Development of integrated pest management approaches for yellow sugarcane aphid Sipha flava in Zambia
| dc.contributor.advisor | Terblanche, J. S. | en_ZA |
| dc.contributor.advisor | Conlong, D. E. | en_ZA |
| dc.contributor.advisor | Barton, Madeleine | en_ZA |
| dc.contributor.author | Thomas, Saskia | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. | en_ZA |
| dc.date.accessioned | 2019-11-26T13:45:28Z | |
| dc.date.accessioned | 2019-12-11T06:39:48Z | |
| dc.date.available | 2021-12-26T03:00:10Z | |
| dc.date.issued | 2019-12 | |
| dc.description | Thesis (MScConsEcol)--Stellenbosch University, 2019. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: The yellow sugarcane aphid Sipha flava (Forbes) (Homoptera: Aphididae) has recently emerged as a pest of concern for sugarcane (Saccharum spp.) farmers in the Mazabuka region of Zambia, and been argued to have contributed to recent declines in productivity and crop yields. Limited options have been available in effective monitoring methodologies of this pest and other more sustainable control options. One of the key factors in the implementation of effective integrated pest management programs is having appropriate methodologies to accurately monitor and detect pest infestation levels, in addition, promoting natural enemies can aid pest management through non-chemical means. Consequently, there is a pressing need to develop monitoring methods and survey strategies to better understand the spatial- temporal dynamics of S. flava population outbreaks. In Chapter 2, smaller sections (± 6ha) of larger sugarcane fields (14- 50ha) were systematically and consistently surveyed for a 7-wk period, weekly during the summer (October-November) and fortnightly for a 12-wk period during the winter season (May- August) for the presence of S. flava. Sampling effort was proven to be reduced from 31 (effort employed in this study) to 17 or 14 stalks/ha, depending on the ‘presence’ or ‘infestation percentage’ method, to produce equally reliable estimates of the infestation levels in the sugarcane field. Most aphids were found on the bottom 4 green leaves for all sugarcane varieties in the different seasons. No systematic spatial pattern of invasion was observed for this aphid’s infestation in the fields during the winter season, but instead were found to have random field distributions with little or weak spatial autocorrelation. However, further studies are required to identify the economic threshold for the proposed monitoring methodologies before they can be adopted more broadly. Little is known about the existence of biological control agents that could be naturally existing within the agroecosystem and assisting in the control of S. flava in Zambia. In Chapter 3, three sites each consisting of 2 subsites in sugarcane fields and 1 subsite in the bordering vegetation areas, were sampled fortnightly over a 10-wk period (May- August) to collect potential predators of S. flava. This was to determine the likelihood and extent of aphidophagous arthropods to be naturally feeding on S. flava, based on ∆13C and ∆15N enrichment, as specialist or generalist predators. The diversity of the aphidophagous predators found within each site and collectively within this agroecosystem were dominated by arachnids, coccinellids and syrphids. Syritta sp. (Syrphidae: Diptera) and Scymnus sp. (Coccinellidae: Coleoptera) were found to be the most common predators, with many other predators identified found to be important specialist and generalist predators too, but their predator behaviour on S. flava appeared to differ between sampling sites. This suite of arthropods can now be used to select which predators to encourage for increased levels of biological control to allow for more sustainable management of this pest. The results of both chapters are discussed in the context of further development of an integrated pest management programme for S. flava on sugarcane in Zambia. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Die onlangse verskyning van Sipha flava (Forbes) (Homoptera: Aphididae), die geel suikerrietluis, in die Mazabuka-streek van Zambië het tot groot kommer gelei vir die suikerrietboere (Saccharum spp.) in die area. Terselfdertyd word die afname in produktiwiteit en opbrengs ook hieraan toegeskryf. Slegs beperkte opsies is tans beskikbaar vir effektiewe metodes van monitering en volhoubare beheer van die pes. Een van die mees belangrike aspekte vir die implementering van ʼn effektiewe geïntegreerde pesbeheerprogram is die beskikbaarheid van toepaslike metodologieë om die pes te kan opspoor, die pes se besmettingsvlakke akkuraat te bepaal, asook die bevordering van natuurlike vyande om pesbeheer op ‘n nie-chemiese manier te bevorder. Gevolglik is daar ʼn dringende behoefte om moniteringsmetodes en opname-strategieë te ontwikkel om die ruimtelike en temporale dinamika van S. flava bevolkingsgroei en uitbrake beter te verstaan. In Hoofstuk 2, is stelselmatige en konstante opnames gemaak vir die teenwoordigheid van S. flava weekliks in die somer (Oktober-November) en elke tweede week in die winter (Mei-Augustus) in klein gedeeltes (± 6ha) van groot suikerrietlande (14- 50ha) vir onderskeidelik sewe en twaalf weke. In hierdie studie het ons gevind dat die monsterneming poging verlaag kan word vanaf 31 na 14 of 17 stingels/ha en steeds betroubare beramings van die infestasievlakke in die suikerrietveld lewer, afhangend of die 'teenwoordigheid' of 'besmettingspersentasie' metode gebruik is. In die verskillende seisoene is die meeste plantluise op die vier onderste groen blare gevind in alle suikerrietvariëteite. Geen sistematiese ruimtelike patroon van die plantluise se teenwoordigheid en verspreiding in die velde kon identifiseer word gedurende die winter nie en lukrake veldverspreiding met min of swak ruimtelike outokorrelasie is gevind. Verdere studies word egter benodig om die ekonomiese drempel te bepaal van die voorgestelde moniterings metodologieë voor hulle toegepas word op ‘n groter skaal. Daar is baie min inligting beskikbaar oor biologiese beheer wat bydra tot die beheer van S. flava wat natuurlik voorkom in die agro-ekosisteem in Zambië. In Hoofstuk 3, is daar gesoek na potensiële predatore elke tweede week in drie areas in die suikerrietplantasie, elk met twee proefareas, sowel as 1 proefarea in die aangrensende plantegroei vir tien weke (Mei-Augustus). Hierdie monsters is gebruik om die waarskynlikheid van geleedpotiges wat natuurlik op S. flava voed as spesialiste of meer algemene predatore te bepaal, deur gebruik te maak van ∆13C en ∆15N verryking. Die diversiteit in hierdie agro- ekosisteem van geleedpotiges wat voed op plantluise is algeheel oorheers deur die Arachnida, Coccinellidae en Syrphidae. Lede van Syritta sp. (Syrphidae: Diptera) en Scymnus sp. (Coccinellidae: Coleoptera) was die mees algemene predatore. Ander predatore is ook geïdentifiseer as belangrike spesialiste en algemene predatore, maar hulle gedrag ten opsigte van S. flava was verskillend tussen die verskillende proefareas. Hierdie versameling van geleedpotiges kan nou gebruik word om predatore te selekteer waarvan die getalle verhoog kan word en sodoende aangemoedig word as meer volhoubare beheer van hierdie pes. Die resultate van beide hierdie hoofstukke word bespreek in die konteks van verdere ontwikkeling van 'n geïntegreerde plaagbestuursprogram vir S. flava op suikerriet in Zambie. | af_ZA |
| dc.description.version | Masters | |
| dc.embargo.terms | 2021-12-26 | |
| dc.format.extent | xviii, 89 pages : illustrations (some color), maps | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/106942 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Sampling methodology | en_ZA |
| dc.subject | Survey strategy | en_ZA |
| dc.subject | Insect pests -- Biological control | en_ZA |
| dc.subject | Aphidophagous predators | en_ZA |
| dc.subject | Aphidophagous predators | en_ZA |
| dc.subject | Sugarcane -- Zambia | en_ZA |
| dc.subject | Sugarcane aphid Sipha flava | en_ZA |
| dc.subject | Sugarcane - Diseases and pests - Control | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.title | Development of integrated pest management approaches for yellow sugarcane aphid Sipha flava in Zambia | en_ZA |
| dc.type | Thesis | en_ZA |