A review of the biocontrol programmes against aquatic weeds in South Africa
- Coetzee, Julie A, Bownes, Angela, Martin, Grant D, Miller, Benjamin E, Smith, Rosalie, Weyl, Philip S R, Hill, Martin P
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D , Miller, Benjamin E , Smith, Rosalie , Weyl, Philip S R , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406965 , vital:70326 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a18"
- Description: Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.
- Full Text:
- Date Issued: 2021
- Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D , Miller, Benjamin E , Smith, Rosalie , Weyl, Philip S R , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/406965 , vital:70326 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a18"
- Description: Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.
- Full Text:
- Date Issued: 2021
Biological control of invasive climbing plants in South Africa
- King, Anthony M, Paterson, Iain D, Simelane, David O, Mawela, Khethani V, Mngeta, Zezethu, Van der Westhuizen, Liamé
- Authors: King, Anthony M , Paterson, Iain D , Simelane, David O , Mawela, Khethani V , Mngeta, Zezethu , Van der Westhuizen, Liamé
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/413471 , vital:71041 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a17"
- Description: Vines and other climbing plants typically invest their resources into growth at the expense of accumulating self-supporting biomass. Adaptive traits that have arisen because of the life history needs of climbing species, such as rapid and extensive growth, as well as resilience to physical damage, make these plants highly competitive. Introduced climbing species therefore have the potential to be particularly damaging in novel ranges where they escape pressure from natural enemies. In South Africa, invasive climbing species negatively influence biodiversity and plant-community structure, and as conventional management is often difficult, biological control (biocontrol) is viewed as the only viable long-term control method. This paper consolidates the work done on biocontrol programmes against climbing species in South Africa, including Anredera cordifolia (Ten.) Steenis (Basellaceae), Cardiospermum grandiflorum Sw. (Sapindaceae), Dolichandra unguis-cati (L.) L.G.Lohmann (Bignoniaceae) and Pereskia aculeata Miller (Cactaceae). To date, these programmes have investigated some 27 potential biocontrol agents, of which nine have been approved for release in the country. Since 2010, three new agents have been introduced, and considerable progress made with post-release evaluations of all the introduced agents. Some positive results have been achieved, most notably the successful reduction in seed set of C. grandiflorum due to Cissanthonomus tuberculipennis Hustache (Curculionidae), but considerable variation in efficacy over time and between infestations has been recorded for many of the other agents. Further work may help explain the factors limiting success, leading to improved control, but in some cases, such as for A. cordifolia, new biocontrol agents should be considered.
- Full Text:
- Date Issued: 2021
- Authors: King, Anthony M , Paterson, Iain D , Simelane, David O , Mawela, Khethani V , Mngeta, Zezethu , Van der Westhuizen, Liamé
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/413471 , vital:71041 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a17"
- Description: Vines and other climbing plants typically invest their resources into growth at the expense of accumulating self-supporting biomass. Adaptive traits that have arisen because of the life history needs of climbing species, such as rapid and extensive growth, as well as resilience to physical damage, make these plants highly competitive. Introduced climbing species therefore have the potential to be particularly damaging in novel ranges where they escape pressure from natural enemies. In South Africa, invasive climbing species negatively influence biodiversity and plant-community structure, and as conventional management is often difficult, biological control (biocontrol) is viewed as the only viable long-term control method. This paper consolidates the work done on biocontrol programmes against climbing species in South Africa, including Anredera cordifolia (Ten.) Steenis (Basellaceae), Cardiospermum grandiflorum Sw. (Sapindaceae), Dolichandra unguis-cati (L.) L.G.Lohmann (Bignoniaceae) and Pereskia aculeata Miller (Cactaceae). To date, these programmes have investigated some 27 potential biocontrol agents, of which nine have been approved for release in the country. Since 2010, three new agents have been introduced, and considerable progress made with post-release evaluations of all the introduced agents. Some positive results have been achieved, most notably the successful reduction in seed set of C. grandiflorum due to Cissanthonomus tuberculipennis Hustache (Curculionidae), but considerable variation in efficacy over time and between infestations has been recorded for many of the other agents. Further work may help explain the factors limiting success, leading to improved control, but in some cases, such as for A. cordifolia, new biocontrol agents should be considered.
- Full Text:
- Date Issued: 2021
Using Translanguaging in Higher Education to Empower Students' Voices and Enable Epistemological Becoming
- Asfour, Fouad, Ndabula, Yanela, Chakona, Gamuchirai, Mason, Paul, Oluwole, David O
- Authors: Asfour, Fouad , Ndabula, Yanela , Chakona, Gamuchirai , Mason, Paul , Oluwole, David O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453268 , vital:75235 , xlink:href="https://doi.org/10.29086/2519-5476/2020/sp31a4"
- Description: This article is based on research conducted by a group of plurilingual postgraduate students from different disciplines who facilitated writing groups at the Centre for Postgraduate Studies at Rhodes University over the past two years. It is based on self-reflective writing of language biographies and aims to raise attention about, and to open up a discussion on, the impact of social and personal language practices. We approach the role of language not only as complex interrogation of academic identity, but also as sense of embodied self, an active element in the formation of geo- and body-politics of knowledge which has been highlighted in recent literature focussing on translanguaging in education and decolonising the curricula of Higher Education. Following selfguided research, we engaged in a critical reflection on the use of home languages in education and consulted relevant literature that argues for the inclusion of translanguaging practices in Higher Education. Our research, therefore, focuses on new epistemologies afforded by a shift away from the monolingual habitus and from the concept of multilingualism towards plurilingualism and translanguaging. Our data suggests that a plurilingual approach towards teaching and learning in Higher Education can afford epistemological access to learners across faculties and disciplines in Higher Education, and we argue that the role of languages of tuition in curricula need to be strategically re-evaluated.
- Full Text:
- Date Issued: 2020
- Authors: Asfour, Fouad , Ndabula, Yanela , Chakona, Gamuchirai , Mason, Paul , Oluwole, David O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453268 , vital:75235 , xlink:href="https://doi.org/10.29086/2519-5476/2020/sp31a4"
- Description: This article is based on research conducted by a group of plurilingual postgraduate students from different disciplines who facilitated writing groups at the Centre for Postgraduate Studies at Rhodes University over the past two years. It is based on self-reflective writing of language biographies and aims to raise attention about, and to open up a discussion on, the impact of social and personal language practices. We approach the role of language not only as complex interrogation of academic identity, but also as sense of embodied self, an active element in the formation of geo- and body-politics of knowledge which has been highlighted in recent literature focussing on translanguaging in education and decolonising the curricula of Higher Education. Following selfguided research, we engaged in a critical reflection on the use of home languages in education and consulted relevant literature that argues for the inclusion of translanguaging practices in Higher Education. Our research, therefore, focuses on new epistemologies afforded by a shift away from the monolingual habitus and from the concept of multilingualism towards plurilingualism and translanguaging. Our data suggests that a plurilingual approach towards teaching and learning in Higher Education can afford epistemological access to learners across faculties and disciplines in Higher Education, and we argue that the role of languages of tuition in curricula need to be strategically re-evaluated.
- Full Text:
- Date Issued: 2020
Using Translanguaging in Higher Education to Empower Students' Voices and Enable Epistemological Becoming
- Asfour, Fouad-Martin, Ndabula, Yanela, Chakona, Gamuchirai, Mason, Paul, Oluwole, David O
- Authors: Asfour, Fouad-Martin , Ndabula, Yanela , Chakona, Gamuchirai , Mason, Paul , Oluwole, David O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425506 , vital:72251 , xlink:href="https://doi.org/10.29086/2519-5476/2020/sp31a4"
- Description: This article is based on research conducted by a group of plurilingual postgraduate students from different disciplines who facilitated writing groups at the Centre for Postgraduate Studies at Rhodes University over the past two years. It is based on self-reflective writing of language biographies and aims to raise attention about, and to open up a discussion on, the impact of social and personal language practices. We approach the role of language not only as complex interrogation of academic identity, but also as sense of embodied self, an active element in the formation of geo- and body-politics of knowledge which has been highlighted in recent literature focussing on translanguaging in education and decolonising the curricula of Higher Education. Following selfguided research, we engaged in a critical reflection on the use of home languages in education and consulted relevant literature that argues for the inclusion of translanguaging practices in Higher Education. Our research, therefore, focuses on new epistemologies afforded by a shift away from the monolingual habitus and from the concept of multilingualism towards plurilingualism and translanguaging. Our data suggests that a plurilingual approach towards teaching and learning in Higher Education can afford epistemological access to learners across faculties and disciplines in Higher Education, and we argue that the role of languages of tuition in curricula need to be strategically re-evaluated.
- Full Text:
- Date Issued: 2020
- Authors: Asfour, Fouad-Martin , Ndabula, Yanela , Chakona, Gamuchirai , Mason, Paul , Oluwole, David O
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425506 , vital:72251 , xlink:href="https://doi.org/10.29086/2519-5476/2020/sp31a4"
- Description: This article is based on research conducted by a group of plurilingual postgraduate students from different disciplines who facilitated writing groups at the Centre for Postgraduate Studies at Rhodes University over the past two years. It is based on self-reflective writing of language biographies and aims to raise attention about, and to open up a discussion on, the impact of social and personal language practices. We approach the role of language not only as complex interrogation of academic identity, but also as sense of embodied self, an active element in the formation of geo- and body-politics of knowledge which has been highlighted in recent literature focussing on translanguaging in education and decolonising the curricula of Higher Education. Following selfguided research, we engaged in a critical reflection on the use of home languages in education and consulted relevant literature that argues for the inclusion of translanguaging practices in Higher Education. Our research, therefore, focuses on new epistemologies afforded by a shift away from the monolingual habitus and from the concept of multilingualism towards plurilingualism and translanguaging. Our data suggests that a plurilingual approach towards teaching and learning in Higher Education can afford epistemological access to learners across faculties and disciplines in Higher Education, and we argue that the role of languages of tuition in curricula need to be strategically re-evaluated.
- Full Text:
- Date Issued: 2020
A perfect end: A study of syllable codas in South African Sign Language
- Köhlo, Mikhaela D.K., Siebörger, Ian, Bennett, William G
- Authors: Köhlo, Mikhaela D.K. , Siebörger, Ian , Bennett, William G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385295 , vital:68005 , xlink:href="https://www.ajol.info/index.php/splp/article/view/156629"
- Description: South African Sign Language (SASL) is an understudied language with a rich and interesting phonology. For instance, while the language allows onsetless syllables, it does not allow codaless syllables, except in a small class of signs which do not include path movement. This article identifies and defines possible constraints on syllable codas in SASL. Using a video dictionary as data, we have coded handshapes at locations occurring at the onset and coda of the more common signs in the lexicon. In handshape, it has been found that the selected fingers may move to create different handshapes in the coda position, but that these coda handshapes are often [1], [5], [A], [Å] or [S], which are the unmarked handshapes of the non-dominant hand in asymmetrical two-handed signs (Sandler and Lillo-Martin 2006). Furthermore, the joint specification for the selected fingers can also vary in the coda position, but there appear to be strict limitations on which joint combinations are permitted in the onset-coda relationship. There are also constraints on coda location. The major body region can change within a single syllable, and the preferred body regions in the coda position are [body] and [H2]. It is evident not only that handshape and location constraints occur at the coda position, but that these constraints show patterns similar to coda neutralisation in many spoken languages.
- Full Text:
- Date Issued: 2017
- Authors: Köhlo, Mikhaela D.K. , Siebörger, Ian , Bennett, William G
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/385295 , vital:68005 , xlink:href="https://www.ajol.info/index.php/splp/article/view/156629"
- Description: South African Sign Language (SASL) is an understudied language with a rich and interesting phonology. For instance, while the language allows onsetless syllables, it does not allow codaless syllables, except in a small class of signs which do not include path movement. This article identifies and defines possible constraints on syllable codas in SASL. Using a video dictionary as data, we have coded handshapes at locations occurring at the onset and coda of the more common signs in the lexicon. In handshape, it has been found that the selected fingers may move to create different handshapes in the coda position, but that these coda handshapes are often [1], [5], [A], [Å] or [S], which are the unmarked handshapes of the non-dominant hand in asymmetrical two-handed signs (Sandler and Lillo-Martin 2006). Furthermore, the joint specification for the selected fingers can also vary in the coda position, but there appear to be strict limitations on which joint combinations are permitted in the onset-coda relationship. There are also constraints on coda location. The major body region can change within a single syllable, and the preferred body regions in the coda position are [body] and [H2]. It is evident not only that handshape and location constraints occur at the coda position, but that these constraints show patterns similar to coda neutralisation in many spoken languages.
- Full Text:
- Date Issued: 2017
Feature-fusion guidelines for image-based multi-modal biometric fusion
- Brown, Dane L, Bradshaw, Karen L
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/460063 , vital:75889 , xlink:href="https://doi.org/10.18489/sacj.v29i1.436"
- Description: The feature level, unlike the match score level, lacks multi-modal fusion guidelines. This work demonstrates a newapproach for improved image-based biometric feature-fusion. The approach extracts and combines the face, fingerprintand palmprint at the feature level for improved human identification accuracy. Feature-fusion guidelines, proposed inour recent work, are extended by adding a new face segmentation method and the support vector machine classifier.The new face segmentation method improves the face identification equal error rate (EER) by 10%. The support vectormachine classifier combined with the new feature selection approach, proposed in our recent work, outperforms otherclassifiers when using a single training sample. Feature-fusion guidelines take the form of strengths and weaknessesas observed in the applied feature processing modules during preliminary experiments. The guidelines are used toimplement an effective biometric fusion system at the feature level, using a novel feature-fusion methodology, reducingthe EER of two groups of three datasets namely: SDUMLA face, SDUMLA fingerprint and IITD palmprint; MUCT Face,MCYT Fingerprint and CASIA Palmprint.
- Full Text:
- Date Issued: 2017
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/460063 , vital:75889 , xlink:href="https://doi.org/10.18489/sacj.v29i1.436"
- Description: The feature level, unlike the match score level, lacks multi-modal fusion guidelines. This work demonstrates a newapproach for improved image-based biometric feature-fusion. The approach extracts and combines the face, fingerprintand palmprint at the feature level for improved human identification accuracy. Feature-fusion guidelines, proposed inour recent work, are extended by adding a new face segmentation method and the support vector machine classifier.The new face segmentation method improves the face identification equal error rate (EER) by 10%. The support vectormachine classifier combined with the new feature selection approach, proposed in our recent work, outperforms otherclassifiers when using a single training sample. Feature-fusion guidelines take the form of strengths and weaknessesas observed in the applied feature processing modules during preliminary experiments. The guidelines are used toimplement an effective biometric fusion system at the feature level, using a novel feature-fusion methodology, reducingthe EER of two groups of three datasets namely: SDUMLA face, SDUMLA fingerprint and IITD palmprint; MUCT Face,MCYT Fingerprint and CASIA Palmprint.
- Full Text:
- Date Issued: 2017
The Tongan maritime expansion: A case in the evolutionary ecology of social complexity
- Shankar, Aswani, Graves, Michael
- Authors: Shankar, Aswani , Graves, Michael
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440025 , vital:73729
- Description: The evolution of the Tongan maritime empire, involving both the development of social complexity and geographic expansion through conquest and trading, are examined by means of evolutionary ecology. This Darwinian evolutionary framework provides the mechanism and identifies the environmental structure, processes, and behavioral strategies by which to account for the geographic and temporal pattern of change in Tonga and related islands. Both ethnohistorical and archaeological data are employed in this analysis, showing how both may reveal overlapping aspects of historical change. The results of this research highlight the importance not only of competition but also of cooperative strategies in the evolution of social complexity and the process of geographic expansion. Key to explaining the evolution of Tongan social complexity are the productive but uncertain environment of Tongatapu, the location of Tongatapu in relation to other islands and prevailing winds, the small landmass of the island, the relatively early integration of the island into a single polity, the creation of collateral ruling lineages, the appropriation of voyaging technology to redirect competition from within Tongatapu to other islands through colonization, aggression, staple and wealth goods trade, and the exchange of spouses.
- Full Text:
- Date Issued: 1998
- Authors: Shankar, Aswani , Graves, Michael
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440025 , vital:73729
- Description: The evolution of the Tongan maritime empire, involving both the development of social complexity and geographic expansion through conquest and trading, are examined by means of evolutionary ecology. This Darwinian evolutionary framework provides the mechanism and identifies the environmental structure, processes, and behavioral strategies by which to account for the geographic and temporal pattern of change in Tonga and related islands. Both ethnohistorical and archaeological data are employed in this analysis, showing how both may reveal overlapping aspects of historical change. The results of this research highlight the importance not only of competition but also of cooperative strategies in the evolution of social complexity and the process of geographic expansion. Key to explaining the evolution of Tongan social complexity are the productive but uncertain environment of Tongatapu, the location of Tongatapu in relation to other islands and prevailing winds, the small landmass of the island, the relatively early integration of the island into a single polity, the creation of collateral ruling lineages, the appropriation of voyaging technology to redirect competition from within Tongatapu to other islands through colonization, aggression, staple and wealth goods trade, and the exchange of spouses.
- Full Text:
- Date Issued: 1998
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