The ethical conduct of new entry level emerging contractors
- Authors: Van Schalkwyk, Tanya Leonie
- Date: 2015
- Subjects: Construction industry -- Moral and ethical aspects , Building -- Moral and ethical aspects , Construction workers -- Professional ethics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4932 , vital:20769
- Description: Ethics is not a new or modern discipline. It was developed thousands of years ago and still remains relevant today. Ethics is applied in all spheres of modern life from philosophy to business and religious environments and even around dinner table conversations. It is applicable to all areas of life. This research is aimed at investigating whether ethical conduct among new entry level emerging contractors can contribute to and ensure their sustainable competitiveness within the South African construction industry. This research is also aimed at determining whether education and knowledge of entrepreneurship, business, project and construction management and building contracts can contribute to new entry level emerging contractors’ ethical conduct and sustainable competitiveness. The literature reviewed and results of quantitative and qualitative research amongst professional consultants in South Africa formed the basis of the study. Ethics is a sensitive topic within the industry and therefor it is difficult to gather data directly from contractors, as they are reluctant to participate in fear of revealing their identities and having it negatively influencing their personal and business credentials. Therefor unbiased respondents who were not directly linked to emerging contractors and who were unafraid to give objective opinions were questioned. These unbiased respondents included consultants within the industry. The study revealed that ethics is an important factor in any business environment and that the correct application thereof can partially contribute to the sustainable competitiveness of new entry level emerging contractors and this in turn can promote the long term survival of a business. Furthermore, knowledge of good management practices and building contracts can contribute to a successfully run business. However, the average new entry level emerging contractor has insufficient experience and knowledge of the management of construction projects, as well as building contracts.
- Full Text:
- Date Issued: 2015
- Authors: Van Schalkwyk, Tanya Leonie
- Date: 2015
- Subjects: Construction industry -- Moral and ethical aspects , Building -- Moral and ethical aspects , Construction workers -- Professional ethics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4932 , vital:20769
- Description: Ethics is not a new or modern discipline. It was developed thousands of years ago and still remains relevant today. Ethics is applied in all spheres of modern life from philosophy to business and religious environments and even around dinner table conversations. It is applicable to all areas of life. This research is aimed at investigating whether ethical conduct among new entry level emerging contractors can contribute to and ensure their sustainable competitiveness within the South African construction industry. This research is also aimed at determining whether education and knowledge of entrepreneurship, business, project and construction management and building contracts can contribute to new entry level emerging contractors’ ethical conduct and sustainable competitiveness. The literature reviewed and results of quantitative and qualitative research amongst professional consultants in South Africa formed the basis of the study. Ethics is a sensitive topic within the industry and therefor it is difficult to gather data directly from contractors, as they are reluctant to participate in fear of revealing their identities and having it negatively influencing their personal and business credentials. Therefor unbiased respondents who were not directly linked to emerging contractors and who were unafraid to give objective opinions were questioned. These unbiased respondents included consultants within the industry. The study revealed that ethics is an important factor in any business environment and that the correct application thereof can partially contribute to the sustainable competitiveness of new entry level emerging contractors and this in turn can promote the long term survival of a business. Furthermore, knowledge of good management practices and building contracts can contribute to a successfully run business. However, the average new entry level emerging contractor has insufficient experience and knowledge of the management of construction projects, as well as building contracts.
- Full Text:
- Date Issued: 2015
Drought responses of selected C₄ photosynthetic NADP-Me and NAD-Me Panicoideae and Aristidoideae grasses
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
- Authors: Venter, Nicolaas
- Date: 2015
- Subjects: Aristida , Panicum , Switchgrass , Grasses -- Effect of drought on , Grasses -- Phylogeny , Photosynthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4272 , http://hdl.handle.net/10962/d1018549
- Description: Grass species within South Africa show a photosynthetic subtype and phylogenetic response to rainfall gradients, with Panicoideae species (NADP-Me and NAD-Me) inhabiting mesic environments, while Aristidoideae species (NADP-Me) inhabit more arid environments. It is predicted that climate change will alter rainfall patterns within southern Africa, which could have implications for grassland distributions and functional composition. Globally, and in South Africa, species distributions indicates that NAD-Me species have a preference for more arid environments, but this may be complicated by phylogeny as most NAD-Me species belong to the Chloridoideae subfamily. Additionally, differences in the metabolism and energetic requirements of different carboxylation types are expected to confer different ecological advantages, such as drought tolerance, but the role of these different pathways is not well understood. Based on natural distribution and photosynthetic subtype differences, it was hypothesised that Panicoideae NADP-Me species would be less drought tolerant than Panicoideae NAD-Me and Aristidoideae NADP-Me species and that subtypes and lineages would show different drought recovery rates. Furthermore, drought sensitivity would be of a metabolic and not a stomatal origin and plants that maintained favourable leaf water status would be more drought tolerant and recover faster. This was tested experimentally by comparing Panicoideae species (NADP-Me and NAD-Me) and NADP-Me species (Panicoideae and Aristidoideae). Plants were subjected to a progressive 58 day drought period and a recovery phase where gas exchange, chlorophyll fluorescence and leaf water relations were measured at select intervals. In conjunction with this, a rapid drought experiment was performed on Zea mays (NADP-Me: Panicoideae) plants where similar parameters were measured. Photosynthetic drought and recovery responses showed both a subtype and phylogenetic response. Panicoideae species were less drought tolerant than Aristidoideae species, although Panicoideae NAD-Me showed better recovery rates than Panicoideae NADP-Me species, while Aristidoideae species recovered the quickest. Panicoideae NAD-Me and Aristidoideae species maintained higher leaf water status during drought which contributed to the maintenance of PSII integrity and thus facilitated rapid photosynthetic recovery. During drought Panicoideae species showed greater metabolic limitations over Aristidoideae species and for the first time, lower metabolic limitations were associated with osmotic adjustment. This is a novel finding whereby osmotic adjustment and the subsequent maintenance of leaf water are key to preventing metabolic limitations of photosynthesis in C₄ grasses. Results from the Z. mays rapid drought study showed the limitations to photosynthesis were exclusively metabolic and unlikely to be a direct consequence of turgor loss. It was apparent that the response to drought was stronger amongst lineages, as NADP-Me species from different subfamilies showed a significant difference in drought tolerances. Aristidoideae species’ exceptional drought tolerance and predicted increased aridification could favour these species over Panicoideae species under future climates.
- Full Text:
- Date Issued: 2015
The relationship between religion/spirituality and the general psychological well-being of the institutionalized elderly population in the Eastern Cape, South Africa
- Authors: Walton, Karen Lynn
- Date: 2015
- Subjects: Psychology, Religious Psychology and religion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5708 , vital:29366
- Description: Psychological well-being has a number of known benefits and is important for the quality of life of the elderly in particular. South Africa can be considered a religious country with the majority of citizens identifying with some religious orientation. The elderly are considered to be a more religious segment of the population, leading to a quantitative exploratory study being undertaken in order to ascertain whether a correlation exists between psychological well-being and religiosity/spirituality in the elderly institutionalised population of South Africa. The General Psychological Well-Being Scale and ASPIRES was administered to a convenience sample of 336 participants in the Eastern Cape Province. A significant but weak positive correlation was found between the variables of psychological well-being and religiosity. A difference was also found between White and African participants’ level of psychological well-being. An ANOVA was performed on the demographic information collected from participants. It was found that higher levels of education and access to private medical care were associated with higher levels of psychological well-being. A regression analysis was also performed on the data. It was found that although religiosity/spirituality does account for some of the variance, there were still a large number of other factors that influence psychological well-being in the elderly that were not captured in this study. Limitations of the study are that the results can’t be generalised to elderly residing at home. All of the participants also lived in urban areas and so differences may be found with rural elderly. Some further directions for research are discussed.
- Full Text:
- Date Issued: 2015
- Authors: Walton, Karen Lynn
- Date: 2015
- Subjects: Psychology, Religious Psychology and religion
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/5708 , vital:29366
- Description: Psychological well-being has a number of known benefits and is important for the quality of life of the elderly in particular. South Africa can be considered a religious country with the majority of citizens identifying with some religious orientation. The elderly are considered to be a more religious segment of the population, leading to a quantitative exploratory study being undertaken in order to ascertain whether a correlation exists between psychological well-being and religiosity/spirituality in the elderly institutionalised population of South Africa. The General Psychological Well-Being Scale and ASPIRES was administered to a convenience sample of 336 participants in the Eastern Cape Province. A significant but weak positive correlation was found between the variables of psychological well-being and religiosity. A difference was also found between White and African participants’ level of psychological well-being. An ANOVA was performed on the demographic information collected from participants. It was found that higher levels of education and access to private medical care were associated with higher levels of psychological well-being. A regression analysis was also performed on the data. It was found that although religiosity/spirituality does account for some of the variance, there were still a large number of other factors that influence psychological well-being in the elderly that were not captured in this study. Limitations of the study are that the results can’t be generalised to elderly residing at home. All of the participants also lived in urban areas and so differences may be found with rural elderly. Some further directions for research are discussed.
- Full Text:
- Date Issued: 2015
Characterisation of the HSP70-HSP90 organising protein gene and its link to cancer
- Authors: Weeks, Stacey
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56006 , vital:26764
- Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
- Full Text:
- Date Issued: 2015
- Authors: Weeks, Stacey
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56006 , vital:26764
- Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
- Full Text:
- Date Issued: 2015
The synthesis and analysis of (2R,3R)-1,1,4,4- tetraphenylbutane-1,2,3,4-tetraol (tetrol) and derivatives, and a study of their host potential
- Authors: Weitz, Selwyn Herbert
- Date: 2015
- Subjects: Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3735 , vital:20459
- Description: This investigation focussed on the inclusion and resolution ability of (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL), studies on the stoichiometry of its derivatives and the formation of inclusion compounds for single crystal analysis. The guest compounds that featured in the main study were cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. It was found that 3- and 4-methylcyclohexanone were trapped in their energetically unfavourable axial conformations in the inclusion crystal. Resolution experiments proved that (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol can be used as a resolving agent for 2- and 3-methylcyclohexanone, with ee values of 13% and 22%, respectively (according to the method of Hiemstra), in favour of the R-enantiomer. Single crystal X-ray diffraction (SCXRD) studies, however, showed that 2-methylcyclohexanone was resolved with an ee of 30% in R. An ee of 56% in R was obtained for 3-methylcyclohexanone. Enantiomer enrichment of 2-methylcyclohexanone was achieved in basic medium (ee of 18% according to the method of Hiemstra) and showed that by using the host in either half or double the molar ratio of the guest, a higher ee was obtained than for a 1:1 ratio. The following TETROL derivatives were also synthesized and their stoichiometries with various guest compounds were determined: (2R,3R)-1,1,4,4-tetra(naphthalen-1-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(naphthalen-2-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-anisyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-tolyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(m-tolyl)butane-1,2,3,4-tetraol and; (2R,3R)-1,1,4,4-tetra(o-tolyl)butane-1,2,3,4-tetraol.
- Full Text:
- Date Issued: 2015
- Authors: Weitz, Selwyn Herbert
- Date: 2015
- Subjects: Chemistry, Organic
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3735 , vital:20459
- Description: This investigation focussed on the inclusion and resolution ability of (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (TETROL), studies on the stoichiometry of its derivatives and the formation of inclusion compounds for single crystal analysis. The guest compounds that featured in the main study were cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. It was found that 3- and 4-methylcyclohexanone were trapped in their energetically unfavourable axial conformations in the inclusion crystal. Resolution experiments proved that (2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol can be used as a resolving agent for 2- and 3-methylcyclohexanone, with ee values of 13% and 22%, respectively (according to the method of Hiemstra), in favour of the R-enantiomer. Single crystal X-ray diffraction (SCXRD) studies, however, showed that 2-methylcyclohexanone was resolved with an ee of 30% in R. An ee of 56% in R was obtained for 3-methylcyclohexanone. Enantiomer enrichment of 2-methylcyclohexanone was achieved in basic medium (ee of 18% according to the method of Hiemstra) and showed that by using the host in either half or double the molar ratio of the guest, a higher ee was obtained than for a 1:1 ratio. The following TETROL derivatives were also synthesized and their stoichiometries with various guest compounds were determined: (2R,3R)-1,1,4,4-tetra(naphthalen-1-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(naphthalen-2-yl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-anisyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(p-tolyl)butane-1,2,3,4-tetraol; (2R,3R)-1,1,4,4-tetra(m-tolyl)butane-1,2,3,4-tetraol and; (2R,3R)-1,1,4,4-tetra(o-tolyl)butane-1,2,3,4-tetraol.
- Full Text:
- Date Issued: 2015
Population estimates and spatial ecology of brown hyaenas in Kwandwe private game reserve
- Authors: Welch, Rebecca Jane
- Date: 2015
- Subjects: Brown hyaena -- Reintroduction -- South Africa , Kwandwe Private Game Reserve
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5932 , http://hdl.handle.net/10962/d1017810
- Description: During the last 25 years, the Eastern Cape Province of South Africa has seen the establishment of many small to medium sized (≤ 440km2) game reserves. These reserves have reintroduced many of the larger indigenous wildlife that had been extirpated by the early 20th century. As such, these reserves and wildlife introductions have created many research opportunities, including investigations on the ecology of reintroduced carnivores in the Thicket biome. Brown hyaenas (Hyaena brunnea) are one of the large carnivore species that have been reintroduced into the area. As these animals have predominantly been studied in more open, arid systems, their reintroduction has provided an excellent opportunity to study the species in an alternate natural habitat. Information gathered from such investigations adds to our knowledge of the species and also provides information for the management of brown hyaenas within small, enclosed reserves. Data were collected over the period of one calendaryear, from February 2013 to February 2014 at Kwandwe Private Game Reserve in the Eastern Cape, South Africa. Brown hyaena population estimates were calculated using capture-recapture methods from individually identifiable images captured during a three month camera trapping survey. Images of brown hyaenas were separated into left- and right-side profiles. Twenty-eight individuals were positively identified from left-side images and 27 from right-side images. Non-spatial and spatially explicit capture-recapture analyses were both run in the program DENSITY 5.0. Density estimates ranged from 14 to 20 individuals/100km2 (equivalent to a total abundance of 26-37 individuals) depending on the method used. Despite the range of estimates, all are considerably higher than in other areaswhere densities have been calculated. Satellite/GPS collars were fitted to three individual brown hyaenas (two males and one female) to measure their home range size and use of space. Home range size was calculated using two different methods, Kernel utilisation distributions and Brownian bridges. Home range estimates were similar using both methods; however Brownian bridge methods appeared to exaggerate the use of space by individuals. Kernel home range sizes for the three individuals ranged between 42.62km2 and 79.88km2. These estimates are considerably smaller than previous findings from other parts of Africa and suggest that sufficient resources may be available within this enclosed system. The results from this study suggest that brown hyaenas are successful generalists in this enclosed system and are able to persist at high densities and occupy relatively small home ranges. This information is important for the managers of small reserves who wish to reintroduce brown hyaenas. Should brown hyaenas be introduced into reserves in the Thicket biome with sufficient resources, the numbers are likely to increase rapidly. If high numbers are not desired then preventative measures (e.g. contraception) should be investigated before release.
- Full Text:
- Date Issued: 2015
- Authors: Welch, Rebecca Jane
- Date: 2015
- Subjects: Brown hyaena -- Reintroduction -- South Africa , Kwandwe Private Game Reserve
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5932 , http://hdl.handle.net/10962/d1017810
- Description: During the last 25 years, the Eastern Cape Province of South Africa has seen the establishment of many small to medium sized (≤ 440km2) game reserves. These reserves have reintroduced many of the larger indigenous wildlife that had been extirpated by the early 20th century. As such, these reserves and wildlife introductions have created many research opportunities, including investigations on the ecology of reintroduced carnivores in the Thicket biome. Brown hyaenas (Hyaena brunnea) are one of the large carnivore species that have been reintroduced into the area. As these animals have predominantly been studied in more open, arid systems, their reintroduction has provided an excellent opportunity to study the species in an alternate natural habitat. Information gathered from such investigations adds to our knowledge of the species and also provides information for the management of brown hyaenas within small, enclosed reserves. Data were collected over the period of one calendaryear, from February 2013 to February 2014 at Kwandwe Private Game Reserve in the Eastern Cape, South Africa. Brown hyaena population estimates were calculated using capture-recapture methods from individually identifiable images captured during a three month camera trapping survey. Images of brown hyaenas were separated into left- and right-side profiles. Twenty-eight individuals were positively identified from left-side images and 27 from right-side images. Non-spatial and spatially explicit capture-recapture analyses were both run in the program DENSITY 5.0. Density estimates ranged from 14 to 20 individuals/100km2 (equivalent to a total abundance of 26-37 individuals) depending on the method used. Despite the range of estimates, all are considerably higher than in other areaswhere densities have been calculated. Satellite/GPS collars were fitted to three individual brown hyaenas (two males and one female) to measure their home range size and use of space. Home range size was calculated using two different methods, Kernel utilisation distributions and Brownian bridges. Home range estimates were similar using both methods; however Brownian bridge methods appeared to exaggerate the use of space by individuals. Kernel home range sizes for the three individuals ranged between 42.62km2 and 79.88km2. These estimates are considerably smaller than previous findings from other parts of Africa and suggest that sufficient resources may be available within this enclosed system. The results from this study suggest that brown hyaenas are successful generalists in this enclosed system and are able to persist at high densities and occupy relatively small home ranges. This information is important for the managers of small reserves who wish to reintroduce brown hyaenas. Should brown hyaenas be introduced into reserves in the Thicket biome with sufficient resources, the numbers are likely to increase rapidly. If high numbers are not desired then preventative measures (e.g. contraception) should be investigated before release.
- Full Text:
- Date Issued: 2015
Post-treatment technologies for integrated algal pond systems
- Authors: Westensee, Dirk Karl
- Date: 2015
- Subjects: Sewage disposal plants -- South Africa -- Grahamstown , Water -- Purification -- Filtration , Water -- Purification -- Slow sand filtration , Sewage -- Purification -- Anaerobic treatment , Sewage -- Purification -- Biological treatment , Algae -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5958 , http://hdl.handle.net/10962/d1018180
- Description: Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation and affords a secondarily treated water for reclamation according to its design specifications which most closely resemble those of the AIWPS® Advanced Secondary Process developed by Oswald. As a consequence, and as might be expected, while the technology performed well and delivered a final effluent superior to most pond systems deployed in South Africa it was unable to meet The Department of Water Affairs General Standard for nutrient removal and effluent discharge. The work described in this thesis involved the design, construction, and evaluation of several tertiary treatment units (TTU') for incorporation into the IAPS process design. Included were; Maturation Ponds (MP), Slow Sand Filter (SSF) and Rock Filters (RF). Three MP's were constructed in series with a 12 day retention time and operated in parallel with a two-layered SSF and a three-stage RF. Water quality of the effluent emerging from each of these TTU's was monitored over a 10 month period. Significant decreases in the chemical oxygen demand (COD), ammonium-N, phosphate-P, nitrate-N, faecal coliforms (FC) and total coliforms (TC) were achieved by these TTU's. On average, throughout the testing period, water quality was within the statutory limit for discharge to a water course that is not a listed water course, with the exception of the total suspended solids (TSS). The RF was determined as the most suitable TTU for commercial use due to production of a better quality water, smaller footprint, lower construction costs and less maintenance required. From the results of this investigation it is concluded that commercial deployment of IAPS for the treatment of municipal sewage requires the inclusion of a suitable TTU. Furthermore, and based on the findings presented, RF appears most appropriate to ensure that quality of the final effluent meets the standard for discharge.
- Full Text:
- Date Issued: 2015
- Authors: Westensee, Dirk Karl
- Date: 2015
- Subjects: Sewage disposal plants -- South Africa -- Grahamstown , Water -- Purification -- Filtration , Water -- Purification -- Slow sand filtration , Sewage -- Purification -- Anaerobic treatment , Sewage -- Purification -- Biological treatment , Algae -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5958 , http://hdl.handle.net/10962/d1018180
- Description: Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation and affords a secondarily treated water for reclamation according to its design specifications which most closely resemble those of the AIWPS® Advanced Secondary Process developed by Oswald. As a consequence, and as might be expected, while the technology performed well and delivered a final effluent superior to most pond systems deployed in South Africa it was unable to meet The Department of Water Affairs General Standard for nutrient removal and effluent discharge. The work described in this thesis involved the design, construction, and evaluation of several tertiary treatment units (TTU') for incorporation into the IAPS process design. Included were; Maturation Ponds (MP), Slow Sand Filter (SSF) and Rock Filters (RF). Three MP's were constructed in series with a 12 day retention time and operated in parallel with a two-layered SSF and a three-stage RF. Water quality of the effluent emerging from each of these TTU's was monitored over a 10 month period. Significant decreases in the chemical oxygen demand (COD), ammonium-N, phosphate-P, nitrate-N, faecal coliforms (FC) and total coliforms (TC) were achieved by these TTU's. On average, throughout the testing period, water quality was within the statutory limit for discharge to a water course that is not a listed water course, with the exception of the total suspended solids (TSS). The RF was determined as the most suitable TTU for commercial use due to production of a better quality water, smaller footprint, lower construction costs and less maintenance required. From the results of this investigation it is concluded that commercial deployment of IAPS for the treatment of municipal sewage requires the inclusion of a suitable TTU. Furthermore, and based on the findings presented, RF appears most appropriate to ensure that quality of the final effluent meets the standard for discharge.
- Full Text:
- Date Issued: 2015
A flight of fancy in the Chorister Robin-Chat (Cossypha dichroa) : an isotopic standpoint
- Wolmarans, Milena Helena Louise
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
- Date Issued: 2015
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
- Full Text:
- Date Issued: 2015
The effects of dietary soya and crystalline phytoestrogens on the growth, gonad development and histology of farmed abalone, Haliotis midae
- Wu, Yu
- Authors: Wu, Yu
- Date: 2015
- Subjects: Haliotis midae , Haliotis midae -- Feeding and feeds , Haliotis midae -- Growth , Haliotis midae -- Histology , Haliotis midae -- Effect of chemicals on , Soybean as feed , Phytoestrogens
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5380 , http://hdl.handle.net/10962/d1017225
- Description: The inclusion of soya as a dietary protein source in the formulated feed, Abfeed® S34 (Marifeed Pty (Ltd), Hermanus) for farmed abalone, Haliotis midae has resulted in larger gonads during reproductive seasons compared to the gonads of abalone fed kelp or diets that included fishmeal as the only main protein source. The aim of this study was to determine if the isoflavones present in the soya were responsible for this increase in gonad size and the subsequent effects on farmed abalone growth. Animals weighing between 40-50 g were fed one of seven isonitrogenous and isoenergetic diets containing either 0, 25, 50 or 100 percent of the soya component of the commercial feed (Abfeed® S34, Marifeed Pty (Ltd), Hermanus) from September 2013 to March 2014. An additional three diets were formulated to include crystalline isoflavone (ISO). These diets were identical to the 0 percent soya diet (i.e. the fishmeal only diet - FM), only ISO was included at the same rate that ISO occurred in the three soya diets. Data were analysed using a multiple forward stepwise regression analysis (MSR) to test the effects of ISO concentration, soya concentration, time, sex, time by concentration interaction and sex by concentration interaction on growth and gonad development and to identify those variables that most contributed to the model. The inclusion of crystalline ISO failed to promote larger gonads and had no effect on abalone growth, while growth and gonad development was dose dependent on soya inclusion rates with sex and time contributing to the models. Mean monthly weight gain in males correlated with increasing soya concentrations (c) (MSR, y = 3.24 + 0.002c, r2 = 0.23, p = 0.03), ranging from 3.11 ± 0.55 g abalone-1 month-1 to 4.43 ± 0.46 g abalone-1 month-1, while both male and female monthly length gain was not influenced by soya concentration with an overall mean of 1.62 ± 0.05 mm abalone-1 month-1 (MSR, p = 0.05 and p = 0.81, respectively). By December, the whole body mass, meat mass and visceral mass in both males and females decreased with increasing soya levels. However, by February, female whole body mass, meat mass and visceral mass positively correlated with soya levels. At the end of the study, male abalone fed FM with soya equivalent to the commercial feed had the highest whole body mass (69.00 ± 2.48 g abalone-1), meat mass (41.80 ± 1.12 g abalone-1), visceral mass (9.00 ± 2.47 g abalone-1) and gonad bulk index (42.70 ± 9.82 g abalone-1), while females were not influenced by soya concentrations with an overall whole body mass of 63.46 ± 0.79 g abalone-1. Weight loss was observed in all treatments between February and March, probably due to a spawning event. The moisture content in the meat was not influenced by treatment, however, visceral water loss was effected by both ISO and soya concentration with time and sex contributing to the model. The visceral water loss of females fed graded levels of soya decreased as a function of soya from December to March, and from December to February for males, whereas females fed ISO-enriched diets decreased as a function of ISO concentration (c) at the end of the study from 74.98 ± 0.88 to 73.10 ± 0.75 percent (MSR, y = 74.97 – 0.0025c, r2 = 0.20, p = 0.048). The inclusion of crystalline ISO had no significant effect on oogenesis in female farmed Haliotis midae, while the distribution of the predominant oocyte stage, stage 7 (second last stage prior to spawning) was dose-dependent in abalone fed increasing soya concentration (c) (MSR, y = 33.38 + 0.03c, r2 = 0.32, F(1, 18) = 8.52, p = 0.01). The increase in stage 7 oocytes in abalone fed FM with soya did not reduce the number of oocytes (44.96 ± 3.01 oocytes mm-2) present within the lumen, while the number of oocytes (o) in abalone fed the FM-only based diets decreased with increasing abundance of stage 7 oocytes (MSR, y = 58.28 – 0.48c, r2 = 0.38, F(1, 18) = 12.51, p = 0.002), possibly due to the increase in size of the oocytes with thicker jelly coats. This study provided evidence that crystalline isoflavone had no influence on abalone gonad development over five months, while soya had a dose-dependent effect on growth, gonad mass and oogenesis in farmed Haliotis midae. Formulated abalone feed could be manipulated at certain times of the year to obtain maximum growth. These implications and further studies were discussed.
- Full Text:
- Date Issued: 2015
- Authors: Wu, Yu
- Date: 2015
- Subjects: Haliotis midae , Haliotis midae -- Feeding and feeds , Haliotis midae -- Growth , Haliotis midae -- Histology , Haliotis midae -- Effect of chemicals on , Soybean as feed , Phytoestrogens
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5380 , http://hdl.handle.net/10962/d1017225
- Description: The inclusion of soya as a dietary protein source in the formulated feed, Abfeed® S34 (Marifeed Pty (Ltd), Hermanus) for farmed abalone, Haliotis midae has resulted in larger gonads during reproductive seasons compared to the gonads of abalone fed kelp or diets that included fishmeal as the only main protein source. The aim of this study was to determine if the isoflavones present in the soya were responsible for this increase in gonad size and the subsequent effects on farmed abalone growth. Animals weighing between 40-50 g were fed one of seven isonitrogenous and isoenergetic diets containing either 0, 25, 50 or 100 percent of the soya component of the commercial feed (Abfeed® S34, Marifeed Pty (Ltd), Hermanus) from September 2013 to March 2014. An additional three diets were formulated to include crystalline isoflavone (ISO). These diets were identical to the 0 percent soya diet (i.e. the fishmeal only diet - FM), only ISO was included at the same rate that ISO occurred in the three soya diets. Data were analysed using a multiple forward stepwise regression analysis (MSR) to test the effects of ISO concentration, soya concentration, time, sex, time by concentration interaction and sex by concentration interaction on growth and gonad development and to identify those variables that most contributed to the model. The inclusion of crystalline ISO failed to promote larger gonads and had no effect on abalone growth, while growth and gonad development was dose dependent on soya inclusion rates with sex and time contributing to the models. Mean monthly weight gain in males correlated with increasing soya concentrations (c) (MSR, y = 3.24 + 0.002c, r2 = 0.23, p = 0.03), ranging from 3.11 ± 0.55 g abalone-1 month-1 to 4.43 ± 0.46 g abalone-1 month-1, while both male and female monthly length gain was not influenced by soya concentration with an overall mean of 1.62 ± 0.05 mm abalone-1 month-1 (MSR, p = 0.05 and p = 0.81, respectively). By December, the whole body mass, meat mass and visceral mass in both males and females decreased with increasing soya levels. However, by February, female whole body mass, meat mass and visceral mass positively correlated with soya levels. At the end of the study, male abalone fed FM with soya equivalent to the commercial feed had the highest whole body mass (69.00 ± 2.48 g abalone-1), meat mass (41.80 ± 1.12 g abalone-1), visceral mass (9.00 ± 2.47 g abalone-1) and gonad bulk index (42.70 ± 9.82 g abalone-1), while females were not influenced by soya concentrations with an overall whole body mass of 63.46 ± 0.79 g abalone-1. Weight loss was observed in all treatments between February and March, probably due to a spawning event. The moisture content in the meat was not influenced by treatment, however, visceral water loss was effected by both ISO and soya concentration with time and sex contributing to the model. The visceral water loss of females fed graded levels of soya decreased as a function of soya from December to March, and from December to February for males, whereas females fed ISO-enriched diets decreased as a function of ISO concentration (c) at the end of the study from 74.98 ± 0.88 to 73.10 ± 0.75 percent (MSR, y = 74.97 – 0.0025c, r2 = 0.20, p = 0.048). The inclusion of crystalline ISO had no significant effect on oogenesis in female farmed Haliotis midae, while the distribution of the predominant oocyte stage, stage 7 (second last stage prior to spawning) was dose-dependent in abalone fed increasing soya concentration (c) (MSR, y = 33.38 + 0.03c, r2 = 0.32, F(1, 18) = 8.52, p = 0.01). The increase in stage 7 oocytes in abalone fed FM with soya did not reduce the number of oocytes (44.96 ± 3.01 oocytes mm-2) present within the lumen, while the number of oocytes (o) in abalone fed the FM-only based diets decreased with increasing abundance of stage 7 oocytes (MSR, y = 58.28 – 0.48c, r2 = 0.38, F(1, 18) = 12.51, p = 0.002), possibly due to the increase in size of the oocytes with thicker jelly coats. This study provided evidence that crystalline isoflavone had no influence on abalone gonad development over five months, while soya had a dose-dependent effect on growth, gonad mass and oogenesis in farmed Haliotis midae. Formulated abalone feed could be manipulated at certain times of the year to obtain maximum growth. These implications and further studies were discussed.
- Full Text:
- Date Issued: 2015
Using the larval parasitoid, Agathis bishopi (Nixon) (Hymenoptera: Braconidae), for early detection of false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) infested fruit
- Authors: Zimba, Kennedy Josaya
- Date: 2015
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
- Full Text:
- Date Issued: 2015
- Authors: Zimba, Kennedy Josaya
- Date: 2015
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- South Africa , Pests -- Biological control -- South Africa , Cryptophlebia leucotreta -- Detection , Parasitoids -- Hosts , Braconidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5919 , http://hdl.handle.net/10962/d1017186
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is one of the major citrus pests of economic importance for South Africa’s citrus industry. It is endemic to Africa, and therefore a phytosanitary pest with zero tolerance by most export markets. The cryptic nature of T. leucotreta makes visual inspection an inefficient method for detecting neonate larvae in fruit in the packhouse. Therefore, a more accurate method for sorting infested fruit at the packhouse, particularly for newly infested fruit could ensure market access. A recent study showed that fruit infested by T. leucotreta emit a chemical profile different from that of a healthy fruit. Several studies provide evidence that parasitoids locate their hosts feeding on fruit by exploiting the novel chemical profiles produced due to host herbivory. The aim of this study was to evaluate the potential of using the naturally occurring behaviour of a larval parasitoid Agathis bishopi (Nixon) (Hymenoptera: Braconidae) for detection of T. leucotreta infested fruit, by determining which compound in infested fruit is attractive to parasitoids. Ytube olfactometer and flight-tunnel bioassays with healthy and T. leucotreta infested fruit showed a significantly stronger response of A. bishopi female parasitoids to infested fruit. Among the volatile compounds associated with T. leucotreta infested fruit, D-limonene elicited the strongest attraction to A. bishopi female parasitoids. Attraction of mated A. bishopi female parasitoids to T. leucotreta infested fruit and D-limonene significantly increased after oviposition experience. Behavioural responses of A. bishopi female parasitoids that were associated with T. leucotreta infested fruit were investigated to determine which behaviours are distinct and interpretable. Probing and oviposition behaviours were the most noticeable and were only elicited on infested fruit when parasitoids contacted T. leucotreta frass, indicating that chemical compounds in frass are short-range cues used for final host location. Since production of D-limonene by fruit is elevated due to herbivory by different pests including mechanical injury on fruit, response of A. bishopi female parasitoids to compounds in frass offers a more specific and potentially useful mechanism for development of a detection system for T. leucotreta infested fruit. Chemical analysis of T. leucotreta frass and conditioning A. bishopi parasitoids to respond behaviourally to compounds in frass is proposed.
- Full Text:
- Date Issued: 2015