Habitat complexity alters predator-prey interactions in a shallow water ecosystem
- Froneman, P William, Cuthbert, Ross N
- Authors: Froneman, P William , Cuthbert, Ross N
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/479242 , vital:78277 , https://doi.org/10.3390/d14060431
- Description: Habitat complexity can profoundly influence interactions between predators and their prey due to changes to foraging efficiencies. In aquatic systems, habitat alterations can alter pursuit times and swimming behaviours of predator–prey participants, which in turn could mediate the strength of their interactions and, thus, population dynamics. The lower reaches of estuarine ecosystems are typically characterised by extensive beds of submerged macrophytes that might influence the trophic dynamics between pelagic predators and their prey. Here, we investigate the influence of increasing habitat complexity on the consumption of the calanoid copepod, Paracartia longipatella, by adult male and female mysid, Mesopodopsis wooldridgei, by means of a comparative functional response approach. Using structures that resembled aquatic vegetation, we quantified and compared feeding rates, attack rates, and handling times across the habitat gradient, and we questioned whether responses to habitat complexity are different between sexes. Feeding rates related significantly negatively to increasing habitat complexity for both males and females, with Type II functional responses consistently displayed. Functional response differed significantly across habitat complexities, with feeding rates at low and intermediate prey densities significantly greater in the absence of habitat compared to more complex structures for both predator sexes. Results of the current study demonstrate that increased habitat complexity mediates outcomes of interactions between M. wooldridgei and the calanoid copepod, P. longipatella across predator sexes, and possibly for other predators and prey in shallow waters. Owing to spatiotemporal differences in habitat structure within shallow waters, the strength of interactions in this predator–prey system likely differs in areas where they co-exist.
- Full Text:
- Authors: Froneman, P William , Cuthbert, Ross N
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/479242 , vital:78277 , https://doi.org/10.3390/d14060431
- Description: Habitat complexity can profoundly influence interactions between predators and their prey due to changes to foraging efficiencies. In aquatic systems, habitat alterations can alter pursuit times and swimming behaviours of predator–prey participants, which in turn could mediate the strength of their interactions and, thus, population dynamics. The lower reaches of estuarine ecosystems are typically characterised by extensive beds of submerged macrophytes that might influence the trophic dynamics between pelagic predators and their prey. Here, we investigate the influence of increasing habitat complexity on the consumption of the calanoid copepod, Paracartia longipatella, by adult male and female mysid, Mesopodopsis wooldridgei, by means of a comparative functional response approach. Using structures that resembled aquatic vegetation, we quantified and compared feeding rates, attack rates, and handling times across the habitat gradient, and we questioned whether responses to habitat complexity are different between sexes. Feeding rates related significantly negatively to increasing habitat complexity for both males and females, with Type II functional responses consistently displayed. Functional response differed significantly across habitat complexities, with feeding rates at low and intermediate prey densities significantly greater in the absence of habitat compared to more complex structures for both predator sexes. Results of the current study demonstrate that increased habitat complexity mediates outcomes of interactions between M. wooldridgei and the calanoid copepod, P. longipatella across predator sexes, and possibly for other predators and prey in shallow waters. Owing to spatiotemporal differences in habitat structure within shallow waters, the strength of interactions in this predator–prey system likely differs in areas where they co-exist.
- Full Text:
Household dietary patterns and food security challenges in Peri-Urban South Africa: A reflection of high unemployment in the wake of rising food prices
- Authors: Chakona, Gamuchirai
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433943 , vital:73013 , ISBN 978-3-030-93072-1 , https://doi.org/10.1007/978-3-030-93072-1_11
- Description: Urbanization is one of the major social changes sweeping the globe, with rapid growth of the urban population and stagnating growth of the rural population, especially in developing regions (UN-Habitat, 2020). In subSaharan Africa, rapid urbanization and poverty are the major fundamental development challenges that are perpetuating and deepening the crisis of food and nutrition insecurity in urban areas (Battersby, 2012). Many people living in urban areas face under-nutrition, mainly due to their lack of income rather than to a lack of capacity to produce food (Satterthwaite et al., 2010). The health and nutritional status of urban populations with very low incomes are at risk from rising prices in staple foods. This became evident with the rising hunger among urban populations after the food price rises in 2007 and the first half of 2008 (Cohen and Garrett, 2009). In South Africa, poverty, unemployment and high food prices are dominant and influence dietary change, which subsequently increases urban food insecurity and malnutrition (Battersby, 2012).
- Full Text:
- Authors: Chakona, Gamuchirai
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433943 , vital:73013 , ISBN 978-3-030-93072-1 , https://doi.org/10.1007/978-3-030-93072-1_11
- Description: Urbanization is one of the major social changes sweeping the globe, with rapid growth of the urban population and stagnating growth of the rural population, especially in developing regions (UN-Habitat, 2020). In subSaharan Africa, rapid urbanization and poverty are the major fundamental development challenges that are perpetuating and deepening the crisis of food and nutrition insecurity in urban areas (Battersby, 2012). Many people living in urban areas face under-nutrition, mainly due to their lack of income rather than to a lack of capacity to produce food (Satterthwaite et al., 2010). The health and nutritional status of urban populations with very low incomes are at risk from rising prices in staple foods. This became evident with the rising hunger among urban populations after the food price rises in 2007 and the first half of 2008 (Cohen and Garrett, 2009). In South Africa, poverty, unemployment and high food prices are dominant and influence dietary change, which subsequently increases urban food insecurity and malnutrition (Battersby, 2012).
- Full Text:
How Great is thy Dictionary? Cross-referencing as a Lexicographic Device in The Greater Dictionary of (isi) Xhosa
- Nkomo, Dion, Nosilela, Bulelwa, Gambushe, Wanga
- Authors: Nkomo, Dion , Nosilela, Bulelwa , Gambushe, Wanga
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467979 , vital:76996 , DOI:10.5788/32-3-1736
- Description: Inspired by Willem Botha's reflections on the compilation of the multi-volume Woordeboek van die Afrikaanse Taal (WAT) in Botha (1994; 2005), this study offers a critical evaluation of cross-referencing in The Greater Dictionary of (isi) Xhosa, henceforth the GDX. The GDX is a tri-volume dictionary, possibly the biggest dictionary, not only in isiXhosa, but in African languages. The evaluation of the dictionary is guided by the notion of cross-reference conditions or cross-reference prerequisites to identify cross-references used in the GDX, analyse the relations revealed by crossreferencing and the effectiveness of the entire mediostructural organisation of the dictionary. The article notes that cross-referencing in the GDX seems to be guided by a generally well-conceived set of guidelines which were largely followed meticulously. Consistency generally prevails in the treatment of similar lexical items and even across the different volumes of the dictionary. Some cross-referencing aspects that could be improved were identified. However, it was noted that most of them would be easily addressed in the prospective digitisation project of the GDX.
- Full Text:
- Authors: Nkomo, Dion , Nosilela, Bulelwa , Gambushe, Wanga
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/467979 , vital:76996 , DOI:10.5788/32-3-1736
- Description: Inspired by Willem Botha's reflections on the compilation of the multi-volume Woordeboek van die Afrikaanse Taal (WAT) in Botha (1994; 2005), this study offers a critical evaluation of cross-referencing in The Greater Dictionary of (isi) Xhosa, henceforth the GDX. The GDX is a tri-volume dictionary, possibly the biggest dictionary, not only in isiXhosa, but in African languages. The evaluation of the dictionary is guided by the notion of cross-reference conditions or cross-reference prerequisites to identify cross-references used in the GDX, analyse the relations revealed by crossreferencing and the effectiveness of the entire mediostructural organisation of the dictionary. The article notes that cross-referencing in the GDX seems to be guided by a generally well-conceived set of guidelines which were largely followed meticulously. Consistency generally prevails in the treatment of similar lexical items and even across the different volumes of the dictionary. Some cross-referencing aspects that could be improved were identified. However, it was noted that most of them would be easily addressed in the prospective digitisation project of the GDX.
- Full Text:
How many people globally actually use non-timber forest products?
- Shackleton, Charlie M, de Vos, Alta
- Authors: Shackleton, Charlie M , de Vos, Alta
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403200 , vital:69933 , xlink:href="https://doi.org/10.1016/j.forpol.2021.102659"
- Description: Non-timber forest products (NTFPs) are widely used wild, biological products harvested from rural and urban landscapes for household subsistence, income and culture, thereby contributing to human wellbeing. Estimates of the numbers of people making use of, or being dependent on, NTFPs vary widely, and global estimates to date have excluded urban populations and also NTFP users in the Global North. Additionally, most global or continental estimates are two or more decades old, and hence do not account for significant worldwide changes in societies, cultures, economies and landscapes since the estimates were made. Here we collate more recent empirical studies reporting the number of NTFP users at fine scales that we extrapolate up for three broad regions, viz. rural areas of the Global South, urban areas of the Global South, and the Global North, as the basis for estimating the number of NTFP users globally. We calculate the lower and upper bounds, as well a median estimate. We find the lowest and median approximations to be 3.5 billion and 5.76 billion users globally, respectively, based on conservative approaches. This is more than double and triple, respectively, the oft cited and dated figure of 1.6 billion. Moreover, we find that only half of the global NTFP users are located in rural regions of the Global South, and that the other half are in urban areas and the Global North, showing that NTFPs are of importance across socio-economic and geographic regions, not just in remote and underdeveloped villages of the Global South. With such large numbers of users around the world, it is imperative that the supply, management, conservation and safeguarding of the values of NTFPs take a more central place in sectoral and development policies.
- Full Text:
- Authors: Shackleton, Charlie M , de Vos, Alta
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403200 , vital:69933 , xlink:href="https://doi.org/10.1016/j.forpol.2021.102659"
- Description: Non-timber forest products (NTFPs) are widely used wild, biological products harvested from rural and urban landscapes for household subsistence, income and culture, thereby contributing to human wellbeing. Estimates of the numbers of people making use of, or being dependent on, NTFPs vary widely, and global estimates to date have excluded urban populations and also NTFP users in the Global North. Additionally, most global or continental estimates are two or more decades old, and hence do not account for significant worldwide changes in societies, cultures, economies and landscapes since the estimates were made. Here we collate more recent empirical studies reporting the number of NTFP users at fine scales that we extrapolate up for three broad regions, viz. rural areas of the Global South, urban areas of the Global South, and the Global North, as the basis for estimating the number of NTFP users globally. We calculate the lower and upper bounds, as well a median estimate. We find the lowest and median approximations to be 3.5 billion and 5.76 billion users globally, respectively, based on conservative approaches. This is more than double and triple, respectively, the oft cited and dated figure of 1.6 billion. Moreover, we find that only half of the global NTFP users are located in rural regions of the Global South, and that the other half are in urban areas and the Global North, showing that NTFPs are of importance across socio-economic and geographic regions, not just in remote and underdeveloped villages of the Global South. With such large numbers of users around the world, it is imperative that the supply, management, conservation and safeguarding of the values of NTFPs take a more central place in sectoral and development policies.
- Full Text:
How the Teaching Development Grant was used (and the problem of common-sense understandings of teaching and learning)
- Moyo, Temwa, McKenna, Sioux, Ndebele, Clever
- Authors: Moyo, Temwa , McKenna, Sioux , Ndebele, Clever
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426917 , vital:72400 , xlink:href="http://dx.doi.org/10.17159/2520-9868/i86a07"
- Description: Teachers at primary and secondary education levels are required to hold a professional qualification but, at the higher education level, all that is required is content expertise. This may well contribute to South Africa's low university throughput and retention rates, in response to which, since 2004, the state has provided ZAR5.5 billion in the form of the Teaching Development Grant (now the University Capacity Development Grant) to address poor completion rates. We present an analysis of the use of the grant across the sector using a social realist framework. Every academic and student has themselves been taught and so have developed untheorised assumptions about curriculum and pedagogy. Such common-sense assumptions about teaching and learning often serve to reinforce the status quo, which is particularly problematic in a sector with poor and racially differentiated throughput and success rates. Many initiatives funded through the grant evidenced a reliance on common-sense assumptions rather than on theorised accounts. In particular, student development often took the form of remedial, add-on initiatives that left the mainstream curriculum untouched-and staff development was often generic and short term. We also found that expertise in academic development, which could potentially challenge common-sense assumptions, was unevenly distributed.
- Full Text:
- Authors: Moyo, Temwa , McKenna, Sioux , Ndebele, Clever
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426917 , vital:72400 , xlink:href="http://dx.doi.org/10.17159/2520-9868/i86a07"
- Description: Teachers at primary and secondary education levels are required to hold a professional qualification but, at the higher education level, all that is required is content expertise. This may well contribute to South Africa's low university throughput and retention rates, in response to which, since 2004, the state has provided ZAR5.5 billion in the form of the Teaching Development Grant (now the University Capacity Development Grant) to address poor completion rates. We present an analysis of the use of the grant across the sector using a social realist framework. Every academic and student has themselves been taught and so have developed untheorised assumptions about curriculum and pedagogy. Such common-sense assumptions about teaching and learning often serve to reinforce the status quo, which is particularly problematic in a sector with poor and racially differentiated throughput and success rates. Many initiatives funded through the grant evidenced a reliance on common-sense assumptions rather than on theorised accounts. In particular, student development often took the form of remedial, add-on initiatives that left the mainstream curriculum untouched-and staff development was often generic and short term. We also found that expertise in academic development, which could potentially challenge common-sense assumptions, was unevenly distributed.
- Full Text:
Hybrid approaches to teaching: Re-imagining the teaching of a foundational science course during a global pandemic
- Parker, Daniel M, Vorster, Jo-Anne E, Quinn, Lynn, Blackie, Margaret A L
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
- Authors: Parker, Daniel M , Vorster, Jo-Anne E , Quinn, Lynn , Blackie, Margaret A L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426662 , vital:72377 , xlink:href="https://www.ajol.info/index.php/cristal/article/view/240803"
- Description: Access to scientific knowledge, and teaching in the sciences, is believed to be about training because scientific knowledge is, generally, specialised. However, for students to gain full epistemological access in the sciences, they also need to be inducted as scientists and learners of science. We use Bernstein’s regulative and instructional discourse to engage with the notion of epistemological access and effectiveness of a foundational science course. We examine how the course can cultivate scientific identities amongst first year students at a recently established South African university. Our analysis assesses the impact of the forced shift from contact teaching to Emergency Remote Teaching due to the COVID-19 pandemic. We demonstrate that the course was able to begin to facilitate the cultivation of different kinds of knowers in science. However, several gaps remain. Thus, we argue that foundational science lecturers should focus on hybrid teaching approaches to promote enhanced learning amongst students.
- Full Text:
Identity, context and mobile media: A critical digital literacy service learning course in a South African township
- Boshoff, Priscilla A, Dalvit, Lorenzo
- Authors: Boshoff, Priscilla A , Dalvit, Lorenzo
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/468195 , vital:77029 , ISBN 978-84-09-45476-1 , doi: 10.21125/edulearn.2022.1419
- Description: In this paper we discuss a critical digital literacy service learning initiative involving post-graduate students in Journalism and Media Studies at Rhodes University in Makhanda (South Africa). As part of their studies, such students co-develop and teach a small-scale, non-credit-bearing short course on mobile critical digital literacy skills to learners in a township school. In South African terms, a township is an (often marginalised) area, present in almost every settlement, in which people classified as Blacks under apartheid were expected to live and to a large extent still do. As a microcosm of the diverse and still profoundly unequal South African reality, Makhanda offers ample opportunities for contact and collaboration across the geographic, socio-economic and digital divides. The Rhodes School of Journalism and Media Studies, recognised as one of the best on the African Continent, partners with a number of local organisations to support community upliftment and mutual learning. Community engagement, of which service learning is but one expression, is recognised as an integral component of academic activities for university staff and students. Rhodes University offers dedicated training and provides institutional support for activities such as the one discussed here. What makes our approach somehow unique is the adoption of photo voice as a pedagogical device in teaching and learning about identity construction in a marginalised context. Under the guidance of postgraduate students and their lecturers, learners learn about the technical aspects of taking photos to represent their identities using their mobile phone. Such photos are then used as a point of departure for facilitated group discussions about (self)representations, the social construction of identities and the importance of understanding these in relation to their lived context. In this paper we document and reflect on the conceptualisation and first iteration of the digital literacy service learning course, drawing some lessons for the future.
- Full Text:
- Authors: Boshoff, Priscilla A , Dalvit, Lorenzo
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/468195 , vital:77029 , ISBN 978-84-09-45476-1 , doi: 10.21125/edulearn.2022.1419
- Description: In this paper we discuss a critical digital literacy service learning initiative involving post-graduate students in Journalism and Media Studies at Rhodes University in Makhanda (South Africa). As part of their studies, such students co-develop and teach a small-scale, non-credit-bearing short course on mobile critical digital literacy skills to learners in a township school. In South African terms, a township is an (often marginalised) area, present in almost every settlement, in which people classified as Blacks under apartheid were expected to live and to a large extent still do. As a microcosm of the diverse and still profoundly unequal South African reality, Makhanda offers ample opportunities for contact and collaboration across the geographic, socio-economic and digital divides. The Rhodes School of Journalism and Media Studies, recognised as one of the best on the African Continent, partners with a number of local organisations to support community upliftment and mutual learning. Community engagement, of which service learning is but one expression, is recognised as an integral component of academic activities for university staff and students. Rhodes University offers dedicated training and provides institutional support for activities such as the one discussed here. What makes our approach somehow unique is the adoption of photo voice as a pedagogical device in teaching and learning about identity construction in a marginalised context. Under the guidance of postgraduate students and their lecturers, learners learn about the technical aspects of taking photos to represent their identities using their mobile phone. Such photos are then used as a point of departure for facilitated group discussions about (self)representations, the social construction of identities and the importance of understanding these in relation to their lived context. In this paper we document and reflect on the conceptualisation and first iteration of the digital literacy service learning course, drawing some lessons for the future.
- Full Text:
IFRS and FPI nexus: does the quality of the institutional framework matter for African countries?
- Simbi, Chipo, Arendse, Jacqueline A, Khumalo, Sibanisezwe A
- Authors: Simbi, Chipo , Arendse, Jacqueline A , Khumalo, Sibanisezwe A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426448 , vital:72354 , xlink:href="https://doi.org/10.1108/JAEE-10-2021-0319"
- Description: The institutional framework of an African country may influence the effectiveness of the International Financial Reporting Standards (IFRS) on foreign investment inflows. The purpose of this paper is to argue that the quality of a country's institutional framework impacts the effectiveness of IFRS to an adopting country and ultimately influences the levels of Foreign Portfolio Investment (FPI).
- Full Text:
- Authors: Simbi, Chipo , Arendse, Jacqueline A , Khumalo, Sibanisezwe A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426448 , vital:72354 , xlink:href="https://doi.org/10.1108/JAEE-10-2021-0319"
- Description: The institutional framework of an African country may influence the effectiveness of the International Financial Reporting Standards (IFRS) on foreign investment inflows. The purpose of this paper is to argue that the quality of a country's institutional framework impacts the effectiveness of IFRS to an adopting country and ultimately influences the levels of Foreign Portfolio Investment (FPI).
- Full Text:
Impacts of the COVID-19 pandemic and unpaid care work on informal workers' livelihoods
- Ogando, Ana C, Rogan, Michael, Moussié, Rachel
- Authors: Ogando, Ana C , Rogan, Michael , Moussié, Rachel
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/477908 , vital:78135 , https://doi.org/10.1111/ilr.12332
- Description: The COVID-19 pandemic triggered a health, economic and care crisis affecting all workers, including those in the informal economy. This article uses data from the first round of a mixed‐methods longitudinal study conducted in June/July 2020 by Women in Informal Employment: Globalizing and Organizing in partnership with informal workers' organizations in 12 cities. It assesses the impacts of the multidimensional crisis on care responsibilities and the resulting effects on livelihoods and food security. A gendered analysis of paid work and unpaid care work sheds light on the unique features of the impacts of the current “pandemic recession” on the world's informal labour force.
- Full Text:
- Authors: Ogando, Ana C , Rogan, Michael , Moussié, Rachel
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/477908 , vital:78135 , https://doi.org/10.1111/ilr.12332
- Description: The COVID-19 pandemic triggered a health, economic and care crisis affecting all workers, including those in the informal economy. This article uses data from the first round of a mixed‐methods longitudinal study conducted in June/July 2020 by Women in Informal Employment: Globalizing and Organizing in partnership with informal workers' organizations in 12 cities. It assesses the impacts of the multidimensional crisis on care responsibilities and the resulting effects on livelihoods and food security. A gendered analysis of paid work and unpaid care work sheds light on the unique features of the impacts of the current “pandemic recession” on the world's informal labour force.
- Full Text:
Impedimetric aptasensor for HER2 biomarker using graphene quantum dots, polypyrrole and cobalt phthalocyanine modified electrodes
- Centane, Sixolile, Nyokong, Tebello
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230960 , vital:49836 , xlink:href="https://doi.org/10.1016/j.sbsr.2021.100467"
- Description: A method is presented for the electrochemical detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER2). A glassy carbon electrode was modified using two techniques known as sequential adsorption and electro-polymerization, and the results are compared. The highly conductive polypyrrole (PPy) is used, in the presence of sulfur/nitrogen doped graphene quantum dots (SNGQDs) and a known cobalt phthalocyanine (CoPc). The different nanomaterials were used as an immobilization platform for the HER2 specific HB5 aptamer via amide linkage. The nanomaterials were arranged in various ways on the glassy carbon electrode, to investigate the effect of the electrode interface on the operational characteristics of a biosensor. The immobilized aptamer selectively recognizes HER2 on the electrode interface, and this leads to an increased charge transfer resistance (Rct) of the electrode when using ferricyanide as the electrochemical probe. The developed immunosensors showed high sensitivity with the best detection limit of 0.00141 ng/mL. The results showed that the method is simple and sensitive enough for the determination of HER2 in serum samples with good reproducibility and accuracy.
- Full Text:
- Authors: Centane, Sixolile , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230960 , vital:49836 , xlink:href="https://doi.org/10.1016/j.sbsr.2021.100467"
- Description: A method is presented for the electrochemical detection of the breast cancer biomarker human epidermal growth factor receptor 2 (HER2). A glassy carbon electrode was modified using two techniques known as sequential adsorption and electro-polymerization, and the results are compared. The highly conductive polypyrrole (PPy) is used, in the presence of sulfur/nitrogen doped graphene quantum dots (SNGQDs) and a known cobalt phthalocyanine (CoPc). The different nanomaterials were used as an immobilization platform for the HER2 specific HB5 aptamer via amide linkage. The nanomaterials were arranged in various ways on the glassy carbon electrode, to investigate the effect of the electrode interface on the operational characteristics of a biosensor. The immobilized aptamer selectively recognizes HER2 on the electrode interface, and this leads to an increased charge transfer resistance (Rct) of the electrode when using ferricyanide as the electrochemical probe. The developed immunosensors showed high sensitivity with the best detection limit of 0.00141 ng/mL. The results showed that the method is simple and sensitive enough for the determination of HER2 in serum samples with good reproducibility and accuracy.
- Full Text:
Improving licence plate detection using generative adversarial networks
- Authors: Boby, Alden , Brown, Dane L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/464145 , vital:76480 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-031-04881-4_47"
- Description: The information on a licence plate is used for traffic law enforcement, access control, surveillance and parking lot management. Existing li-cence plate recognition systems work with clear images taken under controlled conditions. In real-world licence plate recognition scenarios, images are not as straightforward as the ‘toy’ datasets used to bench-mark existing systems. Real-world data is often noisy as it may contain occlusion and poor lighting, obscuring the information on a licence plate. Cleaning input data before using it for licence plate recognition is a complex problem, and existing literature addressing the issue is still limited. This paper uses two deep learning techniques to improve li-cence plate visibility towards more accurate licence plate recognition. A one-stage object detector popularly known as YOLO is implemented for locating licence plates under challenging situations. Super-resolution generative adversarial networks are considered for image upscaling and reconstruction to improve the clarity of low-quality input. The main focus involves training these systems on datasets that include difficult to detect licence plates, enabling better performance in unfavourable conditions and environments.
- Full Text:
- Authors: Boby, Alden , Brown, Dane L
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/464145 , vital:76480 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-031-04881-4_47"
- Description: The information on a licence plate is used for traffic law enforcement, access control, surveillance and parking lot management. Existing li-cence plate recognition systems work with clear images taken under controlled conditions. In real-world licence plate recognition scenarios, images are not as straightforward as the ‘toy’ datasets used to bench-mark existing systems. Real-world data is often noisy as it may contain occlusion and poor lighting, obscuring the information on a licence plate. Cleaning input data before using it for licence plate recognition is a complex problem, and existing literature addressing the issue is still limited. This paper uses two deep learning techniques to improve li-cence plate visibility towards more accurate licence plate recognition. A one-stage object detector popularly known as YOLO is implemented for locating licence plates under challenging situations. Super-resolution generative adversarial networks are considered for image upscaling and reconstruction to improve the clarity of low-quality input. The main focus involves training these systems on datasets that include difficult to detect licence plates, enabling better performance in unfavourable conditions and environments.
- Full Text:
Improving signer-independence using pose estimation and transfer learning for sign language recognition
- Marais, Marc, Brown, Dane L, Connan, James, Boby, Alden
- Authors: Marais, Marc , Brown, Dane L , Connan, James , Boby, Alden
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/463406 , vital:76406 , xlink:href="https://doi.org/10.1007/978-3-031-35644-5"
- Description: Automated Sign Language Recognition (SLR) aims to bridge the com-munication gap between the hearing and the hearing disabled. Com-puter vision and deep learning lie at the forefront in working toward these systems. Most SLR research focuses on signer-dependent SLR and fails to account for variations in varying signers who gesticulate naturally. This paper investigates signer-independent SLR on the LSA64 dataset, focusing on different feature extraction approaches. Two approaches are proposed an InceptionV3-GRU architecture, which uses raw images as input, and a pose estimation LSTM architecture. MediaPipe Holistic is implemented to extract pose estimation landmark coordinates. A final third model applies augmentation and transfer learning using the pose estimation LSTM model. The research found that the pose estimation LSTM approach achieved the best perfor-mance with an accuracy of 80.22%. MediaPipe Holistic struggled with the augmentations introduced in the final experiment. Thus, looking into introducing more subtle augmentations may improve the model. Over-all, the system shows significant promise toward addressing the real-world signer-independence issue in SLR.
- Full Text:
- Authors: Marais, Marc , Brown, Dane L , Connan, James , Boby, Alden
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/463406 , vital:76406 , xlink:href="https://doi.org/10.1007/978-3-031-35644-5"
- Description: Automated Sign Language Recognition (SLR) aims to bridge the com-munication gap between the hearing and the hearing disabled. Com-puter vision and deep learning lie at the forefront in working toward these systems. Most SLR research focuses on signer-dependent SLR and fails to account for variations in varying signers who gesticulate naturally. This paper investigates signer-independent SLR on the LSA64 dataset, focusing on different feature extraction approaches. Two approaches are proposed an InceptionV3-GRU architecture, which uses raw images as input, and a pose estimation LSTM architecture. MediaPipe Holistic is implemented to extract pose estimation landmark coordinates. A final third model applies augmentation and transfer learning using the pose estimation LSTM model. The research found that the pose estimation LSTM approach achieved the best perfor-mance with an accuracy of 80.22%. MediaPipe Holistic struggled with the augmentations introduced in the final experiment. Thus, looking into introducing more subtle augmentations may improve the model. Over-all, the system shows significant promise toward addressing the real-world signer-independence issue in SLR.
- Full Text:
Improving the mental health of women intimate partner violence survivors: Findings from a realist review of psychosocial interventions
- Paphitis, Sharli A, Bentley, Abigail, Asher, Laura, Osrin, David, Oram, Sian
- Authors: Paphitis, Sharli A , Bentley, Abigail , Asher, Laura , Osrin, David , Oram, Sian
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426453 , vital:72355 , xlink:href="https://doi.org/10.1371/journal.pone.0264845"
- Description: Intimate partner violence (IPV) is highly prevalent and is associated with a range of mental health problems. A broad range of psychosocial interventions have been developed to support the recovery of women survivors of IPV, but their mechanisms of action remain unclear.
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- Authors: Paphitis, Sharli A , Bentley, Abigail , Asher, Laura , Osrin, David , Oram, Sian
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/426453 , vital:72355 , xlink:href="https://doi.org/10.1371/journal.pone.0264845"
- Description: Intimate partner violence (IPV) is highly prevalent and is associated with a range of mental health problems. A broad range of psychosocial interventions have been developed to support the recovery of women survivors of IPV, but their mechanisms of action remain unclear.
- Full Text:
In vitro photoinactivation of S. aureus and photocatalytic degradation of tetracycline by novel phthalocyanine-graphene quantum dots nano-assemblies
- Openda, Yolande Ikala, Mgidlana, Sithi, Nyokong, Tebello
- Authors: Openda, Yolande Ikala , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229895 , vital:49721 , xlink:href="https://doi.org/10.1016/j.jlumin.2022.118863"
- Description: A novel asymmetrical zinc (II) phthalocyanine (Pc) 4 bearing three dimethoxy groups and one carboxyl group was linked to glutathione capped graphene quantum dots (GQDs) by the reaction of carboxylic acid substituent on Pc 4 with the amino group on the GQDs. On the other side, the symmetrical Pc analog 3 was linked to the same nanoparticles through π-π interactions. The as-formed nano-photosensitizers were fully characterized by spectroscopic methods and their photophysicochemical properties were investigated as well. Photodynamic antimicrobial chemotherapy was performed on the planktonic cells of S. aureus strain. And the results show that these nano assemblies were able to completely inhibit the metabolic activity of the resistant bacteria strain S. aureus with a 10.26 log reduction in the viable count. Again, asymmetrical Pc showed higher photocatalytic activity compared to the symmetrical complex with higher kobs and fast initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model. The target conjugates showed all the advantages of two different groups existing on a single entity.
- Full Text:
- Authors: Openda, Yolande Ikala , Mgidlana, Sithi , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229895 , vital:49721 , xlink:href="https://doi.org/10.1016/j.jlumin.2022.118863"
- Description: A novel asymmetrical zinc (II) phthalocyanine (Pc) 4 bearing three dimethoxy groups and one carboxyl group was linked to glutathione capped graphene quantum dots (GQDs) by the reaction of carboxylic acid substituent on Pc 4 with the amino group on the GQDs. On the other side, the symmetrical Pc analog 3 was linked to the same nanoparticles through π-π interactions. The as-formed nano-photosensitizers were fully characterized by spectroscopic methods and their photophysicochemical properties were investigated as well. Photodynamic antimicrobial chemotherapy was performed on the planktonic cells of S. aureus strain. And the results show that these nano assemblies were able to completely inhibit the metabolic activity of the resistant bacteria strain S. aureus with a 10.26 log reduction in the viable count. Again, asymmetrical Pc showed higher photocatalytic activity compared to the symmetrical complex with higher kobs and fast initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model. The target conjugates showed all the advantages of two different groups existing on a single entity.
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Indium phthalocyanines
- Pinar, Sen, Mack, John, Nyokong, Tebello
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
- Full Text:
- Authors: Pinar, Sen , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229998 , vital:49731 , xlink:href="https://doi.org/10.1016/j.molstruc.2021.131850"
- Description: In this study, the photodynamic antimicrobial activities of a series of new tetra-substituted indium phthalocyanine (InPc) complexes are assessed. An aldehyde substituted complex (2) was initially prepared, which was converted through a condensatioreaction to an imine-pyrrolidine substituted complex (3), which in turn was quaternized to form a tetracationic species (4). Favorable photophysicochemical properties were obtained by incorporating a heavy In(III) ion into the central cavity. Aggregation studies revealed that 2–4 remain non-aggregated in DMSO at concentration below 25 µM. The photodeactivation of S.aureus and E.coli was studied. Log reduction values > 9.0 were obtained for cationic InPc 4 after 30 min of incubation and exposure to light for 75 min.
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Insights into the Dynamics and Binding of Two Polyprotein Substrate Cleavage Points in the Context of the SARS-CoV-2 Main and Papain-like Proteases
- Sanusi, Zainab K, Lobb, Kevin A
- Authors: Sanusi, Zainab K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452773 , vital:75169 , xlink:href="https://doi.org/10.3390/molecules27238251"
- Description: It is well known that vital enzymes in the replication process of the coronavirus are the SARS-CoV-2 PLpro and SARS-CoV-2 3CLpro, both of which are important targets in the search for anti-coronavirus agents. These two enzymes are responsible for cleavage at various polyprotein sites in the SARS-CoV-2 lifecycle. Herein, the dynamics of the polyprotein cleavage sequences for the boundary between non-structural proteins Nsp1 and Nsp2 (CS1) and between Nsp2 and Nsp3 (CS2) in complex with both the papain-like protein PLpro and the main protease 3CLpro were explored using computational methods. The post dynamics analysis reveals that CS1 and CS2 both have greater stability when complexed with PLpro. Of these two, greater stability is observed for the CS1–PLpro complex, while destabilization resulting in loss of CS2 from the PLpro active site is observed for CS2-PLpro, suggesting the rate of exchange by the papain-like protease is faster for CS2 compared to CS1. On the other hand, the 3CLpro main protease also reveals stability for CS1 suggesting that the main protease could also play a potential role in the cleavage at point CS1. However, destabilization occurs early in the simulation for the complex CLpro–CS2 suggesting a poor interaction and non-plausible protease cleavage of the polyprotein at CS2 by the main protease. These findings could be used as a guide in the development and design of potent COVID-19 antiviral inhibitors that mimic the CS1 cleavage site.
- Full Text:
- Authors: Sanusi, Zainab K , Lobb, Kevin A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/452773 , vital:75169 , xlink:href="https://doi.org/10.3390/molecules27238251"
- Description: It is well known that vital enzymes in the replication process of the coronavirus are the SARS-CoV-2 PLpro and SARS-CoV-2 3CLpro, both of which are important targets in the search for anti-coronavirus agents. These two enzymes are responsible for cleavage at various polyprotein sites in the SARS-CoV-2 lifecycle. Herein, the dynamics of the polyprotein cleavage sequences for the boundary between non-structural proteins Nsp1 and Nsp2 (CS1) and between Nsp2 and Nsp3 (CS2) in complex with both the papain-like protein PLpro and the main protease 3CLpro were explored using computational methods. The post dynamics analysis reveals that CS1 and CS2 both have greater stability when complexed with PLpro. Of these two, greater stability is observed for the CS1–PLpro complex, while destabilization resulting in loss of CS2 from the PLpro active site is observed for CS2-PLpro, suggesting the rate of exchange by the papain-like protease is faster for CS2 compared to CS1. On the other hand, the 3CLpro main protease also reveals stability for CS1 suggesting that the main protease could also play a potential role in the cleavage at point CS1. However, destabilization occurs early in the simulation for the complex CLpro–CS2 suggesting a poor interaction and non-plausible protease cleavage of the polyprotein at CS2 by the main protease. These findings could be used as a guide in the development and design of potent COVID-19 antiviral inhibitors that mimic the CS1 cleavage site.
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Integrated photocatalyst adsorbents based on porphyrin anchored to activated carbon granules for water treatment
- Oyim, James, Amuhaya, Edith K, Matshitse, Refilwe, Mack, John, Nyokong, Tebello
- Authors: Oyim, James , Amuhaya, Edith K , Matshitse, Refilwe , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300101 , vital:57893 , xlink:href="https://doi.org/10.1016/j.cartre.2022.100191"
- Description: Integration of adsorption and photocatalysis processes can lead to several benefits in water treatment. Integrating well-known adsorbents with photocatalysts ensures that all the interesting components are preserved and helps to overcome the serious downsides of each material and technique when operated independently. In this work, we introduce a new concept of combining both absorption and photodegradation mechanisms using organic photocatalytic adsorbents for water purification. This was achieved by formulating photosensitizing hybrids based on a newly synthesized chloroindium (III) 5,10,15,20-tetrakis(4-acetamidophenyl) porphyrin (InTAAP) compound, anchored on oxygen functionalized coconut shell-based activated carbon granules supports. The fashioned integrated photocatalyst adsorbent hybrid (InTAAP(ACO)) was then studied for their adsorption and photodegradation efficiency using methylene blue dye, where InTAAP(ACO) showed excellent photocatalytic activity compared to ACO and unfunctionalized activated carbon granules (AC), with appreciably high and adsorption properties as AC and ACO.
- Full Text:
- Authors: Oyim, James , Amuhaya, Edith K , Matshitse, Refilwe , Mack, John , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/300101 , vital:57893 , xlink:href="https://doi.org/10.1016/j.cartre.2022.100191"
- Description: Integration of adsorption and photocatalysis processes can lead to several benefits in water treatment. Integrating well-known adsorbents with photocatalysts ensures that all the interesting components are preserved and helps to overcome the serious downsides of each material and technique when operated independently. In this work, we introduce a new concept of combining both absorption and photodegradation mechanisms using organic photocatalytic adsorbents for water purification. This was achieved by formulating photosensitizing hybrids based on a newly synthesized chloroindium (III) 5,10,15,20-tetrakis(4-acetamidophenyl) porphyrin (InTAAP) compound, anchored on oxygen functionalized coconut shell-based activated carbon granules supports. The fashioned integrated photocatalyst adsorbent hybrid (InTAAP(ACO)) was then studied for their adsorption and photodegradation efficiency using methylene blue dye, where InTAAP(ACO) showed excellent photocatalytic activity compared to ACO and unfunctionalized activated carbon granules (AC), with appreciably high and adsorption properties as AC and ACO.
- Full Text:
Integrating child rights standards in contraceptive and abortion care for minors in Africa
- Kangaude, Godfrey D, Macleod, Catriona I, Coast, Ernestina, Fetters, Tamara
- Authors: Kangaude, Godfrey D , Macleod, Catriona I , Coast, Ernestina , Fetters, Tamara
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441242 , vital:73869 , xlink:href="https://doi.org/10.1002/ijgo.14502"
- Description: Minor girls in Africa face challenges in accessing high-quality contraceptive and abortion services because laws and policies are not child-friendly. Many countries maintain restrictive laws, policies, or hospital practices that make it difficult for minors to access contraception and safe abortion even when the pregnancy would risk their life or health. Further, the clinical guidelines on contraceptive and abortion care are silent, vague, or ambiguous regarding minors' consent. African states should remedy the situation by ensuring that clinical guidelines integrate child rights principles and standards articulated in child rights treaties to enable health providers to facilitate full, unencumbered access to contraceptive and abortion care for minor girls. A sample of clinical guidelines is analyzed to demonstrate the importance of explicit, consistent, and unambiguous language about children's consent to ensure that healthcare workers provide sexual and reproductive health care in a manner that respects child rights.
- Full Text:
- Authors: Kangaude, Godfrey D , Macleod, Catriona I , Coast, Ernestina , Fetters, Tamara
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/441242 , vital:73869 , xlink:href="https://doi.org/10.1002/ijgo.14502"
- Description: Minor girls in Africa face challenges in accessing high-quality contraceptive and abortion services because laws and policies are not child-friendly. Many countries maintain restrictive laws, policies, or hospital practices that make it difficult for minors to access contraception and safe abortion even when the pregnancy would risk their life or health. Further, the clinical guidelines on contraceptive and abortion care are silent, vague, or ambiguous regarding minors' consent. African states should remedy the situation by ensuring that clinical guidelines integrate child rights principles and standards articulated in child rights treaties to enable health providers to facilitate full, unencumbered access to contraceptive and abortion care for minor girls. A sample of clinical guidelines is analyzed to demonstrate the importance of explicit, consistent, and unambiguous language about children's consent to ensure that healthcare workers provide sexual and reproductive health care in a manner that respects child rights.
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Inter-and intra-specific trophic interactions of coastal delphinids off the eastern coast of South Africa inferred from stable isotope analysis
- Caputo, Michelle, Bouveroux, Thibaut N, Van der Bank, Megan, Cliff, Geremy, Kiszka, Jeremy J, Froneman, P William, Plön, Stephanie
- Authors: Caputo, Michelle , Bouveroux, Thibaut N , Van der Bank, Megan , Cliff, Geremy , Kiszka, Jeremy J , Froneman, P William , Plön, Stephanie
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/10962/466545 , vital:76745 , https://doi.org/10.1016/j.marenvres.2022.105784
- Description: Dietary tracers, such as bulk stable carbon (δ13C) and nitrogen (δ15N) isotopes, can be used to investigate the trophic interactions of marine predators, which is useful to assess their ecological roles within communities. These tracers have also been used to elucidate population structure and substructure, which is critical for the better identification of management units for these species affected by a range of threats, particularly bycatch in fishing gears. Off eastern South Africa, large populations of Indo-Pacific bottlenose (Tursiops aduncus) and common dolphins (Delphinus delphis) co-occur and are thought to follow the pulses of shoaling sardines (Sardinops sagax) heading north-east in the austral winter. Here we used δ13C and δ15N to investigate the trophic interactions and define ecological units of these two species along a ≈800 km stretch of the east coast of South Africa, from Algoa Bay to the coast of KwaZulu-Natal. Common and bottlenose dolphin dietary niche overlapped by 39.7% overall in our study area, with the highest overlap occurring off the Wild Coast (40.7% at Hluleka).
- Full Text:
- Authors: Caputo, Michelle , Bouveroux, Thibaut N , Van der Bank, Megan , Cliff, Geremy , Kiszka, Jeremy J , Froneman, P William , Plön, Stephanie
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/10962/466545 , vital:76745 , https://doi.org/10.1016/j.marenvres.2022.105784
- Description: Dietary tracers, such as bulk stable carbon (δ13C) and nitrogen (δ15N) isotopes, can be used to investigate the trophic interactions of marine predators, which is useful to assess their ecological roles within communities. These tracers have also been used to elucidate population structure and substructure, which is critical for the better identification of management units for these species affected by a range of threats, particularly bycatch in fishing gears. Off eastern South Africa, large populations of Indo-Pacific bottlenose (Tursiops aduncus) and common dolphins (Delphinus delphis) co-occur and are thought to follow the pulses of shoaling sardines (Sardinops sagax) heading north-east in the austral winter. Here we used δ13C and δ15N to investigate the trophic interactions and define ecological units of these two species along a ≈800 km stretch of the east coast of South Africa, from Algoa Bay to the coast of KwaZulu-Natal. Common and bottlenose dolphin dietary niche overlapped by 39.7% overall in our study area, with the highest overlap occurring off the Wild Coast (40.7% at Hluleka).
- Full Text:
Interaction between an entomopathogenic fungus and entomopathogenic nematodes for increased mortality of Thaumatotibia leucotreta (Lepidoptera: Tortricidae)
- Prinsloo, Sandra, Hill, Martin P, Moore, Sean D, Malan, Antoinette P, Coombes, Candice A
- Authors: Prinsloo, Sandra , Hill, Martin P , Moore, Sean D , Malan, Antoinette P , Coombes, Candice A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417738 , vital:71482 , xlink:href="https://doi.org/10.1080/09583157.2022.2099528"
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a major phytosanitary pest of citrus in South Africa. Although several management tools exist, control options registered for use against the soil-dwelling life stages are limited. Both entomopathogenic nematodes (EPNs) and entomopathogenic fungi have been investigated previously, but they have not been studied in combination against T. leucotreta. Thus, this study investigated the interaction of an indigenous entomopathogenic fungus, Metarhizium pinghaense (previously anisopliae) FCM Ar 23 B3 with three indigenous EPNs: Steinernema yirgalemense 157-C, S. jeffreyense J194 and Heterorhabditis noenieputensis 158-C for increased late instar T. leucotreta larval mortality. Before interaction experiments, lethal concentration (LC) values for each of these microbial agents were determined through dose–response bioassays. Heterorhabditis noenieputensis recorded the highest LC50 amongst the nematodes (7.11 IJs/50 µl). Using the pre-determined LC70 value of M. pinghaense and the LC50 values for each of the nematode species, interaction experiments were conducted. Combinations of the nematodes either applied simultaneously with the fungus or at 24, 48, 72 or 96 h post-fungal application showed predominantly additive interactions. Synergy between the simultaneous application of S. yirgalemense and M. pinghaense was found, whilst the interaction between H. noenieputensis and M. pinghaense applied simultaneously and S. jeffreyense applied 24 h post-fungal application, recorded antagonistic interactions. The use of these agents in combination may therefore have the potential to increase control of T. leucotreta soil-dwelling life stages in citrus orchards across South Africa and should be further investigated.
- Full Text:
- Authors: Prinsloo, Sandra , Hill, Martin P , Moore, Sean D , Malan, Antoinette P , Coombes, Candice A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417738 , vital:71482 , xlink:href="https://doi.org/10.1080/09583157.2022.2099528"
- Description: Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is a major phytosanitary pest of citrus in South Africa. Although several management tools exist, control options registered for use against the soil-dwelling life stages are limited. Both entomopathogenic nematodes (EPNs) and entomopathogenic fungi have been investigated previously, but they have not been studied in combination against T. leucotreta. Thus, this study investigated the interaction of an indigenous entomopathogenic fungus, Metarhizium pinghaense (previously anisopliae) FCM Ar 23 B3 with three indigenous EPNs: Steinernema yirgalemense 157-C, S. jeffreyense J194 and Heterorhabditis noenieputensis 158-C for increased late instar T. leucotreta larval mortality. Before interaction experiments, lethal concentration (LC) values for each of these microbial agents were determined through dose–response bioassays. Heterorhabditis noenieputensis recorded the highest LC50 amongst the nematodes (7.11 IJs/50 µl). Using the pre-determined LC70 value of M. pinghaense and the LC50 values for each of the nematode species, interaction experiments were conducted. Combinations of the nematodes either applied simultaneously with the fungus or at 24, 48, 72 or 96 h post-fungal application showed predominantly additive interactions. Synergy between the simultaneous application of S. yirgalemense and M. pinghaense was found, whilst the interaction between H. noenieputensis and M. pinghaense applied simultaneously and S. jeffreyense applied 24 h post-fungal application, recorded antagonistic interactions. The use of these agents in combination may therefore have the potential to increase control of T. leucotreta soil-dwelling life stages in citrus orchards across South Africa and should be further investigated.
- Full Text: