Agent-based model development of a complex socio-ecological system: Methods for overcoming data and domain limitations
- James, C. L, Bradshaw, Karen L
- Authors: James, C. L , Bradshaw, Karen L
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440189 , vital:73755 , xlink:href="https://doi.org/10.1016/j.ecoinf.2023.102224"
- Description: Agent-based models (ABMs) are appropriate tools for modelling socio-ecological systems due to their ability to handle complexity. However, development of such models is often an intensive process. There are many tutorials on the general methods and steps in ABM development but there are not necessarily practical details on how to overcome certain challenges. Honeybush (Cyclopia spp.), a kind of fynbos vegetation found in the Western and Eastern Cape mountains, is an important ecological and agricultural product in South Africa. It is considered a complex system due to its variability and unpredictability. The honeybush tea industry faces the challenge of meeting emerging market demands while maintaining sustainable harvesting practices, in the midst of an uncertain future due to climate change. We created a prototype model, HoneybushModel, using the MARS framework, a C# multi-agent simulation toolkit. The model was validated using historic data. Whilst outlining the development processes used to create the Honeybush Model, this paper provides a methodology for the development of such models and demonstrates techniques for addressing data, domain and framework limitations. The implemented model also acts as a case study for similar systems that could be modelled using an ABM.
- Full Text:
- Date Issued: 2023
- Authors: James, C. L , Bradshaw, Karen L
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440189 , vital:73755 , xlink:href="https://doi.org/10.1016/j.ecoinf.2023.102224"
- Description: Agent-based models (ABMs) are appropriate tools for modelling socio-ecological systems due to their ability to handle complexity. However, development of such models is often an intensive process. There are many tutorials on the general methods and steps in ABM development but there are not necessarily practical details on how to overcome certain challenges. Honeybush (Cyclopia spp.), a kind of fynbos vegetation found in the Western and Eastern Cape mountains, is an important ecological and agricultural product in South Africa. It is considered a complex system due to its variability and unpredictability. The honeybush tea industry faces the challenge of meeting emerging market demands while maintaining sustainable harvesting practices, in the midst of an uncertain future due to climate change. We created a prototype model, HoneybushModel, using the MARS framework, a C# multi-agent simulation toolkit. The model was validated using historic data. Whilst outlining the development processes used to create the Honeybush Model, this paper provides a methodology for the development of such models and demonstrates techniques for addressing data, domain and framework limitations. The implemented model also acts as a case study for similar systems that could be modelled using an ABM.
- Full Text:
- Date Issued: 2023
Combination of photodynamic antimicrobial chemotherapy and ciprofloxacin to combat S. aureus and E. coli resistant biofilms
- Openda, Yolande Ikala, Nyokong, Tebello
- Authors: Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360384 , vital:65084 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.103142"
- Description: Photodynamic antimicrobial chemotherapy (PACT) coupled with an antibiotic, ciprofloxacin (CIP), was investigated using two indium metallated cationic photosensitizers, a porphyrin (1) and a phthalocyanine (2). Applying PACT followed by the antibiotic treatment led to a remarkable reduction in the biofilm cell survival of two antibiotic-resistant bacterial strains, S. aureus (Gram-positive) and E. coli (Gram-nenative). Treating both bacteria strains with PACT alone showed no significant activity at 32 µM with 15 min irradiation, while CIP alone exhibited a minimum biofilm inhibition concentration (MBIC) at 4 and 8 µg/mL on S. aureus and E. coli, respectively following 24 h incubation. The combined treatment resulted in the complete eradication of the matured biofilms with high log10 reduction values of 7.05 and 7.20 on S. aureus and E. coli, respectively, at low concentrations. It was found that 15 min PACT irradiation of 8 µM of complexes (1 and 2) combined with 2 µg/mL of CIP have a 100% reduction of the resistant S. aureus biofilms. Whereas the total killing of E. coli was obtained when combining 8 µM of complex 1 and 16 µM of complex 2 both combined with 4 µg/mL of CIP.
- Full Text:
- Date Issued: 2023
- Authors: Openda, Yolande Ikala , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360384 , vital:65084 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.103142"
- Description: Photodynamic antimicrobial chemotherapy (PACT) coupled with an antibiotic, ciprofloxacin (CIP), was investigated using two indium metallated cationic photosensitizers, a porphyrin (1) and a phthalocyanine (2). Applying PACT followed by the antibiotic treatment led to a remarkable reduction in the biofilm cell survival of two antibiotic-resistant bacterial strains, S. aureus (Gram-positive) and E. coli (Gram-nenative). Treating both bacteria strains with PACT alone showed no significant activity at 32 µM with 15 min irradiation, while CIP alone exhibited a minimum biofilm inhibition concentration (MBIC) at 4 and 8 µg/mL on S. aureus and E. coli, respectively following 24 h incubation. The combined treatment resulted in the complete eradication of the matured biofilms with high log10 reduction values of 7.05 and 7.20 on S. aureus and E. coli, respectively, at low concentrations. It was found that 15 min PACT irradiation of 8 µM of complexes (1 and 2) combined with 2 µg/mL of CIP have a 100% reduction of the resistant S. aureus biofilms. Whereas the total killing of E. coli was obtained when combining 8 µM of complex 1 and 16 µM of complex 2 both combined with 4 µg/mL of CIP.
- Full Text:
- Date Issued: 2023
Diverse values of nature for sustainability
- Pascual, Unai, Balvanera, Patricia, Anderson, Christopher B, Chaplin-Kramer, Rebecca, Christie, Michael, González-Jiménez, David, Martin, Adrian, Raymond, Christopher M, Termansen, Mette, Vatn, Arild, Athayde, Simone, Baptiste, Brigitte, Barton, Davin N, Jacobs, Sander, Kelemen, Eszter, Kumar, Ritesh, Lazos, Elena, Mwampamba, Tuyeni H, Nakangu, Barbara, O’Farrell, Patrick, Subramanian, Suneetha M, van Noordwijk, Meine, Ahn, SoEun, Amaruzaman, Sacha, Amin, Ariane M, Arias-Arévalo, Paola, Arroyo-Robles, Gabriela, Cantú-Fernández, Mariana, Castro, Antonio J, Contreras, Victoria, de Vos, Alta, Dendoncker, Nicolas, Engel, Stefanie, Eser, Uta, Faith, Daniel P, Filyushkina, Anna, Ghazi, Houda, Gómez-Baggethun, Erik, Gould, Rachelle K, Guibrunet, Louise, Gundimeda, Haripriya, Hahn, Thomas, Harmáčková, Zuzana V, Hernández-Blanco, Marcello, Horcea-Milcu, Andra-loana, Huambachano, Mariaelena, Wicher, Natalia L H, Aydın, Cem I, Islar, Mine, Koessler, Ann-Kathrin, Kenter, Jasper O, Kosmus, Marina, Lee, Heera, Leimona, Beria, Lele, Sharachchandra, Lenzi, Dominic, Lliso, Bosco, Mannetii, Lelani M, Merçon, Juliana, Monroy-Sais, Ana S, Mukherjee, Nibedita, Muraca, Barbara, Muradian, Roldan, Murali, Ranjini, Nelson, Sara H, Nemogá-Soto, Gabriel R, Ngouhouo-Poufoun, Jonas, Niamir, Aidin, Nuesiri, Emmanuel, Nyumba, Tobias O, Özkaynak, Begüm, Palomo, Ignacio, Pandit, Ram, Pawłowska-Mainville, Agnieszka, Porter-Bolland, Luciano, Quaas, Martin, Rode, Julian, Rozzi, Ricardo, Sachdeva, Sonya, Aibek, Samakov, Schaafsma, Marije, Sitas, Nadia, Ungar, Paula, Yiu, Evonne, Yoshida, Yuki, Zent, Eglee
- Authors: Pascual, Unai , Balvanera, Patricia , Anderson, Christopher B , Chaplin-Kramer, Rebecca , Christie, Michael , González-Jiménez, David , Martin, Adrian , Raymond, Christopher M , Termansen, Mette , Vatn, Arild , Athayde, Simone , Baptiste, Brigitte , Barton, Davin N , Jacobs, Sander , Kelemen, Eszter , Kumar, Ritesh , Lazos, Elena , Mwampamba, Tuyeni H , Nakangu, Barbara , O’Farrell, Patrick , Subramanian, Suneetha M , van Noordwijk, Meine , Ahn, SoEun , Amaruzaman, Sacha , Amin, Ariane M , Arias-Arévalo, Paola , Arroyo-Robles, Gabriela , Cantú-Fernández, Mariana , Castro, Antonio J , Contreras, Victoria , de Vos, Alta , Dendoncker, Nicolas , Engel, Stefanie , Eser, Uta , Faith, Daniel P , Filyushkina, Anna , Ghazi, Houda , Gómez-Baggethun, Erik , Gould, Rachelle K , Guibrunet, Louise , Gundimeda, Haripriya , Hahn, Thomas , Harmáčková, Zuzana V , Hernández-Blanco, Marcello , Horcea-Milcu, Andra-loana , Huambachano, Mariaelena , Wicher, Natalia L H , Aydın, Cem I , Islar, Mine , Koessler, Ann-Kathrin , Kenter, Jasper O , Kosmus, Marina , Lee, Heera , Leimona, Beria , Lele, Sharachchandra , Lenzi, Dominic , Lliso, Bosco , Mannetii, Lelani M , Merçon, Juliana , Monroy-Sais, Ana S , Mukherjee, Nibedita , Muraca, Barbara , Muradian, Roldan , Murali, Ranjini , Nelson, Sara H , Nemogá-Soto, Gabriel R , Ngouhouo-Poufoun, Jonas , Niamir, Aidin , Nuesiri, Emmanuel , Nyumba, Tobias O , Özkaynak, Begüm , Palomo, Ignacio , Pandit, Ram , Pawłowska-Mainville, Agnieszka , Porter-Bolland, Luciano , Quaas, Martin , Rode, Julian , Rozzi, Ricardo , Sachdeva, Sonya , Aibek, Samakov , Schaafsma, Marije , Sitas, Nadia , Ungar, Paula , Yiu, Evonne , Yoshida, Yuki , Zent, Eglee
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415612 , vital:71270 , xlink:href="https://doi.org/10.1038/s41586-023-06406-9"
- Description: Twenty-five years since foundational publications on valuing ecosystem services for human well-being, addressing the global biodiversity crisis still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF) and the UN Sustainable Development Goals, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change, pandemic emergence and socio-environmental injustices. On the basis of more than 50,000 scientifc publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures.
- Full Text:
- Date Issued: 2023
- Authors: Pascual, Unai , Balvanera, Patricia , Anderson, Christopher B , Chaplin-Kramer, Rebecca , Christie, Michael , González-Jiménez, David , Martin, Adrian , Raymond, Christopher M , Termansen, Mette , Vatn, Arild , Athayde, Simone , Baptiste, Brigitte , Barton, Davin N , Jacobs, Sander , Kelemen, Eszter , Kumar, Ritesh , Lazos, Elena , Mwampamba, Tuyeni H , Nakangu, Barbara , O’Farrell, Patrick , Subramanian, Suneetha M , van Noordwijk, Meine , Ahn, SoEun , Amaruzaman, Sacha , Amin, Ariane M , Arias-Arévalo, Paola , Arroyo-Robles, Gabriela , Cantú-Fernández, Mariana , Castro, Antonio J , Contreras, Victoria , de Vos, Alta , Dendoncker, Nicolas , Engel, Stefanie , Eser, Uta , Faith, Daniel P , Filyushkina, Anna , Ghazi, Houda , Gómez-Baggethun, Erik , Gould, Rachelle K , Guibrunet, Louise , Gundimeda, Haripriya , Hahn, Thomas , Harmáčková, Zuzana V , Hernández-Blanco, Marcello , Horcea-Milcu, Andra-loana , Huambachano, Mariaelena , Wicher, Natalia L H , Aydın, Cem I , Islar, Mine , Koessler, Ann-Kathrin , Kenter, Jasper O , Kosmus, Marina , Lee, Heera , Leimona, Beria , Lele, Sharachchandra , Lenzi, Dominic , Lliso, Bosco , Mannetii, Lelani M , Merçon, Juliana , Monroy-Sais, Ana S , Mukherjee, Nibedita , Muraca, Barbara , Muradian, Roldan , Murali, Ranjini , Nelson, Sara H , Nemogá-Soto, Gabriel R , Ngouhouo-Poufoun, Jonas , Niamir, Aidin , Nuesiri, Emmanuel , Nyumba, Tobias O , Özkaynak, Begüm , Palomo, Ignacio , Pandit, Ram , Pawłowska-Mainville, Agnieszka , Porter-Bolland, Luciano , Quaas, Martin , Rode, Julian , Rozzi, Ricardo , Sachdeva, Sonya , Aibek, Samakov , Schaafsma, Marije , Sitas, Nadia , Ungar, Paula , Yiu, Evonne , Yoshida, Yuki , Zent, Eglee
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415612 , vital:71270 , xlink:href="https://doi.org/10.1038/s41586-023-06406-9"
- Description: Twenty-five years since foundational publications on valuing ecosystem services for human well-being, addressing the global biodiversity crisis still implies confronting barriers to incorporating nature’s diverse values into decision-making. These barriers include powerful interests supported by current norms and legal rules such as property rights, which determine whose values and which values of nature are acted on. A better understanding of how and why nature is (under)valued is more urgent than ever. Notwithstanding agreements to incorporate nature’s values into actions, including the Kunming-Montreal Global Biodiversity Framework (GBF) and the UN Sustainable Development Goals, predominant environmental and development policies still prioritize a subset of values, particularly those linked to markets, and ignore other ways people relate to and benefit from nature. Arguably, a ‘values crisis’ underpins the intertwined crises of biodiversity loss and climate change, pandemic emergence and socio-environmental injustices. On the basis of more than 50,000 scientifc publications, policy documents and Indigenous and local knowledge sources, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) assessed knowledge on nature’s diverse values and valuation methods to gain insights into their role in policymaking and fuller integration into decisions. Applying this evidence, combinations of values-centred approaches are proposed to improve valuation and address barriers to uptake, ultimately leveraging transformative changes towards more just (that is, fair treatment of people and nature, including inter- and intragenerational equity) and sustainable futures.
- Full Text:
- Date Issued: 2023
Do thermal requirements of Dichrorampha odorata, a shoot-boring moth for the biological control of Chromolaena odorata, explain its failure to establish in South Africa?
- Nqayi, Slindile B, Zachariades, Costas, Coetzee, Julie A, Hill, Martin P, Chidawanyika, Frank, Uyi, Osariyekemwen O, McConnachie, Andrew J
- Authors: Nqayi, Slindile B , Zachariades, Costas , Coetzee, Julie A , Hill, Martin P , Chidawanyika, Frank , Uyi, Osariyekemwen O , McConnachie, Andrew J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416851 , vital:71391 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v31_n1_a14"
- Description: Chromolaena odorata (L.) RM King and H Rob. (Asteraceae) has been subject to a biological control programme in South Africa for over three decades. A shoot-tip boring moth, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), originating from Jamaica, was released as a biological control agent in 2013 but despite the release of substantial numbers of the insect, it has not established a permanent field population. Because climate incompatibility is a major constraint for classical biological control of invasive plants, and based on the differences in climate between Jamaica and South Africa and field observations at release sites, aspects of the thermal physiology of D. odorata were investigated to elucidate reasons for its failure to establish. Developmental time decreased with increasing temperatures ranging from 20 °C to 30 °C, with incomplete development for immature stages at 18 °C and 32 °C. The developmental threshold, t, was calculated as 8.45 °C with 872.4 degree-days required to complete development (K). A maximum of 6.5 generations per year was projected for D. odorata in South Africa, with the heavily infested eastern region of the country being the most eco-climatically suitable for establishment. The lower lethal temperature (LLT50) of larvae and adults was –4.5 and 1.8 °C, respectively. The upper lethal temperature (ULT50) for larvae was 39.6 °C whilst that of adults was 41.0 °C. Larvae thus had better cold tolerance compared to adults whereas adults had better heat tolerance compared to larvae. The critical thermal (CT) limits for adults were 3.4 ± 0.07 to 43.7 ± 0.12 °C. Acclimation at 20 °C for 7 days resulted in increased cold and heat tolerance with a CTmin and CTmax of 1.9 ± 0.06 and 44.4 ± 0.07 °C respectively, compared to the relative control, acclimated at 25 °C. Acclimation at 30 °C improved neither cold (CTmin: 5.9 ± 0.08 °C) nor heat tolerance (CTmax: 42.9 ± 0.10 °C). These results suggest that thermal requirements fall within field temperatures and are thus not the main constraining factor leading to poor establishment of D. odorata in South Africa.
- Full Text:
- Date Issued: 2023
- Authors: Nqayi, Slindile B , Zachariades, Costas , Coetzee, Julie A , Hill, Martin P , Chidawanyika, Frank , Uyi, Osariyekemwen O , McConnachie, Andrew J
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416851 , vital:71391 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v31_n1_a14"
- Description: Chromolaena odorata (L.) RM King and H Rob. (Asteraceae) has been subject to a biological control programme in South Africa for over three decades. A shoot-tip boring moth, Dichrorampha odorata Brown and Zachariades (Lepidoptera: Tortricidae), originating from Jamaica, was released as a biological control agent in 2013 but despite the release of substantial numbers of the insect, it has not established a permanent field population. Because climate incompatibility is a major constraint for classical biological control of invasive plants, and based on the differences in climate between Jamaica and South Africa and field observations at release sites, aspects of the thermal physiology of D. odorata were investigated to elucidate reasons for its failure to establish. Developmental time decreased with increasing temperatures ranging from 20 °C to 30 °C, with incomplete development for immature stages at 18 °C and 32 °C. The developmental threshold, t, was calculated as 8.45 °C with 872.4 degree-days required to complete development (K). A maximum of 6.5 generations per year was projected for D. odorata in South Africa, with the heavily infested eastern region of the country being the most eco-climatically suitable for establishment. The lower lethal temperature (LLT50) of larvae and adults was –4.5 and 1.8 °C, respectively. The upper lethal temperature (ULT50) for larvae was 39.6 °C whilst that of adults was 41.0 °C. Larvae thus had better cold tolerance compared to adults whereas adults had better heat tolerance compared to larvae. The critical thermal (CT) limits for adults were 3.4 ± 0.07 to 43.7 ± 0.12 °C. Acclimation at 20 °C for 7 days resulted in increased cold and heat tolerance with a CTmin and CTmax of 1.9 ± 0.06 and 44.4 ± 0.07 °C respectively, compared to the relative control, acclimated at 25 °C. Acclimation at 30 °C improved neither cold (CTmin: 5.9 ± 0.08 °C) nor heat tolerance (CTmax: 42.9 ± 0.10 °C). These results suggest that thermal requirements fall within field temperatures and are thus not the main constraining factor leading to poor establishment of D. odorata in South Africa.
- Full Text:
- Date Issued: 2023
Photoantimicrobial activity of Schiff-base morpholino phthalocyanines against drug resistant micro-organisms in their planktonic and biofilm forms
- Sindelo, Azole, Sen, Pinar, Nyokong, Tebello
- Authors: Sindelo, Azole , Sen, Pinar , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360437 , vital:65088 , xlink:href="https://doi.org/10.1016/j.pdpdt.2023.103519"
- Description: Antimicrobial photodynamic inactivation (aPDI) is a treatment for the eradication of drug-resistant micro-organisms. One of the advantages of this technique, is that there is minimal possibility of microbial resistance. Hence, herein, the preparation and characterization of novel neutral and cationic morpholine containing Schiff base phthalocyanines are reported. The cationic complexes gave moderate singlet oxygen quantum yields (ΦΔ) of ∼0.2 in aqueous media. Conversely, the neutral complexes generated very low ΦΔ values making them very poor candidates for antimicrobial studies. The cationic phthalocyanines showed excellent photodynamic activity against planktonic cells of all micro-organisms (Candida albicans, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella enterica subspecies enterica serovar Choleraesuis, vancomycin-resistant Enterococcus faecium, and methicillin-resistant Staphylococcus aureus). The efficiency of aPDI was shown to be both concentration and light-dose-dependent. Mono biofilms were susceptible when treated with 200 µM of cationic Pcs at 108 J/cm2. However, ∼10% of the mixed biofilm survived after treatment.
- Full Text:
- Date Issued: 2023
- Authors: Sindelo, Azole , Sen, Pinar , Nyokong, Tebello
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/360437 , vital:65088 , xlink:href="https://doi.org/10.1016/j.pdpdt.2023.103519"
- Description: Antimicrobial photodynamic inactivation (aPDI) is a treatment for the eradication of drug-resistant micro-organisms. One of the advantages of this technique, is that there is minimal possibility of microbial resistance. Hence, herein, the preparation and characterization of novel neutral and cationic morpholine containing Schiff base phthalocyanines are reported. The cationic complexes gave moderate singlet oxygen quantum yields (ΦΔ) of ∼0.2 in aqueous media. Conversely, the neutral complexes generated very low ΦΔ values making them very poor candidates for antimicrobial studies. The cationic phthalocyanines showed excellent photodynamic activity against planktonic cells of all micro-organisms (Candida albicans, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Salmonella enterica subspecies enterica serovar Choleraesuis, vancomycin-resistant Enterococcus faecium, and methicillin-resistant Staphylococcus aureus). The efficiency of aPDI was shown to be both concentration and light-dose-dependent. Mono biofilms were susceptible when treated with 200 µM of cationic Pcs at 108 J/cm2. However, ∼10% of the mixed biofilm survived after treatment.
- Full Text:
- Date Issued: 2023
Social innovation that connects people to coasts in the Anthropocene
- Celliers, Louis, Costa, Maria M, Rölfer, Lena, Aswani, Shankar, Ferse, Sebastien
- Authors: Celliers, Louis , Costa, Maria M , Rölfer, Lena , Aswani, Shankar , Ferse, Sebastien
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391410 , vital:68649 , xlink:href="https://doi.org/10.1017/cft.2023.12"
- Description: Post-industrial society is driving global environmental change, which is a challenge for all generations, current and future. The Anthropocene is the geological epoch in which humans dominate and it is rooted in the past, present, and future. Future sustainability is building on the momentum of the fundamental importance of studying human dynamics and governance of coupled social and ecological systems. In the Anthropocene, social innovation may play a critical role in achieving new pathways to sustainability. This conventional narrative review uses a qualitative analysis anchored in the Grounded Theory Method and a systematic collection and analysis of papers to identify broad types of social innovations. Scientific journal articles published since 2018 were prioritised for inclusion. The six types of social innovation proposed are (a) authentic engagement; (b) artful and engaging communication; (c) urging and compelling change; (d) governance for social-ecological systems; (e) anticipation in governance; and (f) lived experiences and values. The six innovations proposed in this paper can be embedded within, and form part of, social action using a science–society compact for the sustainable development of coasts in the Anthropocene.
- Full Text:
- Date Issued: 2023
- Authors: Celliers, Louis , Costa, Maria M , Rölfer, Lena , Aswani, Shankar , Ferse, Sebastien
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/391410 , vital:68649 , xlink:href="https://doi.org/10.1017/cft.2023.12"
- Description: Post-industrial society is driving global environmental change, which is a challenge for all generations, current and future. The Anthropocene is the geological epoch in which humans dominate and it is rooted in the past, present, and future. Future sustainability is building on the momentum of the fundamental importance of studying human dynamics and governance of coupled social and ecological systems. In the Anthropocene, social innovation may play a critical role in achieving new pathways to sustainability. This conventional narrative review uses a qualitative analysis anchored in the Grounded Theory Method and a systematic collection and analysis of papers to identify broad types of social innovations. Scientific journal articles published since 2018 were prioritised for inclusion. The six types of social innovation proposed are (a) authentic engagement; (b) artful and engaging communication; (c) urging and compelling change; (d) governance for social-ecological systems; (e) anticipation in governance; and (f) lived experiences and values. The six innovations proposed in this paper can be embedded within, and form part of, social action using a science–society compact for the sustainable development of coasts in the Anthropocene.
- Full Text:
- Date Issued: 2023
Socioeconomic and geographic variations in antenatal care coverage in Angola: further analysis of the 2015 demographic and health survey
- Shibre, Gebretsadik, Zegeye, Betregiorgis, Idriss-Wheeler, Dina, Ahinkorah, Bright Opoku, Oladimeji, Olanrewaju, Yaya, Sanni
- Authors: Shibre, Gebretsadik , Zegeye, Betregiorgis , Idriss-Wheeler, Dina , Ahinkorah, Bright Opoku , Oladimeji, Olanrewaju , Yaya, Sanni
- Date: 2023
- Subjects: Prenatal care , Mothers -- Mortality , Health surveys
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4489 , vital:44125 , https://doi.org/10.1186/s12889-020-09320-1
- Description: In African countries, including Angola, antenatal care (ANC) coverage is suboptimal and maternal mortality is still high due to pregnancy and childbirth-related complications. There is evidence of disparities in the uptake of ANC services, however, little is known about both the socio-economic and geographic-based disparity in the use of ANC services in Angola. The aim of this study was to assess the extent of socio-economic, urban-rural and subnational inequality in ANC coverage in Angola. We analyzed data from the 2015 Angola Demographic and Health Survey (ADHS) using the World Health Organization (WHO) Health Equity Assessment Toolkit (HEAT) software. The analysis consisted of disaggregated ANC coverage rates using four equity stratifiers (economic status, education, residence, and region) and four summary measures (Difference, Population Attributable Risk, Ratio and Population Attributable Fraction). To measure statistical significance, an uncertainty interval (UI) of 95% was constructed around point estimates. The study showed both absolute and relative inequalities in coverage of ANC services in Angola. More specifically, inequality favored women who were rich (D = 54.2, 95% UI; 49.59, 58.70, PAF = 43.5, 95% UI; 40.12, 46.92), educated (PAR = 19.9, 95% UI; 18.14, 21.64, R = 2.14, 95% UI; 1.96, 2.32), living in regions such as Luanda (D = 51.7, 95% UI; 43.56, 59.85, R = 2.64, 95% UI; 2.01, 3.26) and residing in urban dwellings (PAF = 20, 95% UI; 17.70, 22.38, PAR = 12.3, 95% UI; 10.88, 13.75). The uptake of ANC services were lower among poor, uneducated, and rural residents as well as women from the Cuanza Sul region. Government policy makers must consider vulnerable subpopulations when designing needed interventions to improve ANC coverage in Angola to achieve the 2030 Sustainable Development Goal of reducing global maternal mortality ratio to 70 deaths per 100,000 live births.
- Full Text:
- Date Issued: 2023
- Authors: Shibre, Gebretsadik , Zegeye, Betregiorgis , Idriss-Wheeler, Dina , Ahinkorah, Bright Opoku , Oladimeji, Olanrewaju , Yaya, Sanni
- Date: 2023
- Subjects: Prenatal care , Mothers -- Mortality , Health surveys
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4489 , vital:44125 , https://doi.org/10.1186/s12889-020-09320-1
- Description: In African countries, including Angola, antenatal care (ANC) coverage is suboptimal and maternal mortality is still high due to pregnancy and childbirth-related complications. There is evidence of disparities in the uptake of ANC services, however, little is known about both the socio-economic and geographic-based disparity in the use of ANC services in Angola. The aim of this study was to assess the extent of socio-economic, urban-rural and subnational inequality in ANC coverage in Angola. We analyzed data from the 2015 Angola Demographic and Health Survey (ADHS) using the World Health Organization (WHO) Health Equity Assessment Toolkit (HEAT) software. The analysis consisted of disaggregated ANC coverage rates using four equity stratifiers (economic status, education, residence, and region) and four summary measures (Difference, Population Attributable Risk, Ratio and Population Attributable Fraction). To measure statistical significance, an uncertainty interval (UI) of 95% was constructed around point estimates. The study showed both absolute and relative inequalities in coverage of ANC services in Angola. More specifically, inequality favored women who were rich (D = 54.2, 95% UI; 49.59, 58.70, PAF = 43.5, 95% UI; 40.12, 46.92), educated (PAR = 19.9, 95% UI; 18.14, 21.64, R = 2.14, 95% UI; 1.96, 2.32), living in regions such as Luanda (D = 51.7, 95% UI; 43.56, 59.85, R = 2.64, 95% UI; 2.01, 3.26) and residing in urban dwellings (PAF = 20, 95% UI; 17.70, 22.38, PAR = 12.3, 95% UI; 10.88, 13.75). The uptake of ANC services were lower among poor, uneducated, and rural residents as well as women from the Cuanza Sul region. Government policy makers must consider vulnerable subpopulations when designing needed interventions to improve ANC coverage in Angola to achieve the 2030 Sustainable Development Goal of reducing global maternal mortality ratio to 70 deaths per 100,000 live births.
- Full Text:
- Date Issued: 2023
Understanding foraging practices in Lagos metropolis to redesign urban greenspaces in support of human-nature interactions
- Adeyemi, Opeyemi, Shackleton, Charlie M
- Authors: Adeyemi, Opeyemi , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401353 , vital:69728 , xlink:href="https://doi.org/10.1016/j.ufug.2022.127805"
- Description: Enhancing knowledge of urban foraging across different urban landscapes is an urgent matter given that about two-thirds of the world’s population is projected to live in urban areas by 2050, whilst 50 % of Africa’s population is expected to live in cities by 2030. This study was conducted in Lagos metropolis which is the economic hub of Africa’s most populous country. Data was collected using an in-person, semi-structured questionnaire from 347 persons who were 18 years or older to identify foragers and non-foragers, their sociodemographic profiles, and their foraging practices. Results revealed that about two out of three persons sampled forage to some degree. The collection happened more in domestic gardens (34 %) and streets (27 %) than in other foraging sites (such as unused lands, institutional grounds and lakes and riparian fringes). A total of 35 species were reportedly foraged within the metropolis, mostly for food (71 %) and medicine (26 %). Mango (Mangifera indica), pawpaw (Carica papaya), tropical almond (Terminalia catappa), fish (various species), bitter leaf (Vernonia amygdalina) and spinach (Spinacia oleracea) were the most gathered species. The distance travelled to foraging wild species ranged from 5 m to 25 km. The primary motivation for foraging was the acquisition of fresh and natural materials. However, some felt that foraging was a stressful activity. The unavailability of foraging sites and species was the major constraint to foraging in this megacity. Hence, efforts to increase the edible components of public green spaces and to provide free access could potentially allow more people to forage and make current foraging more secure. We suggest that making provisions for foraging in urban planning goals could contribute to the sustainable development of cities in Africa and elsewhere.
- Full Text:
- Date Issued: 2023
- Authors: Adeyemi, Opeyemi , Shackleton, Charlie M
- Date: 2023
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401353 , vital:69728 , xlink:href="https://doi.org/10.1016/j.ufug.2022.127805"
- Description: Enhancing knowledge of urban foraging across different urban landscapes is an urgent matter given that about two-thirds of the world’s population is projected to live in urban areas by 2050, whilst 50 % of Africa’s population is expected to live in cities by 2030. This study was conducted in Lagos metropolis which is the economic hub of Africa’s most populous country. Data was collected using an in-person, semi-structured questionnaire from 347 persons who were 18 years or older to identify foragers and non-foragers, their sociodemographic profiles, and their foraging practices. Results revealed that about two out of three persons sampled forage to some degree. The collection happened more in domestic gardens (34 %) and streets (27 %) than in other foraging sites (such as unused lands, institutional grounds and lakes and riparian fringes). A total of 35 species were reportedly foraged within the metropolis, mostly for food (71 %) and medicine (26 %). Mango (Mangifera indica), pawpaw (Carica papaya), tropical almond (Terminalia catappa), fish (various species), bitter leaf (Vernonia amygdalina) and spinach (Spinacia oleracea) were the most gathered species. The distance travelled to foraging wild species ranged from 5 m to 25 km. The primary motivation for foraging was the acquisition of fresh and natural materials. However, some felt that foraging was a stressful activity. The unavailability of foraging sites and species was the major constraint to foraging in this megacity. Hence, efforts to increase the edible components of public green spaces and to provide free access could potentially allow more people to forage and make current foraging more secure. We suggest that making provisions for foraging in urban planning goals could contribute to the sustainable development of cities in Africa and elsewhere.
- Full Text:
- Date Issued: 2023
Best of both worlds: The thermal physiology of Hydrellia egeriae, a biological control agent for the submerged aquatic weed, Egeria densa in South Africa
- Smith, Rosali, Coetzee, Julie A, Hill, Martin P
- Authors: Smith, Rosali , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417913 , vital:71494 , xlink:href="https://doi.org/10.1007/s10526-022-10142-w"
- Description: The submerged aquatic weed, Egeria densa Planch. (Hydrocharitaceae) or Brazilian waterweed, is a secondary invader of eutrophic freshwater systems in South Africa, following the successful management of floating aquatic weeds. In 2018, the leaf and stem-mining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae), was released against E. densa, the first agent released against a submerged aquatic weed in South Africa. During its life stages, the biological control agent is exposed to two environments, air and water. The thermal physiology of both life stages was investigated to optimize agent establishment through fine-tuned release strategies. The thermal physiological limits of H. egeriae encompassed its host plant’s optimal temperature range of 10 to 35 °C, with lower and upper critical temperatures of 2.6 to 47.0 °C, lower and upper lethal temperatures of − 5.6 and 40.6 °C for adults, and − 6.3 to 41.3 °C for larvae. Results from development time experiments and degree-day accumulation showed that the agent is capable of establishing at all E. densa sites in South Africa, with between 6.9 and 8.3 generations per year. However, cold temperatures (14 °C) prolonged the agent’s development time to three months, allowing it to only develop through one generation in winter. Predictions obtained from laboratory thermal physiology experiments corroborates field data, where the agent has established at all the sites it was released.
- Full Text:
- Date Issued: 2022
- Authors: Smith, Rosali , Coetzee, Julie A , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417913 , vital:71494 , xlink:href="https://doi.org/10.1007/s10526-022-10142-w"
- Description: The submerged aquatic weed, Egeria densa Planch. (Hydrocharitaceae) or Brazilian waterweed, is a secondary invader of eutrophic freshwater systems in South Africa, following the successful management of floating aquatic weeds. In 2018, the leaf and stem-mining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae), was released against E. densa, the first agent released against a submerged aquatic weed in South Africa. During its life stages, the biological control agent is exposed to two environments, air and water. The thermal physiology of both life stages was investigated to optimize agent establishment through fine-tuned release strategies. The thermal physiological limits of H. egeriae encompassed its host plant’s optimal temperature range of 10 to 35 °C, with lower and upper critical temperatures of 2.6 to 47.0 °C, lower and upper lethal temperatures of − 5.6 and 40.6 °C for adults, and − 6.3 to 41.3 °C for larvae. Results from development time experiments and degree-day accumulation showed that the agent is capable of establishing at all E. densa sites in South Africa, with between 6.9 and 8.3 generations per year. However, cold temperatures (14 °C) prolonged the agent’s development time to three months, allowing it to only develop through one generation in winter. Predictions obtained from laboratory thermal physiology experiments corroborates field data, where the agent has established at all the sites it was released.
- Full Text:
- Date Issued: 2022
Drowning in data, thirsty for information and starved for understanding: A biodiversity information hub for cooperative environmental monitoring in South Africa
- MacFadyen, Sandra, Allsopp, Nicky, Altwegg, Res, Archibald, Sally, Botha, Judith, Bradshaw, Karen L, Carruthers, Jane, De Klerk, Helen, de Vos, Alta, Distiller, Greg, Foord, Stefan, Freitag-Ronaldson, Stefanie, Gibbs, Richard, Hamer, Michelle, Landi, Pietro, MacFayden, Duncan, Manuel, Jeffrey, Midgley, Guy, Moncrieff, Glenn, Munch, Zahn, Mutanga, Onisimo, Sershen, Nenguda, Rendani, Ngwenya, Mzabalazo, Parker, Daniel M, Peel, Mike, Power, John, Pretorius, Joachim, Ramdhani, Syd, Robertson, Mark P, Rushworth, Ian, Skowno, Andrew, Slingsby, Jasper, Turner, Andrew, Visser, Vernon, van Wageningen, Gerhard, Hui, Cang
- Authors: MacFadyen, Sandra , Allsopp, Nicky , Altwegg, Res , Archibald, Sally , Botha, Judith , Bradshaw, Karen L , Carruthers, Jane , De Klerk, Helen , de Vos, Alta , Distiller, Greg , Foord, Stefan , Freitag-Ronaldson, Stefanie , Gibbs, Richard , Hamer, Michelle , Landi, Pietro , MacFayden, Duncan , Manuel, Jeffrey , Midgley, Guy , Moncrieff, Glenn , Munch, Zahn , Mutanga, Onisimo , Sershen , Nenguda, Rendani , Ngwenya, Mzabalazo , Parker, Daniel M , Peel, Mike , Power, John , Pretorius, Joachim , Ramdhani, Syd , Robertson, Mark P , Rushworth, Ian , Skowno, Andrew , Slingsby, Jasper , Turner, Andrew , Visser, Vernon , van Wageningen, Gerhard , Hui, Cang
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415624 , vital:71271 , xlink:href="https://doi.org/10.1016/j.biocon.2022.109736"
- Description: The world is firmly cemented in a notitian age (Latin: notitia, meaning data) – drowning in data, yet thirsty for information and the synthesis of knowledge into understanding. As concerns over biodiversity declines escalate, the volume, diversity and speed at which new environmental and ecological data are generated has increased exponentially. Data availability primes the research and discovery engine driving biodiversity conservation. South Africa (SA) is poised to become a world leader in biodiversity conservation. However, continent-wide resource limitations hamper the establishment of inclusive technologies and robust platforms and tools for biodiversity informatics. In this perspectives piece, we bring together the opinions of 37 co-authors from 20 different departments, across 10 SA universities, 7 national and provincial conservation research agencies, and various institutes and private conservation, research and management bodies, to develop a way forward for biodiversity informatics in SA. We propose the development of a SA Biodiversity Informatics Hub and describe the essential components necessary for its design, implementation and sustainability. We emphasise the importance of developing a culture of cooperation, collaboration and interoperability among custodians of biodiversity data to establish operational workflows for data synthesis. However, our biggest challenges are misgivings around data sharing and multidisciplinary collaboration.
- Full Text:
- Date Issued: 2022
- Authors: MacFadyen, Sandra , Allsopp, Nicky , Altwegg, Res , Archibald, Sally , Botha, Judith , Bradshaw, Karen L , Carruthers, Jane , De Klerk, Helen , de Vos, Alta , Distiller, Greg , Foord, Stefan , Freitag-Ronaldson, Stefanie , Gibbs, Richard , Hamer, Michelle , Landi, Pietro , MacFayden, Duncan , Manuel, Jeffrey , Midgley, Guy , Moncrieff, Glenn , Munch, Zahn , Mutanga, Onisimo , Sershen , Nenguda, Rendani , Ngwenya, Mzabalazo , Parker, Daniel M , Peel, Mike , Power, John , Pretorius, Joachim , Ramdhani, Syd , Robertson, Mark P , Rushworth, Ian , Skowno, Andrew , Slingsby, Jasper , Turner, Andrew , Visser, Vernon , van Wageningen, Gerhard , Hui, Cang
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415624 , vital:71271 , xlink:href="https://doi.org/10.1016/j.biocon.2022.109736"
- Description: The world is firmly cemented in a notitian age (Latin: notitia, meaning data) – drowning in data, yet thirsty for information and the synthesis of knowledge into understanding. As concerns over biodiversity declines escalate, the volume, diversity and speed at which new environmental and ecological data are generated has increased exponentially. Data availability primes the research and discovery engine driving biodiversity conservation. South Africa (SA) is poised to become a world leader in biodiversity conservation. However, continent-wide resource limitations hamper the establishment of inclusive technologies and robust platforms and tools for biodiversity informatics. In this perspectives piece, we bring together the opinions of 37 co-authors from 20 different departments, across 10 SA universities, 7 national and provincial conservation research agencies, and various institutes and private conservation, research and management bodies, to develop a way forward for biodiversity informatics in SA. We propose the development of a SA Biodiversity Informatics Hub and describe the essential components necessary for its design, implementation and sustainability. We emphasise the importance of developing a culture of cooperation, collaboration and interoperability among custodians of biodiversity data to establish operational workflows for data synthesis. However, our biggest challenges are misgivings around data sharing and multidisciplinary collaboration.
- Full Text:
- Date Issued: 2022
Electrocatalytic activity of benzothiazole substituted cobalt phthalocyanine in the presence of detonation nanodiamonds
- Ncwane, Lunathi, Mpeta, Lekhetho S, Nyokong, Tebello
- Authors: Ncwane, Lunathi , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295753 , vital:57375 , xlink:href="https://doi.org/10.1016/j.diamond.2022.109319"
- Description: This work reports on the synthesis and electrochemical sensing properties of benzothiazole substituted cobalt phthalocyanine (CoPc) when π-π stacked on detonation nanodiamonds (to form CoPc-DNDs(ππ). The synthesized materials were characterized using UV–visible, mass, Fourier transform infrared, and Raman spectroscopies as well as transmission electron microscopy and dynamic light scattering. The electrochemical studies were conducted using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. Hydrazine was utilized as an analyte of interest, due to its mutagenic and carcinogenic effects. Glassy carbon electrodes (GCE) were modified with DNDs, CoPc, and CoPc-DNDs(ππ) represented as GCE/DNDs, GCE/CoPc and GCE/ CoPc-DNDs(ππ). GCE was also modified sequential addition of the CoPc and DNDs onto the GCE, represented as GCE/CoPc-DNDs(seq) when CoPc is placed before DNDs on the electrode and GCE/DNDs-CoPc(seq) when DNDs are placed before CoPc, where seq represents sequential. GCE/CoPc-DNDs(ππ) electrode gave better results in terms of limit of detection (1.68 μM), sensitivity (9.59 μA.mM−1) and catalytic rate constant (1.25 × 106 M−1 s−1).
- Full Text:
- Date Issued: 2022
- Authors: Ncwane, Lunathi , Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295753 , vital:57375 , xlink:href="https://doi.org/10.1016/j.diamond.2022.109319"
- Description: This work reports on the synthesis and electrochemical sensing properties of benzothiazole substituted cobalt phthalocyanine (CoPc) when π-π stacked on detonation nanodiamonds (to form CoPc-DNDs(ππ). The synthesized materials were characterized using UV–visible, mass, Fourier transform infrared, and Raman spectroscopies as well as transmission electron microscopy and dynamic light scattering. The electrochemical studies were conducted using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. Hydrazine was utilized as an analyte of interest, due to its mutagenic and carcinogenic effects. Glassy carbon electrodes (GCE) were modified with DNDs, CoPc, and CoPc-DNDs(ππ) represented as GCE/DNDs, GCE/CoPc and GCE/ CoPc-DNDs(ππ). GCE was also modified sequential addition of the CoPc and DNDs onto the GCE, represented as GCE/CoPc-DNDs(seq) when CoPc is placed before DNDs on the electrode and GCE/DNDs-CoPc(seq) when DNDs are placed before CoPc, where seq represents sequential. GCE/CoPc-DNDs(ππ) electrode gave better results in terms of limit of detection (1.68 μM), sensitivity (9.59 μA.mM−1) and catalytic rate constant (1.25 × 106 M−1 s−1).
- Full Text:
- Date Issued: 2022
Electrochemical detection of human epidermal growth factor receptor 2 using an aptamer on cobalt phthalocyanines–Cerium oxide nanoparticle conjugate
- Centane, Sixolile, Mgidlana, Sithi, Openda, Yolanda, Nyokong, Tebello
- Authors: Centane, Sixolile , Mgidlana, Sithi , Openda, Yolanda , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299835 , vital:57859 , xlink:href="https://doi.org/10.1016/j.bioelechem.2022.108146"
- Description: The role of the biointerface design towards the development of an impedimetric biosensor for the electrochemical detection of human epidermal growth factor receptor 2 (HER2) is investigated. Two novel cobalt phthalocyanines: cobalt tetraphenyl acetic acid phthalocyanine and cobalt tetraphenyl propionic acid phthalocyanine are compared as signal amplifiers and immobilization platforms of the HB5 aptamer towards the electrochemical detection of HER2. In addition, the phthalocyanines are coupled with the metal based cerium oxide nanoparticles. The efficiency of each electrode modification step and the performance of the constructed aptasensors were assessed by impedance spectroscopy. The aptasensors showed very low limit of detection values (all less than 0.2 ng/mL) with high sensitivity and stability. Furthermore, the aptasensors showed very good performance even in human serum samples. Considering these results, the aptasensors demonstrate great potential for improved monitoring of human epidermal growth factor receptor 2 levels for the management of breast cancers.
- Full Text:
- Date Issued: 2022
- Authors: Centane, Sixolile , Mgidlana, Sithi , Openda, Yolanda , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/299835 , vital:57859 , xlink:href="https://doi.org/10.1016/j.bioelechem.2022.108146"
- Description: The role of the biointerface design towards the development of an impedimetric biosensor for the electrochemical detection of human epidermal growth factor receptor 2 (HER2) is investigated. Two novel cobalt phthalocyanines: cobalt tetraphenyl acetic acid phthalocyanine and cobalt tetraphenyl propionic acid phthalocyanine are compared as signal amplifiers and immobilization platforms of the HB5 aptamer towards the electrochemical detection of HER2. In addition, the phthalocyanines are coupled with the metal based cerium oxide nanoparticles. The efficiency of each electrode modification step and the performance of the constructed aptasensors were assessed by impedance spectroscopy. The aptasensors showed very low limit of detection values (all less than 0.2 ng/mL) with high sensitivity and stability. Furthermore, the aptasensors showed very good performance even in human serum samples. Considering these results, the aptasensors demonstrate great potential for improved monitoring of human epidermal growth factor receptor 2 levels for the management of breast cancers.
- Full Text:
- Date Issued: 2022
Enhanced mitochondria destruction on MCF-7 and HeLa cell lines in vitro using triphenyl-phosphonium-labelled phthalocyanines in ultrasound-assisted photodynamic therapy activity
- Nene, Lindokuhle Cindy, Magadla, Aviwe, Nyokong, Tebello
- Authors: Nene, Lindokuhle Cindy , Magadla, Aviwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295766 , vital:57376 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2022.112553"
- Description: This work reports on the reactive oxygen species (ROS) generation and the therapeutic activities of new triphenyl-phosphonium-labelled phthalocyanines (Pcs), the 2,9,16,23-tetrakis(N-(N-butyl-4-triphenyl-phosphonium)- pyridine-4-yloxy) Zn(II) Pc (3) and 2,9,16,23-tetrakis-(N-(N-butyl-4-triphenyl-phosphonium)-morpholino) Zn(II) Pc (4) upon exposure to light, ultrasound and the combination of light and ultrasound. Two types of ROS were detected: the singlet oxygen (1O2) and hydroxyl radicals. For light irradiations, only the 1O2 was detected. An increase in the ROS generation was observed for samples treated with the combination of light and ultrasound compared to the light and ultrasound mono-treatments. The in vitro anticancer activity through photodynamic (PDT) and sonodynamic (SDT) therapy for the Pcs were also determined and compared to the photo-sonodynamic combination therapy (PSDT). The two cancer cell lines used for the in vitro studies included the Michigan Cancer Foundation-7 (MCF-7) breast cancer and Henrietta Lacks (HeLa) cervical cancer cell lines. The SDT treatments showed improved therapeutic efficacy on the cancer cells for both the Pcs compared to PDT. PSDT showed better therapeutic efficacy compared to both the PDT and SDT mono-treatments.
- Full Text:
- Date Issued: 2022
- Authors: Nene, Lindokuhle Cindy , Magadla, Aviwe , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295766 , vital:57376 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2022.112553"
- Description: This work reports on the reactive oxygen species (ROS) generation and the therapeutic activities of new triphenyl-phosphonium-labelled phthalocyanines (Pcs), the 2,9,16,23-tetrakis(N-(N-butyl-4-triphenyl-phosphonium)- pyridine-4-yloxy) Zn(II) Pc (3) and 2,9,16,23-tetrakis-(N-(N-butyl-4-triphenyl-phosphonium)-morpholino) Zn(II) Pc (4) upon exposure to light, ultrasound and the combination of light and ultrasound. Two types of ROS were detected: the singlet oxygen (1O2) and hydroxyl radicals. For light irradiations, only the 1O2 was detected. An increase in the ROS generation was observed for samples treated with the combination of light and ultrasound compared to the light and ultrasound mono-treatments. The in vitro anticancer activity through photodynamic (PDT) and sonodynamic (SDT) therapy for the Pcs were also determined and compared to the photo-sonodynamic combination therapy (PSDT). The two cancer cell lines used for the in vitro studies included the Michigan Cancer Foundation-7 (MCF-7) breast cancer and Henrietta Lacks (HeLa) cervical cancer cell lines. The SDT treatments showed improved therapeutic efficacy on the cancer cells for both the Pcs compared to PDT. PSDT showed better therapeutic efficacy compared to both the PDT and SDT mono-treatments.
- Full Text:
- Date Issued: 2022
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:
- Date Issued: 2022
- 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:
- Date Issued: 2022
It's a numbers game: inundative biological control of water hyacinth (Pontederia crassipes), using Megamelus scutellaris (Hemiptera: Delphacidae) yields success at a high elevation, hypertrophic reservoir in South Africa
- Coetzee, Julie A, Miller, Benjamin E, Kinsler, David, Sebola, Keneilwe, Hill, Martin P
- Authors: Coetzee, Julie A , Miller, Benjamin E , Kinsler, David , Sebola, Keneilwe , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417749 , vital:71483 , xlink:href="https://doi.org/10.1080/09583157.2022.2109594"
- Description: Classical biological control of water hyacinth in South Africa has been constrained by cool winter temperatures that limit population growth of the biological control agents, and highly eutrophic waters which enhance plant growth. However, inundative releases of the control agent, Megamelus scutellaris (Hemiptera: Delphacidae), at the Hartbeespoort Dam, South Africa, suggest that water hyacinth can be managed successfully using biological control as a standalone intervention for the first time in the absence of herbicide operations, despite eutrophication and a temperate climate. Sentinel-2 satellite images were used to measure the reduction in water hyacinth cover from over 37% to less than 6% over two consecutive years since M. scutellaris was first released on the dam in 2018, while site surveys confirmed a corresponding increase in M. scutellaris population density from fewer than 500 insects/m2 in October 2019, to more than 6000 insects/m2 by March 2020. Inundative release strategies are recommended for the control of water hyacinth in South Africa at key stages of its invasion, particularly after winter, and flooding events.
- Full Text:
- Date Issued: 2022
- Authors: Coetzee, Julie A , Miller, Benjamin E , Kinsler, David , Sebola, Keneilwe , Hill, Martin P
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417749 , vital:71483 , xlink:href="https://doi.org/10.1080/09583157.2022.2109594"
- Description: Classical biological control of water hyacinth in South Africa has been constrained by cool winter temperatures that limit population growth of the biological control agents, and highly eutrophic waters which enhance plant growth. However, inundative releases of the control agent, Megamelus scutellaris (Hemiptera: Delphacidae), at the Hartbeespoort Dam, South Africa, suggest that water hyacinth can be managed successfully using biological control as a standalone intervention for the first time in the absence of herbicide operations, despite eutrophication and a temperate climate. Sentinel-2 satellite images were used to measure the reduction in water hyacinth cover from over 37% to less than 6% over two consecutive years since M. scutellaris was first released on the dam in 2018, while site surveys confirmed a corresponding increase in M. scutellaris population density from fewer than 500 insects/m2 in October 2019, to more than 6000 insects/m2 by March 2020. Inundative release strategies are recommended for the control of water hyacinth in South Africa at key stages of its invasion, particularly after winter, and flooding events.
- Full Text:
- Date Issued: 2022
Photodegradation of ibuprofen using 5-10-15-20-tetrakis (4-bromophenyl) porphyrin conjugated to graphene quantum dots
- Magaela, N Bridged, Ndlovu, Knowledge S, Tshangana, Charmaine S, Muleia, Adoph A, Mamba, Bhekie B, Nyokong, Tebello, Managa, Muthumuni
- Authors: Magaela, N Bridged , Ndlovu, Knowledge S , Tshangana, Charmaine S , Muleia, Adoph A , Mamba, Bhekie B , Nyokong, Tebello , Managa, Muthumuni
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304819 , vital:58493 , xlink:href="https://doi.org/10.1016/j.optmat.2022.113147"
- Description: Ibuprofen (IBU) is a common anti-inflammatory drug that is consumed by many individuals in the world. As such, analytical studies have detected high concentrations of the drug in many waterbodies, which poses a risk of harmful effects on the environment and public health. The hydroxyl radical technologies, a collective of techniques also known as advanced oxidation processes (AOPs), can be utilized to degrade this emerging pollutant. In this study, the photodegradation of ibuprofen using 5,10,15,20-tetrakis(4-bromophenyl) porphyrin conjugated to graphene quantum dots was investigated using a custom-built photoreactor. Three different concentrations of IBU (200, 300 and 500 μM) were utilized as initial concentrations. The pH of the IBU was varied between acidic (pH 3.0), natural (pH 5.0) and alkaline (pH 9.0) to note the effect on IBU degradation as a function of time. The Highest ФΔ was obtained for InTBrP- GDQs (ФΔ = 0.80), followed by InTBrP (ФΔ = 0.74). The photodegradation efficiency of the TBrP-GQDs and InTBrP-GQDs were determined to be 43.2 and 76.1% respectively.
- Full Text:
- Date Issued: 2022
- Authors: Magaela, N Bridged , Ndlovu, Knowledge S , Tshangana, Charmaine S , Muleia, Adoph A , Mamba, Bhekie B , Nyokong, Tebello , Managa, Muthumuni
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/304819 , vital:58493 , xlink:href="https://doi.org/10.1016/j.optmat.2022.113147"
- Description: Ibuprofen (IBU) is a common anti-inflammatory drug that is consumed by many individuals in the world. As such, analytical studies have detected high concentrations of the drug in many waterbodies, which poses a risk of harmful effects on the environment and public health. The hydroxyl radical technologies, a collective of techniques also known as advanced oxidation processes (AOPs), can be utilized to degrade this emerging pollutant. In this study, the photodegradation of ibuprofen using 5,10,15,20-tetrakis(4-bromophenyl) porphyrin conjugated to graphene quantum dots was investigated using a custom-built photoreactor. Three different concentrations of IBU (200, 300 and 500 μM) were utilized as initial concentrations. The pH of the IBU was varied between acidic (pH 3.0), natural (pH 5.0) and alkaline (pH 9.0) to note the effect on IBU degradation as a function of time. The Highest ФΔ was obtained for InTBrP- GDQs (ФΔ = 0.80), followed by InTBrP (ФΔ = 0.74). The photodegradation efficiency of the TBrP-GQDs and InTBrP-GQDs were determined to be 43.2 and 76.1% respectively.
- Full Text:
- Date Issued: 2022
Phthalocyanine based fabricated exfoliated graphite photoanode for electrodegradation of 4-acetamidophenol under visible light irradiation
- Mpeta, Lekhetho S, Nyokong, Tebello
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295809 , vital:57380 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114115"
- Description: In this study exfoliated graphite (EG) was prepared from natural graphite flakes and incorporated with zinc phthalocyanine for fabrication of photoanode. The electron transfer capabilities of fabricated photoanode were examined by using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy. Electrophotocatalytic degradation of 4-acetamidophenol in 0.1 M Na2SO4 electrolyte was performed. The photoanode with zinc phthalocyanine (EG-ZnPc) displayed better degradation compared to when only exfoliated graphite was used (EG). Furthermore, electrophotocatalytic degradation gave better performance (removal efficiency of 47.76%) than when individual electrochemical degradation and photodegradation techniques were used.
- Full Text:
- Date Issued: 2022
- Authors: Mpeta, Lekhetho S , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/295809 , vital:57380 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114115"
- Description: In this study exfoliated graphite (EG) was prepared from natural graphite flakes and incorporated with zinc phthalocyanine for fabrication of photoanode. The electron transfer capabilities of fabricated photoanode were examined by using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy. Electrophotocatalytic degradation of 4-acetamidophenol in 0.1 M Na2SO4 electrolyte was performed. The photoanode with zinc phthalocyanine (EG-ZnPc) displayed better degradation compared to when only exfoliated graphite was used (EG). Furthermore, electrophotocatalytic degradation gave better performance (removal efficiency of 47.76%) than when individual electrochemical degradation and photodegradation techniques were used.
- Full Text:
- Date Issued: 2022
Sn (IV) porphyrin-biotin decorated nitrogen doped graphene quantum dots nanohybrids for photodynamic therapy
- Magaela, N Bridged, Matshitse, Refilwe, Balaji, Babu, Managa, Muthumuni, Prinsloo, Earl, Nyokong, Tebello
- Authors: Magaela, N Bridged , Matshitse, Refilwe , Balaji, Babu , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230018 , vital:49733 , xlink:href="https://doi.org/10.1016/j.poly.2021.115624"
- Description: Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure for cancer treatment. This study focuses on the synthesis, photophysicochemical properties, and PDT activity of Sn (IV) porphyrin (2), when linked to biotin decorated nitrogen doped graphene quantum dots (B-NGQDs). The porphyrin complex 2 was conjugated through an ester bond to B-NGQDs to form 2-B-NGQDs. Singlet oxygen quantum yield increased for 2 when linked to B-NGQDs to form 2-B-NQGDs. The dark toxicity and photodynamic therapy studies were conducted for 2, NGQDs and their conjugates using MCF-7 breast cancer cells. The cell viability for dark toxicity of all the compounds was above 90%, and 2-B-NGQDs showed high PDT activity at a concentration of 40 µg/mL with cell viability of 22%.
- Full Text:
- Date Issued: 2022
- Authors: Magaela, N Bridged , Matshitse, Refilwe , Balaji, Babu , Managa, Muthumuni , Prinsloo, Earl , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/230018 , vital:49733 , xlink:href="https://doi.org/10.1016/j.poly.2021.115624"
- Description: Photodynamic therapy (PDT) is a minimally invasive therapeutic procedure for cancer treatment. This study focuses on the synthesis, photophysicochemical properties, and PDT activity of Sn (IV) porphyrin (2), when linked to biotin decorated nitrogen doped graphene quantum dots (B-NGQDs). The porphyrin complex 2 was conjugated through an ester bond to B-NGQDs to form 2-B-NGQDs. Singlet oxygen quantum yield increased for 2 when linked to B-NGQDs to form 2-B-NQGDs. The dark toxicity and photodynamic therapy studies were conducted for 2, NGQDs and their conjugates using MCF-7 breast cancer cells. The cell viability for dark toxicity of all the compounds was above 90%, and 2-B-NGQDs showed high PDT activity at a concentration of 40 µg/mL with cell viability of 22%.
- Full Text:
- Date Issued: 2022
The contribution of wild palms to the livelihoods and diversification of rural households in southern Mozambique
- King, Angelina R, Shackleton, Charlie M
- Authors: King, Angelina R , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/399846 , vital:69563 , xlink:href="https://doi.org/10.1016/j.forpol.2022.102793"
- Description: In most low-income countries, rural households combine a range of economic activities to generate income, achieve food and nutritional security and fulfill other livelihood objectives, including: small-scale farming, fishing, hunting, livestock and timber production, and non-timber forest products gathering, as well as off-farm activities such as wage labour and informal trading. This work examines the role of diversification, including palm products income, on rural livelihoods in the Zitundo area, southern Mozambique. Seven livelihood strategies were identified, with every strategy combining cash income from several sources. Most households adopt a wage-based strategy to some degree, although this strategy shows low potential for reducing poverty in the area. Households adopting a palm-based strategy show between 23% and 60% lower poverty incidence than those adopting alternatives strategies. Yet, a palm-based livelihood strategy was adopted by only 11% of households. Traders of palm products earn approximately double the annual income and per capita income than non-traders. Village of residency and some household socio-economic and demographic characteristics correlate with a households' choice of livelihood strategy and palm income dependency. The adherence of many households to a less remunerative wage strategy indicates other factors also influence the choice of livelihood strategies. The study shows that future development plans and policy interventions to mitigate poverty in the area should go beyond the usual agricultural sector and recognize the role of non-timber forest products, especially palm products, for people's livelihoods and poverty alleviation.
- Full Text:
- Date Issued: 2022
- Authors: King, Angelina R , Shackleton, Charlie M
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/399846 , vital:69563 , xlink:href="https://doi.org/10.1016/j.forpol.2022.102793"
- Description: In most low-income countries, rural households combine a range of economic activities to generate income, achieve food and nutritional security and fulfill other livelihood objectives, including: small-scale farming, fishing, hunting, livestock and timber production, and non-timber forest products gathering, as well as off-farm activities such as wage labour and informal trading. This work examines the role of diversification, including palm products income, on rural livelihoods in the Zitundo area, southern Mozambique. Seven livelihood strategies were identified, with every strategy combining cash income from several sources. Most households adopt a wage-based strategy to some degree, although this strategy shows low potential for reducing poverty in the area. Households adopting a palm-based strategy show between 23% and 60% lower poverty incidence than those adopting alternatives strategies. Yet, a palm-based livelihood strategy was adopted by only 11% of households. Traders of palm products earn approximately double the annual income and per capita income than non-traders. Village of residency and some household socio-economic and demographic characteristics correlate with a households' choice of livelihood strategy and palm income dependency. The adherence of many households to a less remunerative wage strategy indicates other factors also influence the choice of livelihood strategies. The study shows that future development plans and policy interventions to mitigate poverty in the area should go beyond the usual agricultural sector and recognize the role of non-timber forest products, especially palm products, for people's livelihoods and poverty alleviation.
- Full Text:
- Date Issued: 2022
The thermal physiology of Lysathia sp.(Coleoptera: Chrysomelidae), a biocontrol agent of parrot’s feather in South Africa, supports its success
- Goddard, Matthew, Owen, Candice A, Martin, Grant D, Coetzee, Julie A
- Authors: Goddard, Matthew , Owen, Candice A , Martin, Grant D , Coetzee, Julie A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417806 , vital:71487 , xlink:href="https://doi.org/10.1080/09583157.2022.2054949"
- Description: The establishment success of biocontrol agents originating from tropical regions is often limited by climate when introduced in temperate regions. However, the flea beetle, Lysathia sp. (Coleoptera: Chrysomelidae), a biocontrol agent of Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae) in South Africa, is an effective agent in regions where other biocontrol agents of tropical aquatic weeds have failed due to winter-induced mortality. The development (degree-day model) and thermal tolerance (critical thermal minimum/maximum [CTmin/max] and lower/upper lethal limits [LLT/ULT50]) of Lysathia sp. were investigated to explain this success. The model predicted that Lysathia sp. could complete 6 to 12 generations per year in the colder regions of the country. The lower threshold for development (t0) was 13.0 °C and thermal constant (K) was 222.4 days, which is considerably lower than the K values of other biocontrol agents of aquatic weeds in South Africa. This suggests that above the temperature threshold, Lysathia sp. can develop faster than those other species and complete multiple life cycles in the cooler winter months, allowing for rapid population growth and thus improving M. aquaticum control. Furthermore, the CTmin of Lysathia sp. was 2.3 ± 0.2 °C and the CTmax was 49.0 ± 0.5 °C. The LLT50 was calculated as ∼ −7.0 °C and the ULT50 as ∼ 43.0 °C. These wide tolerance ranges and survival below freezing show why Lysathia sp. has established at cool sites and suggest that it may be a suitable agent for other cold countries invaded by M. aquaticum.
- Full Text:
- Date Issued: 2022
- Authors: Goddard, Matthew , Owen, Candice A , Martin, Grant D , Coetzee, Julie A
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417806 , vital:71487 , xlink:href="https://doi.org/10.1080/09583157.2022.2054949"
- Description: The establishment success of biocontrol agents originating from tropical regions is often limited by climate when introduced in temperate regions. However, the flea beetle, Lysathia sp. (Coleoptera: Chrysomelidae), a biocontrol agent of Myriophyllum aquaticum (Vell.) Verdc. (Haloragaceae) in South Africa, is an effective agent in regions where other biocontrol agents of tropical aquatic weeds have failed due to winter-induced mortality. The development (degree-day model) and thermal tolerance (critical thermal minimum/maximum [CTmin/max] and lower/upper lethal limits [LLT/ULT50]) of Lysathia sp. were investigated to explain this success. The model predicted that Lysathia sp. could complete 6 to 12 generations per year in the colder regions of the country. The lower threshold for development (t0) was 13.0 °C and thermal constant (K) was 222.4 days, which is considerably lower than the K values of other biocontrol agents of aquatic weeds in South Africa. This suggests that above the temperature threshold, Lysathia sp. can develop faster than those other species and complete multiple life cycles in the cooler winter months, allowing for rapid population growth and thus improving M. aquaticum control. Furthermore, the CTmin of Lysathia sp. was 2.3 ± 0.2 °C and the CTmax was 49.0 ± 0.5 °C. The LLT50 was calculated as ∼ −7.0 °C and the ULT50 as ∼ 43.0 °C. These wide tolerance ranges and survival below freezing show why Lysathia sp. has established at cool sites and suggest that it may be a suitable agent for other cold countries invaded by M. aquaticum.
- Full Text:
- Date Issued: 2022