Ecological impacts of photoautotrophic Euendoliths on South African mussel beds
- Dievart, Alexia Madeleine Angèle
- Authors: Dievart, Alexia Madeleine Angèle
- Date: 2024-04-05
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435650 , vital:73176 , DOI 10.21504/10962/435650
- Description: Aphytis lingnanensis was reared and tested in South Africa in the early 2000s for augmentation against red scale on citrus and was found to be ineffective. Aphytis melinus is now commercially available and it is important that the efficacy of augmentation thereof on red scale is determined locally. Field trials, fitness assessments and molecular identification on A. melinus from two insectaries were done. Field trials was done in seven, five and six pairs of comparable release and control orchards across the Eastern and Western Cape during the seasons of 2019/2020, 2020/2021 and 2021/2022 respectively. Red scale infestation was monitored and a sample of 20 infested fruit from each orchard was randomly collected every four weeks. Aphytis spp. responsible for parasitism were identified and the percentage parasitism recorded. Results of this study of field trials suggest that the augmentation of A. melinus did not significantly increase the level of parasitism above that of the untreated control. Five repetitions with six replicates of flight and longevity tests were performed with wasps from each insectary. Wasps in the longevity test from two insectaries were kept at 23 °C and 65% RH with honey. Flight tests were performed in tubes of 16 by 30 cm, with a light above a clear, sticky ceiling at 23 °C and 65% RH. On average in five replicates, 65%, 33% and 17% A. melinus wasps were alive on day one, five and 10 respectively. The overall sex ratio was 1.58 for females to males, but 1.05, 2.19 and 2.66 for non-flyers, non-crawlers, crawlers, and flyers respectively. In flight tests for both insectaries combined, only 36.97% of wasps could initiate flight in 24 h while 56.96% remained on the tube floor, and 6.05% attempted to crawl upwards. No significant differences in flight performance were recorded between the two insectaries. Wasps from the local insectary lived significantly longer during the longevity tests but were shorter in transit than wasps from the overseas insectary. COI genes were sequenced and compared against Genbank sequences using BLAST. Molecular identifications did not confirm morphological identifications for all species, indicating unexpected genetic complexity. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: Dievart, Alexia Madeleine Angèle
- Date: 2024-04-05
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435650 , vital:73176 , DOI 10.21504/10962/435650
- Description: Aphytis lingnanensis was reared and tested in South Africa in the early 2000s for augmentation against red scale on citrus and was found to be ineffective. Aphytis melinus is now commercially available and it is important that the efficacy of augmentation thereof on red scale is determined locally. Field trials, fitness assessments and molecular identification on A. melinus from two insectaries were done. Field trials was done in seven, five and six pairs of comparable release and control orchards across the Eastern and Western Cape during the seasons of 2019/2020, 2020/2021 and 2021/2022 respectively. Red scale infestation was monitored and a sample of 20 infested fruit from each orchard was randomly collected every four weeks. Aphytis spp. responsible for parasitism were identified and the percentage parasitism recorded. Results of this study of field trials suggest that the augmentation of A. melinus did not significantly increase the level of parasitism above that of the untreated control. Five repetitions with six replicates of flight and longevity tests were performed with wasps from each insectary. Wasps in the longevity test from two insectaries were kept at 23 °C and 65% RH with honey. Flight tests were performed in tubes of 16 by 30 cm, with a light above a clear, sticky ceiling at 23 °C and 65% RH. On average in five replicates, 65%, 33% and 17% A. melinus wasps were alive on day one, five and 10 respectively. The overall sex ratio was 1.58 for females to males, but 1.05, 2.19 and 2.66 for non-flyers, non-crawlers, crawlers, and flyers respectively. In flight tests for both insectaries combined, only 36.97% of wasps could initiate flight in 24 h while 56.96% remained on the tube floor, and 6.05% attempted to crawl upwards. No significant differences in flight performance were recorded between the two insectaries. Wasps from the local insectary lived significantly longer during the longevity tests but were shorter in transit than wasps from the overseas insectary. COI genes were sequenced and compared against Genbank sequences using BLAST. Molecular identifications did not confirm morphological identifications for all species, indicating unexpected genetic complexity. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
The promotion of the right to access adequate housing for street children in Kenya
- Authors: Wanjala, Esther Nasimiyu
- Date: 2024-04
- Subjects: Children's rights , Children's act , Street children
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64358 , vital:73679
- Description: This thesis explores the fundamental right to housing and shelter, recognised at national, regional, and international levels, focusing on its application to street children in Kenya. Despite constitutional provisions, street children in Kenya face exclusion from socio-economic interventions, particularly in the realm of housing and shelter. This exclusion stems from the absence of specific legislation addressing their unique needs. Existing laws, such as the Children Act, 2022 and the Housing Act, 2007 fall short of safeguarding the rights of street children, perpetuating discrimination based on economic status. The research examines international, regional, and national legal frameworks to uncover obstacles hindering street children from enjoying their legally protected human rights, including housing and shelter. Legal instruments such as the Universal Declaration of Human Rights, International Covenant on Economic, Social, and Cultural Rights, International Covenant on Civil and Political Rights, Convention on the Rights of the Child, the African Charter on Human and Peoples Rights, and the African Charter on the Rights and Welfare of a Child and policies like the Sustainable Development Goals 2030, the African Union Agenda 2063, and Agenda 2040 were considered. The research employed qualitative research methodology that included theoretical and non-empirical methods. It used a combination of descriptive, correlative, and limited comparative analysis of the status of street children in the East African Community State Parties of Tanzania, Uganda, and Rwanda, as well as South Africa. Theoretical perspectives, including human rights-based, vulnerability, othering, and capability theories, informed the discussions on improving the status of street children in Kenya. The study employed critical social justice and vulnerability theories to analyse how discrimination and prejudices in society can violate fundamental rights, particularly street children's rights. The findings of the study revealed the inadequate legal and institutional frameworks in promoting street children's rights in Kenya. The study referred to the best practices in the select East African Community State Parties and South Africa that Kenya can emulate to benefit street children and realise the right to shelter and adequate housing. The study recommends legal and policy reviews to protect street children's rights to adequate housing and shelter guided by constitutional and international standards. , Thesis (LLD) -- Faculty of Law, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Wanjala, Esther Nasimiyu
- Date: 2024-04
- Subjects: Children's rights , Children's act , Street children
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64358 , vital:73679
- Description: This thesis explores the fundamental right to housing and shelter, recognised at national, regional, and international levels, focusing on its application to street children in Kenya. Despite constitutional provisions, street children in Kenya face exclusion from socio-economic interventions, particularly in the realm of housing and shelter. This exclusion stems from the absence of specific legislation addressing their unique needs. Existing laws, such as the Children Act, 2022 and the Housing Act, 2007 fall short of safeguarding the rights of street children, perpetuating discrimination based on economic status. The research examines international, regional, and national legal frameworks to uncover obstacles hindering street children from enjoying their legally protected human rights, including housing and shelter. Legal instruments such as the Universal Declaration of Human Rights, International Covenant on Economic, Social, and Cultural Rights, International Covenant on Civil and Political Rights, Convention on the Rights of the Child, the African Charter on Human and Peoples Rights, and the African Charter on the Rights and Welfare of a Child and policies like the Sustainable Development Goals 2030, the African Union Agenda 2063, and Agenda 2040 were considered. The research employed qualitative research methodology that included theoretical and non-empirical methods. It used a combination of descriptive, correlative, and limited comparative analysis of the status of street children in the East African Community State Parties of Tanzania, Uganda, and Rwanda, as well as South Africa. Theoretical perspectives, including human rights-based, vulnerability, othering, and capability theories, informed the discussions on improving the status of street children in Kenya. The study employed critical social justice and vulnerability theories to analyse how discrimination and prejudices in society can violate fundamental rights, particularly street children's rights. The findings of the study revealed the inadequate legal and institutional frameworks in promoting street children's rights in Kenya. The study referred to the best practices in the select East African Community State Parties and South Africa that Kenya can emulate to benefit street children and realise the right to shelter and adequate housing. The study recommends legal and policy reviews to protect street children's rights to adequate housing and shelter guided by constitutional and international standards. , Thesis (LLD) -- Faculty of Law, 2024
- Full Text:
- Date Issued: 2024-04
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