Ring nematode (Criconemoides xenoplax), distribution, characterisation and culture methods
| dc.contributor.advisor | Malan, Antoinette P. | en_ZA |
| dc.contributor.advisor | Storey, Sheila G. | en_ZA |
| dc.contributor.author | Odendaal, Maryna | en_ZA |
| dc.contributor.other | Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology. | en_ZA |
| dc.date.accessioned | 2018-02-06T12:08:56Z | |
| dc.date.accessioned | 2018-04-09T06:51:24Z | |
| dc.date.available | 2018-02-06T12:08:56Z | |
| dc.date.available | 2018-04-09T06:51:24Z | |
| dc.date.issued | 2018-03 | |
| dc.description | Thesis (MScConsEcol)--Stellenbosch University, 2018. | en_ZA |
| dc.description.abstract | ENGLISH ABSTRACT: The ring nematode, Criconemoides xenoplax (Raski, 1952) Loof & De Grisse, is described as a migratory ectoparasitic nematode that feeds entirely on the roots of plants, mainly those of woody perennials. The ring nematode is regarded, worldwide, as a significant pest in stone fruit orchards and vineyards, and it has become a common soil pest in South African production areas. To determine the distribution of the ring nematode, a survey was conducted in grapevine and stone fruit production areas, in both the Western and Northern Cape provinces. Nematode specimens collected during the study were characterised morphometrically and molecularly to determine the ring nematode species present in the areas. Soil samples were obtained from randomly selected farms, with additional data acquired from the diagnostic laboratory, Nemlab (Klapmuts, Paarl, Western Cape province), being investigated in relation to ring nematode occurrence in soil samples from the stone fruit and grapevine areas. After DNA characterisation of the Internal Transcribed Spacer (ITS) region and the study of the morphology of the ring nematodes collected, the most abundant ring nematode species present in the stone fruit and grapevine production areas was concluded to be C. xenoplax. Another unknown species of ring nematode was recovered at a single site during the course of the study. Criconemoides xenoplax occurred in all the soil samples obtained during the survey, with nematode numbers ranging from 20 to > 2000 individuals per 250 ml of soil. Criconemoides xenoplax infestation in South Africa shows similar trends, as have been observed globally, demonstrating its importance as an economically significant pest. It is, therefore, essential to develop alternative management options to minimise the amount of damage incurred, and to manage C. xenoplax in the areas concerned, to sustain production. Control of the ring nematode is difficult and is highly dependent on the use of chemicals. Alternative, more sustainable and eco-friendly management options, such as the use of resistant rootstocks in the grapevine and stone fruit industries, have become common practice. Six commercially available grapevine rootstocks were assessed for their susceptibility to C. xenoplax in a glasshouse pot trial. Additional data, from routine grapevine soil samples analysed by Nemlab, were used in conjunction with the glasshouse trial data. Grapevine rootstock susceptibility was evaluated by taking into account the reproductive factor (RF), and the nematode numbers recovered in the soil of the different rootstocks. The results of the glasshouse trial indicated a significant difference in grapevine rootstock susceptibility to C. xenoplax. Ring nematode numbers were recorded to be highest on the rootstock 110 Richter for both trials conducted in the glasshouse, whereas rootstocks 1103 Paulsen and 140 Ruggeri performance remained similar in both trials. Contrasting results were recorded between the 99 Richter and Ramsey rootstocks in the two trials, with Ramsey showing higher resistance than 99 Richter in the first trial, yet a lower resistance than 99 Richter in the second trial. The data analysed from Nemlab samples showed that the C. xenoplax numbers were generally higher from the field samples evaluated during the study. Further studies are required to further examine rootstock resistance to C. xenoplax. To do the above, however, a reliable source of C. xenoplax cultures needs to be available for future studies. In addition to its preferred hosts, being grapevine and stone fruit, C. xenoplax has also been recorded on a variety of other plant species. Five annuals, specifically tomato (Lycopersicon esculentum), lettuce (Lactuca sativa), mint (Mentha), carnation (Dianthus caryophyllus), white clover (Trifolium repens), and sweetcorn (Zea mays var. saccharata), were investigated in a glasshouse trial. The investigation was conducted to determine whether a monoxenic C. xenoplax population could be cultured en masse on alternative hosts, thus providing a more successful and rapid method of culturing the nematodes for future use. Criconemoides xenoplax was used to inoculate the host plants selected six weeks after replanting the seedlings, where after the plants were left for a duration of seven weeks to allow for nematode reproduction. None of the annual hosts tested during the trial were considered a suitable host for the nematode, as no increases in the population were observed for the duration of the trial. As the RF values calculated were all below 1, using these annuals as an alternative option to culture C. xenoplax is not a viable option for future experiments. The use of grapevine and stone fruit plants should, as a result, remain the primary hosts for the sustained ring nematode populations in culture, with grapevine being the preferred host. To conclude, C. xenoplax is a significant nematode that requires more research in South Africa. Doing so would enhance the understanding and amount of knowledge pertaining to the biology of such an economically important pest, as well as promoting the understanding of future host damage and plant resistance. The above mentioned will be critical for the employment of efficient control methods to manage nematode populations in the future. | en_ZA |
| dc.description.abstract | AFRIKAANSE OPSOMMING: Die ringaalwurm, Criconemoides xenoplax (Raski, 1952), Loof & De Grisse, word beskryf as 'n migrerende ektoparasitiese nematode wat hoofsaaklik op plantwortels van houtagtige meerjarige plante voed. Die ringaalwurm word wêreldwyd beskou as 'n beduidende plaag in steenvrugteboorde en wingerde, en dit het 'n algemene probleem in Suid-Afrikaanse produksiegebiede geword. Om die verspreiding van die ringaalwurm te bepaal, is 'n opname in wingerd- en steenvrugte produksiegebiede in beide die Wes- en Noord-Kaap provinsies uitgevoer. Grondmonsters is verkry deur lukraak geselekteerde plase te selekteer. Addisionele data wat ontvang was van die diagnostiese laboratorium, Nemlab, was ook ondersoek in verband met ringaalwurm voorkoms vanuit steenvrugte en wingerd gebiede. Ringaalwurms wat tydens die studie versamel is, is morfologies en molekulêr gekarakteriseer. Na die DNS karakterisering van die ITS-streek asook die morfologiese studie, is dit bevind dat C. xenoplax die volopste ringaalwurm spesie is wat voorkom in die steenvrugte- en wingerdproduksiegebiede. Gedurende die studie is 'n onbekende ring-aalwurmspesie in een monster gevind. Criconemoides xenoplax het in 100% van die grondmonsters voorgekom wat tydens die opname versamel is, met aalwurm getalle wat gewissel het tussen 20 tot > 2000 individue per 250 ml grond. Met betrekking tot C. xenoplax besmetting, toon Suid-Afrika soortgelyke patrone as wat wêreldwyd gevind is en bewys dus die erns van die nematode as ʼn ekonomies beduidende plaag. Om produksie te volhou, is dit noodsaaklik om alternatiewe bestuurs opsies te ontwikkel, wat ringaalwurm skade verminder deur die pes in die betrokke gebiede effektief te bestuur. Die beheer van die ringaalwurm is 'n uitdagende taak, wat tans afhanklik is van die gebruik van chemikalieë. Alternatiewe bestuurs opsies, soos die gebruik van weerstandbiedende onderstokke in die wingerd- en steenvrugbedrywe, word meer geskik beskou weens hulle meer volhoubare en omgewingsvriendelike eienskappe. Die vatbaarheid van ses kommersiële beskikbare wingerd onderstokke vir C. xenoplax was geassesseer, in 'n glashuis pot proef. Bykomende data, wat verkry is tydens Nemlab se roetine analise van wingerd grondmonsters, is saam met die glashuisproef inligting gebruik. Onderstok vatbaarheid is geëvalueer deur die vermeerderings faktor (RF), en die aalwurm getalle wat in die grond van die verskillende onderstokke gevind was, in ag te neem. Die resultate van die glashuisproef het 'n beduidende verskil in onderstok vatbaarheid vir C. xenoplax getoon. In albei glashuis proewe, was die hoogste ringaalwurm getalle gevind op die 110 Richter onderstok, terwyl die 1103 Paulsen en 140 Ruggeri onderstokke soortgelyk presteer het in beide proewe. Die 99 Richter en Ramsey onderstokke het egter kontrasterende uitslae getoon tussen die twee eksperimente, met Ramsey wat meer weerstand gebied het teen die ringaalwurm in die eerste eksperiment, maar wel laer weerstand gebied het teenoor 99 Richter in die tweede eksperiment. Die data wat ontleed is vanuit die Nemlab monsters, het getoon dat die C. xenoplax getalle oor die algemeen hoër was as dié wat tydens die veldmonsterstudie geëvalueer is. Verdere studies word benodig om die onderstamweerstand teen C. xenoplax te bepaal. Om die bogenoemde te kan uitvoer, moet 'n betroubare bron van C. xenoplax kulture beskikbaar wees vir toekomstige studies. Benewens sy voorkeurgashere wat wingerd en steenvrugte is, is gevind dat C. xenoplax ook op 'n verskeidenheid van ander plantspesies voorkom. Vyf eenjarige gewasse, spesifiek tamatie (Lycopersicon esculentum), blaarslaai (Lactuca sativa), kruisement (Mentha), angelier (Dianthus caryophyllus), wit klawer (Trifolium repens) en suikermielies (Zea mays var. Saccharata), is in 'n glashuis ondersoek. Die ondersoek is uitgevoer om vas te stel of 'n monokultuur C. xenoplax bevolking op alternatiewe gashere gekweek kan word, en sodoende 'n meer suksesvolle en vinnige metode te voorsien om die nematodes te kweek vir toekomstige gebruik. Criconemoides xenoplax is gebruik om gasheer plante, wat ses weke na die herplanting van die saailinge gekies is, te inokuleer, waarna die plante vir sewe weke in ʼn glashuis gelaat is om aalwurm voorplanting te bevorder. Geen van die jaarlikse gashere wat tydens die proef getoets was, word beskou as 'n geskikte gasheer vir die ringaalwurm nie, aangesien geen toename in die bevolking vir die duur van die eksperiment waargeneem is nie. Aangesien die berekende RF waardes almal onder 1 was, bewys dit dat hierdie jaarlikse plante nie as 'n alternatiewe opsie vir die kultuur van C. xenoplax gebruik kan word vir toekomstige eksperimente nie. Die gebruik van wingerd- en steenvrugplante, moet gevolglik die primêre gashere bly vir die aanteling van ringaalwurms, met wingerd wat beskou word as die voorkeur gasheer. Ten laaste, C. xenoplax is 'n problematiese plantparasitiese nematode en vereis dat meer navorsing op die pes gedoen moet word in Suid-Afrika. Verdere navorsing sal die insig en kennis, aangaande die biologie van die ekonomiese belangrike plaag verbeter, asook die kennis van toekomstige gasheerskade en plantweerstand bevorder. Om aalwurmbevolkings in die toekoms te bestuur, is die bogenoemde krities om doeltreffende beheermaatreëls te handhaaf. | af_ZA |
| dc.format.extent | 120 pages : illustrations, map | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/10019.1/103269 | |
| dc.language.iso | en_ZA | en_ZA |
| dc.publisher | Stellenbosch : Stellenbosch University | en_ZA |
| dc.rights.holder | Stellenbosch University | en_ZA |
| dc.subject | Ring Nematode (Criconemoides xenoplax) -- Western Province. | en_ZA |
| dc.subject | Ring nematode -- Distribution | en_ZA |
| dc.subject | Ring nematode -- Characterisation | en_ZA |
| dc.subject | UCTD | en_ZA |
| dc.subject | Ring nematode (Criconemoides xenoplax) -- Northern Cape province | en_ZA |
| dc.subject | Fruit -- Diseases and pests | en_ZA |
| dc.title | Ring nematode (Criconemoides xenoplax), distribution, characterisation and culture methods | en_ZA |
| dc.type | Thesis | en_ZA |