Indolyl-3-ethanone-α-thioethers: a promising new class of non-toxic antimalarial agents
- Svogie, Archibald L, Isaacs, Michelle, Hoppe, Heinrich C, Khanye, Setshaba D, Veale, Clinton G L
- Authors: Svogie, Archibald L , Isaacs, Michelle , Hoppe, Heinrich C , Khanye, Setshaba D , Veale, Clinton G L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66233 , vital:28920 , https://doi.org/10.1016/j.ejmech.2016.02.056
- Description: publisher version , The success of chemotherapeutics in easing the burden of malaria is under continuous threat from ever-evolving parasite resistance, including resistance to artemisinin combination therapies. Therefore, the discovery of new classes of antimalarials which inhibit new biological targets is imperative to controlling malaria. Accordingly, we report here the discovery of indolyl-3-ethanone-α-thioethers, a new class of antimalarial compounds with encouraging activity. Synthesis of a focused library of compounds revealed important insight into the SAR of this class of compounds, including critical information regarding the position and chemical nature of substituents on both the thiophenol and indole rings. This investigation ultimately led to the discovery of two hit compounds (16 and 27) which exhibited nano molar in vitro antimalarial activity coupled to no observable toxicity against a HeLa cell line.
- Full Text: false
- Date Issued: 2016
- Authors: Svogie, Archibald L , Isaacs, Michelle , Hoppe, Heinrich C , Khanye, Setshaba D , Veale, Clinton G L
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66233 , vital:28920 , https://doi.org/10.1016/j.ejmech.2016.02.056
- Description: publisher version , The success of chemotherapeutics in easing the burden of malaria is under continuous threat from ever-evolving parasite resistance, including resistance to artemisinin combination therapies. Therefore, the discovery of new classes of antimalarials which inhibit new biological targets is imperative to controlling malaria. Accordingly, we report here the discovery of indolyl-3-ethanone-α-thioethers, a new class of antimalarial compounds with encouraging activity. Synthesis of a focused library of compounds revealed important insight into the SAR of this class of compounds, including critical information regarding the position and chemical nature of substituents on both the thiophenol and indole rings. This investigation ultimately led to the discovery of two hit compounds (16 and 27) which exhibited nano molar in vitro antimalarial activity coupled to no observable toxicity against a HeLa cell line.
- Full Text: false
- Date Issued: 2016
A case study on the health risks related to flood disasters in South Africa
- Tandlich, Roman, Ncube, Mbonisi, Khamanga, Sandile M, Zuma, Bongumusa M
- Authors: Tandlich, Roman , Ncube, Mbonisi , Khamanga, Sandile M , Zuma, Bongumusa M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75917 , vital:30482 , DOI: 10.20965/jdr.2016.p0732
- Description: Floods occurred in the Ndlambe Local Municipality in South Africa in October 2012. During various stages of the post-disaster recovery, bacterial concentrations were measured in water and soil samples from the flood zone. All drinking water concentrations of E. coli were below 1–3 colony forming units per 100 millilitres (CFUs/100 mL). The flood waters contained between 46500 to more than 100000 CFUs/100 mL of E. coli. {The concentrations of Salmonella spp. in the flood waters varied from 5000 to 250000 CFUs/100 mL. The presumptive Vibrio spp. concentrations in flood waters ranged from 1000 to over 150000 CFUs/100 mL. {The soil concentrations for E. coli ranged from 1 to above 330 colony-forming units per 1 g of soil dry weight (CFUs/g). The soil concentrations of Salmonella spp. varied from below 1 to 22 CFUs/g. The estimated airborne fungal concentrations ranged from 16820 to 28540 colony-forming units per 1 cubic meter. An outbreak of an infectious disease was recorded among the volunteers who assisted with the post-disaster recovery. The likely bacterial causative agents included strains of Aeromonas spp. and Vibrio cholerae. Any human contact with either the contaminated flood waters or of flooded dwellings should only occur, if the individuals in questions are equipped with the full-body personal protective gear. Non-governmental stakeholders performed majority of the post-disaster recovery operations, as the local government could only cover 11% of the required costs. Applying sanitation funds to disaster recovery and increased use of the low-cost flood defence products in high risk areas could provide a solution for the future.
- Full Text: false
- Date Issued: 2016
- Authors: Tandlich, Roman , Ncube, Mbonisi , Khamanga, Sandile M , Zuma, Bongumusa M
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/75917 , vital:30482 , DOI: 10.20965/jdr.2016.p0732
- Description: Floods occurred in the Ndlambe Local Municipality in South Africa in October 2012. During various stages of the post-disaster recovery, bacterial concentrations were measured in water and soil samples from the flood zone. All drinking water concentrations of E. coli were below 1–3 colony forming units per 100 millilitres (CFUs/100 mL). The flood waters contained between 46500 to more than 100000 CFUs/100 mL of E. coli. {The concentrations of Salmonella spp. in the flood waters varied from 5000 to 250000 CFUs/100 mL. The presumptive Vibrio spp. concentrations in flood waters ranged from 1000 to over 150000 CFUs/100 mL. {The soil concentrations for E. coli ranged from 1 to above 330 colony-forming units per 1 g of soil dry weight (CFUs/g). The soil concentrations of Salmonella spp. varied from below 1 to 22 CFUs/g. The estimated airborne fungal concentrations ranged from 16820 to 28540 colony-forming units per 1 cubic meter. An outbreak of an infectious disease was recorded among the volunteers who assisted with the post-disaster recovery. The likely bacterial causative agents included strains of Aeromonas spp. and Vibrio cholerae. Any human contact with either the contaminated flood waters or of flooded dwellings should only occur, if the individuals in questions are equipped with the full-body personal protective gear. Non-governmental stakeholders performed majority of the post-disaster recovery operations, as the local government could only cover 11% of the required costs. Applying sanitation funds to disaster recovery and increased use of the low-cost flood defence products in high risk areas could provide a solution for the future.
- Full Text: false
- Date Issued: 2016
Thermoluminescence of K-Mg-Al-Zn fluorophosphate glass
- Thomas, Sunil, Chithambo, Makaiko L
- Authors: Thomas, Sunil , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124188 , vital:35574 , https://doi.org/10.1016/j.optmat.2016.12.035
- Description: The thermoluminescence of beta irradiated K-Mg-Al-Zn fluorophosphate glass is reported. A glow-curve corresponding to 10 Gy measured at 1 °C/s shows two peaks, a weaker-intensity one at 70 °C and a more prominent one at 235 °C, the subject of this report. The main peak was observed to fade with delay between irradiation and measurement and specifically, by 11% in 15 h. Its dose response is superlinear in the dose range 1–190 Gy although the change was linear for the initial 10 Gy. Regarding kinetic analysis, the activation energy of the higher temperature peak was evaluated as 1.31 eV and that of the lower temperature peak was found as 0.47 eV. It was also noted that the main peak is affected by thermal quenching with an activation energy for thermal quenching equal to 1.37 eV. It is proposed that the mechanism associated with the thermoluminescence in K-Mg-Al-Zn fluorophosphate glass is that electrons trapped by the metal cations are released during heating and then recombine with holes at oxygen sites.
- Full Text: false
- Date Issued: 2017
- Authors: Thomas, Sunil , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124188 , vital:35574 , https://doi.org/10.1016/j.optmat.2016.12.035
- Description: The thermoluminescence of beta irradiated K-Mg-Al-Zn fluorophosphate glass is reported. A glow-curve corresponding to 10 Gy measured at 1 °C/s shows two peaks, a weaker-intensity one at 70 °C and a more prominent one at 235 °C, the subject of this report. The main peak was observed to fade with delay between irradiation and measurement and specifically, by 11% in 15 h. Its dose response is superlinear in the dose range 1–190 Gy although the change was linear for the initial 10 Gy. Regarding kinetic analysis, the activation energy of the higher temperature peak was evaluated as 1.31 eV and that of the lower temperature peak was found as 0.47 eV. It was also noted that the main peak is affected by thermal quenching with an activation energy for thermal quenching equal to 1.37 eV. It is proposed that the mechanism associated with the thermoluminescence in K-Mg-Al-Zn fluorophosphate glass is that electrons trapped by the metal cations are released during heating and then recombine with holes at oxygen sites.
- Full Text: false
- Date Issued: 2017
The effect of land-use on small mammal diversity inside and outside the Great Fish River Nature Reserve, Eastern Cape, South Africa
- Thondhlana, Gladman, Lagesse, Juliette V
- Authors: Thondhlana, Gladman , Lagesse, Juliette V
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67823 , vital:29150 , https://doi.org/10.1016/j.jaridenv.2016.03.006
- Description: Publisher version , This study investigated small mammal species diversity at 10 paired contrast sites along a fence line inside and outside the Great Fish River Nature Reserve (GFRNR), Eastern Cape, South Africa. The sites outside the GFRNR are used for subsistence land-based activities including livestock production and fuelwood harvesting. From 145 live captures, a total of 114 unique individuals of five small mammal species (four rodents and one elephant shrew) were recorded over 1170 trap nights. Average small mammal species diversity and abundance were significantly higher inside the reserve than outside. Human activities such as livestock grazing seemed to explain low levels of small mammal diversity and abundance at the communal sites. Vegetation variables showed a complex interplay with small mammal diversity. In general, high vegetation diversity had a positive influence on small mammal diversity though the influence of some environmental variables was species-dependent. We conclude that the GFRNR is effective in protecting small mammals but the findings raise questions around the influence of land use practices such as livestock grazing on biodiversity, especially given that local communities in South Africa are continuously seeking greater access to reserves for livestock grazing and other provisioning services.
- Full Text: false
- Date Issued: 2016
- Authors: Thondhlana, Gladman , Lagesse, Juliette V
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67823 , vital:29150 , https://doi.org/10.1016/j.jaridenv.2016.03.006
- Description: Publisher version , This study investigated small mammal species diversity at 10 paired contrast sites along a fence line inside and outside the Great Fish River Nature Reserve (GFRNR), Eastern Cape, South Africa. The sites outside the GFRNR are used for subsistence land-based activities including livestock production and fuelwood harvesting. From 145 live captures, a total of 114 unique individuals of five small mammal species (four rodents and one elephant shrew) were recorded over 1170 trap nights. Average small mammal species diversity and abundance were significantly higher inside the reserve than outside. Human activities such as livestock grazing seemed to explain low levels of small mammal diversity and abundance at the communal sites. Vegetation variables showed a complex interplay with small mammal diversity. In general, high vegetation diversity had a positive influence on small mammal diversity though the influence of some environmental variables was species-dependent. We conclude that the GFRNR is effective in protecting small mammals but the findings raise questions around the influence of land use practices such as livestock grazing on biodiversity, especially given that local communities in South Africa are continuously seeking greater access to reserves for livestock grazing and other provisioning services.
- Full Text: false
- Date Issued: 2016
Students’ reception of peer assessment of group-work contributions: problematics in terms of race and gender emerging from a South African case study
- Thondhlana, Gladman, Belluigi, Dina Z
- Authors: Thondhlana, Gladman , Belluigi, Dina Z
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59784 , vital:27649 , https://doi.org/10.1080/02602938.2016.1235133
- Description: Participatory assessment is increasingly employed in higher education worldwide as a formative mechanism to support students’ active learning. But do students in an increasingly relationally diverse environment perceive that peer assessment of individuals’ contributions to group-work tasks enhances their learning? Recognising the impact of students’ conceptions on the quality of their learning, this study considers students’ perspectives of peer assessment of group-work contributions at a South African university. Questionnaires elicited students’ perspectives of and general attitudes towards assessment of and by their peers. A growing measure of discontent with the process of assessing peer contributions to group tasks emerged, including actual and perceived racial and gender stereotyping, and related rejection-sensitivity. These initial findings were checked against the students’ experiences in a report-and-respond process that enabled probing discussions of the interpretations. This paper examines and explores the implications of such identifications and receptions for learning engagement and group-work curriculum development in the context of a rapidly transforming higher education sector.
- Full Text: false
- Date Issued: 2016
- Authors: Thondhlana, Gladman , Belluigi, Dina Z
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59784 , vital:27649 , https://doi.org/10.1080/02602938.2016.1235133
- Description: Participatory assessment is increasingly employed in higher education worldwide as a formative mechanism to support students’ active learning. But do students in an increasingly relationally diverse environment perceive that peer assessment of individuals’ contributions to group-work tasks enhances their learning? Recognising the impact of students’ conceptions on the quality of their learning, this study considers students’ perspectives of peer assessment of group-work contributions at a South African university. Questionnaires elicited students’ perspectives of and general attitudes towards assessment of and by their peers. A growing measure of discontent with the process of assessing peer contributions to group tasks emerged, including actual and perceived racial and gender stereotyping, and related rejection-sensitivity. These initial findings were checked against the students’ experiences in a report-and-respond process that enabled probing discussions of the interpretations. This paper examines and explores the implications of such identifications and receptions for learning engagement and group-work curriculum development in the context of a rapidly transforming higher education sector.
- Full Text: false
- Date Issued: 2016
Co-management, land rights, and conflicts around South Africa’s Silaka Nature Reserve
- Thondhlana, Gladman, Cundill, Georgina, Kepe, Thembele
- Authors: Thondhlana, Gladman , Cundill, Georgina , Kepe, Thembele
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67781 , vital:29144 , https://doi.org/10.1080/08941920.2015.1089609
- Description: Publisher version , Globally, co-management of protected areas (PAs) offers promise in efforts to achieve ecological integrity and livelihood needs. Most co-management agreements are premised on joint decision making in defining equitable sharing of benefits from and the management responsibilities for natural resource management. However, co-managed PAs are often conflict ridden. The forceful closure of Silaka Nature Reserve in South Africa in 2013 by a local community epitomizes the conflicts that can emerge in co-management arrangements. Using Silaka Reserve as a case study, we ask questions related to the meaning of land to local people, with an interrogative focus beyond “material benefits” in co-management discourse. The results of this study show that apart from nonaccrual of material benefits, conflicts arise from nonrecognition of nonmaterial aspects such as cultural values of and historical attachment to land and limited involvement of land claimants in decision making. The implications for co-management as a desired outcome on settled land claims are discussed.
- Full Text: false
- Date Issued: 2016
- Authors: Thondhlana, Gladman , Cundill, Georgina , Kepe, Thembele
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/67781 , vital:29144 , https://doi.org/10.1080/08941920.2015.1089609
- Description: Publisher version , Globally, co-management of protected areas (PAs) offers promise in efforts to achieve ecological integrity and livelihood needs. Most co-management agreements are premised on joint decision making in defining equitable sharing of benefits from and the management responsibilities for natural resource management. However, co-managed PAs are often conflict ridden. The forceful closure of Silaka Nature Reserve in South Africa in 2013 by a local community epitomizes the conflicts that can emerge in co-management arrangements. Using Silaka Reserve as a case study, we ask questions related to the meaning of land to local people, with an interrogative focus beyond “material benefits” in co-management discourse. The results of this study show that apart from nonaccrual of material benefits, conflicts arise from nonrecognition of nonmaterial aspects such as cultural values of and historical attachment to land and limited involvement of land claimants in decision making. The implications for co-management as a desired outcome on settled land claims are discussed.
- Full Text: false
- Date Issued: 2016
Optimising design and effort for environmental surveys using dung beetles (Coleoptera: Scarabaeidae):
- Tocco, Claudia, Quinn, Danielle, Midgley, John M, Villet, Martin H
- Authors: Tocco, Claudia , Quinn, Danielle , Midgley, John M , Villet, Martin H
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140670 , vital:37908 , DOI: 10.4039/tce.2016.48
- Description: In biological monitoring, deploying an effective standardised quantitative sampling method, optimised by trap design and sampling effort, is an essential consideration. To exemplify this using dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae and Aphodiinae) communities, three pitfall trap designs (un-baited (TN), baited at ground level (flat trap, TF), and baited above the trap (hanging trap, TH)), employed with varying levels of sampling effort (number of traps = 1, 2, 3… 10; number of days = 1, 2, 3), were evaluated for sampling completeness and efficiency in the Eastern Cape, South Africa. Modelling and resampling simulation approaches were used to suggest optimal sampling protocols across environmentally diverse sites. Overall, TF recovered the greatest abundance and species richness of dung beetles, but behavioural guilds showed conflicting trends: endocoprids preferred TH while paracoprids and telocoprids preferred TF. Resampling simulation of trap type and the two components of sampling effort suggested that six TF traps left for three days was most efficient in obtaining a representative sample and allowed differentiation between trap types, allowing the improved efficiency to be recognised. The effect of trap type on non-target specimens, particularly ants, was also investigated. TF and TH caught almost no by-catch, which is ethically desirable.
- Full Text:
- Date Issued: 2016
- Authors: Tocco, Claudia , Quinn, Danielle , Midgley, John M , Villet, Martin H
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140670 , vital:37908 , DOI: 10.4039/tce.2016.48
- Description: In biological monitoring, deploying an effective standardised quantitative sampling method, optimised by trap design and sampling effort, is an essential consideration. To exemplify this using dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae and Aphodiinae) communities, three pitfall trap designs (un-baited (TN), baited at ground level (flat trap, TF), and baited above the trap (hanging trap, TH)), employed with varying levels of sampling effort (number of traps = 1, 2, 3… 10; number of days = 1, 2, 3), were evaluated for sampling completeness and efficiency in the Eastern Cape, South Africa. Modelling and resampling simulation approaches were used to suggest optimal sampling protocols across environmentally diverse sites. Overall, TF recovered the greatest abundance and species richness of dung beetles, but behavioural guilds showed conflicting trends: endocoprids preferred TH while paracoprids and telocoprids preferred TF. Resampling simulation of trap type and the two components of sampling effort suggested that six TF traps left for three days was most efficient in obtaining a representative sample and allowed differentiation between trap types, allowing the improved efficiency to be recognised. The effect of trap type on non-target specimens, particularly ants, was also investigated. TF and TH caught almost no by-catch, which is ethically desirable.
- Full Text:
- Date Issued: 2016
Spotlight on the Art of Darkness: The Kin Artstudio
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146434 , vital:38525 , https://artafricamagazine.org/magazine-archive/?v=e4dd286dc7d7
- Description: Issue December 2016. What Really Matters.
- Full Text:
- Date Issued: 2016
- Authors: Tshilumba Mukendi, J S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/146434 , vital:38525 , https://artafricamagazine.org/magazine-archive/?v=e4dd286dc7d7
- Description: Issue December 2016. What Really Matters.
- Full Text:
- Date Issued: 2016
Enhancing Life Sciences Teachers’ Biodiversity Knowledge
- Authors: Tshiningayamwe, Sirkka A N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387991 , vital:68296 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/152733"
- Description: In the last two decades, South Africa has made efforts to integrate biodiversity content in its Life Sciences curriculum; however its implementation lacks systemic coherence. This is due to ineffective professional development approaches. This paper provides insights into how Life Sciences teachers in the Eastern Cape can be supported through professional learning communities (PLCs) as a potential approach to enhancing their biodiversity knowledge. PLCs are communities that provide the setting and necessary support for groups of classroom teachers to participate collectively in determining their own developmental trajectories, and to set up activities that will drive their development. The case study presented in this paper is part of a broader qualitative PhD study which explored the functionings and conversion factors in biodiversity teacher PLCs in South Africa. Drawing on teachers’ and facilitators’ experiences and the observation of the PLC approaches, the capability approach was used to analyse the functionings and conversion factors that enhance teachers’ biodiversity knowledge. The paper highlights that for PLCs to be effective approaches for professional development, they need to be aligned to teachers’ valued functionings. It also reveals that different conversion factors enable teachers’ achievements of valued functionings in the PLC. The paper aims to contribute to wider policies on capacity building for teachers.
- Full Text:
- Date Issued: 2016
- Authors: Tshiningayamwe, Sirkka A N
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387991 , vital:68296 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/152733"
- Description: In the last two decades, South Africa has made efforts to integrate biodiversity content in its Life Sciences curriculum; however its implementation lacks systemic coherence. This is due to ineffective professional development approaches. This paper provides insights into how Life Sciences teachers in the Eastern Cape can be supported through professional learning communities (PLCs) as a potential approach to enhancing their biodiversity knowledge. PLCs are communities that provide the setting and necessary support for groups of classroom teachers to participate collectively in determining their own developmental trajectories, and to set up activities that will drive their development. The case study presented in this paper is part of a broader qualitative PhD study which explored the functionings and conversion factors in biodiversity teacher PLCs in South Africa. Drawing on teachers’ and facilitators’ experiences and the observation of the PLC approaches, the capability approach was used to analyse the functionings and conversion factors that enhance teachers’ biodiversity knowledge. The paper highlights that for PLCs to be effective approaches for professional development, they need to be aligned to teachers’ valued functionings. It also reveals that different conversion factors enable teachers’ achievements of valued functionings in the PLC. The paper aims to contribute to wider policies on capacity building for teachers.
- Full Text:
- Date Issued: 2016
Temperature-dependent performance and potential distribution of Pareuchaetes insulata, a biological control agent of Chromolaena odorata in South Africa
- Uyi, Osariyekemwen O, Zachariades, Costas, Hill, Martin P, McConnachie, Andrew J
- Authors: Uyi, Osariyekemwen O , Zachariades, Costas , Hill, Martin P , McConnachie, Andrew J
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418067 , vital:71505 , xlink:href="https://doi.org/10.1007/s10526-016-9760-1"
- Description: Despite the release of about 1.9 million individuals of Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae) in KwaZulu-Natal for the biological control of Chromolaena odorata (L.) King and Robinson (Asteraceae) in South Africa, the moth probably only established at one of the 30 release sites and its population level is generally low in the field. To determine whether climate incompatibility in South Africa is responsible for the poor performance of P. insulata, the effects of temperature on life-history traits were investigated under several constant temperatures. Although a degree-day model estimated between 3.9 and 10.0 generations of the moth per year in the weed’s invaded range, survival and fecundity declined while development time was prolonged at constant temperatures below 25 °C, indicating that both direct and indirect negative impacts of low winter temperatures, such as increased mortality, slow development and reduced fecundity as well as exposure to natural enemies, may partly explain the poor performance of P. insulata in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Uyi, Osariyekemwen O , Zachariades, Costas , Hill, Martin P , McConnachie, Andrew J
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/418067 , vital:71505 , xlink:href="https://doi.org/10.1007/s10526-016-9760-1"
- Description: Despite the release of about 1.9 million individuals of Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae) in KwaZulu-Natal for the biological control of Chromolaena odorata (L.) King and Robinson (Asteraceae) in South Africa, the moth probably only established at one of the 30 release sites and its population level is generally low in the field. To determine whether climate incompatibility in South Africa is responsible for the poor performance of P. insulata, the effects of temperature on life-history traits were investigated under several constant temperatures. Although a degree-day model estimated between 3.9 and 10.0 generations of the moth per year in the weed’s invaded range, survival and fecundity declined while development time was prolonged at constant temperatures below 25 °C, indicating that both direct and indirect negative impacts of low winter temperatures, such as increased mortality, slow development and reduced fecundity as well as exposure to natural enemies, may partly explain the poor performance of P. insulata in South Africa.
- Full Text:
- Date Issued: 2016
Nitrogen fertilisation improves growth of Chromolaena odorata (Asteraceae) and the performance of the biological control agent, Pareuchaetes insulata (Erebidae)
- Uyi, Osariyekemwen O, Zacharariades, Costas, Hill, Martin P
- Authors: Uyi, Osariyekemwen O , Zacharariades, Costas , Hill, Martin P
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416880 , vital:71393 , xlink:href="https://doi.org/10.1080/09583157.2015.1118615"
- Description: Recent studies have demonstrated, through their contrasting results, that relationships between nitrogen levels in host plants and phytophagous insect performance are not simple. This study examined the effect of varying fertilisation regimes on the invasive alien plant, Chromolaena odorata (L.) (Asteraceae) and the response of a specialist folivore (a biological control agent), Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae). C. odorata plants were treated with 3 different levels of fertilisation and plant characteristics were measured within 2–3 months of fertiliser application. Leaves from each of the three treatments were fed to newly hatched larvae until pupation in order to determine the effect of nitrogen fertilisation on herbivore performance metrics such as survival, development time, fecundity and longevity. High and medium fertilisation significantly increased foliar nitrogen concentrations, basal stem diameter, leaf length, shoot height and above-ground biomass of C. odorata plants relative to low fertilisation. When individuals of P. insulata were fed on leaves from medium- or high-fertilisation treatments, they developed faster, grew to a larger size (by 8%) and achieved higher fecundity (19–22%) than leaves from the low-fertilisation treatment. The results suggest that in mass-rearing, increased production of this biological control agent will occur in high- or medium-fertilised plants.
- Full Text:
- Date Issued: 2016
- Authors: Uyi, Osariyekemwen O , Zacharariades, Costas , Hill, Martin P
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416880 , vital:71393 , xlink:href="https://doi.org/10.1080/09583157.2015.1118615"
- Description: Recent studies have demonstrated, through their contrasting results, that relationships between nitrogen levels in host plants and phytophagous insect performance are not simple. This study examined the effect of varying fertilisation regimes on the invasive alien plant, Chromolaena odorata (L.) (Asteraceae) and the response of a specialist folivore (a biological control agent), Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae). C. odorata plants were treated with 3 different levels of fertilisation and plant characteristics were measured within 2–3 months of fertiliser application. Leaves from each of the three treatments were fed to newly hatched larvae until pupation in order to determine the effect of nitrogen fertilisation on herbivore performance metrics such as survival, development time, fecundity and longevity. High and medium fertilisation significantly increased foliar nitrogen concentrations, basal stem diameter, leaf length, shoot height and above-ground biomass of C. odorata plants relative to low fertilisation. When individuals of P. insulata were fed on leaves from medium- or high-fertilisation treatments, they developed faster, grew to a larger size (by 8%) and achieved higher fecundity (19–22%) than leaves from the low-fertilisation treatment. The results suggest that in mass-rearing, increased production of this biological control agent will occur in high- or medium-fertilised plants.
- Full Text:
- Date Issued: 2016
Linking the ‘know-that’ and ‘know-how’ knowledge through games: a quest to evolve the future for science and engineering education
- Vahed, Anisa, McKenna, Sioux, Singh, S
- Authors: Vahed, Anisa , McKenna, Sioux , Singh, S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66785 , vital:28993 , ISSN 1573-174X , https://doi.org/10.1007/s10734-015-9956-9
- Description: Publisher version , This paper responds to Muller’s notions of ‘knowing-that’ and ‘knowing how’. The paper addresses how educational interventions that are designed in line with targeted discipline-specific subjects can enhance the balance between professional practice and disciplinary knowledge in professionally accredited programmes at universities of technology. The context is a Dental Technology programme at a University of Technology in South Africa. Teaching through discipline-specific games, conceptualised from a game literacies perspective, is proposed as an engaging, interactive pedagogy for learning disciplinary knowledge that potentially encourages access to a particular affinity group. The authors use concepts from Bernstein and Maton to investigate whether epistemic relations or social relations are emphasised through board and digital games designed for two Dental Technology subjects. This paper offers valuable insight into alternative pedagogies that can be adopted into science, technology, engineering, and mathematics education with the aim of paving a pathway towards Muller’s Scenario 3.
- Full Text: false
- Date Issued: 2016
- Authors: Vahed, Anisa , McKenna, Sioux , Singh, S
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/66785 , vital:28993 , ISSN 1573-174X , https://doi.org/10.1007/s10734-015-9956-9
- Description: Publisher version , This paper responds to Muller’s notions of ‘knowing-that’ and ‘knowing how’. The paper addresses how educational interventions that are designed in line with targeted discipline-specific subjects can enhance the balance between professional practice and disciplinary knowledge in professionally accredited programmes at universities of technology. The context is a Dental Technology programme at a University of Technology in South Africa. Teaching through discipline-specific games, conceptualised from a game literacies perspective, is proposed as an engaging, interactive pedagogy for learning disciplinary knowledge that potentially encourages access to a particular affinity group. The authors use concepts from Bernstein and Maton to investigate whether epistemic relations or social relations are emphasised through board and digital games designed for two Dental Technology subjects. This paper offers valuable insight into alternative pedagogies that can be adopted into science, technology, engineering, and mathematics education with the aim of paving a pathway towards Muller’s Scenario 3.
- Full Text: false
- Date Issued: 2016
Mapping epistemic cultures and learning potential of participants in citizen science projects
- Vallabh, Priya, Lotz-Sisitka, Heila, O'Donoghue, Rob, Schudel, Ingrid J
- Authors: Vallabh, Priya , Lotz-Sisitka, Heila , O'Donoghue, Rob , Schudel, Ingrid J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128939 , vital:36192 , https://doi.org/10.1111/cobi.12701
- Description: The ever-widening scope and range of global change and interconnected systemic risks arising from people–environment relationships (social‐ecological risks) appears to be increasing concern among, and involvement of, citizens in an increasingly diversified number of citizen science projects responding to these risks. We examined the relationship between epistemic cultures in citizen science projects and learning potential related to matters of concern. We then developed a typology of purposes and a citizen science epistemic‐cultures heuristic and mapped 56 projects in southern Africa using this framework. The purpose typology represents the range of knowledge‐production purposes, ranging from laboratory science to social learning, whereas the epistemic‐cultures typology is a relational representation of scientist and citizen participation and their approach to knowledge production. Results showed an iterative relationship between matters of fact and matters of concern across the projects; the nexus of citizens’ engagement in knowledge‐production activities varied. The knowledge‐production purposes informed and shaped the epistemic cultures of all the sampled citizen science projects, which in turn influenced the potential for learning within each project. Through a historical review of 3 phases in a long‐term river health‐monitoring project, we found that it is possible to evolve the learning curve of citizen science projects. This evolution involved the development of scientific water monitoring tools, the parallel development of pedagogic practices supporting monitoring activities, and situated engagement around matters of concern within social activism leading to learning‐led change. We conclude that such evolutionary processes serve to increase potential for learning and are necessary if citizen science is to contribute to wider restructuring of the epistemic culture of science under conditions of expanding social-ecological risk.
- Full Text:
- Date Issued: 2016
- Authors: Vallabh, Priya , Lotz-Sisitka, Heila , O'Donoghue, Rob , Schudel, Ingrid J
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128939 , vital:36192 , https://doi.org/10.1111/cobi.12701
- Description: The ever-widening scope and range of global change and interconnected systemic risks arising from people–environment relationships (social‐ecological risks) appears to be increasing concern among, and involvement of, citizens in an increasingly diversified number of citizen science projects responding to these risks. We examined the relationship between epistemic cultures in citizen science projects and learning potential related to matters of concern. We then developed a typology of purposes and a citizen science epistemic‐cultures heuristic and mapped 56 projects in southern Africa using this framework. The purpose typology represents the range of knowledge‐production purposes, ranging from laboratory science to social learning, whereas the epistemic‐cultures typology is a relational representation of scientist and citizen participation and their approach to knowledge production. Results showed an iterative relationship between matters of fact and matters of concern across the projects; the nexus of citizens’ engagement in knowledge‐production activities varied. The knowledge‐production purposes informed and shaped the epistemic cultures of all the sampled citizen science projects, which in turn influenced the potential for learning within each project. Through a historical review of 3 phases in a long‐term river health‐monitoring project, we found that it is possible to evolve the learning curve of citizen science projects. This evolution involved the development of scientific water monitoring tools, the parallel development of pedagogic practices supporting monitoring activities, and situated engagement around matters of concern within social activism leading to learning‐led change. We conclude that such evolutionary processes serve to increase potential for learning and are necessary if citizen science is to contribute to wider restructuring of the epistemic culture of science under conditions of expanding social-ecological risk.
- Full Text:
- Date Issued: 2016
Back to the future: revival, relevance and route of an anarchist/syndicalist approach for twenty-first-century left, labour and national liberation movements
- Authors: van der Walt, Lucien
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144812 , vital:38381 , DOI: 10.1080/02589001.2016.1235365
- Description: The failings of classical Marxism, social democracy and anti-imperialist nationalism point to the need for a radical left politics at a distance from the state. This paper examines the impact, revival and promise of the anarchist/syndicalist tradition, a rich, continuous praxis in labour, left, anti-imperialist, anti-racist and egalitarian movements, worldwide, since the 1860s. Outlining its core ideas – anti-hierarchy, anti-capitalism, anti-statism, opposition to social and economic inequality, internationalist class-based mobilisation – and critique of mainstream Marxism and nationalism, it highlights the arguments there is a basic incompatibility between state rule, and bottom-up, egalitarian, democratic, socialist relationships. The anarchist/syndicalist project cannot be reduced to an organising style, protest politics or spontaneism: for it, transition to a just, self-managed society requires organised popular capacity for a revolutionary rupture, developed through prefigurative, class-based, democratic organs of counter-power, including syndicalist unions aiming at collectivised property, and revolutionary counter-culture. Success needs formal organisation, unified strategy and anarchist / syndicalist political organisations.
- Full Text:
- Date Issued: 2016
- Authors: van der Walt, Lucien
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144812 , vital:38381 , DOI: 10.1080/02589001.2016.1235365
- Description: The failings of classical Marxism, social democracy and anti-imperialist nationalism point to the need for a radical left politics at a distance from the state. This paper examines the impact, revival and promise of the anarchist/syndicalist tradition, a rich, continuous praxis in labour, left, anti-imperialist, anti-racist and egalitarian movements, worldwide, since the 1860s. Outlining its core ideas – anti-hierarchy, anti-capitalism, anti-statism, opposition to social and economic inequality, internationalist class-based mobilisation – and critique of mainstream Marxism and nationalism, it highlights the arguments there is a basic incompatibility between state rule, and bottom-up, egalitarian, democratic, socialist relationships. The anarchist/syndicalist project cannot be reduced to an organising style, protest politics or spontaneism: for it, transition to a just, self-managed society requires organised popular capacity for a revolutionary rupture, developed through prefigurative, class-based, democratic organs of counter-power, including syndicalist unions aiming at collectivised property, and revolutionary counter-culture. Success needs formal organisation, unified strategy and anarchist / syndicalist political organisations.
- Full Text:
- Date Issued: 2016
What lies beneath: exploring the deeper purposes of feedback on student writing through considering disciplinary knowledge and knowers
- Van Heerden, Martina, Clarence, Sherran, Bharuthram, Sharita
- Authors: Van Heerden, Martina , Clarence, Sherran , Bharuthram, Sharita
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59856 , vital:27669 , https://doi.org/10.1080/02602938.2016.1212985
- Description: Feedback plays an integral role in students’ learning and development, as it is often the only personal communication that students have with tutors or lecturers about their own work. Yet, in spite of its integral role in student learning, there is disagreement between how students and tutors or lecturers perceive the pedagogic purpose of feedback. Central to this disagreement is the role that feedback has to play in ensuring that students produce the ‘right’ kinds of knowledge, and become the ‘right’ kinds of knowers within their disciplines. This paper argues that, in order to find common ground between students and tutors or lecturers on what feedback is for, and how to both give and use it effectively, we need to conceptualise disciplinary knowledge and knowers anew. We offer, as a useful starting point, the Specialisation dimension of Legitimation Code Theory as both practical theory and methodological tool for exploring knowledge and knowers in English Studies and Law as two illustrative cases. The paper concludes that this analysis offers lecturers and tutors a fresh understanding of the disciplinary knowledge and knower structures they work within and, relatedly, a clearer view of the work their feedback needs to do within these.
- Full Text: false
- Date Issued: 2016
- Authors: Van Heerden, Martina , Clarence, Sherran , Bharuthram, Sharita
- Date: 2016
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/59856 , vital:27669 , https://doi.org/10.1080/02602938.2016.1212985
- Description: Feedback plays an integral role in students’ learning and development, as it is often the only personal communication that students have with tutors or lecturers about their own work. Yet, in spite of its integral role in student learning, there is disagreement between how students and tutors or lecturers perceive the pedagogic purpose of feedback. Central to this disagreement is the role that feedback has to play in ensuring that students produce the ‘right’ kinds of knowledge, and become the ‘right’ kinds of knowers within their disciplines. This paper argues that, in order to find common ground between students and tutors or lecturers on what feedback is for, and how to both give and use it effectively, we need to conceptualise disciplinary knowledge and knowers anew. We offer, as a useful starting point, the Specialisation dimension of Legitimation Code Theory as both practical theory and methodological tool for exploring knowledge and knowers in English Studies and Law as two illustrative cases. The paper concludes that this analysis offers lecturers and tutors a fresh understanding of the disciplinary knowledge and knower structures they work within and, relatedly, a clearer view of the work their feedback needs to do within these.
- Full Text: false
- Date Issued: 2016
Fat in a time of slim: the reinscription of race in the framing of fat desirability in post-apartheid South Africa
- Authors: Vincent, Louise
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141591 , vital:37988 , DOI: 10.1177/1363460716640730
- Description: This article critically examines the way in which the reported sexual desire of black African men for fat women is contained and managed in South African media representations of fat. While sexual desire for fat women represents a potential challenge to the dominant framing of fat as diseased/dysfunctional/disgusting, the article shows how the reduction of this desire to one of two (racialized) ‘explanations’ – either evidence of racial primitivism or a (black male) strategy to avoid infection with HIV – emasculates the potentially powerful oppositional framing of fat as sexy. It is a mark of the dominant frame’s influence that it is capable of co-opting oppositional frames and recasting them in its own image. From the point of view of critiques of the fat-as-disease orthodoxy, the claim to the existence of an alternative norm of fat as sexually desirable in ‘black culture’ emerges as a problematic oppositional frame – saturated with raced assumptions in the way in which it is reported. The counter framing of the (black) fat body as sexually desirable is given column space to be derided and dismissed as an instance of deviant black sexuality, as a mistaken belief in need of ‘correction’, or it is subsumed under a medicalized frame as a strategy for the avoidance of disease rather than an expression of genuine sexual desire.
- Full Text:
- Date Issued: 2016
- Authors: Vincent, Louise
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141591 , vital:37988 , DOI: 10.1177/1363460716640730
- Description: This article critically examines the way in which the reported sexual desire of black African men for fat women is contained and managed in South African media representations of fat. While sexual desire for fat women represents a potential challenge to the dominant framing of fat as diseased/dysfunctional/disgusting, the article shows how the reduction of this desire to one of two (racialized) ‘explanations’ – either evidence of racial primitivism or a (black male) strategy to avoid infection with HIV – emasculates the potentially powerful oppositional framing of fat as sexy. It is a mark of the dominant frame’s influence that it is capable of co-opting oppositional frames and recasting them in its own image. From the point of view of critiques of the fat-as-disease orthodoxy, the claim to the existence of an alternative norm of fat as sexually desirable in ‘black culture’ emerges as a problematic oppositional frame – saturated with raced assumptions in the way in which it is reported. The counter framing of the (black) fat body as sexually desirable is given column space to be derided and dismissed as an instance of deviant black sexuality, as a mistaken belief in need of ‘correction’, or it is subsumed under a medicalized frame as a strategy for the avoidance of disease rather than an expression of genuine sexual desire.
- Full Text:
- Date Issued: 2016
Interpreting press coverage of South Africa’s post-apartheid “obesity epidemic”:
- Vincent, Louise, Malan, Chantelle
- Authors: Vincent, Louise , Malan, Chantelle
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141866 , vital:38011 , DOI: 10.1080/21604851.2015.1015397
- Description: This study examines news reporting on South Africa’s alleged “obesity” epidemic between 1997 and 2012. Results indicate that fatness is equated with disease, crisis, and dysfunction and the fat black body is singled out for particular attention as a social problem. News reporting on fat in South Africa uncritically takes up the views of sources with commercial interests who are presented as “experts” on fat. Their interpretations of the fat black body as a social problem are influenced by the imperative of new markets for products that are to be found principally in the ranks of the post-apartheid black middle class.
- Full Text:
- Date Issued: 2016
- Authors: Vincent, Louise , Malan, Chantelle
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141866 , vital:38011 , DOI: 10.1080/21604851.2015.1015397
- Description: This study examines news reporting on South Africa’s alleged “obesity” epidemic between 1997 and 2012. Results indicate that fatness is equated with disease, crisis, and dysfunction and the fat black body is singled out for particular attention as a social problem. News reporting on fat in South Africa uncritically takes up the views of sources with commercial interests who are presented as “experts” on fat. Their interpretations of the fat black body as a social problem are influenced by the imperative of new markets for products that are to be found principally in the ranks of the post-apartheid black middle class.
- Full Text:
- Date Issued: 2016
The pattern-richness of graphical passwords
- Vorster, Johannes, Van Heerden, Renier, Irwin, Barry V W
- Authors: Vorster, Johannes , Van Heerden, Renier , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68322 , vital:29238 , https://doi.org/10.1109/ISSA.2016.7802931
- Description: Publisher version , Conventional (text-based) passwords have shown patterns such as variations on the username, or known passwords such as “password”, “admin” or “12345”. Patterns may similarly be detected in the use of Graphical passwords (GPs). The most significant such pattern - reported by many researchers - is hotspot clustering. This paper qualitatively analyses more than 200 graphical passwords for patterns other than the classically reported hotspots. The qualitative analysis finds that a significant percentage of passwords fall into a small set of patterns; patterns that can be used to form attack models against GPs. In counter action, these patterns can also be used to educate users so that future password selection is more secure. It is the hope that the outcome from this research will lead to improved behaviour and an enhancement in graphical password security.
- Full Text: false
- Date Issued: 2016
- Authors: Vorster, Johannes , Van Heerden, Renier , Irwin, Barry V W
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/68322 , vital:29238 , https://doi.org/10.1109/ISSA.2016.7802931
- Description: Publisher version , Conventional (text-based) passwords have shown patterns such as variations on the username, or known passwords such as “password”, “admin” or “12345”. Patterns may similarly be detected in the use of Graphical passwords (GPs). The most significant such pattern - reported by many researchers - is hotspot clustering. This paper qualitatively analyses more than 200 graphical passwords for patterns other than the classically reported hotspots. The qualitative analysis finds that a significant percentage of passwords fall into a small set of patterns; patterns that can be used to form attack models against GPs. In counter action, these patterns can also be used to educate users so that future password selection is more secure. It is the hope that the outcome from this research will lead to improved behaviour and an enhancement in graphical password security.
- Full Text: false
- Date Issued: 2016
Natural resource use, incomes, and poverty along the rural–urban continuum of two medium-sized, South African towns
- Ward, Catherine D, Shackleton, Charlie M
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
Emergent effects of structural complexity and temperature on predator–prey interactions
- Wasserman, Ryan J, Alexander, Mhairi E, Weyl, Olaf L F, Barrios‐O'Neill, Daniel, Froneman, P William, Dalu, Tatenda
- Authors: Wasserman, Ryan J , Alexander, Mhairi E , Weyl, Olaf L F , Barrios‐O'Neill, Daniel , Froneman, P William , Dalu, Tatenda
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69190 , vital:29444 , https://doi.org/10.1002/ecs2.1239
- Description: Ephemeral aquatic environments are important habitats for a variety of species. They are highly variable with regards to vegetation structure and physico‐chemical features that potentially mediate outcomes of biotic interactions. Multiple environmental variables and their emergent impacts on the relationship between prey consumption rate by a predator and prey density (functional response), however, are rarely assessed. Here, we investigated the combined effects of temperature and habitat complexity on the functional response of the freshwater predatory notonectid Enithares sobria on the cladoceran prey organism Daphnia longispina. A Type II functional response was observed for E. sobria predating on D. longispina and while temperature and habitat complexity had no effect on the response type, these environmental variables interacted with consequences for the magnitude of the functional responses. Overall, structural complexity favored the predator as greater consumption was observed in the most complex habitat treatment. Temperature effects were also evident although these effects were not unidirectional with regard to treatment factor gradients as predators were the most successful at intermediary temperatures. Furthermore, there was a complex interplay between habitat complexity and temperature, with attack rates being greatest at low and high complexities within intermediate temperatures, while at zero complexity attack rates were greatest at the lowest temperature. The effect of habitat on handling times was only evident in the low temperature treatments which decreased steadily with each increase in complexity. Through the application of functional responses the synergistic effects of multiple environmental drivers on predator–prey interaction outcomes have been highlighted, adding insight into how interactions among species may be affected by natural or artificially induced environmental variability.
- Full Text:
- Date Issued: 2016
- Authors: Wasserman, Ryan J , Alexander, Mhairi E , Weyl, Olaf L F , Barrios‐O'Neill, Daniel , Froneman, P William , Dalu, Tatenda
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69190 , vital:29444 , https://doi.org/10.1002/ecs2.1239
- Description: Ephemeral aquatic environments are important habitats for a variety of species. They are highly variable with regards to vegetation structure and physico‐chemical features that potentially mediate outcomes of biotic interactions. Multiple environmental variables and their emergent impacts on the relationship between prey consumption rate by a predator and prey density (functional response), however, are rarely assessed. Here, we investigated the combined effects of temperature and habitat complexity on the functional response of the freshwater predatory notonectid Enithares sobria on the cladoceran prey organism Daphnia longispina. A Type II functional response was observed for E. sobria predating on D. longispina and while temperature and habitat complexity had no effect on the response type, these environmental variables interacted with consequences for the magnitude of the functional responses. Overall, structural complexity favored the predator as greater consumption was observed in the most complex habitat treatment. Temperature effects were also evident although these effects were not unidirectional with regard to treatment factor gradients as predators were the most successful at intermediary temperatures. Furthermore, there was a complex interplay between habitat complexity and temperature, with attack rates being greatest at low and high complexities within intermediate temperatures, while at zero complexity attack rates were greatest at the lowest temperature. The effect of habitat on handling times was only evident in the low temperature treatments which decreased steadily with each increase in complexity. Through the application of functional responses the synergistic effects of multiple environmental drivers on predator–prey interaction outcomes have been highlighted, adding insight into how interactions among species may be affected by natural or artificially induced environmental variability.
- Full Text:
- Date Issued: 2016