Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control
Thesis (PhD (Genetics))--University of Pretoria, 2024.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2024
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613522763972608 |
|---|---|
| access_status_str | Open Access |
| author2 | Slippers, Bernard |
| author_browse | Slippers, Bernard |
| author_facet | Slippers, Bernard |
| collection | Thesis |
| dc_rights_str_mv | © 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD (Genetics))--University of Pretoria, 2024. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/95423 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:29.594Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/95423 Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control Slippers, Bernard fire.eshetu@fabi.up.ac.za Barnes, Irene Nahrung, Helen Eshetu, Firehiwot Birhane Biological control nematode Insect-fungus co-invasion Nematode-fungus compatibility Population genetics Symbiosis UCTD SDG-12: Responsible consumption and production Natural and agricultural sciences theses SDG-12 Thesis (PhD (Genetics))--University of Pretoria, 2024. The joint invasion of Sirex noctilio and its symbiotic fungus Amylostereum areolatum has threatened pine plantations in Australasia, and many other countries worldwide. The biological control nematode Deladenus siricidicola has been used to manage the populations of this pest complex for over 60 years. This thesis examined levels of genetic diversity, population structure and introduction history of the S. noctilio-A. areolatum-D. siricidicola populations in Australia and New Zealand, in comparison to global populations in the native and introduced regions. To gain insight into any potential ‘strains’ that may contribute to variable biocontrol success I further examined the reproductive rates of nematode diversity in Australia on different fungal strains and media types. Mitochondrial (mtCOI and mtSSU rRNA) sequence data and microsatellite markers were applied in the population genetics studies. This study identified unexpected diversity of D. siricidicola in Australia and New Zealand. Apart from the extensive diversity of known lineages (A, B and C) of the nematode, a previously unknown (lineage D) was discovered. The shared history between D. siricidicola populations in New Zealand and North America was unexpected. The higher-than-expected diversity suggests multiple introductions over time that have influenced these populations (either assisted or accidental), which increases the potential for the evolution of these populations. I found nonaligned diversity between the insect-fungal joint invasion in Australia and New Zealand, showing a similar pattern to previous studies. The diversity between the populations of S. noctilio was unique. Compared to other introduced populations worldwide, lower genetic diversity was found in Australasia, and there was no structure in populations between Australia and New Zealand. I was also in a unique position to compare the current populations of S. noctilio to that of museum collections in Australia and New Zealand. These collections of S. noctilio illustrated the link between the current and historical populations, but there was also a distinct shift evident in the diversity, likely due to the genetic drift in the population. Unlike the S. noctilio populations, widespread clonal populations of A. areolatum were found in the field in Australia and New Zealand, which formed a cluster distinct from fungal populations in all other countries. The high level of clonality in the A. areolatum population could be exploited for the management program using the nematode by rearing the nematode on the dominant clone. The behavioral study between the lineages B and D strains of D. siricidicola indicates significant variation in the reproductive rates when feeding on four different fungal strains and two media types. Lineage D strains show higher reproductive rates than the Kamona strain and other strains in lineage B, on all treatments in our trials. Taken together, the diversity identified in D. siricidicola populations in this thesis underscores the importance of post-release monitoring in the biocontrol program. The diversity of the D. siricidicola population in this thesis has significant consequences to re-visit applications of the biological control program. At the same time, the diversity results in the woodwasp and the fungus populations reflects an efficient quarantine system in recent decades, that isolated the woodwasp-fungal populations and reduced their complexity compared to other parts of the world. The Australian National Sirex Co-ordination Committee (NSCC) The Tree Protection Co-operative Programme (TPCP) at the Forestry and Agricultural Biotechnology Institute (FABI) of the University of Pretoria Forestry and Agricultural Biotechnology Institute (FABI) PhD (Genetics) Unrestricted Faculty of Natural and Agricultural Sciences SDG-12: Responsible consumption and production 2024-04-02T08:59:40Z 2024-04-02T08:59:40Z 2024-09 2024-03-29 Dissertation *In this thesis, Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control, the candidate studied the population genetics of an invasive woodwasp Sirex noctilio, its symbiotic fungus, Amylostereum areolatum, and their biological control agent, the nematode Deladenus siricidicola, in Australasia. The study collates an unprecedented collection of these organisms, including historical samples dating back to 1952, and compares them to the known global genetic diversity. The results show, for example, lower genetic diversity and the lack of population structure in the S. noctilio and A. areolatum populations in Australasia. Unexpectedly the study uncovered high genetic diversity of D. siricidicola in Australasia that included a novel lineage. The candidate further illustrated the influence of nematode-fungus diversity on the nematode reproductive traits and its consequences for the success of the Sirex biocontrol program. The results presented in this thesis have significant implications for improving the management program that uses D. siricidicola to control S. noctilio's impact on Pinus plantations globally. S2024 http://hdl.handle.net/2263/95423 DOI: https://doi.org/10.25403/UPresearchdata.25506832.v1 https://doi.org/10.25403/UPresearchdata.25506832 en © 2023 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Biological control nematode Insect-fungus co-invasion Nematode-fungus compatibility Population genetics Symbiosis UCTD SDG-12: Responsible consumption and production Natural and agricultural sciences theses SDG-12 Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title | Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title_full | Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title_fullStr | Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title_full_unstemmed | Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title_short | Diversity in Sirex noctilio, Amylostereum areolatum and Deladenus siricidicola populations in Australasia and its implications for biological control |
| title_sort | diversity in sirex noctilio amylostereum areolatum and deladenus siricidicola populations in australasia and its implications for biological control |
| topic | Biological control nematode Insect-fungus co-invasion Nematode-fungus compatibility Population genetics Symbiosis UCTD SDG-12: Responsible consumption and production Natural and agricultural sciences theses SDG-12 |
| url | http://hdl.handle.net/2263/95423 https://doi.org/10.25403/UPresearchdata.25506832 |