Developing biological control agents for the management of the invasive tree Robinia pseudoacacia
- Authors: Wolmarans, Abigail
- Date: 2024-04-05
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435717 , vital:73181 , DOI 10.21504/10962/435717
- Description: Robinia pseudoacacia (Fabaceae) is a deciduous tree native to the Appalachian Mountains of North America but has become naturalised and invasive in other countries such as temperate North America, Europe, Australia, and Southern Africa. In South Africa the tree is classified as a category 1B invasive alien under the National Environmental Management Act (NEMBA), which stipulates the species requires some form of control as it has already caused extensive negative ecological and economic impacts. In the invaded range the tree creates monocultures that displace native species and spreads rapidly from suckering roots, making it a proficient invader. The South Africa plant prioritisation system suggests R. pseudoacacia is in the top three species which should be considered for classical weed biological control in South Africa. This thesis investigates which insects known to be associated with tree should be prioritised as candidate agents, as well as offering interesting insights into prioritising insects for weed biological control and using plant phylogenies and available literature to predict insect specificity. To ensure that no candidate biological control agents were already present in South Africa as well as to prioritise which guilds of the tree to prioritise for potential biological control, pre-release surveys were conducted across nine sites where the tree has invaded South Africa. It was found that no insects from the native range of R. pseudoacacia were present in South Africa. Seed surveys revealed that generalist insects attack a sizable proportion (68 %) of the seeds on the trees. In combination with a low seed soil bank (15.8 %) this suggests that seed- feeding agents may be helpful, however, candidate agents which damage leaves should be prioritised due to R. pseudoacacia relying heavily upon vegetative reproduction and much less on sexual reproduction. Leaves may therefor reduce the spread of these invasive trees. The insect assemblages in the native range of R. pseudoacacia are well understood. In addition, several associated insects have unintentionally followed the tree on its global spread, where they are often regarded as pests. The third chapter is therefore aimed at prioritising the known insects associated with the tree in both the native and invaded range. Literature surveys and Harris (1973) prioritisation systems were used to prioritise close to 64 candidate biological control agents down to three foliage- feeding agents, namely Odontota dorsalis (Coleoptera, Chrysomelidae), Macrosaccus robiniella (Lepidoptera, Gracillariidae) and Obolodiplosis robiniae (Diptera, Cecidomyiidae). To further prioritise the six selected agents in Chapter 4, species distribution were modelled with known climatic variables. This was done by using the species known occurrence localities, from both the native and where applicable invaded ranges, to identify which species that would best match with South Africa’s climate. The study showed that O. dorsalis is best suited to survive in South Africa, followed by O. robiniae and then M. robiniella. Collected data aided in the introduction of the prioritised O. robiniae into South African quarantine facilities. Unfortunately, despite several attempts, cultures could not be established, making conventional host specificity testing impossible. Thus, in Chapter 5 we aimed to determine the potential host range of the midge using information from experts in the field of galling insects, literature surveys, agricultural pest lists, and social science platforms coupled with native and invaded range surveys. The list of non-target species to consider as potential hosts was refined by developing phylogenetic trees of closely related Fabaceae that share the same distribution (native and invaded) as R. pseudoacacia. Through the available information gathered, and field surveys of these species, O. robiniae has not been shown to utilise any species, other than those from the Robinoid clade. In addition, the midge has also never been recorded on a number of closely related leguminous fodder and horticultural species growing in close proximity at high densities to R. pseudoacacia - suggesting negligible risk to South African growers of the same species. Host-specificity assessments through field surveys can be regarded as one of the best indicators of the ecological host range, however, this information is difficult to quantify and infrequently available, thus seldom used when determining the safety of a candidate biocontrol agent. In this unique study, using the extensive data collected we are able to show that O. robiniae would be potentially safe for release in South Africa. However, open field tests exposing closely related non-target plant species under natural and semi-natural conditions are planned in Switzerland over the next two years aiming to confirm these conclusions. By identifying and prioritizing potential biological control agents, this research contributes to the development of a targeted and sustainable solution for managing R. pseudoacacia in South Africa. The economic implications of successful biological control include reduced costs associated with invasive species management and ecosystem restoration. Additionally, by mitigating the negative ecological impacts, the agricultural systems in affected regions stand to benefit from enhanced resilience and productivity. Furthermore, the study's approach of using plant phylogenies and available literature to predict insect specificity offers a valuable methodological contribution to the broader field of weed biological control. This methodology can be adapted and applied to other invasive species, providing a framework for efficient and informed decision-making in weed management strategies. In essence, this research not only addresses the specific challenges posed by R. pseudoacacia in South Africa but also provides a template for tackling similar issues in different geographical contexts, thereby contributing to global efforts in sustainable agriculture and environmental conservation. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Authors: Wolmarans, Abigail
- Date: 2024-04-05
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435717 , vital:73181 , DOI 10.21504/10962/435717
- Description: Robinia pseudoacacia (Fabaceae) is a deciduous tree native to the Appalachian Mountains of North America but has become naturalised and invasive in other countries such as temperate North America, Europe, Australia, and Southern Africa. In South Africa the tree is classified as a category 1B invasive alien under the National Environmental Management Act (NEMBA), which stipulates the species requires some form of control as it has already caused extensive negative ecological and economic impacts. In the invaded range the tree creates monocultures that displace native species and spreads rapidly from suckering roots, making it a proficient invader. The South Africa plant prioritisation system suggests R. pseudoacacia is in the top three species which should be considered for classical weed biological control in South Africa. This thesis investigates which insects known to be associated with tree should be prioritised as candidate agents, as well as offering interesting insights into prioritising insects for weed biological control and using plant phylogenies and available literature to predict insect specificity. To ensure that no candidate biological control agents were already present in South Africa as well as to prioritise which guilds of the tree to prioritise for potential biological control, pre-release surveys were conducted across nine sites where the tree has invaded South Africa. It was found that no insects from the native range of R. pseudoacacia were present in South Africa. Seed surveys revealed that generalist insects attack a sizable proportion (68 %) of the seeds on the trees. In combination with a low seed soil bank (15.8 %) this suggests that seed- feeding agents may be helpful, however, candidate agents which damage leaves should be prioritised due to R. pseudoacacia relying heavily upon vegetative reproduction and much less on sexual reproduction. Leaves may therefor reduce the spread of these invasive trees. The insect assemblages in the native range of R. pseudoacacia are well understood. In addition, several associated insects have unintentionally followed the tree on its global spread, where they are often regarded as pests. The third chapter is therefore aimed at prioritising the known insects associated with the tree in both the native and invaded range. Literature surveys and Harris (1973) prioritisation systems were used to prioritise close to 64 candidate biological control agents down to three foliage- feeding agents, namely Odontota dorsalis (Coleoptera, Chrysomelidae), Macrosaccus robiniella (Lepidoptera, Gracillariidae) and Obolodiplosis robiniae (Diptera, Cecidomyiidae). To further prioritise the six selected agents in Chapter 4, species distribution were modelled with known climatic variables. This was done by using the species known occurrence localities, from both the native and where applicable invaded ranges, to identify which species that would best match with South Africa’s climate. The study showed that O. dorsalis is best suited to survive in South Africa, followed by O. robiniae and then M. robiniella. Collected data aided in the introduction of the prioritised O. robiniae into South African quarantine facilities. Unfortunately, despite several attempts, cultures could not be established, making conventional host specificity testing impossible. Thus, in Chapter 5 we aimed to determine the potential host range of the midge using information from experts in the field of galling insects, literature surveys, agricultural pest lists, and social science platforms coupled with native and invaded range surveys. The list of non-target species to consider as potential hosts was refined by developing phylogenetic trees of closely related Fabaceae that share the same distribution (native and invaded) as R. pseudoacacia. Through the available information gathered, and field surveys of these species, O. robiniae has not been shown to utilise any species, other than those from the Robinoid clade. In addition, the midge has also never been recorded on a number of closely related leguminous fodder and horticultural species growing in close proximity at high densities to R. pseudoacacia - suggesting negligible risk to South African growers of the same species. Host-specificity assessments through field surveys can be regarded as one of the best indicators of the ecological host range, however, this information is difficult to quantify and infrequently available, thus seldom used when determining the safety of a candidate biocontrol agent. In this unique study, using the extensive data collected we are able to show that O. robiniae would be potentially safe for release in South Africa. However, open field tests exposing closely related non-target plant species under natural and semi-natural conditions are planned in Switzerland over the next two years aiming to confirm these conclusions. By identifying and prioritizing potential biological control agents, this research contributes to the development of a targeted and sustainable solution for managing R. pseudoacacia in South Africa. The economic implications of successful biological control include reduced costs associated with invasive species management and ecosystem restoration. Additionally, by mitigating the negative ecological impacts, the agricultural systems in affected regions stand to benefit from enhanced resilience and productivity. Furthermore, the study's approach of using plant phylogenies and available literature to predict insect specificity offers a valuable methodological contribution to the broader field of weed biological control. This methodology can be adapted and applied to other invasive species, providing a framework for efficient and informed decision-making in weed management strategies. In essence, this research not only addresses the specific challenges posed by R. pseudoacacia in South Africa but also provides a template for tackling similar issues in different geographical contexts, thereby contributing to global efforts in sustainable agriculture and environmental conservation. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
A grounded theory study of the identity and career decisions of artistic creative entrepreneurs
- Gibson-Tessendorf, Jacoba Cornelia
- Authors: Gibson-Tessendorf, Jacoba Cornelia
- Date: 2023-10-13
- Subjects: Entrepreneurship , Creative entrepreneurship , Personality and creative ability , Career choice , Creative industries , Identity (Psychology)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419208 , vital:71625 , DOI 10.21504/10962/419208
- Description: This 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, 2023
- Full Text:
- Authors: Gibson-Tessendorf, Jacoba Cornelia
- Date: 2023-10-13
- Subjects: Entrepreneurship , Creative entrepreneurship , Personality and creative ability , Career choice , Creative industries , Identity (Psychology)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419208 , vital:71625 , DOI 10.21504/10962/419208
- Description: This 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, 2023
- Full Text:
Analysis of the role and regulation of HOP1a and HOP1b splice variants in cancer biology
- Authors: Schwarz, Kelly
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432240 , vital:72854
- Description: Restricted access. Expected lease date in 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Authors: Schwarz, Kelly
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432240 , vital:72854
- Description: Restricted access. Expected lease date in 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
Esibelekweni: Ingqokelela Yemibongo ngesiXhosa nangesiNgesi
- Authors: Busakwe, Yenzokuhle
- Date: 2023-10-13
- Subjects: Creative writing (Higher education) South Africa , Diaries Authorship , Books Reviews , South African essays (English) 21st century , Xhosa poetry 21st century
- Language: English , Xhosa
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424917 , vital:72193
- Description: My thesis is a collection of poems that is written in isiXhosa and English. It explores African spirituality, my relationship with God, heartache from romantic and platonic relationships. I make use of dual languages because some themes that I write about such as African spirituality I find words that capture their truest emotion in my Xhosa vocabulary, and I cannot find them in English. My poems use the narrative form because it allows me to tell stories through poetry without having to commit my writing to musicality or rhyming that a lyric poetry normally has. My work is shaped by writers such as Kate Beinhemer, Mangaliso Buzani, Amy Saul Zerby, Nontsizi Mgqwethio, Simphiwe Nolutshungu and Oiu Miaojin. Buzani makes use of images and few lines in his writing but still manages to capture a story with brevity. Saul-Zerby makes use of text lingo in some of her poems, and I make use of it to close a gap that I have identified with the books that I was reading that are all written in a formal and serious format. Mgqwetho’s poems explore Christianity and African Spirituality which is one of the subjects that my work is exploring too but in a manner that differs. I talk about how they have been my guidance instead of praising their powers like Nontsizi normally does in her poems. Simphiwe Nolutshungu’s poems has influenced the structure of my poems. Fairy tales written by writers like Kate helps my writing to bring to life issues that sound too dreamy to be true but have manifested as visions and memories that I cannot wipe out from my conscience. Oiu Miaojin’s novel “Last words from Montmantre” I am fascinated by how the writer detail emotions such as vulnerability and heartbreak in his storytelling. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2023
- Full Text:
- Authors: Busakwe, Yenzokuhle
- Date: 2023-10-13
- Subjects: Creative writing (Higher education) South Africa , Diaries Authorship , Books Reviews , South African essays (English) 21st century , Xhosa poetry 21st century
- Language: English , Xhosa
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424917 , vital:72193
- Description: My thesis is a collection of poems that is written in isiXhosa and English. It explores African spirituality, my relationship with God, heartache from romantic and platonic relationships. I make use of dual languages because some themes that I write about such as African spirituality I find words that capture their truest emotion in my Xhosa vocabulary, and I cannot find them in English. My poems use the narrative form because it allows me to tell stories through poetry without having to commit my writing to musicality or rhyming that a lyric poetry normally has. My work is shaped by writers such as Kate Beinhemer, Mangaliso Buzani, Amy Saul Zerby, Nontsizi Mgqwethio, Simphiwe Nolutshungu and Oiu Miaojin. Buzani makes use of images and few lines in his writing but still manages to capture a story with brevity. Saul-Zerby makes use of text lingo in some of her poems, and I make use of it to close a gap that I have identified with the books that I was reading that are all written in a formal and serious format. Mgqwetho’s poems explore Christianity and African Spirituality which is one of the subjects that my work is exploring too but in a manner that differs. I talk about how they have been my guidance instead of praising their powers like Nontsizi normally does in her poems. Simphiwe Nolutshungu’s poems has influenced the structure of my poems. Fairy tales written by writers like Kate helps my writing to bring to life issues that sound too dreamy to be true but have manifested as visions and memories that I cannot wipe out from my conscience. Oiu Miaojin’s novel “Last words from Montmantre” I am fascinated by how the writer detail emotions such as vulnerability and heartbreak in his storytelling. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2023
- Full Text:
Exploring the interplay between foundation phase learners’ home and school literacy practices
- Authors: Magxala, Xoliswa Patience
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431587 , vital:72788 , DOI 10.21504/10962/431587
- Description: The thesis looked at Foundation Phase children’s early home literacy practices and examined how these literacy practices are adopted at school in Libode, Eastern Cape Province, South Africa, a rural area. The purpose of the study was to determine how early literacy practices at home are adopted in classrooms. The study aimed to determine the relationship between home and school literacy. To understand the literacy practices used at home and school by four Foundation Phase children and four Foundation Phase teachers, an interpretive ethnographic study design was used. Participants who spoke isiXhosa as their first language participated in data collection using structured observations, video and audio recordings, field notes, and unstructured interviews. The study’s framework, the Cultural Historical Activity Theory, was used as a tool to collect, examine, and interpret data through its various components. Themes were identified, arranged, and categorized. The findings revealed children from low socioeconomic backgrounds have rich literacy practices. Teachers do not acknowledge or recognize the contributions that these children’s cultural backgrounds make. The study recommends that schools start acknowledging the advantages that children’s environments have for them. It also suggests that teachers build on the knowledge that children bring from home, as this will have an impact on how they behave in class because students bring their family’s literacy habits, which serve as the foundation for their academic literacy habits, to school. , Thesis (PhD) -- Faculty of Education, Institute for the Study of Englishes in Africa, 2023
- Full Text:
- Authors: Magxala, Xoliswa Patience
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431587 , vital:72788 , DOI 10.21504/10962/431587
- Description: The thesis looked at Foundation Phase children’s early home literacy practices and examined how these literacy practices are adopted at school in Libode, Eastern Cape Province, South Africa, a rural area. The purpose of the study was to determine how early literacy practices at home are adopted in classrooms. The study aimed to determine the relationship between home and school literacy. To understand the literacy practices used at home and school by four Foundation Phase children and four Foundation Phase teachers, an interpretive ethnographic study design was used. Participants who spoke isiXhosa as their first language participated in data collection using structured observations, video and audio recordings, field notes, and unstructured interviews. The study’s framework, the Cultural Historical Activity Theory, was used as a tool to collect, examine, and interpret data through its various components. Themes were identified, arranged, and categorized. The findings revealed children from low socioeconomic backgrounds have rich literacy practices. Teachers do not acknowledge or recognize the contributions that these children’s cultural backgrounds make. The study recommends that schools start acknowledging the advantages that children’s environments have for them. It also suggests that teachers build on the knowledge that children bring from home, as this will have an impact on how they behave in class because students bring their family’s literacy habits, which serve as the foundation for their academic literacy habits, to school. , Thesis (PhD) -- Faculty of Education, Institute for the Study of Englishes in Africa, 2023
- Full Text:
Freshwater invasive alien crayfish species in South Africa: testing eDNA assessment and DNA barcoding
- Mdidimba, Nonkazimulo Dorothea
- Authors: Mdidimba, Nonkazimulo Dorothea
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424413 , vital:72151
- Description: The expansion of the wild populations of the two invasive alien crayfish species, i.e., Cherax quadricarinatus and Procambarus clarkii in South Africa is of high concern. Given this, innovative and improved monitoring methods are required to be explored in order to effectively detect and manage their spread. Environmental DNA (eDNA) has shown promising and reliable results to detect and monitor alien crayfish in freshwater systems even at low densities. This research study aimed to field-test the application of eDNA for detecting and monitoring invasive alien freshwater crayfish species (IAFCs) in South African freshwater systems (Chapter 2). Further, this study also aimed to confirm the true taxonomic identity of the IAFCs in South African freshwater systems by using DNA barcoding to avoid potential misidentifications with morphological identification alone (Chapter 3). Also, ectocommensal temnocephalans and leeches attached to the crayfishes were also identified with DNA barcoding. The mitochondrial COI gene fragment of the crayfishes and the ectocommensal temnocephalans and leeches was amplified, sequenced, and used for species identification. For eDNA monitoring of C. cainii, C. quadricarinatus and P. clarkii, water samples were collected from Eastern Cape, Free State and KwaZulu Natal sites that are known to house these species. The current study did not detect the eDNA of the wild populations of both C. quadricarinatus and P. clarkii. This failure was encountered despite employing several methods, such as, end-point polymerase chain reaction (PCR), quantitative PCR (qPCR) and next-generation sequencing (NGS). The eDNA assessment to detect IAFCs in the wild populations is discussed in detail, and corrective measures suggested (Chapter 2). However, only C. cainii was able to be detected by eDNA. Cherax cainii is housed/farmed in an aquaculture facility (Vaughn Bursey’s Stock Farm in Eastern Cape) with large number of individuals per pond. For this, NGS was able to detect C. cainii but the other two methods, end-point PCR and qPCR were not able to detect the species. Based on the results, refinement of eDNA monitoring methods for the South African freshwater systems is recommended. Evaluation of different DNA collection methods, preservation, DNA extraction kits and primer design to obtain effective eDNA detection is discussed as possible sources of error. Interestingly, the newly established population of P. clarkii in Mimosa Dam in Free State was infested with alien leeches, that were confirmed by DNA barcoding to be Helobdella europaea and Helobdella octatestica. Consequently, this study reports for the first time in South Africa the presence of this alien freshwater leeches. The presence of alien leeches and P. clarkii suggests a double invasion in Mimosa Dam, P. clarkii seems to continue expanding its range in the country. However, the long-established population of P. clarkii in Driehoek Farm in Mpumalanga, which has been in the country for over 30 years did not have any leech or temnocephalan infestation. This could suggest several interesting ecological phenomena, including environmental filtering over time of the co-invaders, differential source populations, and post-introduction adaptation. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
- Full Text:
- Authors: Mdidimba, Nonkazimulo Dorothea
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424413 , vital:72151
- Description: The expansion of the wild populations of the two invasive alien crayfish species, i.e., Cherax quadricarinatus and Procambarus clarkii in South Africa is of high concern. Given this, innovative and improved monitoring methods are required to be explored in order to effectively detect and manage their spread. Environmental DNA (eDNA) has shown promising and reliable results to detect and monitor alien crayfish in freshwater systems even at low densities. This research study aimed to field-test the application of eDNA for detecting and monitoring invasive alien freshwater crayfish species (IAFCs) in South African freshwater systems (Chapter 2). Further, this study also aimed to confirm the true taxonomic identity of the IAFCs in South African freshwater systems by using DNA barcoding to avoid potential misidentifications with morphological identification alone (Chapter 3). Also, ectocommensal temnocephalans and leeches attached to the crayfishes were also identified with DNA barcoding. The mitochondrial COI gene fragment of the crayfishes and the ectocommensal temnocephalans and leeches was amplified, sequenced, and used for species identification. For eDNA monitoring of C. cainii, C. quadricarinatus and P. clarkii, water samples were collected from Eastern Cape, Free State and KwaZulu Natal sites that are known to house these species. The current study did not detect the eDNA of the wild populations of both C. quadricarinatus and P. clarkii. This failure was encountered despite employing several methods, such as, end-point polymerase chain reaction (PCR), quantitative PCR (qPCR) and next-generation sequencing (NGS). The eDNA assessment to detect IAFCs in the wild populations is discussed in detail, and corrective measures suggested (Chapter 2). However, only C. cainii was able to be detected by eDNA. Cherax cainii is housed/farmed in an aquaculture facility (Vaughn Bursey’s Stock Farm in Eastern Cape) with large number of individuals per pond. For this, NGS was able to detect C. cainii but the other two methods, end-point PCR and qPCR were not able to detect the species. Based on the results, refinement of eDNA monitoring methods for the South African freshwater systems is recommended. Evaluation of different DNA collection methods, preservation, DNA extraction kits and primer design to obtain effective eDNA detection is discussed as possible sources of error. Interestingly, the newly established population of P. clarkii in Mimosa Dam in Free State was infested with alien leeches, that were confirmed by DNA barcoding to be Helobdella europaea and Helobdella octatestica. Consequently, this study reports for the first time in South Africa the presence of this alien freshwater leeches. The presence of alien leeches and P. clarkii suggests a double invasion in Mimosa Dam, P. clarkii seems to continue expanding its range in the country. However, the long-established population of P. clarkii in Driehoek Farm in Mpumalanga, which has been in the country for over 30 years did not have any leech or temnocephalan infestation. This could suggest several interesting ecological phenomena, including environmental filtering over time of the co-invaders, differential source populations, and post-introduction adaptation. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
- Full Text:
Kenyan comedy: transmogrifying stereotypes and fashioning a ‘Kenyanness’ of aesthetic escapism
- Authors: Lumasia, Patrick Chesi
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432477 , vital:72874 , DOI 10.21504/10962/432477
- Description: Despite the proliferation of stereotypes in Kenyan comedy, little research exists to show the two intersect to shape a peculiar notion of ‘Kenyanness’. Indeed, Kenyan comedy, besides reproducing and playing on the quotidian and the historical, is heavily invested with ethnic and gender stereotypes that reflect the Kenyan milieu as it intersects with the global. This comedy is oftentimes seen by some critics as detrimental to Kenyan society because it supposedly shapes and reinforces ethnic and/or gender relations in the country. However, this study contends that Kenyan comedy is open to multiple interpretations and meaning contestations that are not necessarily clear to the comedians and audiences due to the asymmetry that abounds between the production and consumption ends of the comedy’s spectrum. The comedy is therefore ambivalent. This research seeks to demonstrate that Kenyan comedy—as a form of entertainment and critique of society—does not seek to fix and reify Kenyan identities. Instead, the comedy frees these identities from the presumed vice-hold, constricting world of stereotypes by disrupting the linearity of the stereotypes, thereby unsettling the hierarchical structure of hegemonic ideology embedded in them through postmodern humour: a form of humour amenable to postmodern sensibilities. To this end, the comedy offers Kenyans momentary escape into a comedic utopia, through which, they address pertinent issues affecting their nationhood, even as they endeavor to fashion a ‘Kenyanness’ of aesthetic escapism that is celebratory of the country’s rich socio-cultural diversity. The study employs Jörg Schweinitz’s (2011) stereotype theory and the postpositivist realist theory of identity in its study of stand-up, scripted episodic and topical comedy as transposed on to YouTube. Specifically, the thesis considers: the Churchill Show (2012 – 2022) that aired on NTV; 2012–2022; The Real Househelps of Kawangware (2014–2021) on KTN/NTV; Auntie Boss (2016–2021) on NTV; The Wicked Edition and The Trending Trend Talkers (2014–). , Thesis (PhD) -- Faculty of Humanities, Literary Studies in English, 2023
- Full Text:
- Authors: Lumasia, Patrick Chesi
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432477 , vital:72874 , DOI 10.21504/10962/432477
- Description: Despite the proliferation of stereotypes in Kenyan comedy, little research exists to show the two intersect to shape a peculiar notion of ‘Kenyanness’. Indeed, Kenyan comedy, besides reproducing and playing on the quotidian and the historical, is heavily invested with ethnic and gender stereotypes that reflect the Kenyan milieu as it intersects with the global. This comedy is oftentimes seen by some critics as detrimental to Kenyan society because it supposedly shapes and reinforces ethnic and/or gender relations in the country. However, this study contends that Kenyan comedy is open to multiple interpretations and meaning contestations that are not necessarily clear to the comedians and audiences due to the asymmetry that abounds between the production and consumption ends of the comedy’s spectrum. The comedy is therefore ambivalent. This research seeks to demonstrate that Kenyan comedy—as a form of entertainment and critique of society—does not seek to fix and reify Kenyan identities. Instead, the comedy frees these identities from the presumed vice-hold, constricting world of stereotypes by disrupting the linearity of the stereotypes, thereby unsettling the hierarchical structure of hegemonic ideology embedded in them through postmodern humour: a form of humour amenable to postmodern sensibilities. To this end, the comedy offers Kenyans momentary escape into a comedic utopia, through which, they address pertinent issues affecting their nationhood, even as they endeavor to fashion a ‘Kenyanness’ of aesthetic escapism that is celebratory of the country’s rich socio-cultural diversity. The study employs Jörg Schweinitz’s (2011) stereotype theory and the postpositivist realist theory of identity in its study of stand-up, scripted episodic and topical comedy as transposed on to YouTube. Specifically, the thesis considers: the Churchill Show (2012 – 2022) that aired on NTV; 2012–2022; The Real Househelps of Kawangware (2014–2021) on KTN/NTV; Auntie Boss (2016–2021) on NTV; The Wicked Edition and The Trending Trend Talkers (2014–). , Thesis (PhD) -- Faculty of Humanities, Literary Studies in English, 2023
- Full Text:
Learning to make a difference: Small-scale women farmers in social learning spaces for climate action
- Authors: Chanyau, Ludwig
- Date: 2023-10-13
- Subjects: Social learning South Africa Amathole District Municipality , Value creation , Environmental education South Africa Amathole District Municipality , Climatic changes Study and teaching South Africa Amathole District Municipality , Communities of practice , Crops and climate South Africa Amathole District Municipality , Women farmers South Africa Amathole District Municipality , Farms, Small South Africa , Agricultural ecology South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/402944 , vital:69908 , DOI 10.21504/10962/402944
- Description: How do women farmers in Africa learn about climate change? What is quality climate change learning for farmers? How do farmers interface new knowledge with their long-held and trusted traditional knowledge? How do we evaluate learning at farm level and beyond? Using Okoli’s theory mining review, I untangled a tripartite knot of social learning literature to find Social Learning Theory (SLT) suitable for a study to explore my practical and scholarly curiosity as reflected in the above questions. Wenger’s theory of Social Learning emerged as the most appropriate for my research. The second phase of my study explored the climate change learning and practice terrain for small-scale women farmers, analysing the connection between learning, practice, and the resultant value in two case study areas, municipalities in the Amathole District of the Eastern Cape Province of South Africa. In addition to a paper on SLT mining review that unravels and chooses between the strands of social learning, the two case studies resulted in three articles that responded to the study’s objectives and the research questions. The thesis is introduced and synthesised through five 'book-end' chapters, as well as through these four articles. What were my findings? In the first case study, in the drought-stricken Raymond Mhlaba Municipality, I gathered the data through individual semi-structured interviews with farmers, extension officers and representatives of the involved organisations. I also conducted a group interview with farmers and analysed documents to supplement interview data. I analysed the data using concepts of Communities of Practice (CoP) and SLT to map out the learning and practice landscape. I discovered a constellation of CoPs interconnected by the shared drive for adaptive water management. The constellation is made up of tertiary institutions, government departments, non-governmental organisations and farmers of varying experiences and competencies, with women emerging as the more proactive gender, and state-led extension services being willing but overstretched and under-resourced. SLT effectively traced the apparent fragmented learning within and outside the CoPs and the sudden and extensive shifts in the CoP boundaries, especially in the context of COVID-19 pandemic lockdowns and the increased adoption of digital learning platforms. Despite the richness and diversity brought by the emergent new learning networks that involve participants in the province and further afield, the adoption of digital learning platforms worsened the existing generational digital divide among farmers. iii In the second case study, in the water scarce Buffalo City Metropolitan Municipality, I adopted the Value Creation Framework (VCF) to conduct an ethnographic evaluation that used semi-structured interviews, participant observation and document analysis of the learning experiences of women farmers in a social movement on agroecology. I found that the farmer-centred learning approach of the movement has created value for the farmers involved, evidenced by the adoption of agroecology by over 2700 members (including new urban farmers who are occupying open spaces typically used as dumpsites). The learning approach has facilitated expansive learning, enhanced resource mobilisation, new collaborations, partnerships, and seed sharing networks. Additionally, it necessitated context-appropriate and transformative changes to intersectional justice issues associated with historical inequalities in access to land and water and gender discrimination, leading to improved practices, new access to markets and improved quality yields. These are examples of immediate, potential, applied, realised, orienting, enabling and transformative as well as strategic value, as defined by the VCF. In reflecting on how women farmers learn in these social learning spaces I elucidate the learning impact pathways and local contextual influences in shifting CoP boundaries, domains, and practices during the climate crisis as it intersects with other compounding factors. I generated insights that could be useful for stakeholders in the agricultural (extension) sector to build better pathways for emancipatory and empowering expansive social learning in contexts characterised by resource constraints, but also by strong women-led agency. Such learning could make a difference and cushion small-scale farming from collapse especially in times of unprecedented changes. The agroecology movement and associated communities of practice explored in this study create transformative social learning spaces that are able to respond to climate change, and hence a model that state-led extension might want to adopt in other resource-constrained contexts. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
- Authors: Chanyau, Ludwig
- Date: 2023-10-13
- Subjects: Social learning South Africa Amathole District Municipality , Value creation , Environmental education South Africa Amathole District Municipality , Climatic changes Study and teaching South Africa Amathole District Municipality , Communities of practice , Crops and climate South Africa Amathole District Municipality , Women farmers South Africa Amathole District Municipality , Farms, Small South Africa , Agricultural ecology South Africa
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/402944 , vital:69908 , DOI 10.21504/10962/402944
- Description: How do women farmers in Africa learn about climate change? What is quality climate change learning for farmers? How do farmers interface new knowledge with their long-held and trusted traditional knowledge? How do we evaluate learning at farm level and beyond? Using Okoli’s theory mining review, I untangled a tripartite knot of social learning literature to find Social Learning Theory (SLT) suitable for a study to explore my practical and scholarly curiosity as reflected in the above questions. Wenger’s theory of Social Learning emerged as the most appropriate for my research. The second phase of my study explored the climate change learning and practice terrain for small-scale women farmers, analysing the connection between learning, practice, and the resultant value in two case study areas, municipalities in the Amathole District of the Eastern Cape Province of South Africa. In addition to a paper on SLT mining review that unravels and chooses between the strands of social learning, the two case studies resulted in three articles that responded to the study’s objectives and the research questions. The thesis is introduced and synthesised through five 'book-end' chapters, as well as through these four articles. What were my findings? In the first case study, in the drought-stricken Raymond Mhlaba Municipality, I gathered the data through individual semi-structured interviews with farmers, extension officers and representatives of the involved organisations. I also conducted a group interview with farmers and analysed documents to supplement interview data. I analysed the data using concepts of Communities of Practice (CoP) and SLT to map out the learning and practice landscape. I discovered a constellation of CoPs interconnected by the shared drive for adaptive water management. The constellation is made up of tertiary institutions, government departments, non-governmental organisations and farmers of varying experiences and competencies, with women emerging as the more proactive gender, and state-led extension services being willing but overstretched and under-resourced. SLT effectively traced the apparent fragmented learning within and outside the CoPs and the sudden and extensive shifts in the CoP boundaries, especially in the context of COVID-19 pandemic lockdowns and the increased adoption of digital learning platforms. Despite the richness and diversity brought by the emergent new learning networks that involve participants in the province and further afield, the adoption of digital learning platforms worsened the existing generational digital divide among farmers. iii In the second case study, in the water scarce Buffalo City Metropolitan Municipality, I adopted the Value Creation Framework (VCF) to conduct an ethnographic evaluation that used semi-structured interviews, participant observation and document analysis of the learning experiences of women farmers in a social movement on agroecology. I found that the farmer-centred learning approach of the movement has created value for the farmers involved, evidenced by the adoption of agroecology by over 2700 members (including new urban farmers who are occupying open spaces typically used as dumpsites). The learning approach has facilitated expansive learning, enhanced resource mobilisation, new collaborations, partnerships, and seed sharing networks. Additionally, it necessitated context-appropriate and transformative changes to intersectional justice issues associated with historical inequalities in access to land and water and gender discrimination, leading to improved practices, new access to markets and improved quality yields. These are examples of immediate, potential, applied, realised, orienting, enabling and transformative as well as strategic value, as defined by the VCF. In reflecting on how women farmers learn in these social learning spaces I elucidate the learning impact pathways and local contextual influences in shifting CoP boundaries, domains, and practices during the climate crisis as it intersects with other compounding factors. I generated insights that could be useful for stakeholders in the agricultural (extension) sector to build better pathways for emancipatory and empowering expansive social learning in contexts characterised by resource constraints, but also by strong women-led agency. Such learning could make a difference and cushion small-scale farming from collapse especially in times of unprecedented changes. The agroecology movement and associated communities of practice explored in this study create transformative social learning spaces that are able to respond to climate change, and hence a model that state-led extension might want to adopt in other resource-constrained contexts. , Thesis (PhD) -- Faculty of Education, Education, 2023
- Full Text:
Quinolone-Pyrazinamide Derivatives: synthesis, characterisation, in silico ADME analysis and in vitro biological evaluation against Mycobacterium tuberculosis
- Authors: Rukweza, Kudakwashe Gerald
- Date: 2023-10-13
- Subjects: Quinolone antibacterial agents , Mycobacterium tuberculosis , Antitubercular agents , Tuberculosis Chemotherapy , Drug resistance , Moxifloxacin , Isoniazid
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/390901 , vital:68596
- Description: Tuberculosis is one of the leading causes of death worldwide caused by an infectious species, Mycobacterium tuberculosis (Mtb). Some of the factors that contribute to the prevalence of this disease include the complexity of diagnosis, prolonged period of therapy, side effects associated with current TB drugs, the prevalence of resistance against the current treatment options and a high incidence of co-infection with HIV/AIDS. Thus, there is a need for new alternative drugs to provide safer and shorter treatment therapy options that are not susceptible to the development of drug resistance. In this project, we focus our attention on the quinolone pharmacophore. Quinolones are currently used as alternative options in the treatment of resistant strains of Mtb. Previous work pertaining to quinolone-isoniazid hybrid compounds showed promising in vitro activity against the H37Rv strain of Mtb and served as the inspiration to pursue this project. The journey commenced with the synthesis of quinolone-pyrazinamide hybrid compounds (Figure 3.1). These compounds were synthesised, through the attachment of the quinolone and the pyrazinamide entity through a hydrazine linker. The synthesised compounds were purified, and their structural identity confirmed using common spectroscopic techniques including 1H and 13C NMR, infra-red (IR) and mass spectrometry. In vitro biological assays were performed by testing for the activity against the H37RvMA strain of Mtb. The bioassays were performed in triplicates to ensure the accuracy of the results. Moxifloxacin and isoniazid were tested as control compounds. Finally, the resultant compounds were profiled in silico for physicochemical and ADMET properties using open access software SwissADME. All the synthesised compounds 3.8a-f showed no activity against H37RvMA. In most cases, the resulting compounds showed minimal to no activity (MICs ≥ 57.3 μM) in all three media. During the in vitro studies, the compounds showed significant precipitation in the media over time suggesting poor aqueous solubility. The SwissADME analysis of these compounds indicated poor solubility in aqueous media, which is likely linked to their molecular size and complexity. Despite poor aqueous solubility, compounds 3.8a-f showed acceptable physicochemical properties and ADME parameters. No PAINs (Pan-assay interference compounds) were observed. Minimal to no interaction with CYP enzymes were predicted. Most of the compounds were compatible with the Lipinski’s rules of five. , Thesis (MSc) -- Faculty of Science, Pharmacy, 2023
- Full Text:
- Authors: Rukweza, Kudakwashe Gerald
- Date: 2023-10-13
- Subjects: Quinolone antibacterial agents , Mycobacterium tuberculosis , Antitubercular agents , Tuberculosis Chemotherapy , Drug resistance , Moxifloxacin , Isoniazid
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/390901 , vital:68596
- Description: Tuberculosis is one of the leading causes of death worldwide caused by an infectious species, Mycobacterium tuberculosis (Mtb). Some of the factors that contribute to the prevalence of this disease include the complexity of diagnosis, prolonged period of therapy, side effects associated with current TB drugs, the prevalence of resistance against the current treatment options and a high incidence of co-infection with HIV/AIDS. Thus, there is a need for new alternative drugs to provide safer and shorter treatment therapy options that are not susceptible to the development of drug resistance. In this project, we focus our attention on the quinolone pharmacophore. Quinolones are currently used as alternative options in the treatment of resistant strains of Mtb. Previous work pertaining to quinolone-isoniazid hybrid compounds showed promising in vitro activity against the H37Rv strain of Mtb and served as the inspiration to pursue this project. The journey commenced with the synthesis of quinolone-pyrazinamide hybrid compounds (Figure 3.1). These compounds were synthesised, through the attachment of the quinolone and the pyrazinamide entity through a hydrazine linker. The synthesised compounds were purified, and their structural identity confirmed using common spectroscopic techniques including 1H and 13C NMR, infra-red (IR) and mass spectrometry. In vitro biological assays were performed by testing for the activity against the H37RvMA strain of Mtb. The bioassays were performed in triplicates to ensure the accuracy of the results. Moxifloxacin and isoniazid were tested as control compounds. Finally, the resultant compounds were profiled in silico for physicochemical and ADMET properties using open access software SwissADME. All the synthesised compounds 3.8a-f showed no activity against H37RvMA. In most cases, the resulting compounds showed minimal to no activity (MICs ≥ 57.3 μM) in all three media. During the in vitro studies, the compounds showed significant precipitation in the media over time suggesting poor aqueous solubility. The SwissADME analysis of these compounds indicated poor solubility in aqueous media, which is likely linked to their molecular size and complexity. Despite poor aqueous solubility, compounds 3.8a-f showed acceptable physicochemical properties and ADME parameters. No PAINs (Pan-assay interference compounds) were observed. Minimal to no interaction with CYP enzymes were predicted. Most of the compounds were compatible with the Lipinski’s rules of five. , Thesis (MSc) -- Faculty of Science, Pharmacy, 2023
- Full Text:
- «
- ‹
- 1
- ›
- »