Investigations into the ecology and management of the polyphagous shot hole borer beetle (PSHB, Euwallacea fornicatus) in South Africa

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dc.contributor.advisorRoets, Francoisen_ZA
dc.contributor.advisorPaap, Trudyen_ZA
dc.contributor.authorRoberts, Eliseen_ZA
dc.contributor.otherStellenbosch University. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology.en_ZA
dc.date.accessioned2023-11-29T16:38:54Z
dc.date.accessioned2024-01-08T17:55:43Z
dc.date.available2023-11-29T16:38:54Z
dc.date.available2024-01-08T17:55:43Z
dc.date.issued2023-12
dc.descriptionThesis (MScConsEcol)--Stellenbosch University, 2023. en_ZA
dc.description.abstractENGLISH ABSTRACT: The polyphagous shot hole borer beetle (PSHB) (Euwallacea fornicatus) (Coleoptera: Curculionidae: Scolytinae) and its primary fungal symbiont, Fusarium euwallaceae, is a pest-disease complex that has killed a wide range of tree species in multiple countries on six continents, including South Africa. As with any invasive pest, monitoring programmes reveal the drivers behind species population dynamics in invaded regions, which helps to mitigate potential impacts and inform management strategies. This study involved a 26- month monitoring programme in an urban-agricultural fringe setting of the Western Cape province, South Africa. Baited traps were used to determine activity patterns in comparison with temperature, as well as infestation dynamics over time in comparison with climatic and biological factors. Results suggest that activity is strongly temperature dependent, and numbers peak in late summer. The number of surrounding infested reproductive hosts was an important explanatory variable for increasing beetle abundance and infestation levels, while focal tree infestation “saturation”, tree stress and tree size may also play a role. Infested host tree removal may be important for agricultural areas where crops are surrounded by reproductive hosts either deliberately planted as windbreaks or growing naturally. Two prominent management strategies for invasive forest pests were trialled: tree removal and therapeutic chemical treatment. Results suggest that tree removal and appropriate disposal of infested wood can decrease local propagule pressure, especially if conducted in colder months. Furthermore, some therapeutic chemical treatments reduced fungal growth, number of new PSHB attacks, and beetle colony success, but control was never completely successful. These results indicate that a combination of physical and chemical control options may help to reduce propagule pressure, but is unlikely to prevent infestations for long periods.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die polifagiese stompkopboorder kewer (PSHB) (Euwallacea fornicatus) (Coleoptera: Curculionidae: Scolytinae) en sy primêre swamsymbiont, Fusarium euwallaceae, is 'n plaagsiektekompleks wat 'n wye verskeidenheid boomspesies in verskeie lande op ses kontinente doodgemaak het, insluitend Suid-Afrika. Soos met enige indringerplaag, help moniteringsprogrammeme om die dryfvere agter spesiebevolkingsdinamika in binnegevalle streke te openbaar, wat help om potensiële impakte te evalueer en te versag en bestuurstrategieë in te lig. Hierdie studie het 'n moniteringsprogramme van 26 maande in 'n stedelike-landbou-omgewing van die Wes-Kaap provinsie, Suid-Afrika, ingesluit. Lokvalle is gebruik om aktiwiteitspatrone te bepaal in vergelyking met temperatuur, sowel as besmettingsdinamika oor tyd in vergelyking met belangrike klimaats- en biologiese faktore. Resultate dui daarop dat aktiwiteit sterk temperatuurafhanklik is, met getalle wat in die laat somer 'n hoogtepunt bereik. Die aantal omliggende broeigashere en die aantal besmette gashere was belangrik om keweraktiviteit en besmettingsvlakke te verhoog, terwyl gasheerboom-“versadiging”, boomstres en boomgrootte ook ’n rol kan speel. Verwydering van besmette gasheerbome kan veral belangrik wees vir landbougebiede waar gewasse omring word deur reproduktiewe gashere wat óf doelbewus as windskerms geplant is óf natuurlik groei. Twee prominente bestuurstrategieë vir indringerbosplae is op hierdie studieterrein geëksperimenteer: boomverwydering en terapeutiese chemiese behandeling. Resultate dui daarop dat behoorlike boomverwydering plaaslike voortplantingsdruk kan verminder, veral as dit in kouer maande uitgevoer word. Verder het sommige terapeutiese chemiese behandelings swamgroei, aantal nuwe PSHB-aanvalle en kewerkolonie-sukses verminder, maar beheer was nooit heeltemal suksesvol nie. Hierdie resultate dui daarop dat 'n kombinasie van fisiese en chemiese beheeropsies kan help om voortplantingsdruk te verminder, maar waarskynlik nie besmettings vir lang periodes sal voorkom nie.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentxvi, 107 pages : illustrations (some color), mapsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/128977
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshPolyphagous shot hole borer beetleen_ZA
dc.subject.lcshEuwallacea fornicatusen_ZA
dc.subject.lcshTrees -- South Africa -- Western Capeen_ZA
dc.subject.lcshTrees -- Diseases and pests -- Control -- South Africa -- Western Capeen_ZA
dc.subject.lcshAmbrosia beetles -- Effect of temperature onen_ZA
dc.subject.lcshLandscape ecology -- South Africa -- Western Capeen_ZA
dc.subject.lcshUrban agriculture -- Environmental aspects -- South Africa -- Western Capeen_ZA
dc.subject.lcshClimatic changes -- South Africa -- Western Capeen_ZA
dc.subject.lcshTrees -- Effect of stress onen_ZA
dc.subject.lcshPests -- Control -- Managementen_ZA
dc.subject.lcshUCTDen_ZA
dc.titleInvestigations into the ecology and management of the polyphagous shot hole borer beetle (PSHB, Euwallacea fornicatus) in South Africaen_ZA
dc.typeThesisen_ZA
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