Plaxenone A and B: Cytotoxic halogenated monoterpenes from the South African red seaweed Plocamium maxillosum
- Knott, Michael G, de la Mare, Jo-Anne, Edkins, Adrienne L, Zhang, Angel, Stillman, Martin J, Bolton, John J, Antunes, Edith M, Beukes, Denzil R
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
- Authors: Knott, Michael G , de la Mare, Jo-Anne , Edkins, Adrienne L , Zhang, Angel , Stillman, Martin J , Bolton, John J , Antunes, Edith M , Beukes, Denzil R
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/164446 , vital:41119 , https://doi.org/10.1016/j.phytol.2018.12.009
- Description: The endemic South African red seaweed Plocamium maxillosum (Poiret) Lamouroux produces two unusual isomeric dichlorinated cyclohexenone monoterpenes, plaxenone A and B (1 and 2). The structures of the isolated compounds were determined from spectroscopic data and their absolute configuration was determined by comparison of the experimental and calculated ECD spectra. Compounds 1 and 2 inhibit the growth of MDA-MB-231 breast cancer cells.
- Full Text:
- Date Issued: 2019
The complete mitochondrial genome of Africa's largest freshwater copepod, Lovenula raynerae
- Jooste, Candice M, Emami-Khoyi, Arsalan, Gan, Han M, Wasserman, Ryan J, Dalu, Tatenda, Teske, Peter R
- Authors: Jooste, Candice M , Emami-Khoyi, Arsalan , Gan, Han M , Wasserman, Ryan J , Dalu, Tatenda , Teske, Peter R
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445151 , vital:74353 , https://doi.org/10.1080/23802359.2018.1555013
- Description: Lovenula raynerae is the largest known African freshwater copepod. To date, it has only been sampled from ephemeral freshwater ecosystems. This paper reports the complete mitochondrial genome of L. raynerae, which was found to be 14,365 bp long. A base composition of 33.5% base A, 19.3% base G, 34.6% base T, and 12.5% base C was found, with 13 protein-coding genes, 22 tRNAs, and 2 rRNAs. This paper contributes to an improved understanding of phylogenetic relationships in an important crustacean group.
- Full Text:
- Date Issued: 2019
- Authors: Jooste, Candice M , Emami-Khoyi, Arsalan , Gan, Han M , Wasserman, Ryan J , Dalu, Tatenda , Teske, Peter R
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/445151 , vital:74353 , https://doi.org/10.1080/23802359.2018.1555013
- Description: Lovenula raynerae is the largest known African freshwater copepod. To date, it has only been sampled from ephemeral freshwater ecosystems. This paper reports the complete mitochondrial genome of L. raynerae, which was found to be 14,365 bp long. A base composition of 33.5% base A, 19.3% base G, 34.6% base T, and 12.5% base C was found, with 13 protein-coding genes, 22 tRNAs, and 2 rRNAs. This paper contributes to an improved understanding of phylogenetic relationships in an important crustacean group.
- Full Text:
- Date Issued: 2019
The influence of dopants on thermoluminescence of Sr2MgSi2O7
- Thomas, Sunil, Kalita, Jitumani M, Chithambo, Makaiko L, Ntwaeaborwa, Odireleng M
- Authors: Thomas, Sunil , Kalita, Jitumani M , Chithambo, Makaiko L , Ntwaeaborwa, Odireleng M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105148 , vital:32469 , https://doi.org/10.1016/j.jlumin.2018.12.035
- Description: We report the influence of dopants on the thermoluminescence of Sr2MgSi2O7. Samples studied comprise undoped Sr2MgSi2O7 and doped versions, namely, Sr2MgSi2O7:Dy3+, Sr2MgSi2O7:Eu3+, Sr2MgSi2O7:Tb3+ and Sr2MgSi2O7:Tb3+,Eu3+ phosphors. All samples show a broad glow peak near 60 °C when measured at 1 °C/s after irradiation to 10 Gy. The peak changes with partial heating, irradiation and fades between irradiation and measurement in a manner expected of a composite one. The behaviour is used to exemplify the analysis of a composite peak on the basis that particular features reflect those of the dominant component.
- Full Text: false
- Date Issued: 2019
- Authors: Thomas, Sunil , Kalita, Jitumani M , Chithambo, Makaiko L , Ntwaeaborwa, Odireleng M
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/105148 , vital:32469 , https://doi.org/10.1016/j.jlumin.2018.12.035
- Description: We report the influence of dopants on the thermoluminescence of Sr2MgSi2O7. Samples studied comprise undoped Sr2MgSi2O7 and doped versions, namely, Sr2MgSi2O7:Dy3+, Sr2MgSi2O7:Eu3+, Sr2MgSi2O7:Tb3+ and Sr2MgSi2O7:Tb3+,Eu3+ phosphors. All samples show a broad glow peak near 60 °C when measured at 1 °C/s after irradiation to 10 Gy. The peak changes with partial heating, irradiation and fades between irradiation and measurement in a manner expected of a composite one. The behaviour is used to exemplify the analysis of a composite peak on the basis that particular features reflect those of the dominant component.
- Full Text: false
- Date Issued: 2019
Introduction: On (still) rediscovering the ordinary
- Authors: Wessels, Paul
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458513 , vital:75750 , https://hdl.handle.net/10520/EJC-1061aba2b5
- Description: The essays included in this special issue of English in Africa are written by published writers of fiction and poetry who have close ties to academic departments as teachers, writers, scholars and editors. While they are scholarly in form, these articles seek to evoke a broader range of response than the purely academic, and for this reason they may not always strictly follow academic conventions. For example, to preserve the flow of the discussion parenthetical references may, at times, have been excluded, and ‘creative’ poetry and prose are often drawn into the argument for effect. We hope that the tone of the keynote address, while it has been abridged and edited for print, remains conversational and anecdotal, in keeping with its oral delivery.
- Full Text:
- Date Issued: 2018
- Authors: Wessels, Paul
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/458513 , vital:75750 , https://hdl.handle.net/10520/EJC-1061aba2b5
- Description: The essays included in this special issue of English in Africa are written by published writers of fiction and poetry who have close ties to academic departments as teachers, writers, scholars and editors. While they are scholarly in form, these articles seek to evoke a broader range of response than the purely academic, and for this reason they may not always strictly follow academic conventions. For example, to preserve the flow of the discussion parenthetical references may, at times, have been excluded, and ‘creative’ poetry and prose are often drawn into the argument for effect. We hope that the tone of the keynote address, while it has been abridged and edited for print, remains conversational and anecdotal, in keeping with its oral delivery.
- Full Text:
- Date Issued: 2018
Photoluminescence and thermoluminescence properties of BaGa2O4
- Noto, L L, Poelman, D, Orante-Barrón, V R, Swart, H C, Mathevula, Langutani E, Nyenge, R, Chithambo, Makaiko L, Mothudi, B M, Dhlamini, M S
- Authors: Noto, L L , Poelman, D , Orante-Barrón, V R , Swart, H C , Mathevula, Langutani E , Nyenge, R , Chithambo, Makaiko L , Mothudi, B M , Dhlamini, M S
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116037 , vital:34292 , https://doi.org/10.1016/j.physb.2017.07.059
- Description: Rare–Earth free luminescent materials are fast becoming important as the cost of rare earth ions gradually increases. In this work, a Rare–Earth free BaGa2O4 luminescent compound was prepared by solid state chemical reaction, which was confirmed to have a single phase by X-ray Diffraction. The Backscattered Electron image and Energy Dispersive X-ray spectroscopy maps confirmed irregular particle and homogeneous compound formation, respectively. The Photoluminescence spectrum displayed broad emission between 350 to 650 nm, which was deconvoluted into two components. The photoluminescence excitation peak was positioned at 254 nm, which corresponds with the band-to-band position observed from the diffuse reflectance spectrum. The band gap was extrapolated to 4.65 ± 0.02 eV using the Kubelka-Munk model. The preliminary thermoluminescence results indicated that the kinetics involved were neither of first nor second order. Additionally, the activation energy of the electrons within the trap centres was approximated to 0.61 ± 0.01 eV using the Initial Rise model.
- Full Text: false
- Date Issued: 2018
- Authors: Noto, L L , Poelman, D , Orante-Barrón, V R , Swart, H C , Mathevula, Langutani E , Nyenge, R , Chithambo, Makaiko L , Mothudi, B M , Dhlamini, M S
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116037 , vital:34292 , https://doi.org/10.1016/j.physb.2017.07.059
- Description: Rare–Earth free luminescent materials are fast becoming important as the cost of rare earth ions gradually increases. In this work, a Rare–Earth free BaGa2O4 luminescent compound was prepared by solid state chemical reaction, which was confirmed to have a single phase by X-ray Diffraction. The Backscattered Electron image and Energy Dispersive X-ray spectroscopy maps confirmed irregular particle and homogeneous compound formation, respectively. The Photoluminescence spectrum displayed broad emission between 350 to 650 nm, which was deconvoluted into two components. The photoluminescence excitation peak was positioned at 254 nm, which corresponds with the band-to-band position observed from the diffuse reflectance spectrum. The band gap was extrapolated to 4.65 ± 0.02 eV using the Kubelka-Munk model. The preliminary thermoluminescence results indicated that the kinetics involved were neither of first nor second order. Additionally, the activation energy of the electrons within the trap centres was approximated to 0.61 ± 0.01 eV using the Initial Rise model.
- Full Text: false
- Date Issued: 2018
Silent and Complex Histories: in conversation with Buhlebezwe Siwani
- Authors: Makandula, Sikhumbuzo
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147236 , vital:38607 , https://artthrob.co.za/2018/11/05/silent-and-complex-histories-in-conversation-with-buhlebezwe-siwani/
- Description: A feature by Sikhumbuzo Makandula on the 5th of November 2018
- Full Text:
- Date Issued: 2018
- Authors: Makandula, Sikhumbuzo
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147236 , vital:38607 , https://artthrob.co.za/2018/11/05/silent-and-complex-histories-in-conversation-with-buhlebezwe-siwani/
- Description: A feature by Sikhumbuzo Makandula on the 5th of November 2018
- Full Text:
- Date Issued: 2018
‘They tell you about the risks’: Exploring sources of sexuality education among very young adolescents in rural Mpumalanga
- Essop, R, Tolla, T, Lynch, Ingrid, Mokoae, M
- Authors: Essop, R , Tolla, T , Lynch, Ingrid , Mokoae, M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453282 , vital:75242 , https://hdl.handle.net/10520/EJC-10de5bde91
- Description: Early adolescence (ages 10 - 14) is a crucial stage of development. The importance of early intervention in improving adolescent sexual and reproductive health (SRH) is increasingly acknowledged. Yet, school-based sexuality education largely focuses on older adolescents, leaving very young adolescents to contend with conflicting information from different sources. This study responds to the need for contextually nuanced research with very young adolescents, which can inform policy and programmes aimed at improving their SRH outcomes.
- Full Text:
- Date Issued: 2018
- Authors: Essop, R , Tolla, T , Lynch, Ingrid , Mokoae, M
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/453282 , vital:75242 , https://hdl.handle.net/10520/EJC-10de5bde91
- Description: Early adolescence (ages 10 - 14) is a crucial stage of development. The importance of early intervention in improving adolescent sexual and reproductive health (SRH) is increasingly acknowledged. Yet, school-based sexuality education largely focuses on older adolescents, leaving very young adolescents to contend with conflicting information from different sources. This study responds to the need for contextually nuanced research with very young adolescents, which can inform policy and programmes aimed at improving their SRH outcomes.
- Full Text:
- Date Issued: 2018
A record of cheetah (Acinonyx jubatus) diet in the Northern Tuli Game Reserve, Botswana
- Craig, Christie A, Brassine, Eleanor I, Parker, Daniel M
- Authors: Craig, Christie A , Brassine, Eleanor I , Parker, Daniel M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123004 , vital:35395 , https://doi.org/10.1111/aje.12374
- Description: Cheetahs (Acinonyx jubatus) typically prey upon the most available small to medium-sized (23–56 kg) antelope (Hayward et al., 2006). In Botswana, impala (Aepyceros melampus) and springbok (Antidorcas marsupialis), followed by steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), are the prey species most frequently killed by cheetahs (Klein, 2007). Juvenile eland (Tragelaphus oryx), gemsbok (Oryx gazella), hartebeest (Alcelaphus buselaphus) and kudu (Tragelaphus strepsiceros) are also taken (Klein, 2007). The Northern Tuli Game Reserve (NOTUGRE) in eastern Botswana is naturally delineated by the nonperennial Shashe and Limpopo rivers in the east and south and has relatively porous game fencing along portions of the western and southern boundaries (Fig. 1) (Jackson, McNutt & Apps, 2012). Neither the fences nor the rivers restrict the movement of large carnivores such as cheetahs, lions (Panthera leo), leopards (Panthera pardus), spotted hyaenas (Crocuta crocuta) and African wild dogs (Lycaon pictus) onto neighbouring pastoral land (Jackson, McNutt & Apps, 2012). It is thus possible that cheetahs are feeding on livestock outside of the park. However, the diet of the cheetahs in NOTUGRE has not been evaluated. Our study serves to describe the diet of the cheetahs in NOTUGRE using both scats and kill sightings.
- Full Text:
- Date Issued: 2017
- Authors: Craig, Christie A , Brassine, Eleanor I , Parker, Daniel M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123004 , vital:35395 , https://doi.org/10.1111/aje.12374
- Description: Cheetahs (Acinonyx jubatus) typically prey upon the most available small to medium-sized (23–56 kg) antelope (Hayward et al., 2006). In Botswana, impala (Aepyceros melampus) and springbok (Antidorcas marsupialis), followed by steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), are the prey species most frequently killed by cheetahs (Klein, 2007). Juvenile eland (Tragelaphus oryx), gemsbok (Oryx gazella), hartebeest (Alcelaphus buselaphus) and kudu (Tragelaphus strepsiceros) are also taken (Klein, 2007). The Northern Tuli Game Reserve (NOTUGRE) in eastern Botswana is naturally delineated by the nonperennial Shashe and Limpopo rivers in the east and south and has relatively porous game fencing along portions of the western and southern boundaries (Fig. 1) (Jackson, McNutt & Apps, 2012). Neither the fences nor the rivers restrict the movement of large carnivores such as cheetahs, lions (Panthera leo), leopards (Panthera pardus), spotted hyaenas (Crocuta crocuta) and African wild dogs (Lycaon pictus) onto neighbouring pastoral land (Jackson, McNutt & Apps, 2012). It is thus possible that cheetahs are feeding on livestock outside of the park. However, the diet of the cheetahs in NOTUGRE has not been evaluated. Our study serves to describe the diet of the cheetahs in NOTUGRE using both scats and kill sightings.
- Full Text:
- Date Issued: 2017
Blue Cranes Anthropoides paradiseus at Etosha Pan, Namibia: what is the origin of this isolated population?
- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465347 , vital:76596 , https://doi.org/10.25226/bboc.v137i3.2017.a4
- Description: There is an isolated breeding population of Blue Cranes Anthropoides paradiseus around Etosha Pan, in northern Namibia, despite a lack of regular reports of the species from adjoining regions of Botswana, southern Namibia or even north-western South Africa. A search for historical records of Blue Cranes north of South Africa suggests occasional vagrancy to southern Namibia, eastern Botswana and perhaps Zimbabwe, with consistent sightings of resident, breeding birds only from Etosha since 1918. It is apparently not a relict population. While the natural establishment of a breeding population by rare vagrants appears unlikely, there is no documented evidence for the alternative explanation that birds were deliberately introduced to this locality.
- Full Text:
- Date Issued: 2017
- Authors: Craig, Adrian J F K
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465347 , vital:76596 , https://doi.org/10.25226/bboc.v137i3.2017.a4
- Description: There is an isolated breeding population of Blue Cranes Anthropoides paradiseus around Etosha Pan, in northern Namibia, despite a lack of regular reports of the species from adjoining regions of Botswana, southern Namibia or even north-western South Africa. A search for historical records of Blue Cranes north of South Africa suggests occasional vagrancy to southern Namibia, eastern Botswana and perhaps Zimbabwe, with consistent sightings of resident, breeding birds only from Etosha since 1918. It is apparently not a relict population. While the natural establishment of a breeding population by rare vagrants appears unlikely, there is no documented evidence for the alternative explanation that birds were deliberately introduced to this locality.
- Full Text:
- Date Issued: 2017
Looking after freedom?:
- Authors: Dantas, Nancy
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147081 , vital:38591 , https://www.buala.org/en/ill-visit/looking-after-freedom
- Description: Did freedom come to South Africa in 1994? Should it be marked and set in time, or is it a fragile process, an ambition and a becoming? Do we see ourselves coming closer to this ideal, or desperately receding from it as an invisible rip current pulls us away? To think of freedom as a given, a day in the year or a landmark on the horizon is to neglect that liberty from bondage and oppression, in all its disastrous and fatidic forms requires vigilance, nurturing and a spirit of insatiable demand. When our freedom becomes commodified, transformed into a mark on annual calendars, a mere commemoration; something we think have obtained and cannot possibly stand to loose, we are all in for trouble.
- Full Text:
- Date Issued: 2017
- Authors: Dantas, Nancy
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/147081 , vital:38591 , https://www.buala.org/en/ill-visit/looking-after-freedom
- Description: Did freedom come to South Africa in 1994? Should it be marked and set in time, or is it a fragile process, an ambition and a becoming? Do we see ourselves coming closer to this ideal, or desperately receding from it as an invisible rip current pulls us away? To think of freedom as a given, a day in the year or a landmark on the horizon is to neglect that liberty from bondage and oppression, in all its disastrous and fatidic forms requires vigilance, nurturing and a spirit of insatiable demand. When our freedom becomes commodified, transformed into a mark on annual calendars, a mere commemoration; something we think have obtained and cannot possibly stand to loose, we are all in for trouble.
- Full Text:
- Date Issued: 2017
MD-TASK: a software suite for analyzing molecular dynamics trajectories
- Brown, David K, Penkler, David L, Amamuddy, Olivier S, Ross, Caroline J, Atilgan, Ali R, Atilgan, Canan, Tastan Bishop, Özlem
- Authors: Brown, David K , Penkler, David L , Amamuddy, Olivier S , Ross, Caroline J , Atilgan, Ali R , Atilgan, Canan , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125138 , vital:35735 , https://doi.10.1093/bioinformatics/btx349
- Description: Molecular dynamics (MD) determines the physical motions of atoms of a biological macromolecule in a cell-like environment and is an important method in structural bioinformatics. Traditionally, measurements such as root mean square deviation, root mean square fluctuation, radius of gyration, and various energy measures have been used to analyze MD simulations. Here, we present MD-TASK, a novel software suite that employs graph theory techniques, perturbation response scanning, and dynamic cross-correlation to provide unique ways for analyzing MD trajectories.
- Full Text:
- Date Issued: 2017
- Authors: Brown, David K , Penkler, David L , Amamuddy, Olivier S , Ross, Caroline J , Atilgan, Ali R , Atilgan, Canan , Tastan Bishop, Özlem
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125138 , vital:35735 , https://doi.10.1093/bioinformatics/btx349
- Description: Molecular dynamics (MD) determines the physical motions of atoms of a biological macromolecule in a cell-like environment and is an important method in structural bioinformatics. Traditionally, measurements such as root mean square deviation, root mean square fluctuation, radius of gyration, and various energy measures have been used to analyze MD simulations. Here, we present MD-TASK, a novel software suite that employs graph theory techniques, perturbation response scanning, and dynamic cross-correlation to provide unique ways for analyzing MD trajectories.
- Full Text:
- Date Issued: 2017
Relative features of the principal and secondary luminescence lifetimes in quartz
- Chithambo, Makaiko L, Ogundare, F O
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125821 , vital:35820 , https://doi.10.1002/pssc.200673721
- Description: Quartz is a common natural mineral with properties that make it amenable for application in radiation dosimetry using luminescence methods [1]. The luminescence properties of quartz including its sensitivity and luminescence lifetimes undergo notable changes when the quartz is annealed, and in particular, near its phase inversion temperatures of 573 and 867 oC [2, 3]. The physical processes leading up to the emission of luminescence in quartz may be investigated using time-resolved optical stimulation. The aim of this method is to separate in time the stimulation and emission of luminescence to enable measurement of time-resolved luminescence spectra which may be resolved into associated lifetimes, defined in this sense as the delay between stimulation and emission of luminescence [4, 5]. A number of such studies show that annealing defines the detailed distribution of lifetimes with measurement temperature as well as the irradiation-dependent characteristics of the lifetimes [3, 6]. In particular, it was noted [3] that spectra measured at certain temperatures could be accurately resolved into more than one component, a scenario that pointed to the possibility of involvement of multiple luminescence centers in the emission of luminescence from quartz. The aim of this work is to build on the findings described, specifically to study the influence of measurement temperature and irradiation on the principal and subsidiary luminescence lifetimes in natural quartz.
- Full Text:
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Ogundare, F O
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125821 , vital:35820 , https://doi.10.1002/pssc.200673721
- Description: Quartz is a common natural mineral with properties that make it amenable for application in radiation dosimetry using luminescence methods [1]. The luminescence properties of quartz including its sensitivity and luminescence lifetimes undergo notable changes when the quartz is annealed, and in particular, near its phase inversion temperatures of 573 and 867 oC [2, 3]. The physical processes leading up to the emission of luminescence in quartz may be investigated using time-resolved optical stimulation. The aim of this method is to separate in time the stimulation and emission of luminescence to enable measurement of time-resolved luminescence spectra which may be resolved into associated lifetimes, defined in this sense as the delay between stimulation and emission of luminescence [4, 5]. A number of such studies show that annealing defines the detailed distribution of lifetimes with measurement temperature as well as the irradiation-dependent characteristics of the lifetimes [3, 6]. In particular, it was noted [3] that spectra measured at certain temperatures could be accurately resolved into more than one component, a scenario that pointed to the possibility of involvement of multiple luminescence centers in the emission of luminescence from quartz. The aim of this work is to build on the findings described, specifically to study the influence of measurement temperature and irradiation on the principal and subsidiary luminescence lifetimes in natural quartz.
- Full Text:
- Date Issued: 2017
Undefined cellulase formulations hinder scientific reproducibility
- Himmel, Michael E, Abbas, Charles A, Baker, John O, Bayer, Edward A, Bomble, Yannick J, Brunecky, Roman, Chen, Xiaowen, Felby, Claus, Jeoh, Tina, Kumar, Rajeev, McCleary, Barry V, Pletschke, Brett I, Tucker, Melvin P, Wyman, Charles E, Decker, Stephen R
- Authors: Himmel, Michael E , Abbas, Charles A , Baker, John O , Bayer, Edward A , Bomble, Yannick J , Brunecky, Roman , Chen, Xiaowen , Felby, Claus , Jeoh, Tina , Kumar, Rajeev , McCleary, Barry V , Pletschke, Brett I , Tucker, Melvin P , Wyman, Charles E , Decker, Stephen R
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61402 , vital:28022 , https://doi.org/10.1186/s13068-017-0974-y
- Description: In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or more engineered cellulase formulations or natural exoproteomes of known performance serving as positive controls. When these formulations have unknown composition, as is the case with several widely used commercial products, it becomes impossible to compare or reproduce work done today to work done in the future, where, for example, such preparations may not be available. Therefore, being a critical tenet of science publishing, experimental reproducibility is endangered by the continued use of these undisclosed products. We propose the introduction of standard procedures and materials to produce specific and reproducible cellulase formulations. These formulations are to serve as yardsticks to measure improvements and performance of new cellulase formulations.
- Full Text:
- Date Issued: 2017
- Authors: Himmel, Michael E , Abbas, Charles A , Baker, John O , Bayer, Edward A , Bomble, Yannick J , Brunecky, Roman , Chen, Xiaowen , Felby, Claus , Jeoh, Tina , Kumar, Rajeev , McCleary, Barry V , Pletschke, Brett I , Tucker, Melvin P , Wyman, Charles E , Decker, Stephen R
- Date: 2017
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/61402 , vital:28022 , https://doi.org/10.1186/s13068-017-0974-y
- Description: In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or more engineered cellulase formulations or natural exoproteomes of known performance serving as positive controls. When these formulations have unknown composition, as is the case with several widely used commercial products, it becomes impossible to compare or reproduce work done today to work done in the future, where, for example, such preparations may not be available. Therefore, being a critical tenet of science publishing, experimental reproducibility is endangered by the continued use of these undisclosed products. We propose the introduction of standard procedures and materials to produce specific and reproducible cellulase formulations. These formulations are to serve as yardsticks to measure improvements and performance of new cellulase formulations.
- Full Text:
- Date Issued: 2017
Application of Baylis-Hillman methodology in the direct construction of chromone derivatives
- Faridoon, H, Olomola, Temitope O, Klein, Rosalyn, Kaye, Perry T
- Authors: Faridoon, H , Olomola, Temitope O , Klein, Rosalyn , Kaye, Perry T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442488 , vital:73992 , https://doi.org/10.1016/j.tet.2015.11.039
- Description: Pyridinium chlorochromate oxidation of Baylis-Hillman-derived tert-butyl 2H-chromene-3-carboxylates affords chromone-3-carboxylate esters, providing the first application of Baylis-Hillman methodology in a direct and convenient three-step synthesis of chromone derivatives.
- Full Text:
- Date Issued: 2016
- Authors: Faridoon, H , Olomola, Temitope O , Klein, Rosalyn , Kaye, Perry T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442488 , vital:73992 , https://doi.org/10.1016/j.tet.2015.11.039
- Description: Pyridinium chlorochromate oxidation of Baylis-Hillman-derived tert-butyl 2H-chromene-3-carboxylates affords chromone-3-carboxylate esters, providing the first application of Baylis-Hillman methodology in a direct and convenient three-step synthesis of chromone derivatives.
- Full Text:
- Date Issued: 2016
Employment and diversity in the cultural and creative industries in South Africa: research note
- Authors: Snowball, Jeanette D
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71493 , vital:29858 , https://hdl.handle.net/10520/EJC188591
- Description: The publication of Richard Florida's (2002) The Rise of the Creative Class marked a growing international interest in the creative economy. There are several ways of understanding the creative economy, often divided into the cultural and creative industries. Cultural industries are those whose major outputs have some symbolic value, such as fine arts, film and craft, jewelry design, publishing and fashion. Creative industries are defined more broadly as those that have knowledge as their major input. In addition to cultural goods and services, these include things like software design and internet services. UNESCO (2009) provides guidelines for defining the cultural and creative industries and the ways in which they can be measured, but there is currently no international consensus. Nor is there likely to be, since different countries will have very different levels of involvement and focus that may shape what information is useful, for example, for shaping policy.
- Full Text: false
- Date Issued: 2016
- Authors: Snowball, Jeanette D
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71493 , vital:29858 , https://hdl.handle.net/10520/EJC188591
- Description: The publication of Richard Florida's (2002) The Rise of the Creative Class marked a growing international interest in the creative economy. There are several ways of understanding the creative economy, often divided into the cultural and creative industries. Cultural industries are those whose major outputs have some symbolic value, such as fine arts, film and craft, jewelry design, publishing and fashion. Creative industries are defined more broadly as those that have knowledge as their major input. In addition to cultural goods and services, these include things like software design and internet services. UNESCO (2009) provides guidelines for defining the cultural and creative industries and the ways in which they can be measured, but there is currently no international consensus. Nor is there likely to be, since different countries will have very different levels of involvement and focus that may shape what information is useful, for example, for shaping policy.
- Full Text: false
- Date Issued: 2016
Ericoid fungal inoculation of blueberry under commercial production in South Africa
- Bizabani, Christine, Fontenla, Sonia, Dames, Joanna F
- Authors: Bizabani, Christine , Fontenla, Sonia , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448610 , vital:74746 , https://doi.org/10.1016/j.scienta.2016.06.029
- Description: Ericoid mycorrhizal (ERM) fungi are known to enhance growth of plants belonging to the Ericaceae family. However, the outcomes of root-fungal associations in this family are influenced by several factors such as soil nutrient status, climatic conditions, host variety and fungal partner. The aim of this study was (i) to determine whether symbiotic fungal structures form in roots of Misty (Vaccinium corymbosum) and Brightwell (V. ashei) blueberry varieties, following inoculation with Leohumicola, Oidiodendron maius and Meliniomyces fungal species, and (ii) evaluate inoculation effects on the growth of blueberry varieties. The study was conducted for 60 weeks under commercial production conditions at Amathole Berries, Sutterheim, South Africa. All three fungi were isolated from Erica plants growing naturally in Albany Centre of Endemism of South Africa. All ERM formed mycorrhizal structures characteristic of typical ericoid colonisation in the roots of both Misty and Brightwell. However, percentage colonisation was low. The highest colonisation percentage, 20.4%, was observed in Misty inoculated with Oidiodendron maius. Colonisation was significantly different compared to un-inoculated controls in the Misty variety. In both varieties inoculated with either Leohumicola or Meliniomyces did not improve (p > 0.05) shoot growth and biomass. All fungal species improved root biomass in Misty but not in Brightwell. This indicates that ERM inoculation may potentially benefit plant of Misty and that responses to ERM inoculation vary between blueberry varieties.
- Full Text:
- Date Issued: 2016
- Authors: Bizabani, Christine , Fontenla, Sonia , Dames, Joanna F
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448610 , vital:74746 , https://doi.org/10.1016/j.scienta.2016.06.029
- Description: Ericoid mycorrhizal (ERM) fungi are known to enhance growth of plants belonging to the Ericaceae family. However, the outcomes of root-fungal associations in this family are influenced by several factors such as soil nutrient status, climatic conditions, host variety and fungal partner. The aim of this study was (i) to determine whether symbiotic fungal structures form in roots of Misty (Vaccinium corymbosum) and Brightwell (V. ashei) blueberry varieties, following inoculation with Leohumicola, Oidiodendron maius and Meliniomyces fungal species, and (ii) evaluate inoculation effects on the growth of blueberry varieties. The study was conducted for 60 weeks under commercial production conditions at Amathole Berries, Sutterheim, South Africa. All three fungi were isolated from Erica plants growing naturally in Albany Centre of Endemism of South Africa. All ERM formed mycorrhizal structures characteristic of typical ericoid colonisation in the roots of both Misty and Brightwell. However, percentage colonisation was low. The highest colonisation percentage, 20.4%, was observed in Misty inoculated with Oidiodendron maius. Colonisation was significantly different compared to un-inoculated controls in the Misty variety. In both varieties inoculated with either Leohumicola or Meliniomyces did not improve (p > 0.05) shoot growth and biomass. All fungal species improved root biomass in Misty but not in Brightwell. This indicates that ERM inoculation may potentially benefit plant of Misty and that responses to ERM inoculation vary between blueberry varieties.
- Full Text:
- Date Issued: 2016
On luminescence stimulated from deep traps using thermally-assisted time-resolved optical stimulation in α-Al2O3: C
- Nyirenda, Angel N, Chithambo, Makaiko L, Polymeris, G S
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L , Polymeris, G S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124627 , vital:35639 , https://doi.org/10.1016/j.radmeas.2016.01.016
- Description: We report a study of charge transfer mechanisms of electrons stimulated optically from very deep traps, also known as donor traps, in α-Al2O3:C. The investigations were carried out using thermally-assisted time-resolved optical stimulation, thermoluminescence and by way of residual thermoluminescence from the main electron trap. When the charges are optically stimulated from the deep traps, they are redistributed via the conduction band to the main electron trap and the shallow trap from where they are optically or thermally released for recombination at luminescence centres. The luminescence is strongly quenched at high measurement temperature as evident by very short luminescence lifetimes at these temperatures. The main peak due to residual thermoluminescence is located at a higher temperature than the conventional main peak.
- Full Text: false
- Date Issued: 2016
- Authors: Nyirenda, Angel N , Chithambo, Makaiko L , Polymeris, G S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124627 , vital:35639 , https://doi.org/10.1016/j.radmeas.2016.01.016
- Description: We report a study of charge transfer mechanisms of electrons stimulated optically from very deep traps, also known as donor traps, in α-Al2O3:C. The investigations were carried out using thermally-assisted time-resolved optical stimulation, thermoluminescence and by way of residual thermoluminescence from the main electron trap. When the charges are optically stimulated from the deep traps, they are redistributed via the conduction band to the main electron trap and the shallow trap from where they are optically or thermally released for recombination at luminescence centres. The luminescence is strongly quenched at high measurement temperature as evident by very short luminescence lifetimes at these temperatures. The main peak due to residual thermoluminescence is located at a higher temperature than the conventional main peak.
- Full Text: false
- Date Issued: 2016
SEAmester – South Africa’s first class afloat
- Ansorge, Isabelle J, Brundrit, Geoff, Brundrit, Jean, Dorrington, Rosemary A, Fawcett, Sarah, Gammon, David, Henry, Tahlia, Hermes, Juliet, Hölscher, Beate, d’Hotman, Jethan, Meiklejohn, Ian, Morris, Tammy, Pinto, Izidine, Du Plessis, Marcel, Roman, Raymond, Saunders, Clinton, Shabangu, Fannie W, De Vos, Marc, Walker, David R, Louw, Gavin
- Authors: Ansorge, Isabelle J , Brundrit, Geoff , Brundrit, Jean , Dorrington, Rosemary A , Fawcett, Sarah , Gammon, David , Henry, Tahlia , Hermes, Juliet , Hölscher, Beate , d’Hotman, Jethan , Meiklejohn, Ian , Morris, Tammy , Pinto, Izidine , Du Plessis, Marcel , Roman, Raymond , Saunders, Clinton , Shabangu, Fannie W , De Vos, Marc , Walker, David R , Louw, Gavin
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/65539 , vital:28808 , https://doi.org/10.17159/sajs.2016/a0171
- Description: publisher version , From Introduction: Marine science is a highly competitive environment. The need to improve the cohort of South African postgraduates, who would be recognised both nationally and internationally for their scientific excellence, is crucial. It is possible to attract students early on in their careers to this discipline via cutting-edge science, technology and unique field experiences. Through the engagement of students with real-life experiences such as SEAmester, universities supporting marine science postgraduate degree programmes can attract a sustainable throughput of numerically proficient students. By achieving a more quantitative and experienced input into our postgraduate degree programmes, we will, as a scientific community, greatly improve our long-term capabilities to accurately measure, model and predict the impacts of current climate change scenarios. The short-term goal is to attract and establish a cohort of proficient marine and atmospheric science graduates who will contribute to filling the capacity needs of South African marine science as a whole. The SEAmester programme, by involving researchers from across all the relevant disciplines and tertiary institutions, provides an opportunity to build a network of collaborative teaching within the marine field. In doing so, these researchers will foster and strengthen new and current collaborations between historically white and black universities (Figure 1). The long-term objective of SEAmester is to build critical mass within the marine sciences to ensure sustained growth of human capacity in marine science in South Africa – aligning closely with the current DST Research and Development strategies and the Operation Phakisa Oceans Economy initiative.
- Full Text:
- Date Issued: 2016
- Authors: Ansorge, Isabelle J , Brundrit, Geoff , Brundrit, Jean , Dorrington, Rosemary A , Fawcett, Sarah , Gammon, David , Henry, Tahlia , Hermes, Juliet , Hölscher, Beate , d’Hotman, Jethan , Meiklejohn, Ian , Morris, Tammy , Pinto, Izidine , Du Plessis, Marcel , Roman, Raymond , Saunders, Clinton , Shabangu, Fannie W , De Vos, Marc , Walker, David R , Louw, Gavin
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/65539 , vital:28808 , https://doi.org/10.17159/sajs.2016/a0171
- Description: publisher version , From Introduction: Marine science is a highly competitive environment. The need to improve the cohort of South African postgraduates, who would be recognised both nationally and internationally for their scientific excellence, is crucial. It is possible to attract students early on in their careers to this discipline via cutting-edge science, technology and unique field experiences. Through the engagement of students with real-life experiences such as SEAmester, universities supporting marine science postgraduate degree programmes can attract a sustainable throughput of numerically proficient students. By achieving a more quantitative and experienced input into our postgraduate degree programmes, we will, as a scientific community, greatly improve our long-term capabilities to accurately measure, model and predict the impacts of current climate change scenarios. The short-term goal is to attract and establish a cohort of proficient marine and atmospheric science graduates who will contribute to filling the capacity needs of South African marine science as a whole. The SEAmester programme, by involving researchers from across all the relevant disciplines and tertiary institutions, provides an opportunity to build a network of collaborative teaching within the marine field. In doing so, these researchers will foster and strengthen new and current collaborations between historically white and black universities (Figure 1). The long-term objective of SEAmester is to build critical mass within the marine sciences to ensure sustained growth of human capacity in marine science in South Africa – aligning closely with the current DST Research and Development strategies and the Operation Phakisa Oceans Economy initiative.
- Full Text:
- Date Issued: 2016
South Africa in the Antarctic Circumnavigation Expedition: a multi-institutional and interdisciplinary scientific project
- Halo, Issufo, Dorrington, Rosemary A, Bornman, Thomas G, De Villiers, Stephanie, Fawcett, Sarah
- Authors: Halo, Issufo , Dorrington, Rosemary A , Bornman, Thomas G , De Villiers, Stephanie , Fawcett, Sarah
- Date: 2016
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/10962/65428 , vital:28790 , https://doi.org/10.17159/sajs.2016/a0173
- Description: publisher version , The polar regions are more critically affected by climate change than any other region on our planet.1,2 On the Antarctic continent and in its surrounding oceans, the effects of climate change are likely to be dramatic,3 and include largescale catastrophic ice melt, loss of habitat and biodiversity, and global sea level rise. The ‘Southern Ocean’ refers to the region where Atlantic, Indian and Pacific Ocean waters come together to encircle Antarctica. These waters connect the different ocean basins by linking the shallow and deep limbs of the global ocean current system (‘overturning circulation’) and play a critical role in storing and distributing heat and carbon dioxide (CO2 ). The Southern Ocean thus regulates not only the climate of the Antarctic, but of the entire earth system.1,4 By extension, the capacity of the global ocean to ameliorate earth’s changing climate is strongly controlled by the Southern Ocean. Marine phytoplankton (microscopic plants inhabiting the sunlit upper ocean) convert CO2 (an inorganic form of carbon) dissolved in surface waters into organic carbon through photosynthesis. This organic carbon fuels upper trophic levels such as fish, mammals and birds, and a portion sinks into the deep ocean where it remains stored for hundreds to thousands of years. This mechanism, which lowers the atmospheric concentration of CO2 , is termed the ‘biological pump’.5 The efficiency of the global ocean’s biological pump is currently limited by the Southern Ocean, where the macronutrients (nitrate and phosphate) required for photosynthesis are never fully consumed in surface waters. In theory, increased consumption of these nutrients could drive higher organic carbon removal to the deep ocean, enhancing the oceanic uptake of atmospheric CO2 . Indeed, more complete consumption of Southern Ocean nutrients is a leading hypothesis for the decrease in atmospheric CO2 that characterised the ice ages.6 Despite the global importance of the Southern Ocean, knowledge of the controls on and interactions among the physical, chemical and biological processes operating in Antarctic ecosystems is limited, largely because of a scarcity of in-situ observational data, compounded by the challenge of integrating siloed scientific fields. Given predictions that diverse aspects of Southern Ocean physics and carbon biogeochemistry are likely to change in the coming decades, a transdisciplinary approach to studying Antarctic systems is critical.
- Full Text:
- Date Issued: 2016
- Authors: Halo, Issufo , Dorrington, Rosemary A , Bornman, Thomas G , De Villiers, Stephanie , Fawcett, Sarah
- Date: 2016
- Language: English
- Type: article
- Identifier: http://hdl.handle.net/10962/65428 , vital:28790 , https://doi.org/10.17159/sajs.2016/a0173
- Description: publisher version , The polar regions are more critically affected by climate change than any other region on our planet.1,2 On the Antarctic continent and in its surrounding oceans, the effects of climate change are likely to be dramatic,3 and include largescale catastrophic ice melt, loss of habitat and biodiversity, and global sea level rise. The ‘Southern Ocean’ refers to the region where Atlantic, Indian and Pacific Ocean waters come together to encircle Antarctica. These waters connect the different ocean basins by linking the shallow and deep limbs of the global ocean current system (‘overturning circulation’) and play a critical role in storing and distributing heat and carbon dioxide (CO2 ). The Southern Ocean thus regulates not only the climate of the Antarctic, but of the entire earth system.1,4 By extension, the capacity of the global ocean to ameliorate earth’s changing climate is strongly controlled by the Southern Ocean. Marine phytoplankton (microscopic plants inhabiting the sunlit upper ocean) convert CO2 (an inorganic form of carbon) dissolved in surface waters into organic carbon through photosynthesis. This organic carbon fuels upper trophic levels such as fish, mammals and birds, and a portion sinks into the deep ocean where it remains stored for hundreds to thousands of years. This mechanism, which lowers the atmospheric concentration of CO2 , is termed the ‘biological pump’.5 The efficiency of the global ocean’s biological pump is currently limited by the Southern Ocean, where the macronutrients (nitrate and phosphate) required for photosynthesis are never fully consumed in surface waters. In theory, increased consumption of these nutrients could drive higher organic carbon removal to the deep ocean, enhancing the oceanic uptake of atmospheric CO2 . Indeed, more complete consumption of Southern Ocean nutrients is a leading hypothesis for the decrease in atmospheric CO2 that characterised the ice ages.6 Despite the global importance of the Southern Ocean, knowledge of the controls on and interactions among the physical, chemical and biological processes operating in Antarctic ecosystems is limited, largely because of a scarcity of in-situ observational data, compounded by the challenge of integrating siloed scientific fields. Given predictions that diverse aspects of Southern Ocean physics and carbon biogeochemistry are likely to change in the coming decades, a transdisciplinary approach to studying Antarctic systems is critical.
- Full Text:
- Date Issued: 2016
The role of entomopathogenic fungi in the control of citrus pests in South Africa: cause for optimism
- Coombes, Candice A, Chartier-Fizgerald, Veronique C, Wiblin, Danielle, Dames, Joanna F, Hill, Martin P, Moore, Sean D
- Authors: Coombes, Candice A , Chartier-Fizgerald, Veronique C , Wiblin, Danielle , Dames, Joanna F , Hill, Martin P , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453480 , vital:75257 , ISBN 978-1-83768-091-7 , https://iobc-wprs.org/product/the-role-of-entomopathogenic-fungi-in-the-control-of-citrus-pests-in-south-africa-cause-for-optimism/
- Description: Citrus is a highly productive crop in South Africa, but it is damaged by a number of pests that result in yield loss and have the potential to limit market access. Maximum residue limits (MRLs) imposed by importing countries have driven the need for alternative control technologies, including the use of entomopathogenic fungi (EPF). Bioprospecting in citrus orchards and seven years of bioassay trials identified Beauveria bassiana G Ar 17 B3 and Metarhizium anisopliae G 11 3 L6 and FCM Ar 23 B3 as the most virulent fungal isolates. Preliminary trials with these three fungi against the arboreal pests, California red scale, Aonidiella aurantii (Maskell), citrus mealybug, Planococcus citri (Risso) and citrus thrips, Scirtothrips aurantii Faure, have been promising. False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) is the most important citrus pest in South Africa and while considerable research has been conducted on controlling the insect on the tree, the soil borne stages of this insect have largely been ignored. After laboratory bioassays, the three fungal isolates were taken to field trials. All three isolates persisted for at least six months after application to the soil. A large scale field trial, showed that although all three isolates reduced FCM infestation, isolate B. bassiana G Ar 17 B3 performed best, recording a consistent 80% reduction in FCM infestation throughout the trial period. The results of nearly 10 years of research on the potential of EPFs in the control of citrus pests in South Africa are certainly cause for optimism.
- Full Text:
- Date Issued: 2016
- Authors: Coombes, Candice A , Chartier-Fizgerald, Veronique C , Wiblin, Danielle , Dames, Joanna F , Hill, Martin P , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/453480 , vital:75257 , ISBN 978-1-83768-091-7 , https://iobc-wprs.org/product/the-role-of-entomopathogenic-fungi-in-the-control-of-citrus-pests-in-south-africa-cause-for-optimism/
- Description: Citrus is a highly productive crop in South Africa, but it is damaged by a number of pests that result in yield loss and have the potential to limit market access. Maximum residue limits (MRLs) imposed by importing countries have driven the need for alternative control technologies, including the use of entomopathogenic fungi (EPF). Bioprospecting in citrus orchards and seven years of bioassay trials identified Beauveria bassiana G Ar 17 B3 and Metarhizium anisopliae G 11 3 L6 and FCM Ar 23 B3 as the most virulent fungal isolates. Preliminary trials with these three fungi against the arboreal pests, California red scale, Aonidiella aurantii (Maskell), citrus mealybug, Planococcus citri (Risso) and citrus thrips, Scirtothrips aurantii Faure, have been promising. False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) is the most important citrus pest in South Africa and while considerable research has been conducted on controlling the insect on the tree, the soil borne stages of this insect have largely been ignored. After laboratory bioassays, the three fungal isolates were taken to field trials. All three isolates persisted for at least six months after application to the soil. A large scale field trial, showed that although all three isolates reduced FCM infestation, isolate B. bassiana G Ar 17 B3 performed best, recording a consistent 80% reduction in FCM infestation throughout the trial period. The results of nearly 10 years of research on the potential of EPFs in the control of citrus pests in South Africa are certainly cause for optimism.
- Full Text:
- Date Issued: 2016