A study on the application technology of the sterile insect technique, with focus on false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a pest of citrus in South Africa
- Authors: Nepgen, Eugene Stephan
- Date: 2014
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- Control -- South Africa , Insect pests -- Control -- South Africa , Insect sterilization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5879 , http://hdl.handle.net/10962/d1013199
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is considered the most important indigenous pest of citrus in southern Africa. Major concerns such as progressive insecticidal resistance, the negative impact of insecticides on the environment, as well as the influence of consumers opposed to chemical residues on fruit, created opportunities for biological control methods such as Sterile Insect Technology (SIT). This technology is now established in the Western and Eastern Cape provinces of South Africa as an effective, sustainable alternative to conventional FCM control methods. Due to the prevalence of the pest in all citrus producing areas of South Africa, potential for SIT to expand is enormous. Success of an SIT programme is highly dependent on efficient application of the technology to achieve its objectives in a timeous manner. The aim of this study was to advance the application of SIT for control of FCM on citrus in South Africa, by investigating the effect of certain critical stages in the process. The effect of long-distance transportation on fitness of irradiated FCM was determined, showing reduced performance with cold-immobilized transport. A significant decrease in flight ability and longevity of irradiated FCM was found, although critically, realized fecundity was not affected. The effect of two different insecticides in the pyrethroid and organophosphate chemical groups were investigated for their residual effect on mortality of released irradiated FCM, to determine if these pest control programmes could be integrated. Both chlorpyrifos and tau-fluvalinate were effective in killing irradiated FCM for a number of days after application, after which degradation of the active ingredient rendered it harmless. This effect was found to be similar for irradiated and non-irradiated males, consequently ratios of sterile : wild male FCM should be retained regardless of whether sprays are applied or not. The modes for release of sterile FCM in an SIT programme were investigated. Efficacy of ground and aerial release platforms were tested by evaluating the recovery of released irradiated male FCM in these orchards. More irradiated FCM were recovered in orchards released from the ground compared to air. However, an economic analysis of both methods shows application of irradiated insects over a large geographical area is more cost-effective by air. Depending on the terrain and size of the target area, a combination of both methods is ideal for application of SIT for control of FCM in citrus. Development of application technology for advance of the programme is discussed and recommendations for future research and development are offered.
- Full Text:
- Date Issued: 2014
- Authors: Nepgen, Eugene Stephan
- Date: 2014
- Subjects: Cryptophlebia leucotreta , Citrus -- Diseases and pests -- Control -- South Africa , Insect pests -- Control -- South Africa , Insect sterilization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5879 , http://hdl.handle.net/10962/d1013199
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is considered the most important indigenous pest of citrus in southern Africa. Major concerns such as progressive insecticidal resistance, the negative impact of insecticides on the environment, as well as the influence of consumers opposed to chemical residues on fruit, created opportunities for biological control methods such as Sterile Insect Technology (SIT). This technology is now established in the Western and Eastern Cape provinces of South Africa as an effective, sustainable alternative to conventional FCM control methods. Due to the prevalence of the pest in all citrus producing areas of South Africa, potential for SIT to expand is enormous. Success of an SIT programme is highly dependent on efficient application of the technology to achieve its objectives in a timeous manner. The aim of this study was to advance the application of SIT for control of FCM on citrus in South Africa, by investigating the effect of certain critical stages in the process. The effect of long-distance transportation on fitness of irradiated FCM was determined, showing reduced performance with cold-immobilized transport. A significant decrease in flight ability and longevity of irradiated FCM was found, although critically, realized fecundity was not affected. The effect of two different insecticides in the pyrethroid and organophosphate chemical groups were investigated for their residual effect on mortality of released irradiated FCM, to determine if these pest control programmes could be integrated. Both chlorpyrifos and tau-fluvalinate were effective in killing irradiated FCM for a number of days after application, after which degradation of the active ingredient rendered it harmless. This effect was found to be similar for irradiated and non-irradiated males, consequently ratios of sterile : wild male FCM should be retained regardless of whether sprays are applied or not. The modes for release of sterile FCM in an SIT programme were investigated. Efficacy of ground and aerial release platforms were tested by evaluating the recovery of released irradiated male FCM in these orchards. More irradiated FCM were recovered in orchards released from the ground compared to air. However, an economic analysis of both methods shows application of irradiated insects over a large geographical area is more cost-effective by air. Depending on the terrain and size of the target area, a combination of both methods is ideal for application of SIT for control of FCM in citrus. Development of application technology for advance of the programme is discussed and recommendations for future research and development are offered.
- Full Text:
- Date Issued: 2014
Dangerous people and places : a community newspaper's constructions of crime
- Authors: Raymond, Leigh Alice
- Date: 2014
- Subjects: Grocott's Mail (Grahamstown, South Africa) , Community newspapers -- South Africa -- Grahamstown , Crime and the press -- South Africa -- Grahamstown , Newspapers -- Objectivity , Mass media policy -- South Africa -- Grahamstown , Social responsibility of business -- South Africa -- Grahamstown , Police and the press -- South Africa -- Grahamstown
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3527 , http://hdl.handle.net/10962/d1013091
- Description: This thesis argues that there is a clear imbalance in the representation of crime in the newspaper, Grocott’s Mail, in Grahamstown, in the Eastern Cape of South Africa. The thesis concludes that the system of marginalisation and segregation which was established during the apartheid era is the foundation for the continued segregation and marginalisation of certain groups of people in Grahamstown as depicted in crime journalism. Previous research shows that not only people, but spaces are marginalised through media representations of crime. As people are represented as dangerous, so too the spaces they occupy become dangerous spaces. Importantly, the research shows that discourses of marginalisation are present in newspaper reports reproducing the discourses prominent in society, and in turn, the newspaper itself perpetuates these marginalising discourses. This extends into the coverage that different crimes receive in newspapers. For instance, the reports show that a middle-class audience will be more concerned with property crime in middle-class neighbourhoods, than other crimes in lower-class neighbourhoods. I argue that not only the type of crime, but the severity, the effect, and the necessity for justice represented by the newspaper, are all largely determined by the region of the crime. Further, I show that the criminal is not only demonised and represented as individually deviant in the reports in the newspaper, but that these representations are made by this newspaper because they are deeply imbedded as a discourse in society. This is partly because this newspaper has taken on a monitorial role, requiring neutral reporting from journalists, and a dedication to surveying the processes of state institutions, like the police and courts. As a result, the ways in which crime is reported on in the newspaper is fairly well fixed, making it difficult for journalists to conceive of different ways of reporting crime. The representations of the criminal justice system that the monitorial media, this newspaper included present, are a careful balance between the interest of the public, and the need to preserve relationships with sources. The monitorial media in general, and this newspaper in particular, represent the criminal justice system. The relationship between the police and the newspaper, and the courts and the media, therefore strongly influences the way in which crime news is reported. In particular, crime news is represented from the perspective of the criminal justice system. This research was carried out using Critical Discourse Analysis, qualitative interviews, and focus group interviews.
- Full Text:
- Date Issued: 2014
- Authors: Raymond, Leigh Alice
- Date: 2014
- Subjects: Grocott's Mail (Grahamstown, South Africa) , Community newspapers -- South Africa -- Grahamstown , Crime and the press -- South Africa -- Grahamstown , Newspapers -- Objectivity , Mass media policy -- South Africa -- Grahamstown , Social responsibility of business -- South Africa -- Grahamstown , Police and the press -- South Africa -- Grahamstown
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3527 , http://hdl.handle.net/10962/d1013091
- Description: This thesis argues that there is a clear imbalance in the representation of crime in the newspaper, Grocott’s Mail, in Grahamstown, in the Eastern Cape of South Africa. The thesis concludes that the system of marginalisation and segregation which was established during the apartheid era is the foundation for the continued segregation and marginalisation of certain groups of people in Grahamstown as depicted in crime journalism. Previous research shows that not only people, but spaces are marginalised through media representations of crime. As people are represented as dangerous, so too the spaces they occupy become dangerous spaces. Importantly, the research shows that discourses of marginalisation are present in newspaper reports reproducing the discourses prominent in society, and in turn, the newspaper itself perpetuates these marginalising discourses. This extends into the coverage that different crimes receive in newspapers. For instance, the reports show that a middle-class audience will be more concerned with property crime in middle-class neighbourhoods, than other crimes in lower-class neighbourhoods. I argue that not only the type of crime, but the severity, the effect, and the necessity for justice represented by the newspaper, are all largely determined by the region of the crime. Further, I show that the criminal is not only demonised and represented as individually deviant in the reports in the newspaper, but that these representations are made by this newspaper because they are deeply imbedded as a discourse in society. This is partly because this newspaper has taken on a monitorial role, requiring neutral reporting from journalists, and a dedication to surveying the processes of state institutions, like the police and courts. As a result, the ways in which crime is reported on in the newspaper is fairly well fixed, making it difficult for journalists to conceive of different ways of reporting crime. The representations of the criminal justice system that the monitorial media, this newspaper included present, are a careful balance between the interest of the public, and the need to preserve relationships with sources. The monitorial media in general, and this newspaper in particular, represent the criminal justice system. The relationship between the police and the newspaper, and the courts and the media, therefore strongly influences the way in which crime news is reported. In particular, crime news is represented from the perspective of the criminal justice system. This research was carried out using Critical Discourse Analysis, qualitative interviews, and focus group interviews.
- Full Text:
- Date Issued: 2014
The impact of social network sites on written isiXhosa : a case study of a rural and an urban high school
- Authors: Dlutu, Bongiwe Agrienette
- Date: 2014
- Subjects: Online social networks -- South Africa -- Eastern Cape -- Use studies Mobile communication systems -- Social aspects -- South Africa -- Eastern Cape Interpersonal communication -- Technological innovations -- Social aspects -- South Africa -- Eastern Cape Mobile communication systems in education -- South Africa -- Eastern Cape Teaching -- South Africa -- Eastern Cape -- Aids and devices Xhosa language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Electronic mail systems -- South Africa -- Eastern Cape -- Slang Smartphones -- South Africa -- Use studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3629 , http://hdl.handle.net/10962/d1011826
- Description: The use of cellphones has increased all over the world. That invites many academics to conduct research on the usage of these devices, especially by young people, since young people join Social Network Sites (Facebook, Mxit, 2go, Whatsapp) and use a shorthand language. Most studies are related to the use of English and other languages that are recognised by computer software. There are few studies, if any, that have been done in relation to the use of African Languages on these sites. This research therefore aims to seek to explore the use of African Languages, especially isiXhosa, in assessing how technology might help in language development through the usage of SNSs that learners already use to equip them with educational material in their mother tongue. This study was conducted in two high schools, Nogemane Senior Secondary School in a disadvantaged and remote rural community with limited access to additional educational material such as magazines, newspapers, and television. The school also lacks basic study materials such as textbooks from the Education Department and they have no access to a library and laboratory. They also only have very few subjects to choose from. Nombulelo Senior Secondary School is in Grahamstown. This school has good infrastructure and learners have access to different technological devices and they can access libraries. What is common between learners in both schools is that they are all doing isiXhosa as a first language and are using SNSs to interact with each other. This study has found that learners enjoy using SNSs rather than reading the printed books. Furthermore, they enjoy and prefer interacting in isiXhosa in their conversations. Learners also use the web to post and show their creative writing, regardless of the shorthand form writing they use on the SNSs. This study has found that learners are not well equipped with basic isiXhosa skills when reaching the FET phase. They lack the understanding of standard isiXhosa idioms and proverbs. That clearly means that they are equipped in the more modern forms of literature rather than the traditional oral forms. IsiXhosa teachers also see SNSs as the better platform to engage with learners and they suggest that there must be a section in the subjects at school that teaches about cyber bullying and being safe online. This thesis also presents examples of new and contemporary forms of SNS-speak that are used by learners in both the rural and urban schools. This study is more concerned with SNSs for literacy development and to assess whether the shorthand writing has negative or positive effects in writing isiXhosa. This is done against the backdrop of a literature review which explores new literacies, computer mediated communication, social identity models as well as language policy and planning.
- Full Text:
- Date Issued: 2014
- Authors: Dlutu, Bongiwe Agrienette
- Date: 2014
- Subjects: Online social networks -- South Africa -- Eastern Cape -- Use studies Mobile communication systems -- Social aspects -- South Africa -- Eastern Cape Interpersonal communication -- Technological innovations -- Social aspects -- South Africa -- Eastern Cape Mobile communication systems in education -- South Africa -- Eastern Cape Teaching -- South Africa -- Eastern Cape -- Aids and devices Xhosa language -- Study and teaching (Secondary) -- South Africa -- Eastern Cape Electronic mail systems -- South Africa -- Eastern Cape -- Slang Smartphones -- South Africa -- Use studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3629 , http://hdl.handle.net/10962/d1011826
- Description: The use of cellphones has increased all over the world. That invites many academics to conduct research on the usage of these devices, especially by young people, since young people join Social Network Sites (Facebook, Mxit, 2go, Whatsapp) and use a shorthand language. Most studies are related to the use of English and other languages that are recognised by computer software. There are few studies, if any, that have been done in relation to the use of African Languages on these sites. This research therefore aims to seek to explore the use of African Languages, especially isiXhosa, in assessing how technology might help in language development through the usage of SNSs that learners already use to equip them with educational material in their mother tongue. This study was conducted in two high schools, Nogemane Senior Secondary School in a disadvantaged and remote rural community with limited access to additional educational material such as magazines, newspapers, and television. The school also lacks basic study materials such as textbooks from the Education Department and they have no access to a library and laboratory. They also only have very few subjects to choose from. Nombulelo Senior Secondary School is in Grahamstown. This school has good infrastructure and learners have access to different technological devices and they can access libraries. What is common between learners in both schools is that they are all doing isiXhosa as a first language and are using SNSs to interact with each other. This study has found that learners enjoy using SNSs rather than reading the printed books. Furthermore, they enjoy and prefer interacting in isiXhosa in their conversations. Learners also use the web to post and show their creative writing, regardless of the shorthand form writing they use on the SNSs. This study has found that learners are not well equipped with basic isiXhosa skills when reaching the FET phase. They lack the understanding of standard isiXhosa idioms and proverbs. That clearly means that they are equipped in the more modern forms of literature rather than the traditional oral forms. IsiXhosa teachers also see SNSs as the better platform to engage with learners and they suggest that there must be a section in the subjects at school that teaches about cyber bullying and being safe online. This thesis also presents examples of new and contemporary forms of SNS-speak that are used by learners in both the rural and urban schools. This study is more concerned with SNSs for literacy development and to assess whether the shorthand writing has negative or positive effects in writing isiXhosa. This is done against the backdrop of a literature review which explores new literacies, computer mediated communication, social identity models as well as language policy and planning.
- Full Text:
- Date Issued: 2014
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