Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for +publisher:"Stellenbosch University" +contributor:("Johnson, Shelley"). Showing records 1 – 3 of 3 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Stellenbosch University

1. Huysamer, Anton Jean. An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa.

Degree: MSc, Conservation Ecology and Entomology, 2018, Stellenbosch University

ENGLISH ABSTRACT: A successful industry has developed around the export of fresh Proteaceae cut flowers from South Africa. Phytosanitary insects are a barrier to export, as South African Proteaceae associates with a considerable entomofauna. The development of alternative postharvest disinfestation technologies could reduce these interceptions and promote market access. Surveys on export material were conducted to determine which pests are most problematic when exporting Proteaceae. A total of 82 interceptions were made, comprising of eight insect orders and 26 insect families. Although many interceptions were as a result of solitary individuals, multiple interceptions consisted of many individuals of western flower thrips (Frankliniella occidentalis) and protea itch mite (Procotolaelaps vandenbergii). These pests were selected as the key pests on which to focus for disinfestation using alternative postharvest technologies not yet utilised for Proteaceae. Controlled Atmosphere and Temperature Treatment Systems (CATTS) technology was assessed as a potential disinfestation tool for fresh Proteaceae cut flowers. The tested commodities were Leucospermum ‗Veldfire‘, Protea magnifica ‗Barbi‘, Leucadendron ‗Safari sunset‘ and ‗Jade pearl‘, and Geraldton wax ‗Ofir‘ (Myrtaceae). CATTS treatments consisted of temperature ramps of 35°C/hour and 30°C/hour from 23°C to 40°C, with a 15 min soak at 40°C, and 35°C/hour and 30°C/hour from 23°C to 50°C, with a 15 min soak at 50°C, under modified atmospheres of 1% O2, 15% CO2 in N2. Treated stems were subjected to vase life studies after treatment, or following air- and sea-freight storage simulations at 2°C for 3 or 21 days respectively. Leucospermum ‗Veldfire‘ did not withstand treatments, as style wilting reduced overall quality. Protea magnifica ‗Barbi‘ withstood some treatments, maintaining comparable quality to control stems in the vase immediately after treatment. Both Leucadendron commodities withstood treatments well, and maintained marketable quality following treatment, air- and sea-freight simulations. Geraldton wax ‗Ofir‘ maintained quality in vase immediately after and following air-freight simulations. CATTS treatments of 35°C/hour and 30°C/hour to 40°C in 1% O2, 15% CO2 in N2 resulted in 100% mortality in western flower thrips and protea itch mites within 24 hours of treatment. Postharvest fumigation treatment with ethyl formate (EF) was also assessed as a potential disinfestation technology. Concentrations ranged from 18.53g/m3 to 151.47g/m3 EF, and durations ranging from 30 mins to 3 hours for the same cut flower commodities listed above for CATTS treatments. Further trials on Geraldton wax ‗Ofir‘ consisted of 10g/m3 and 20g/m3 for 1 and 2 hours. All treatments resulted in reduction in overall quality of treated fresh goods. EF fumigations of 18.53g/m3 for 1 and 2 hours achieved 100% mortality within 24 hours of treatment in western flower thrips and protea itch mites, but excessive post fumigation damage renders EF unsuitable. The… Advisors/Committee Members: Johnson, Shelley, Hoffman, Lynne, Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology..

Subjects/Keywords: Proteaceae  – Exports  – South Africa; Cape flora cut flowers  – Exports  – South Africa; Cape cut flowers  – exports  – South Africa; Thrips  – Insect pests  – Proteaceae  – South Africa; Controlled atmosphere and temperature systems; Postharvest technology of Cape flora cut flowers  – Fumigation  – South Africa; Cape flora cut flowers  – Postharvest technology  – Fumigation  – South Africa; UCTD

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Huysamer, A. J. (2018). An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa. (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/104880

Chicago Manual of Style (16th Edition):

Huysamer, Anton Jean. “An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa.” 2018. Masters Thesis, Stellenbosch University. Accessed December 08, 2019. http://hdl.handle.net/10019.1/104880.

MLA Handbook (7th Edition):

Huysamer, Anton Jean. “An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa.” 2018. Web. 08 Dec 2019.

Vancouver:

Huysamer AJ. An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa. [Internet] [Masters thesis]. Stellenbosch University; 2018. [cited 2019 Dec 08]. Available from: http://hdl.handle.net/10019.1/104880.

Council of Science Editors:

Huysamer AJ. An assessment of alternative postharvest technologies for the disinfestation of fresh Cape Flora cut flowers for export from South Africa. [Masters Thesis]. Stellenbosch University; 2018. Available from: http://hdl.handle.net/10019.1/104880


Stellenbosch University

2. Okosun, Olabimpe Olayem. Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit.

Degree: MScAgric, Conservation Ecology and Entomology, 2012, Stellenbosch University

ENGLISH ABSTRACT: The grain chinch bug, Macchiademus diplopterus, is an endemic pest of cultivated grain crops and wild grasses in the south-western Cape region of South Africa. In early summer when host plants dry out, adult grain chinch bugs aggregate in large numbers in shelter sites in surrounding areas and enter into aestivation. These shelter sites sometimes include the stalk or calyx ends of fruit, and shelter-seeking bugs can also contaminate export fruit cartons, consequently posing a phytosanitary/quarantine risk to importing countries. Presently, there are no feasible pre- or post-harvest control measures to manage this quarantine risk. The aggregating behaviour of grain chinch bugs suggests the involvement of pheromones. Therefore, investigating the chemical ecology of grain chinch bugs for potential use in control measures is the focus of the first research chapter of this study. Gas chromatography-mass spectrometry (GC-MS) was used to identify headspace volatiles collected from aggregating bugs. Olfactometer bioassays were conducted to assess the attractiveness of each gender to separate sexes, individual compounds and a mixture of the compounds as a formulated lure. The lure was tested in field trapping trials with delta and bucket traps. In the bioassays with the live insects the response of each gender to live females was greater than the responses of each gender to live males, suggesting that females may disseminate the pheromones more efficiently than males. The following eight volatile compounds were indentified from the GC-MS analysis: hexanal, (E)-2-hexenal, (E)-2-hexenol, (E)-2-hexenyl acetate, (E)-2-octenal, (E)-2-octenol, (E)-2-octenyl acetate and tridecane. In the bioassays with individual compounds, three of these eight compounds, hexanal, (E)-2-hexenal, and tridecane, elicited attraction of both females and males. The formulated lure was attractive to both males and females in the laboratory bioassay, but this attraction was not evident in the field. In the field, there was only one occasion when a significantly higher number of bugs were caught in baited traps compared to unbaited traps. Trap catches were very low compared to the actual level of infestation in the field which was evident from corrugated cardboard bands tied around tree trunks which contained many sheltering bugs. The low trap catches seen in the field were partly due to competition between the synthetic pheromone lure and the natural pheromones emitted by aggregating live insects. Also, the characteristic shelter-seeking behaviour of grain chinch bugs influenced trap catches, as more bugs were found in places that provide shelter, like cardboard bands and walls of the delta traps. This behavior of aestivating bugs could be used to the advantage of trapping bugs by integrating sheltering sites into traps in future trials. Also, the lure needs to be improved for optimum efficiency in the field. The second research chapter also addresses the quarantine risk posed by grain chinch bugs, by investigating the thermal biology of… Advisors/Committee Members: Johnson, Shelley, Addison, P., Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology..

Subjects/Keywords: Conservation ecology and entomology; Conservation Ecology and Entomology

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Okosun, O. O. (2012). Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit. (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/20046

Chicago Manual of Style (16th Edition):

Okosun, Olabimpe Olayem. “Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit.” 2012. Masters Thesis, Stellenbosch University. Accessed December 08, 2019. http://hdl.handle.net/10019.1/20046.

MLA Handbook (7th Edition):

Okosun, Olabimpe Olayem. “Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit.” 2012. Web. 08 Dec 2019.

Vancouver:

Okosun OO. Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit. [Internet] [Masters thesis]. Stellenbosch University; 2012. [cited 2019 Dec 08]. Available from: http://hdl.handle.net/10019.1/20046.

Council of Science Editors:

Okosun OO. Chemical ecology and eco-physiology of the grain chinch bug, Macchiademus diplopterus (Distant) (Hemiptera: Lygaeidae: Blissidae), a phytosanitary pest of South African export fruit. [Masters Thesis]. Stellenbosch University; 2012. Available from: http://hdl.handle.net/10019.1/20046


Stellenbosch University

3. Morris, Courtney Anne. Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options.

Degree: MScConsEcol, Conservation Ecology and Entomology, 2019, Stellenbosch University

ENGLISH ABSTRACT: Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae), has developed pest status in vineyards in the Northern Cape and Limpopo (Groblersdal area) provinces of South Africa. Larvae feed on new vine growth and, if not detected early, the subsequent defoliation of vineyards can be severe, resulting in crop losses. Outbreaks are sporadic, and infestation levels vary. Little is known about the biology and behaviour of Trimen’s false tiger moth, and no official monitoring methods or economic thresholds yet exist. Consequently, management and control options are lacking. Hence, attention has been drawn to the use of environment-friendly alternative pest control technologies. In this study, observational studies and visual scouting provided insight into the biology, seasonal development and behaviour of A. trimenii. The use of pheromone traps, live bait traps and light traps was tested as potential monitoring strategies of A. trimenii. The potential of different biocontrol agents, including entomopathogenic nematodes (EPN), entomopathogenic fungi (EPF), pathogenic bacteria and insect growth regulators were tested against A. trimenii, to be considered for later use in an integrated pest management (IPM) system. The use of pheromone traps, light traps and visual scouting as potential monitoring strategies of A. trimenii was tested in the field. Various life stages of A. trimenii were identified, peak flight times were established, overlapping generations were determined, and the behavioural traits of all life stages were documented. Ultraviolet blue light traps proved to be the most promising potential monitoring strategy, with the prospect for an A. trimenii pheromone lure holding potential as an alternative monitoring strategy. The susceptibility of larvae and pupae to EPNs of Steinernematidae and Heterorhabditidae and two commercially available EPF isolates, under laboratory conditions, were tested. The pathogenicity of two local species, Steinernema yirgalemense and Heterorhabditis noenieputensis, was screened against larvae and pupae of A. trimenii, using a concentration of 100 infective juveniles in 50 l of water. After 48 h, 100% mortality of the larval stage was found. However, in the case of the pupae, no infection with EPNs was observed. The pathogenicity of two commercially available EPF isolates, Metarhizium anisopliae and Beauveria bassiana, was screened against larvae and pupae by means of a dipping test undertaken at a concentration of 0.2 ml/500 ml water and 0.5 g/500 ml water, respectively. At 15 days post treatment, 100% larval mortality was recorded. However, no mortality of the pupae was observed. The susceptibility of larvae to three commercial products, Delegate®WG, Steward®150 EC and three different doses of DiPel®DF under laboratory conditions was examined. Semi-field trials were performed to test the potential of DiPel ® DF against larvae, applied at different water volumes (50g/1000L/ha and 42g/1200L/ha) and to compare spray coverage between top and bottom leaves… Advisors/Committee Members: Johnson, Shelley, De Waal, Jeanne Y., Malan, Antoinette P., Stellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology..

Subjects/Keywords: Trimen's false tiger moth; Integrated pest management (IPM) system; Trimen's false tiger moth  – Biological control; UCTD

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Morris, C. A. (2019). Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options. (Masters Thesis). Stellenbosch University. Retrieved from http://hdl.handle.net/10019.1/105841

Chicago Manual of Style (16th Edition):

Morris, Courtney Anne. “Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options.” 2019. Masters Thesis, Stellenbosch University. Accessed December 08, 2019. http://hdl.handle.net/10019.1/105841.

MLA Handbook (7th Edition):

Morris, Courtney Anne. “Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options.” 2019. Web. 08 Dec 2019.

Vancouver:

Morris CA. Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options. [Internet] [Masters thesis]. Stellenbosch University; 2019. [cited 2019 Dec 08]. Available from: http://hdl.handle.net/10019.1/105841.

Council of Science Editors:

Morris CA. Trimen’s false tiger moth, Agoma trimenii (Lepidoptera: Agaristidae) : biology and potential control options. [Masters Thesis]. Stellenbosch University; 2019. Available from: http://hdl.handle.net/10019.1/105841

.