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Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions
Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2009.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : University of Stellenbosch
2009
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| _version_ | 1867613857485160448 |
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| access_status_str | Open Access |
| author | Stokwe, Nomakholwa Faith |
| author2 | Malan, Antoinette P. |
| author_browse | Malan, Antoinette P. Stokwe, Nomakholwa Faith |
| author_facet | Malan, Antoinette P. Stokwe, Nomakholwa Faith |
| author_sort | Stokwe, Nomakholwa Faith |
| collection | Thesis |
| dc_rights_str_mv | University of Stellenbosch |
| description | Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2009. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/2463 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:48.374Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2009 |
| publishDateRange | 2009 |
| publishDateSort | 2009 |
| publisher | Stellenbosch : University of Stellenbosch |
| publisherStr | Stellenbosch : University of Stellenbosch |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/2463 Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions Stokwe, Nomakholwa Faith Malan, Antoinette P. Addison, Pia University of Stellenbosch. Faculty of Agrisciences. Dept. of Conservation Ecology and Entomology. Entomopathogenic nematodes Mealybugs Characterization Cryopreservation Dissertations -- Conservation ecology and entomology Theses -- Conservation ecology and entomology Insect nematodes -- South Africa Mealybugs -- Biological control -- South Africa Apples -- Diseases and pests -- Biological control -- South Africa Pear -- Diseases and pests -- Biological control -- South Africa Thesis (MScAgric (Conservation Ecology and Entomology)--University of Stellenbosch, 2009. ENGLISH ABSTRACT: The obscure mealybug, Pseudococcus viburni (Signoret) (Pseudococcidae), is one of the common and serious pests of apples and pears in South Africa. The management of this pest in South Africa is dominated by the use of insecticides, while research into using natural enemies for biological control of mealybugs is still ongoing. Increasing concern over the environmental impact, pesticide residues in fruits, resistance, and expense associated with frequent use of insecticides make it necessary to investigate alternative biological control methods, such as the use of entomopathogenic nematodes, for the control of mealybugs. Entomopathogenic nematodes have proven comparable or even superior to chemicals in controlling certain insect pests, without residue problems or a harmful effect on the environment. An important aspect of using endemic nematodes includes the identification of species of nematodes and their symbiotic bacterial cells. A study was carried out to describe a new species of Steinernema, which was recovered during a previous survey in citrus orchards in three provinces of South Africa. Morphometrics, morphology, crossbreeding, drawings, light microscopy and Scanning Electron Microscopy (SEM) photographs were used to describe the new species. A cryopreservation method has been simplified and optimised for the long-term storage of Steinernema khoisanae (SF87) and Heterorhabditis zealandica (J34). Different cryoprotectants used included 15% glycerol, 8% ethylene glycol and 8% dimethyl sulfoxide (DMSO), in which S. khoisanae was incubated at room temperature for periods of two, three, four and five days, followed by a methanol wash. An optimum survival rate of 69% was obtained for S. khoisanae after a four-day incubation period in 15% glycerol. This technique has been used for the cryopreservation of H. zealandica, with a 78% survival rate. The thawed nematodes of both species were able to infect Galleria mellonella larvae after 42 days of cryopreservation (-196ºC) and were able to complete their life cycles. AFRIKAANSE OPSOMMING: Die ligrooswitluis, Pseudococcus viburni (Signoret) (Pseudococcidae), is een van die algemene en ernstige peste van appels en pere in Suid-Afrika. Die bestuur van hierdie pes word tans in Suid-Afrika deur die gebruik van insekdoders gedomineer terwyl navorsing oor die gebruik van natuurlike vyande vir die beheer van P. viburni nog aan die gang is. Die verhoogde kommer oor die omgewing, residue in vrugte, weerstand, en die koste verbonde aan die gereelde gebruik van chemiese middels maak dit nodig om alternatiewe biologiese metodes van beheer, soos die gebruik van entomopatogeniese nematodes vir die beheer van witluis, te ondersoek. In ander lande is reeds aangetoon dat entomopatogeniese nematodes onder sekere omstandighede en vir sekere insekte gelykwaardige of selfs beter beheer kan gee as chemiese middels. ʼn Belangrike aspek van die gebruik van endemiese nematodes vir die beheer van insekte sluit die korrekte identifikasie van die spesies met hul geassosieerde bakteriese simbionte in. ʼn Nuwe spesie van Steinernema is uit ʼn vorige opname van entomopatogeniese nematodes in sitrusboorde in drie provinsies van Suid-Afrika geïsoleer. Morfometrie, morfologie, kruisteling, ligmikroskoop en SEM fotografie is gebruik om ʼn nuwe spesies te beskryf. ʼn Kriopreserveringsmetode is ontwikkel en ge-optimaliseer vir die langtermyn bewaring van Steinernema khoisanae (SF87) en Heterorhabditis zealandica (J34). Verskillende kriobeskermingsmiddels insluitend 15% gliserol, 8% dimetiel sulfokied (DMSO) en 8% etileen glikol, waarin S. khoisanae vir periodes van twee, drie, vier, en vyf dae geïnkubeer is, is teen kamertemperatuur, getoets, gevolg deur ʼn metanolbad. Optimum oorlewing van 69% is verkry vir S. khoisanae nadat die infektiewe larwes (IJ) vir vier dae in 15% gliserol gehou is. Hierdie tegniek is ook toegepas op H. zealandica, met 78% oorlewing van die IJ. Die ontvriesde nematodes van beide spesies was in staat om Galleria mellonella larwes suksesvol te infekteer en hulle lewensiklus te voltooi nadat hulle vir 45 dae onder kriopreservering gehou is teen -196ºC. Masters 2009-11-25T11:01:33Z 2010-06-01T08:49:22Z 2009-11-25T11:01:33Z 2010-06-01T08:49:22Z 2009-12 Thesis http://hdl.handle.net/10019.1/2463 en_ZA University of Stellenbosch application/pdf Stellenbosch : University of Stellenbosch |
| spellingShingle | Entomopathogenic nematodes Mealybugs Characterization Cryopreservation Dissertations -- Conservation ecology and entomology Theses -- Conservation ecology and entomology Insect nematodes -- South Africa Mealybugs -- Biological control -- South Africa Apples -- Diseases and pests -- Biological control -- South Africa Pear -- Diseases and pests -- Biological control -- South Africa Stokwe, Nomakholwa Faith Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title | Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title_full | Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title_fullStr | Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title_full_unstemmed | Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title_short | Entomopathogenic nematodes : characterization of a new species, long–term storage and control of obscure mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae) under laboratory conditions |
| title_sort | entomopathogenic nematodes characterization of a new species long term storage and control of obscure mealybug pseudococcus viburni hemiptera pseudococcidae under laboratory conditions |
| topic | Entomopathogenic nematodes Mealybugs Characterization Cryopreservation Dissertations -- Conservation ecology and entomology Theses -- Conservation ecology and entomology Insect nematodes -- South Africa Mealybugs -- Biological control -- South Africa Apples -- Diseases and pests -- Biological control -- South Africa Pear -- Diseases and pests -- Biological control -- South Africa |
| url | http://hdl.handle.net/10019.1/2463 |
| work_keys_str_mv | AT stokwenomakholwafaith entomopathogenicnematodescharacterizationofanewspecieslongtermstorageandcontrolofobscuremealybugpseudococcusviburnihemipterapseudococcidaeunderlaboratoryconditions |