for Ockham’s Razor is truth and that therefore certain philosophical positions are excluded from using the razor to animate their positions. There is an additional, second criteria for the success of our inquiry, namely the justification must in some way be consistent with the razor, which means the chosen explanation for the razor, must be simpler than any of its rivals and not have superfluous entities, otherwise our justification would be contrary to the advice of the razor. We are presented with a Scylla and Charybdis type problem, we avoid a circularity on the one hand and on the other we must not contradict the razor itself, these are contrary intellectual impulses. So firstly I will look at disciplines outside philosophy for some initial inspiration. If we could answer this question in a ‘non’ philosophical way, the problem would have solved itself in a way that require little change of practice. If lawyers or scientist can account for the razor properly, there is not really a problem of justification, at least not a philosophical one. Second, I consider the realist and theist positions, namely an argument of Aristotle’s in the Posterior Analytics and part of Aquinas’ On the Divine Simplicity. Further, I consider the work of Ockham as a nominalist. Lastly, I consider modern and contemporary philosophy, in the form of Hume, Quine and Sober (a modern writer on the razor). The aim here is to ‘stress test’ the philosophical resources of the various systems and analyse the results to see if they can produce a non-circular result. , Thesis (MA) -- Faculty of Humanities, Philosophy, 2022
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- Date Issued: 2022-10-14
Regulation of Oct4 expression during cell stress
- Authors: Samson, William John
- Date: 2022-10-14
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365712 , vital:65778
- Description: Thesis embargoed. Expected release date early 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
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- Date Issued: 2022-10-14
Foraging behaviour of the Sooty Albatross in relation to climatic variability and fisheries
- Authors: Banda, Shamiso
- Date: 2022-04
- Subjects: Spatial behavior in animals , Conservation of natural resources --South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55632 , vital:53383
- Description: As top predators, seabirds occupy the upper trophic level of marine ecosystems. They are consequently important for the maintenance of ecosystem structure and function, while also possessing characteristics which are useful for identifying climate-driven changes in oceanography at all trophic levels. This important faunal group is one of the most threatened, with climate change and fisheries bycatch mortality being the primary drivers of population declines. Understanding these threats is important for the management of threatened seabird populations. One impact of climate change and variability in climate occurs through changes in prey availability. As central place foragers, breeding seabirds have trip duration constraints due to the obligation of nest duties. This makes them particularly vulnerable to changes in prey availability within their foraging ranges. The ability to adjust foraging behaviour during environmental conditions which alter prey availability is an important attribute which can contribute to breeding success. Thus, investigating for this foraging behavioural plasticity during different breeding stages provides insights into how a species is likely to be impacted by climate change. The sooty albatross population on Marion Island was studied and displayed a degree of foraging behavioural plasticity during the five-year period of pronounced climatic variability studied. Incubating birds mainly foraged in the subtropical convergence zone (STCZ), the Sub Antarctic Front (SAF) and Subtropical Front (STF) which border it, and the region north of the STF. Brooding birds mainly used the SAF and Polar Frontal Zone (PFZ). Significantly different areas were used between years during both breeding stages. This population showed a lack of consistent habitat preferences which may offer resilience to progressive climatic variability and change. Interactions of sooty albatrosses, as well as white-chinned petrels for comparative purposes, with fisheries were also assessed. The two species were compared to shed light on possible explanations for differences in seabird-fishery interactions between the species. The impact of fisheries-related mortality (bycatch) is dependent on exposure to fishing activity and attraction to fishing boats encountered while foraging. Bycatch mortality has previously been proposed as the main cause of this sooty albatross population’s decline. Exposure and 6 attraction to fishing boats was found to be lower than that of white-chinned petrels which are bycatch prone. However, the current level of attraction exhibited by this sooty albatross population may expose a significant fraction of the population to bycatch risk due to its small population size. Additionally, all fishing boats were encountered north of the STF where non breeding individuals are now known to be distributed. Thus, the impact of fisheries on this population may mainly be mediated by more bycatch prone non-breeding individuals. Overall, the relative impact of fisheries bycatch mortality is suggested to be higher than that of climatic impacts on the sooty albatross population on Marion Island. However, this study did not incorporate dietary and demographic information which would reveal whether there are nutritional differences between years that may impact on breeding success. An integrated rather than independent assessment of foraging behavioural responses to climatic variability and fishing activity is recommended for improving our understanding of current and future conservation priorities. , Thesis (MSc) -- Faculty of Science, Zoology , 2021
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- Date Issued: 2022-04
Optimization of liposomes for enhanced stability against degradation by gastrointestinal fluid content
- Authors: Scholtz, Carla Chleo
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54117 , vital:46305
- Description: Motivation: Liposomes are nanoparticulate carriers consisting of a hydrophobic bilayer and a hydrophilic core. Their application as drug carrier systems arises from their unique physiochemical structure, biocompatibility and biodegradability. Their biphasic nature is significant in the delivery of peptide and protein drug molecules as it is thus able to encompass both hydrophobic and hydrophilic molecules. Liposomes are actively being used for drug delivery intravenously. These formulations have been successful in reducing side effects and improving therapeutic efficacy. However, the intravenous route poses many challenges and is not the preferred route of administration amongst patients. The oral route of administration is non-invasive, and administration is of ease, therefore it is the preferred route of administration amongst patients, especially those with complex medicine regimes. Problem: The gastrointestinal tract is a harsh environment. In order for liposomes to maintain their integrity during their course they require a level of stability against gastric and intestinal fluids and its associated constituents such as gastric and pancreatic enzymes, low pH and bile acid. Methodology: Based on recommendations extrapolated from literature, the incorporation of a bile salt, sodium glycocholate, into liposomes in conjunction with coating the surface with chitosan was selected as the optimization strategies to enhance the stability of liposomes against degradation in the gastrointestinal tract. Bilosomes with encapsulated calce in were produced using the thin-film hydration method and coated with chitosan. An in vitrocalce in release assay was conducted in simulated gastric and intestinal fluids which presented with in vivo conditions in terms of pH and enzymes and additional constituents such as a bile salt. Stability was determined by the extent of digestion within the simulated fluids with time. Results: Characterization results suggested that the addition of chitosan and sodium glycocholate to the liposomal formulation has significant effects on the physiochemical properties. The colloidal dispersions could not retain their stability during storage which was noticeable during HRTEM. Despite optimization of the liposomes, in vitro studies showed significant release in both simulated gastric and intestinal fluids, with majority release seen in the presence of pepsin and pancreatic, at low pH and in the presence of bile acid. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
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- Date Issued: 2021-12
Studies on seed germination and response to fertilization of Amaranthus accessions collected in the Eastern Cape Province, South Africa
- Authors: Ramangoele, Mpaballeng Alinah
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54112 , vital:46307
- Description: Studies were conducted at Döhne Agricultural Development Institute (D.A.D.I.), geographically located between latitude 32°31'34.077"S and longitude 27°27'37.473"E in Stutterheim, Eastern Cape Province from summer 2018 until autumn 2019.The objectives were to determine seed germination and seedling vigour of four local Amaranthus accessions and to evaluate the effect of organic and inorganic fertilization on the growth, yield and nutrient composition. In the germination studies, herein referred to as Experiment 1,laboratory assessments were laid out in a Complete Randomized Design (CRD) replicated four times to test seed germination, seedling emergence and seedling vigour of four Amaranthus accessions namely: A. Hypochondriacus, A. Retroflexus 1, A. Hybridus and A. Retroflexus 2. Data collection included germination percentage, radicle length, co-efficient of velocity of germination and seedling vigour. A.Retroflexus2 gave the highest germination percentage in summer (85%) and autumn (87.75%).Seed weight resulted in the highest germination percentage and was observed to have shown a high positive correlation of {R2=0.91} in summer and{R2=0.92} in autumn respectively. The highest seedling vigour (p<0.001) in summer was attained from A. Hypochondriacus and A. Retroflexus2.In the greenhouse in summer, the highest emergence percentage was observed from A. Hypochondriacus(93.00%), whilst in autumn it was A.Retroflexus2 (88.38%).A. Retroflexus1 was the least performer in both seasons. In summer, A. Hypochondriacus and A. Retroflexus2 resulted in very high seedling vigour. In autumn A. Hypochondriacus, A. Retroflexus2 and A. Hybridus resulted in high seedling vigour and A. Retroflexus1 in moderate seedling vigour. The relationship observed between seed weight and seedling vigour showed a negative (inverse)correlation in summer {R2=0.58} and autumn {R2=0.62}.In Experiment 2, seedlings of A. Hypochondriacus and A. Retroflexus 2were transplanted in 5litrebasal perforated plastic pots which were filled with soil. The experimental layout was a CRD replicated four times. The treatments were: control (no amendment), goat manure, cattle manure and NPK fertilizer. Growth performance data were collected for plant height, the number of leaves and stem girth. In summer, when goat manure was applied both accessions resulted in the tallest plants (78.80cm) yet A. Retroflexus 2 and vA. Hypochondriacus gave the greatest stem girthand highest number of leaves respectively. In autumn, the tallest plants and highest number of leaves were observed from A. Retroflexus 2fertilized with NPK and the greatest stem girth was observed from A. Hypochondriacus fertilized with goat manure. The interaction of fertilization and accessions resulted in A. Retroflexus 2 fertilized with goat manure generating the greatest fresh shoot biomass (137.27g plant-1) and the least from the control. Both accessions fertilized with goat manure attained the greatest dry leaf biomass. Insummer, A.Retroflexus2 outperformed A. Hypochondriacus in calcium content despite the treatments. Unfertilized A. Retroflexus2 produced leaves with high potassium. Both unfertilized accessions showed the highest magnesium content. All A. Retroflexus2 treatments outperformed A. Hypochondriacus treatments on iron content except the control. The summer season was the best in terms of growth and yield of the tested accessions. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
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- Date Issued: 2021-12
Ubomi Sisilonda: Ingqokelela Yemibongo
- Authors: Manxiwa, Mzuvukile
- Date: 2021-10-29
- Subjects: Xhosa poetry 21st century , Xhosa poetry History and criticism , Buzani, Nompumezo Criticism and interpretation , Gwala, Mafika Pascal, 1946-2014 Criticism and interpretation , Xhosa language Rhythm , Xhosa language Rhyme , Creative writing (Higher education) South Africa
- Language: Xhosa
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192265 , vital:45210
- Description: Le thisisi igxila kwiintlobo ngeentlobo zokubhala imibongo. Iqamele kakhulu kwilinge lokubhodla isingqala isebenzisa isandi sengoma yesiNtu komameleyo, oko kukuthi isondele kwi-lyric poetry ngolwasemzini. Oku kufezwe ngokusebenzisa isingqisho, imfano-zandi, imvano-siqalo nemvano-siphelo, njalo njalo. Iinjongo zale thisisi kukongeza kuncwadi lwesiXhosa nakwinkcubeko yesiNtu, nokuhlab’ ikhwelo elikhuthaza uluntu ukuba lubuyele kwinkcubeko yesiNtu, ukuhlonipha imo-ntlalo yabo nokuxabisa abantu ababhinqileyo. Umbali ophum’ izandla kuncwadi lwesiXhosa, uNompumezo Buzani, umsebenzi wakhe ngakumbi kwenye yeencwadi zakhe ethi Imida, ube nefuthe elikhulu kulo msebenzi, ngakumbi indlela athe walusebenzisa ngayo ulwimi; ngesimbo seli xesha ukudlulisa umyalezo ngolwimi oluqhelekileyo, lungafihlakali kodwa lube namandla okudlwengula umxhelo kulowo ufundayo. Ndeyame nakwincwadi kaNgcwabe, uKhala Zome; undikhumbuzile ngemibongo yakhe eyayame kakhulu kwimo yentlalo yamandulo, kunye nemibongo kaMafika Gwala kuJolinkomo, efana nale: The Children of Nonti kunye noThe Shebeen Queen. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
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- Date Issued: 2021-10-29
Ethical leadership by the senior managers within the South African Police Services in Grahamstown cluster
- Authors: Mafele, Khayakazi Innocentia
- Date: 2020-10
- Subjects: South African Police Service , Management -- Moral and ethical aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/19870 , vital:43604
- Description: SAPS has an organisational form of ethics that guides the police officials’ behaviour which is SAPS code of conduct and all SAPS members are expected to adhere to this code of conduct. The code of conduct provides that “each of the SAPS members is bound to create a safe and secure environment for all the citizens of the Republic of South Africa” (SAPS code of conduct). Ethical leadership is becoming more relevant; ethical leadership is an idea that appears to be uncertain and includes many diverse elements. The literature proposes that ethical leadership should be perceived as a view that is enabling people to do the right thing more than preventing people from doing the wrong thing. Current SAPS leadership must be able to make sure that SAPS become the professional and respected police agency to the citizens of the Republic of South Africa. This study sought to investigate the use of ethical leadership by the senior managers within the South African Police Service in the Grahamstown cluster. The study also investigated some of the various causes of corrupt practices among senior managers which resulted in the unethical behaviour in the South African Police Service. In this study, the purposive sampling technique was used to choose the participants and the following participants were interviewed: One Colonel as a cluster commander, two full Colonels as station commanders, two Lt Colonels and two Captains from Grahamstown and Joza stations. The study made the following recommendation: Senior officials at SAPS need to go through a capacity building programme so as to assist them to deal with challenges of ethics. It is very important to increase the detection of and punishment of corrupt acts in order to deter all officers from engaging in corrupt acts. Accountability is needed by senior officials and therefore the Independent Investigation Directorate (IPID) needs to be given more constitutional powers to be able to investigate the police in South Africa in order to make disciplinary recommendations in respect of members of the SAPS resulting from investigations conducted by the directorate. The enforcement of disciplinary procedures as guided by the code of conduct should be promoted and sustained. , Thesis (MPA) -- Faculty of Management and Commerce, 2021
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- Date Issued: 2020-10
Yeast-baculovirus synergism: investigating mixed infections for improved management of the false codling moth, Thaumatotibia leucotreta
- Authors: Van der Merwe, Marcel
- Date: 2018
- Subjects: Cryptophlebia leucotreta , Baculoviruses , Yeast , Citrus Diseases and pests , Biological pest control agents , Pests Integrated control
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/62963 , vital:28347
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) or otherwise commonly known as the false codling moth is an indigenous pest of the citrus industry in southern Africa. The pest is highly significant as it impacts negatively on the export of fresh citrus fruits from South Africa to international markets. To control T. leucotreta in South Africa, an integrated pest management (IPM) programme has been implemented. One component of this programme is the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV-SA) which has been formulated into the products Cryptogran™ and Cryptex®. It has previously been reported that there is a mutualistic association between Cydia pomonella (L.) (Lepidoptera: Tortricidae) also known as codling moth, and epiphytic yeasts. Cydia pomonella larval feeding galleries were colonised by yeasts and this, in turn, reduced larval mortality and enhanced larval development. It has been demonstrated in laboratory assays and field trials that combining yeast and brown cane sugar with Cydia pomonella granulovirus (CpGV) significantly increased larval mortality and lowered the proportion of injured apple fruit. This suggests that yeasts can enhance the effectiveness of an insect virus in managing pest larvae. In this study, we proposed to determine which species of yeast occur naturally in the digestive tract, frass and on the epidermis of T. leucotreta larvae and to examine whether any of these yeasts, when combined with the CrleGV-SA, have a synergistic effect in increasing mortality of T. leucotreta larvae. Firstly, Navel oranges infested with T. leucotreta larvae were collected from orchards in Sundays River Valley in Eastern Cape of South Africa. Larvae were extracted and analysed for the presence of yeast on their surface, or in their gut and frass. Four yeasts were isolated from T. leucotreta larvae and identified down to species level via PCR amplification and sequencing of internal transcribed spacer (ITS) region and D1/D2 domain of the large subunit (LSU) of rDNA region. These yeasts were isolated from the frass, epidermis and digestive tract of T. leucotreta larvae. The yeast isolates were identified as Meyerozyma caribbica, Pichia kluyveri, Pichia kudriavzevii and Hanseniaspora opuntiae. A yeast preference assay was conducted on female T. leucotreta moths to examine whether any of the isolated yeast species affected their oviposition preference. Navel oranges were inoculated with the isolated yeast species at a concentration of 6 × 108 cells.ml-1. The assay also included a Brewer’s yeast and distilled water control. Pichia kudriavzevii was shown to be the preferred yeast species for oviposition, as significantly more eggs were deposited on Navel oranges inoculated with this yeast compared to the other treatments. Lastly, a detached fruit bioassay was performed to evaluate the efficacy of mixing P. kudriavzevii with CrleGV-SA to enhance T. leucotreta larvae mortality. Pichia kudriavzevii was selected as it was demonstrated as having an effect on the oviposition preference of female T. leucotreta moths. The concentration at which P. kudriavzevii was applied remained the same as in the preference assay while CrleGV-SA was applied at lethal concentration required to kill 50 % of the population (9.31 × 107 OBs.ml-1). Although an increase in larval mortality was observed between CrleGV-SA being applied alone and the yeast/virus mixture, this result was determined not to be statistically significant. The experiments performed in this study provide a platform for further research into the application of a yeast-virus combination as a novel control option for T. leucotreta in the field. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2018
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- Date Issued: 2018