Comparison of a novel HPLC method and conventional protein assays for the quantitation of insulin aspart in Novorapid®
- Authors: Dickson, Courtney Rae
- Date: 2022-04-06
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/290704 , vital:56776
- Description: Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
- Authors: Dickson, Courtney Rae
- Date: 2022-04-06
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/290704 , vital:56776
- Description: Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
Fabrication and characterization of ciprofloxacin loaded niosomes for transtympanic delivery
- Authors: Mhlanga, Asavela
- Date: 2022-04-06
- Subjects: Drug delivery systems , Liposomes , Ciprofloxacin , Quinolone antibacterial agents , Drug carriers (Pharmacy) , Drug stability , Lamellarity , Niosomes
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290715 , vital:56777
- Description: Ciprofloxacin (CPH) is a broad-spectrum antibiotic used to treat bone, joint, and skin infections. It is commercially available as an extended-release tablet and as a cream dosage form. CPH is a bactericidal active pharmaceutical ingredient (API) of the fluoroquinolone drug class. It inhibits deoxyribonucleic acid (DNA) replication by inhibiting bacterial DNA topoisomerase and DNA gyrase enzymes. Common adverse effects include nausea, vomiting, unusual fatigue, pale skin, and may increase the risk of tendinitis, which could be a major concern. CPH is, according to the Biopharmaceutics Classification System (BCS), classified as a BCS class IV drug exhibiting low oral bioavailability, low solubility, and intestinal permeability. CPH was chosen as a good candidate for the study because of its stability in solutions, its low molecular weight (331.4 g/mol), and its moderate lipophilicity (log P = 0.28) [16]. The use of conventional ear drops in the ear is effective, avoids hepatic first metabolism and extensive protein binding and may reduce adverse effects as a low dose may be used to achieve a therapeutic effect. However, conventional ear drops and oral antibiotics have a long onset of action and have to be taken/applied in short intervals. For convenience and assurance of a long residence time in the ear, CPH may be delivered by using a niosomal formulation, a liquid at room temperature, to allow administration into the ear without the need to constantly apply the ear drops for long periods of time. A simple, rapid, precise, accurate, reproducible, and specific reversed-phase high-performance liquid chromatography (RP-HPLC) method using ultraviolet (UV) detection for the quantitation of CPH was developed and optimized using a central composite design (CCD). The method was validated using International Conference on Harmonisation (ICH) guidelines and was found to be linear, precise, accurate, and specific for the analysis of CPH. Since the method is specific, it was used to quantify CPH in commercial and experimental formulations and monitor CPH released during in-vitro release testing. The compatibility of CPH and potential excipients was investigated during preformulation studies using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) to identify and select suitable excipients for use during formulation development activities. No apparent interactions were evident between CPH, and the excipients tested. The probe sonication method was used to manufacture CPH loaded niosomes using different surfactants/surfactant combinations, and a combination of Tween® 80: sodium lauryl sulfate (SLS) was found to be the best composition in terms of both entrapment efficiency and Zeta potential. The limits for the independent input variables used for the manufacture included amplitude, sonication time, and amount of cholesterol were determined. Design of experiments (DOE) was used to design the study. The input variables investigated included amplitude, amount of cholesterol, and sonication time. The output or responses monitored included Zeta potential, vesicle size, polydispersity index (PDI), and entrapment efficiency. Non-ionic surfactant systems are predominantly stabilized by steric stabilization, and there is only a minor electrostatic element from adsorbed hydroxyl ions. With the inclusion of SLS it is to be expected that Zeta potential will be a contributing factor. DOE using Box-Behnken design (BBD) and response surface methodology (RSM) in addition to Artificial Neural Networks (ANN) were used for the optimization of the formulation. The optimized formulation had a composition of 1 g cholesterol, 1 g of Tween® 80, 1 g of SLS and was prepared at an amplitude of 11.294 % with a sonication time of 3.304 minutes. The formulation exhibited zero-order release kinetics and had an average pH of 7.45. The formulation was stored at 4 ℃ and 25 ℃ and was assessed for vesicle size, entrapment efficiency, Zeta potential, colour, lamellarity, and PDI every 7 days for 4 weeks. The lead formulation stored at 4 ℃ was more stable than the formulation at 25 ℃ in terms of entrapment efficiency, PDI and vesicle size during the 4-week period. CPH loaded niosomes for transtympanic delivery in the treatment of otitis media were developed and optimized. The technology exhibits sustained release of CPH and has the potential for further development and optimization. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
- Authors: Mhlanga, Asavela
- Date: 2022-04-06
- Subjects: Drug delivery systems , Liposomes , Ciprofloxacin , Quinolone antibacterial agents , Drug carriers (Pharmacy) , Drug stability , Lamellarity , Niosomes
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290715 , vital:56777
- Description: Ciprofloxacin (CPH) is a broad-spectrum antibiotic used to treat bone, joint, and skin infections. It is commercially available as an extended-release tablet and as a cream dosage form. CPH is a bactericidal active pharmaceutical ingredient (API) of the fluoroquinolone drug class. It inhibits deoxyribonucleic acid (DNA) replication by inhibiting bacterial DNA topoisomerase and DNA gyrase enzymes. Common adverse effects include nausea, vomiting, unusual fatigue, pale skin, and may increase the risk of tendinitis, which could be a major concern. CPH is, according to the Biopharmaceutics Classification System (BCS), classified as a BCS class IV drug exhibiting low oral bioavailability, low solubility, and intestinal permeability. CPH was chosen as a good candidate for the study because of its stability in solutions, its low molecular weight (331.4 g/mol), and its moderate lipophilicity (log P = 0.28) [16]. The use of conventional ear drops in the ear is effective, avoids hepatic first metabolism and extensive protein binding and may reduce adverse effects as a low dose may be used to achieve a therapeutic effect. However, conventional ear drops and oral antibiotics have a long onset of action and have to be taken/applied in short intervals. For convenience and assurance of a long residence time in the ear, CPH may be delivered by using a niosomal formulation, a liquid at room temperature, to allow administration into the ear without the need to constantly apply the ear drops for long periods of time. A simple, rapid, precise, accurate, reproducible, and specific reversed-phase high-performance liquid chromatography (RP-HPLC) method using ultraviolet (UV) detection for the quantitation of CPH was developed and optimized using a central composite design (CCD). The method was validated using International Conference on Harmonisation (ICH) guidelines and was found to be linear, precise, accurate, and specific for the analysis of CPH. Since the method is specific, it was used to quantify CPH in commercial and experimental formulations and monitor CPH released during in-vitro release testing. The compatibility of CPH and potential excipients was investigated during preformulation studies using Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) to identify and select suitable excipients for use during formulation development activities. No apparent interactions were evident between CPH, and the excipients tested. The probe sonication method was used to manufacture CPH loaded niosomes using different surfactants/surfactant combinations, and a combination of Tween® 80: sodium lauryl sulfate (SLS) was found to be the best composition in terms of both entrapment efficiency and Zeta potential. The limits for the independent input variables used for the manufacture included amplitude, sonication time, and amount of cholesterol were determined. Design of experiments (DOE) was used to design the study. The input variables investigated included amplitude, amount of cholesterol, and sonication time. The output or responses monitored included Zeta potential, vesicle size, polydispersity index (PDI), and entrapment efficiency. Non-ionic surfactant systems are predominantly stabilized by steric stabilization, and there is only a minor electrostatic element from adsorbed hydroxyl ions. With the inclusion of SLS it is to be expected that Zeta potential will be a contributing factor. DOE using Box-Behnken design (BBD) and response surface methodology (RSM) in addition to Artificial Neural Networks (ANN) were used for the optimization of the formulation. The optimized formulation had a composition of 1 g cholesterol, 1 g of Tween® 80, 1 g of SLS and was prepared at an amplitude of 11.294 % with a sonication time of 3.304 minutes. The formulation exhibited zero-order release kinetics and had an average pH of 7.45. The formulation was stored at 4 ℃ and 25 ℃ and was assessed for vesicle size, entrapment efficiency, Zeta potential, colour, lamellarity, and PDI every 7 days for 4 weeks. The lead formulation stored at 4 ℃ was more stable than the formulation at 25 ℃ in terms of entrapment efficiency, PDI and vesicle size during the 4-week period. CPH loaded niosomes for transtympanic delivery in the treatment of otitis media were developed and optimized. The technology exhibits sustained release of CPH and has the potential for further development and optimization. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2022
- Full Text:
Integrating blockchain and microgrid technology to enable peer-to-peer energy trading: a business process model
- Authors: Higgs, James
- Date: 2022-04-06
- Subjects: Blockchains (Databases) , Peer-to-peer architecture (Computer networks) , Electric power-plants Decentralization South Africa , Microgrids (Smart power grids) South Africa , Energy trading , Business process model
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/284559 , vital:56074
- Description: Traditional centralised energy systems are coming under increasing pressure because of decarbonisation, decentralisation, and digitisation. A lack of energy security and the inability to manage bi-directional electricity flows constitute two of the biggest challenges faced by centralised systems. Furthermore, in South Africa, the country’s energy system remains monopolised with one large utility satisfying most of the country’s electricity demand. This study is motivated by the need to address energy security within such a monopolised market. To redress the problems highlighted above, this study explores how blockchain and microgrid technology can be integrated to enable decentralised energy production and trading in South Africa. As such, this study develops a fully integrated blockchain-based microgrid energy trading system model. The functional requirements of the system are presented in the form of a business process model. Amongst other benefits, an active blockchain-based microgrid energy trading system provides a means to bolster energy security for the systems’ users. A unique aspect of this study’s approach to energy trading is the utilisation of blockchain’s native tokenizing capabilities. Prosumer energy tokens are minted to create a digital currency for local peer-to-peer energy exchange. A commons-rule based approach is adopted for governing energy resources. As such, this study demonstrates that commons-based solutions provide a feasible alternative to market and profit driven trading for organizing local energy exchange. The primary deliverable of this study satisfies the request of various blockchain researchers for blockchain research to focus on holistic conceptualisations, rather than on the minutiae of blockchain technicalities. Eight core functional requirements of a blockchain energy trading system were identified prior to the construction of the process model. The functional requirements were elicited during a scoping review as a part of the secondary data collection process. Expert review was utilised to verify the functional requirements of the blockchain energy trading system. Once the experts were identified, each expert completed a questionnaire with the intention to verify the requirements. The above process constituted the expert review process for the study. Additionally, the syntactic correctness of the business process model was verified by a business process modelling expert. Weber’s Theory of Evaluation constitutes the theoretical underpinning for the evaluation of the system parts. This study contributes the first publicly accessible business process models of a blockchain-based microgrid energy trading system. This study seeks to advance the discussion of a more integrative and cross disciplinary approach concerning blockchain research, particularly as it pertains to microgrid energy trading. , Thesis (MCom) -- Faculty of Commerce, Department of Information Systems, 2022
- Full Text:
- Authors: Higgs, James
- Date: 2022-04-06
- Subjects: Blockchains (Databases) , Peer-to-peer architecture (Computer networks) , Electric power-plants Decentralization South Africa , Microgrids (Smart power grids) South Africa , Energy trading , Business process model
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/284559 , vital:56074
- Description: Traditional centralised energy systems are coming under increasing pressure because of decarbonisation, decentralisation, and digitisation. A lack of energy security and the inability to manage bi-directional electricity flows constitute two of the biggest challenges faced by centralised systems. Furthermore, in South Africa, the country’s energy system remains monopolised with one large utility satisfying most of the country’s electricity demand. This study is motivated by the need to address energy security within such a monopolised market. To redress the problems highlighted above, this study explores how blockchain and microgrid technology can be integrated to enable decentralised energy production and trading in South Africa. As such, this study develops a fully integrated blockchain-based microgrid energy trading system model. The functional requirements of the system are presented in the form of a business process model. Amongst other benefits, an active blockchain-based microgrid energy trading system provides a means to bolster energy security for the systems’ users. A unique aspect of this study’s approach to energy trading is the utilisation of blockchain’s native tokenizing capabilities. Prosumer energy tokens are minted to create a digital currency for local peer-to-peer energy exchange. A commons-rule based approach is adopted for governing energy resources. As such, this study demonstrates that commons-based solutions provide a feasible alternative to market and profit driven trading for organizing local energy exchange. The primary deliverable of this study satisfies the request of various blockchain researchers for blockchain research to focus on holistic conceptualisations, rather than on the minutiae of blockchain technicalities. Eight core functional requirements of a blockchain energy trading system were identified prior to the construction of the process model. The functional requirements were elicited during a scoping review as a part of the secondary data collection process. Expert review was utilised to verify the functional requirements of the blockchain energy trading system. Once the experts were identified, each expert completed a questionnaire with the intention to verify the requirements. The above process constituted the expert review process for the study. Additionally, the syntactic correctness of the business process model was verified by a business process modelling expert. Weber’s Theory of Evaluation constitutes the theoretical underpinning for the evaluation of the system parts. This study contributes the first publicly accessible business process models of a blockchain-based microgrid energy trading system. This study seeks to advance the discussion of a more integrative and cross disciplinary approach concerning blockchain research, particularly as it pertains to microgrid energy trading. , Thesis (MCom) -- Faculty of Commerce, Department of Information Systems, 2022
- Full Text:
Mediating transition to household electricity conservation through co-designing in Makhanda, South Africa
- Authors: Mutumbi, Uzziah
- Date: 2022-04-06
- Subjects: Households Energy consumption South Africa Makhanda , Renewable energy sources South Africa , Consumer behavior South Africa Makhanda , Energy conservation South Africa Makhanda Citizen participation , Low-income consumers South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291262 , vital:56838
- Description: Households consume up to 20% of total global electricity consumption, hence they are important role players in efforts for promoting sustainable consumption. Research on electricity-use behaviour and effectiveness of interventions is important for informing intervention strategies. However, relative to developed countries, research on this subject is lacking in developing countries, where electricity access is limited, and a substantial proportion of households are energy poor. The main goal of this study was to examine reported electricity-use behaviour and the effects of co-designed interventions on household electricity consumption in low-income households in Makhanda, South Africa, using a field-based experiment. Findings from self-reported electricity-use practices showed mixed results, with households reporting both good electricity-use behaviour (e.g., cooling down hot food before refrigeration) and wasteful actions (e.g., leaving appliances on standby). Results showed that electricity-use behaviour was influenced by socio-psychological values including universalism, benevolence, hedonism, and power. Over the intervention period, households exposed to co-designed electricity-saving interventions showed mean electricity savings of about 5.5%, while households in the Partial Treatment and Control group showed increased electricity consumption. Socio-demographic factors such as age and psychological factors (involvement and perceived behavioural control) were very important determinants of household consumption. Broadly, the findings empirically validate the impact of collective problem formulation and co-designing interventions in promoting sustainable actions. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
- Full Text:
- Authors: Mutumbi, Uzziah
- Date: 2022-04-06
- Subjects: Households Energy consumption South Africa Makhanda , Renewable energy sources South Africa , Consumer behavior South Africa Makhanda , Energy conservation South Africa Makhanda Citizen participation , Low-income consumers South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/291262 , vital:56838
- Description: Households consume up to 20% of total global electricity consumption, hence they are important role players in efforts for promoting sustainable consumption. Research on electricity-use behaviour and effectiveness of interventions is important for informing intervention strategies. However, relative to developed countries, research on this subject is lacking in developing countries, where electricity access is limited, and a substantial proportion of households are energy poor. The main goal of this study was to examine reported electricity-use behaviour and the effects of co-designed interventions on household electricity consumption in low-income households in Makhanda, South Africa, using a field-based experiment. Findings from self-reported electricity-use practices showed mixed results, with households reporting both good electricity-use behaviour (e.g., cooling down hot food before refrigeration) and wasteful actions (e.g., leaving appliances on standby). Results showed that electricity-use behaviour was influenced by socio-psychological values including universalism, benevolence, hedonism, and power. Over the intervention period, households exposed to co-designed electricity-saving interventions showed mean electricity savings of about 5.5%, while households in the Partial Treatment and Control group showed increased electricity consumption. Socio-demographic factors such as age and psychological factors (involvement and perceived behavioural control) were very important determinants of household consumption. Broadly, the findings empirically validate the impact of collective problem formulation and co-designing interventions in promoting sustainable actions. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2022
- Full Text:
Motives and barriers to the implementation of renewable energy sources in South African tertiary institutions
- Authors: Sibindi, Siyangiso
- Date: 2022-04-06
- Subjects: Renewable energy sources South Africa , Education, Higher South Africa , Education, Higher Environmental aspects South Africa , Environmental responsibility South Africa , Climate change mitigation South Africa , Sustainable development South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/284537 , vital:56072
- Description: Organisations face major challenges to address the exploitation of non-renewable resources and consider management considerations for dealing with climate change. Organisations have been pushed to play a part in their carbon footprints and in curbing climate change. Among these organisations are tertiary institutions that can greatly impact environmental sustainability and address carbon dioxide emissions by embarking on renewable energy technologies. Tertiary institutions play a major role in society by the provision of skilled labour and personnel that are equipped to deal with a range of advancements and challenges. The sustainability of these tertiary institutions has thus been called into question due to the impact they can bring to societies. This research thus aims to identify the motives and barriers to renewable energy adoption in tertiary education institutions. To do this, a literature review was conducted to identify possible motives and barriers to renewable energy adoption. These were then compiled into a questionnaire that was sent to respondents of three different institutions. Respondents were then requested to give feedback on each of the motives and barriers. The respondents were also asked general questions found in literature that addressed the adoption of renewable energy technologies in tertiary institutions. The data was collected using the designed questionnaires. The respondents were able to articulate their perceived barriers and motives to the implementation of renewable energy technologies in tertiary institutions. Data analysis was done using thematic analysis. The results showed that the barriers in the implementation of renewable energy technologies in tertiary institutions were: ‘Cost to Install’, ‘Transition Process’ and ‘Government Policies’. The motives on why educational institutions need to embark on renewable energy projects were found to be ‘Energy Independence’, ‘Cleaner Source of Energy’ and ‘Reduction in Carbon Emissions’. The cost of renewable energy technologies, the process of moving from the Eskom grid, and renewable energy policies that are ambiguous were some factors that were highlighted by respondents on why it is challenging to adopt renewable energies in tertiary institutions. On the other hand, the effects of load shedding currently being experienced in the country and the migration to cleaner sources of energy that cause less harm to the environment, are some of the drivers noted by respondents on why tertiary institutions need to embark on renewable energy technologies. More emphasis needs to be put by stakeholders on tertiary institutions to migrate to cleaner sources of energy, and policies need to be put in place in order to promote institutions to adopt these types of energies. Governments and other role-players need to be visible at all times in addressing energy challenges in tertiary institutions in the wake of the recent load-shedding concerns that have been crippling South Africa. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2022
- Full Text:
- Authors: Sibindi, Siyangiso
- Date: 2022-04-06
- Subjects: Renewable energy sources South Africa , Education, Higher South Africa , Education, Higher Environmental aspects South Africa , Environmental responsibility South Africa , Climate change mitigation South Africa , Sustainable development South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/284537 , vital:56072
- Description: Organisations face major challenges to address the exploitation of non-renewable resources and consider management considerations for dealing with climate change. Organisations have been pushed to play a part in their carbon footprints and in curbing climate change. Among these organisations are tertiary institutions that can greatly impact environmental sustainability and address carbon dioxide emissions by embarking on renewable energy technologies. Tertiary institutions play a major role in society by the provision of skilled labour and personnel that are equipped to deal with a range of advancements and challenges. The sustainability of these tertiary institutions has thus been called into question due to the impact they can bring to societies. This research thus aims to identify the motives and barriers to renewable energy adoption in tertiary education institutions. To do this, a literature review was conducted to identify possible motives and barriers to renewable energy adoption. These were then compiled into a questionnaire that was sent to respondents of three different institutions. Respondents were then requested to give feedback on each of the motives and barriers. The respondents were also asked general questions found in literature that addressed the adoption of renewable energy technologies in tertiary institutions. The data was collected using the designed questionnaires. The respondents were able to articulate their perceived barriers and motives to the implementation of renewable energy technologies in tertiary institutions. Data analysis was done using thematic analysis. The results showed that the barriers in the implementation of renewable energy technologies in tertiary institutions were: ‘Cost to Install’, ‘Transition Process’ and ‘Government Policies’. The motives on why educational institutions need to embark on renewable energy projects were found to be ‘Energy Independence’, ‘Cleaner Source of Energy’ and ‘Reduction in Carbon Emissions’. The cost of renewable energy technologies, the process of moving from the Eskom grid, and renewable energy policies that are ambiguous were some factors that were highlighted by respondents on why it is challenging to adopt renewable energies in tertiary institutions. On the other hand, the effects of load shedding currently being experienced in the country and the migration to cleaner sources of energy that cause less harm to the environment, are some of the drivers noted by respondents on why tertiary institutions need to embark on renewable energy technologies. More emphasis needs to be put by stakeholders on tertiary institutions to migrate to cleaner sources of energy, and policies need to be put in place in order to promote institutions to adopt these types of energies. Governments and other role-players need to be visible at all times in addressing energy challenges in tertiary institutions in the wake of the recent load-shedding concerns that have been crippling South Africa. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2022
- Full Text:
The host specificity and efficacy of Phenrica guerini (Bechyné) (Coleoptera: Chrysomelidae), a candidate biological control agent of Pereskia aculeata Miller (Cactaceae) in Australia
- Authors: Dixon, Elizabeth Anne
- Date: 2022-04-06
- Subjects: Chrysomelidae Australia , Pereskia Australia , Pereskia Biological control Australia , Invasive plants Biological control Australia , Insects as biological pest control agents Australia , Cactus Biological control Australia
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290826 , vital:56789
- Description: Pereskia aculeata Miller (Cactaceae) is a primitive creeping cactus that originated from South America and has become an invasive alien plant in South Africa and Australia. Due to its vine-like growth form mechanical and chemical control are not feasible options for its control, therefore biological control is the best option for controlling this plant. Phenrica guerini (Bechyné) (Chrysomelidae) is a leaf-feeding flea beetle that has been released as a biological control agent against Pe. aculeata in South Africa and has been shown to be damaging at some sites in the country. In this thesis, further studies into the use of Ph. guerini as a biological control agent against Pe. aculeata were conducted to determine whether the beetle should be released as an agent against the target weed in Australia. The host range of a potential biological control agent is important to determine as only monophagous agents, or agents with suitably restricted host ranges, should be considered for release. Host specificity testing was conducted to determine if Ph. guerini was suitably specific for release in Australia. Phenrica guerini larvae only fed and partially developed on three out of 25 test plants, but failed to pupate on any plants besides Pe. aculeata. Adult beetles did not feed on any test plants and only oviposited on one test plant species. Phenrica guerini did not develop on any plant other than the target weed and is therefore suitably host specific for release in Australia. The efficacy of a potential agent is also important to consider as the release of an ineffective agent can reduce the success of a biological control programme. A laboratory based pre-release efficacy assessment was done to determine the impact that Ph. guerini could have on Pe. aculeata. There was a significant difference between the control plants and those with larvae, with an average of 72 (S.E. ± 12.33) less leaves on plants with feeding and the main stem of the plant being 11.1 cm (S.E. ± 7.17) shorter. Although there were no significant differences observed in the number of additional stems, and weights of the different plant parts, this was not a long term study and many of these differences would not have been observed in a short period. Based on the impact observed on the leaves and the main stem, and various field studies that have been done to assess the impact of Ph. guerini on Pe. aculeata in the field in South Africa, Ph. guerini appears to be a potentially damaging agent. As Pe. aculeata is still in its early stages of invasion in Australia the beetle has the potential to be damaging and reduce the invasion trajectory of the plant. This study showed that the beetle is suitably host specific and potentially damaging enough to be recommended for release as a biological control agent against Pe. aculeata in Australia. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
- Authors: Dixon, Elizabeth Anne
- Date: 2022-04-06
- Subjects: Chrysomelidae Australia , Pereskia Australia , Pereskia Biological control Australia , Invasive plants Biological control Australia , Insects as biological pest control agents Australia , Cactus Biological control Australia
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/290826 , vital:56789
- Description: Pereskia aculeata Miller (Cactaceae) is a primitive creeping cactus that originated from South America and has become an invasive alien plant in South Africa and Australia. Due to its vine-like growth form mechanical and chemical control are not feasible options for its control, therefore biological control is the best option for controlling this plant. Phenrica guerini (Bechyné) (Chrysomelidae) is a leaf-feeding flea beetle that has been released as a biological control agent against Pe. aculeata in South Africa and has been shown to be damaging at some sites in the country. In this thesis, further studies into the use of Ph. guerini as a biological control agent against Pe. aculeata were conducted to determine whether the beetle should be released as an agent against the target weed in Australia. The host range of a potential biological control agent is important to determine as only monophagous agents, or agents with suitably restricted host ranges, should be considered for release. Host specificity testing was conducted to determine if Ph. guerini was suitably specific for release in Australia. Phenrica guerini larvae only fed and partially developed on three out of 25 test plants, but failed to pupate on any plants besides Pe. aculeata. Adult beetles did not feed on any test plants and only oviposited on one test plant species. Phenrica guerini did not develop on any plant other than the target weed and is therefore suitably host specific for release in Australia. The efficacy of a potential agent is also important to consider as the release of an ineffective agent can reduce the success of a biological control programme. A laboratory based pre-release efficacy assessment was done to determine the impact that Ph. guerini could have on Pe. aculeata. There was a significant difference between the control plants and those with larvae, with an average of 72 (S.E. ± 12.33) less leaves on plants with feeding and the main stem of the plant being 11.1 cm (S.E. ± 7.17) shorter. Although there were no significant differences observed in the number of additional stems, and weights of the different plant parts, this was not a long term study and many of these differences would not have been observed in a short period. Based on the impact observed on the leaves and the main stem, and various field studies that have been done to assess the impact of Ph. guerini on Pe. aculeata in the field in South Africa, Ph. guerini appears to be a potentially damaging agent. As Pe. aculeata is still in its early stages of invasion in Australia the beetle has the potential to be damaging and reduce the invasion trajectory of the plant. This study showed that the beetle is suitably host specific and potentially damaging enough to be recommended for release as a biological control agent against Pe. aculeata in Australia. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2022
- Full Text:
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