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The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata
Thesis (MScConsEcol)--Stellenbosch University, 2026.
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Stellenbosch : Stellenbosch University
2026
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| access_status_str | Open Access |
| author | Dlamini, Simphiwe Ntombikhona |
| author2 | Stokwe, Nomakholwa Faith |
| author_browse | Dlamini, Simphiwe Ntombikhona Stokwe, Nomakholwa Faith |
| author_facet | Stokwe, Nomakholwa Faith Dlamini, Simphiwe Ntombikhona |
| author_sort | Dlamini, Simphiwe Ntombikhona |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MScConsEcol)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/135748 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-07-01T04:11:33.102Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/135748 The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata Dlamini, Simphiwe Ntombikhona Stokwe, Nomakholwa Faith Mathulwe, Letodi Luki Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. Mediterranean fruit fly -- South Africa Mediterranean fruit-fly -- Biological control Fruit -- Diseases and pests -- Control -- Environmental aspects Metarhizium Entomopathogenic fungi UCTD Thesis (MScConsEcol)--Stellenbosch University, 2026. Dlamini, S. N. 2026. The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/890e6948-4721-4ea3-8df8-8321603e6c90 ENGLISH ABSTRACT: The Mediterranean fruit fly (medfly), Ceratitis capitata Wiedemann (Diptera: Tephritidae), is an economically important and invasive agricultural insect pest affecting fruit production including citrus fruits. Females of C. capitata oviposition beneath the fruit skin and the hatched larvae feed on the fruit pulp. Feeding results in fruit damage and reduces both the fruit yield and quality. The presence of C. capitata on export consignments affects the marketability of the fruit due to strict phytosanitary measures and often results in rejection of the produce in C. capitata free status countries. Current management techniques of C. capitata in citrus fruit orchards include the use of both chemical and biological control, and the sterile‑insect technique (SIT). However, some of the management techniques have proven to be ineffective and the use of certain synthetic chemical insecticides is prohibited. Therefore, there is a need to develop alternative and effective management strategies to control the presence of C. capitata in citrus orchards. Entomopathogenic fungi (EPF) have previously proven to be effective biological control agents of various agricultural insect pests. The main aim of this study was to investigate the efficacy of three South African EPF isolates of the Metarhizium species complex, Metarhizium robertsii (6EIKEN), M. majus (TH152) and M. pinghaense (5HEID), as potential biological control agents of C. capitata. The pathogenicity of the isolates was tested against third instar larvae, pupae, and adults of C. capitata under both laboratory and semi-field conditions. Under laboratory conditions, at a conidial concentration of 1 × 10⁷ conidia/mL, M. majus (TH152) induced the highest mortality rate against the medfly larvae (62% ± 16%) (mean± SD). For the pupae and adult stage, M. pinghaense (5HEID) proved to be the most effective isolate (58% ± 16%) and (89% ± 17%), respectively. The infective conidia of the most effective isolates for each life stage of C. capitata were mass-produced using rice grains and formulated using canola oil as a carrier material. The viability of the formulated conidia was tested over a period of eight weeks. The oil formulated conidia was observed to maintain a viability of > 80% at week eight for both M. majus (TH152) and M. pinghaense (5HEID). The effect of changes in temperature on the efficacy of the formulated conidia against C. capitata was evaluated under three temperature conditions (15°C, 25°C, and 35°C) using sand-bioassays. This study showed that with an increase in temperature (25°C and 35°C) the isolates induced the highest mortality rates for the larvae and adults. For the pupae, the highest insect mortality rate was recorded at 15°C and 35°C compared to 25°C. Further evaluation of the efficacy of the oil formulated conidia of M. majus (TH152) and M. pinghaense (5HEID) against C. capitata under semi-field conditions, during the winter and spring seasons, showed that for both winter and spring, M. majus (TH152) was the most effective isolate against the larvae (76% and 87%). For the pupae and adults, M. pinghaense (5HEID) was the most effective isolate for winter (73% and 79%, respectively) and spring (91% and 97%, respectively). Both M. majus (TH152) and M. pinghaense (5HEID) proved to be effective biological control agents of C. capitata under both laboratory and semi-field conditions. The efficacy of the oil formulated conidia of both isolates against the various life stages of C. capitata should be further evaluated under large scale commercial production for extended periods of time in citrus orchards. AFRIKAANSE OPSOMMING: Die Meditereense vrugtevlieg, Ceratitis capitata Weidemann (Diptera: Tephritidae), is ‘n ekonomiese belangrike indringer pes in die landbou-sektor wat vrugte produksie, soos sitrus negatief beïnvloed. Die wyfie van C. Capitata lê eiers onder die huid van die vrug en die uitgebroeide larwe voed op die vrug pulp. Die voeding lei tot die beskadiging van die vrug, wat beide die opbrengs en kwaliteit van die vrugte beïnvloed. Streng fito-sanitêre maatreëls verhoed die uitvoer van vrugte met die teenwoordigheid van C. capitata veral in lande waar die pes nie voorkom nie. Huidige bestuurstegnieke van C. capitata in sitrusboorde sluit die gebruik van beide chemiese en biologies beheer in, asook die steriele-insek tegniek (SIT). Alhoewel goeie Beheer-tegnieke ingestel kan word, is daar egter steeds sommige tegnieke wat as oneffektief beskou word en die gebruik van seker sintetiese insektisiede is reeds verband. Daarom is dit noodsaaklik om ‘n alternatiewe, effektiewe beheer strategie te onwikkel vir die teenwoordigheid van C. Capitata in sitrusboorde. Entomopatogeniese fungi (EPF) het in die verlede alreeds bewys dat dit ‘n effektiewe biologiese beheer strategie is teen verskeie landbou-verwante peste. Die hoof doel van hierdie studie was om ondersoek in te stel teen die effektiwiteit van drie Suid-Afrikaanse EPF-isolate van die Metarhizium-spesie kompleks (Metarhizium robertsii (6EIKEN), M. majus (TH152) en M. pinghaense (5HEID), as potensiële biologiese beheer agente teen C. Capitata. Die patogenisiteit van die isolate was getoets teen die derde-instar larwe, papies en volwasse stadia van C. Capitata onder beide laboratorium en semi-veld kondisies. Onder laboratorium kondisies by ‘n konidiale-konsentrasie van 1 x 107 kondia/mL, het die isolaat M. majus (TH152) die hoogste mortaliteit Gehad teen C. capitata larwe (62% ± 16%) (mean± SD). Vir beide die papie en volwasse stadia was die isolaat M. pinghaense (5HEID) die meeste effektief (58% ± 16%) en (89% ± 17%), onderskeidelik. Die mees infektiewe kondia van die mees effektiewe isolate vir elke lewens-stadia van C. Capitata was op groot skaal vervaardig deur die gebruik van ryskorrels en geformuleer deur die gebruik van kanola olie as oordrag materiaal. Die lewensvatbaarheid van die geformuleerde konidia is oor 'n tydperk van agt weke getoets. Die olie-geformuleerde konidia het 'n lewensvatbaarheid van > 80% bereik teen week agt vir beide M. majus (TH152) en M. pinghaense (5HEID). Die effek van temperatuurveranderinge op die doeltreffendheid van die geformuleerde konidia teen C. capitata is onder drie temperatuurtoestande (15°C, 25°C en 35°C) geëvalueer met behulp van sand-bio-assays. Hierdie studie het getoon dat met 'n toename in temperatuur (25°C en 35°C) het die isolate die hoogste mortaliteitsyfers vir die larwes veroorsaak. Vir die papies is die hoogste insek mortaliteitsyfer aangeteken by 15°C en 35°C in vergelyking met 25°C. Verdere evaluering van die doeltreffendheid van die olie-geformuleerde konidia van M. majus (TH152) en M. pinghaense (5HEID) teen C. capitata onder semi-veld toestande, gedurende die winter- en lenteseisoene, het getoon dat M. majus (TH152) vir beide die winter en lente die mees effektiewe isolaat teen die larwes was (76% en 87%). Vir die papies en volwassenes was M. pinghaense (5HEID) die mees effektiewe isolaat onder winter-toestande (onderskeidelik 73% en 79%) asook lente-toestande (onderskeidelik 91% en 97%). Beide M. majus (TH152) en M. pinghaense (5HEID) bewys die effektiwiteit van die EPF’s as biologiese beheermiddels van C. capitata onder beide laboratorium- en semi-veld toestande. Die doeltreffendheid van die olie-geformuleerde konidia van beide isolate teen die verskillende lewensfases van C. capitata moet egter verder geëvalueer word onder grootskaalse kommersiële produksie vir lang tydperke in sitrusboorde. Masters 2026-04-09T08:10:27Z 2026-04-09T08:10:27Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/135748 en Stellenbosch University xvi, 97 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Mediterranean fruit fly -- South Africa Mediterranean fruit-fly -- Biological control Fruit -- Diseases and pests -- Control -- Environmental aspects Metarhizium Entomopathogenic fungi UCTD Dlamini, Simphiwe Ntombikhona The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title | The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title_full | The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title_fullStr | The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title_full_unstemmed | The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title_short | The efficacy of South African entomopathogenic fungi isolates against immature and mature stages of the Mediterranean fruit fly, Ceratitis capitata |
| title_sort | efficacy of south african entomopathogenic fungi isolates against immature and mature stages of the mediterranean fruit fly ceratitis capitata |
| topic | Mediterranean fruit fly -- South Africa Mediterranean fruit-fly -- Biological control Fruit -- Diseases and pests -- Control -- Environmental aspects Metarhizium Entomopathogenic fungi UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/135748 |
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