Augmentative releases of Dactylopius austrinus De Lotto (Dactylopiidae; Hemiptera) for biological control of Opuntia aurantiaca Lindley (Cactaceae), in South Africa
- Authors: Mulateli, Thifhelimbilu
- Date: 2019
- Subjects: Opuntia aurantiaca -- Biolotical control -- South Africa , Invasive plants -- Biolotical control -- South Africa , Dactylopius austrinus De Lotto -- South Africa , Dactylopius -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92931 , vital:30765
- Description: Opuntia aurantiaca Lindely (Cactaceae) is an invasive alien cactus which has detrimental effects on agroecosystems and indigenous biodiversity in South Africa. Dense infestations over large areas reduce grazing capacity and indigenous biodiversity. Despite the release of a biological control agent, the cochineal insect Dactylopius austrinus De Lotto (Dactylopiidae), the weed is still considered a major problem in many parts of the country. Biological control has relied heavily on classical biological control, with little augmentative biological control implemented. This study investigated the outcome of mass-rearing and augmentative releases of D. austrinus for the control of O. aurantiaca. Augmentative releases are thought to improve the level of control by increasing agent densities in the field and thus increasing the level of damage inflicted to the plants. All data were collected with the intention to optimize release strategies so that the maximum benefit from the biological control agent could be achieved. An impact study was conducted using potted plants in a greenhouse to quantify the efficacy of multiple releases of the agent on the target weed. All three of the release treatments showed consistently higher proportion of cochineal than the controls, as well as the insect exclusion treatments, and these differences were statistically significant. The number of cladodes per plant increased significantly for the insect exclusion and control treatment over the period of the study, whilst all three release treatments decreased steadily over the same period. This study indicated that the agent is damaging to O. aurantiaca and that a single release event was beneficial but that multiple releases did not result in greater levels of control. A post-release evaluation was carried out to quantify the impact of releases of D. austrinus on O. aurantiaca in the field. Plots where the agent was excluded were compared with those where the agent was left at natural field densities and three treatments where agent populations were augmented to varying degrees through releases. The percentage of cochineal infested cladodes for all treatments decreased over time from the initiation of the experiment in October 2017 until the end of the experiment in October 2018. Opuntia aurantiaca densities also decreased over time for all treatments. The insect exclusion treatment had the greatest number of plants for the duration of the study, but this was not significantly different from other treatments. Dactylopius austrinus was damaging to O. aurantiaca, but climatic conditions in the field limited the efficacy of releases. Although O. aurantiaca density decreased during the experiment, it was evident that the reduced number of plants was not due to augmentation of the cochineal populations from the releases that were conducted. The experiment was conducted over a very dry period, when cochineal was particularly effective, so although augmentative releases did not improve the level of control, the natural population of cochineal was high and very damaging to O. aurantiaca over the course of the experiment. Releasing during wet periods, when the agent is less effective, could augment agent populations at a time when natural populations would be low, and hence improve levels of control further. Although this study was limited to a short period of two years, the results of this study suggest that the number of releases is less important than the timing of releases. Releasing immediately after periods of high rainfall is likely to be beneficial, while releasing during dry periods, or during winter when temperatures are low, is less effective. Dactylopius austrinus populations should be constantly monitored so that releases can be conducted when cochineal populations are low and the climatic conditions are correct. If the timing of release events is appropriate, then the over level of control of O. aurantiaca using D. austrinus could be improved.
- Full Text:
- Authors: Mulateli, Thifhelimbilu
- Date: 2019
- Subjects: Opuntia aurantiaca -- Biolotical control -- South Africa , Invasive plants -- Biolotical control -- South Africa , Dactylopius austrinus De Lotto -- South Africa , Dactylopius -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92931 , vital:30765
- Description: Opuntia aurantiaca Lindely (Cactaceae) is an invasive alien cactus which has detrimental effects on agroecosystems and indigenous biodiversity in South Africa. Dense infestations over large areas reduce grazing capacity and indigenous biodiversity. Despite the release of a biological control agent, the cochineal insect Dactylopius austrinus De Lotto (Dactylopiidae), the weed is still considered a major problem in many parts of the country. Biological control has relied heavily on classical biological control, with little augmentative biological control implemented. This study investigated the outcome of mass-rearing and augmentative releases of D. austrinus for the control of O. aurantiaca. Augmentative releases are thought to improve the level of control by increasing agent densities in the field and thus increasing the level of damage inflicted to the plants. All data were collected with the intention to optimize release strategies so that the maximum benefit from the biological control agent could be achieved. An impact study was conducted using potted plants in a greenhouse to quantify the efficacy of multiple releases of the agent on the target weed. All three of the release treatments showed consistently higher proportion of cochineal than the controls, as well as the insect exclusion treatments, and these differences were statistically significant. The number of cladodes per plant increased significantly for the insect exclusion and control treatment over the period of the study, whilst all three release treatments decreased steadily over the same period. This study indicated that the agent is damaging to O. aurantiaca and that a single release event was beneficial but that multiple releases did not result in greater levels of control. A post-release evaluation was carried out to quantify the impact of releases of D. austrinus on O. aurantiaca in the field. Plots where the agent was excluded were compared with those where the agent was left at natural field densities and three treatments where agent populations were augmented to varying degrees through releases. The percentage of cochineal infested cladodes for all treatments decreased over time from the initiation of the experiment in October 2017 until the end of the experiment in October 2018. Opuntia aurantiaca densities also decreased over time for all treatments. The insect exclusion treatment had the greatest number of plants for the duration of the study, but this was not significantly different from other treatments. Dactylopius austrinus was damaging to O. aurantiaca, but climatic conditions in the field limited the efficacy of releases. Although O. aurantiaca density decreased during the experiment, it was evident that the reduced number of plants was not due to augmentation of the cochineal populations from the releases that were conducted. The experiment was conducted over a very dry period, when cochineal was particularly effective, so although augmentative releases did not improve the level of control, the natural population of cochineal was high and very damaging to O. aurantiaca over the course of the experiment. Releasing during wet periods, when the agent is less effective, could augment agent populations at a time when natural populations would be low, and hence improve levels of control further. Although this study was limited to a short period of two years, the results of this study suggest that the number of releases is less important than the timing of releases. Releasing immediately after periods of high rainfall is likely to be beneficial, while releasing during dry periods, or during winter when temperatures are low, is less effective. Dactylopius austrinus populations should be constantly monitored so that releases can be conducted when cochineal populations are low and the climatic conditions are correct. If the timing of release events is appropriate, then the over level of control of O. aurantiaca using D. austrinus could be improved.
- Full Text:
Careerism and capitalism as women’s emancipation: a critical analysis of Rand Merchant Bank’s ‘Athena Programme', South Africa
- Authors: Mosesi, Poloko Prudence
- Date: 2019
- Subjects: Rand Merchant Bank (South Africa) , Women in economic development -- South Africa , Women in finance -- South Africa , Neoliberalism -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/140344 , vital:37881
- Description: Against the backdrop of debates on feminism and neo– liberalism, this thesis presents a critical analysis of Rand Merchant Bank’s (RMB) Athena programme in South Africa – an award– winning programme run by women, which aims to develop women as senior managers – and of the type of feminism it represents, using a Marxist feminist theoretical framework. Rand Merchant Bank’s is one of the largest investment banks in Africa, part of the giant First Rand Group (FRG) alongside First National Bank (FNB) group. The thesis, based on a detailed case study using qualitative methods, argues that Athena is a very much product of its time: it advances the argument that if more women were in position of power, women in general would be free, and it views the problem of women’s oppression with an individualist lens, which focuses on attitudes and confidence. Athena, like many initiatives of the neo– liberal era, such as Sandberg’s Lean– In philosophy and the Nike Foundation’s ‘Girl Effect’ promote individual understanding and emancipation of women, which sees emancipation in terms of creating a neo– liberal subject that operates more effectively within a capitalist framework, sees capitalism as the solution – rather than the cause – of women’s unequal circumstance and ignores structural issues like class. In effect, Athena argues that the free market and big corporations are neutral tools that can answer the question of women equality, if only women had the correct attitudes, and so long as corporate hierarchies and profits are accepted as fair, and women are seen as an untapped resource that can be used in a ‘smart economics.’ What all these initiatives have in common is shifting the burden and responsibility to women without proper interrogation of the systems that perpetuate inequalities, and a trickle– down theory, according to which more women capitalists and more women in the ruling class will empower the women in the working class.
- Full Text:
- Authors: Mosesi, Poloko Prudence
- Date: 2019
- Subjects: Rand Merchant Bank (South Africa) , Women in economic development -- South Africa , Women in finance -- South Africa , Neoliberalism -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/140344 , vital:37881
- Description: Against the backdrop of debates on feminism and neo– liberalism, this thesis presents a critical analysis of Rand Merchant Bank’s (RMB) Athena programme in South Africa – an award– winning programme run by women, which aims to develop women as senior managers – and of the type of feminism it represents, using a Marxist feminist theoretical framework. Rand Merchant Bank’s is one of the largest investment banks in Africa, part of the giant First Rand Group (FRG) alongside First National Bank (FNB) group. The thesis, based on a detailed case study using qualitative methods, argues that Athena is a very much product of its time: it advances the argument that if more women were in position of power, women in general would be free, and it views the problem of women’s oppression with an individualist lens, which focuses on attitudes and confidence. Athena, like many initiatives of the neo– liberal era, such as Sandberg’s Lean– In philosophy and the Nike Foundation’s ‘Girl Effect’ promote individual understanding and emancipation of women, which sees emancipation in terms of creating a neo– liberal subject that operates more effectively within a capitalist framework, sees capitalism as the solution – rather than the cause – of women’s unequal circumstance and ignores structural issues like class. In effect, Athena argues that the free market and big corporations are neutral tools that can answer the question of women equality, if only women had the correct attitudes, and so long as corporate hierarchies and profits are accepted as fair, and women are seen as an untapped resource that can be used in a ‘smart economics.’ What all these initiatives have in common is shifting the burden and responsibility to women without proper interrogation of the systems that perpetuate inequalities, and a trickle– down theory, according to which more women capitalists and more women in the ruling class will empower the women in the working class.
- Full Text:
Labour market perceptions of students at a Technical and Vocational Education and Training (TVET) college in Grahamstown, South Africa
- Authors: Khambule, Nelisa
- Date: 2019
- Subjects: Eastcape Midlands College (Makhanda, South Africa) -- Students -- Attitudes , College students -- South Africa -- Makhanda -- Attitudes , College graduates -- Employment -- South Africa , Labor market -- South Africa , Employability -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/96515 , vital:31289
- Description: In the context of South Africa, the supply of intermediate to high-level skills is central to economic growth and development. The post-school education and training sector is a critical source of these skills. Technical and Vocational Education and Training (TVET) colleges are expected to provide the intermediate to high-level skills that are required in a fast-changing global and national economy. In addition to fulfilling the goal of meeting the skills needs of the country, TVET colleges are expected to expand access to education and training opportunities and create pathways that will ensure smooth transitions for learners from college to employment. Using the third-generation labour market segmentation approach to the study of labour markets, this study sought to investigate the various socio-political factors that influence TVET college students’ perceptions about employment opportunities in the labour market with a NCV qualification. Using a qualitative methodology, this research investigated whether TVET students at Eastcape Midlands College felt adequately prepared for the labour market with their prospective post-secondary school qualification. The findings varied, with some students being of the view that the theoretical component of their programme of study could be improved to better prepare them for the labour market, and others, being of the view that the practical component could be improved. At a general level, the findings showed that the students did not have perfect knowledge of the availability of employment opportunities for their prospective qualifications.
- Full Text:
- Authors: Khambule, Nelisa
- Date: 2019
- Subjects: Eastcape Midlands College (Makhanda, South Africa) -- Students -- Attitudes , College students -- South Africa -- Makhanda -- Attitudes , College graduates -- Employment -- South Africa , Labor market -- South Africa , Employability -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/96515 , vital:31289
- Description: In the context of South Africa, the supply of intermediate to high-level skills is central to economic growth and development. The post-school education and training sector is a critical source of these skills. Technical and Vocational Education and Training (TVET) colleges are expected to provide the intermediate to high-level skills that are required in a fast-changing global and national economy. In addition to fulfilling the goal of meeting the skills needs of the country, TVET colleges are expected to expand access to education and training opportunities and create pathways that will ensure smooth transitions for learners from college to employment. Using the third-generation labour market segmentation approach to the study of labour markets, this study sought to investigate the various socio-political factors that influence TVET college students’ perceptions about employment opportunities in the labour market with a NCV qualification. Using a qualitative methodology, this research investigated whether TVET students at Eastcape Midlands College felt adequately prepared for the labour market with their prospective post-secondary school qualification. The findings varied, with some students being of the view that the theoretical component of their programme of study could be improved to better prepare them for the labour market, and others, being of the view that the practical component could be improved. At a general level, the findings showed that the students did not have perfect knowledge of the availability of employment opportunities for their prospective qualifications.
- Full Text:
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