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Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds
Includes bibliographical references (leaves 78-94).
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Biological Sciences
2014
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| _version_ | 1867613732814716928 |
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| access_status_str | Open Access |
| author | Impson, F A C |
| author2 | Hoffmann, John |
| author_browse | Hoffmann, John Impson, F A C |
| author_facet | Hoffmann, John Impson, F A C |
| author_sort | Impson, F A C |
| collection | Thesis |
| description | Includes bibliographical references (leaves 78-94). |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/6272 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:40:49.953Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2014 |
| publishDateRange | 2014 |
| publishDateSort | 2014 |
| publisher | Department of Biological Sciences |
| publisherStr | Department of Biological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/6272 Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds Impson, F A C Hoffmann, John Moran, Cliff Zoology Includes bibliographical references (leaves 78-94). Acacia cyclops A. Cunn ex G. Don, or rooikrans (Fabaceae), of Australian origin, is an invasive environmental weed in South Africa where it threatens the unique vegetation of the Cape Floral Kingdom. The invasiveness of the plant in South Africa is, in part, due to its high annual seed-yields, together with the suitable climatic and edaphic factors found here. This study investigated the role of a seed-feeding weevil, Melanterius servulus, which was first introduced into South Africa during 1991, as a biological control agent of A. cyclops seeds, together with the combined effects of indigenous seed-sucking bugs and birds. The weevils utilise filled green pods of A. cyclops for adult feeding, oviposition and larval development and completely destroy seeds during these activities. Examination of the reproductive phenology of A. cyclops showed that seeds are produced annually, during summer and that the presence of filled green pods on the plants coincides with the period of reproductive activity of the weevils. Melanterius servulus populations have established readily at all the original release sites, and within four years of release, damage levels to seeds commonly reached 90%. The weevils have dispersed at an average rate of approximately 2 km per year. Since becoming established in South Africa. the seeds of A. cyclops have been utilised by a variety of generalist vertebrate and invertebrate organisms. Indigenous polyphagous alydid bugs feed on the mature seeds, rendering a portion of the crop inviable when damage levels are high (more than five feeding-punctures per seed). Several bird species are attracted to and feed on the fleshy aril that surrounds theseeds of A. cyclops. Passage of the seeds through the gut of birds enhances germination rates. There is a synergetic relationship between alydids and birds because seeds with low levels of alydid feeding (one to four punctures per seed) germinated more readily after passage through birds than seeds that were not eaten by birds. 2014-08-13T14:21:02Z 2014-08-13T14:21:02Z 2005 Master Thesis Masters MSc http://hdl.handle.net/11427/6272 eng application/pdf Department of Biological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Zoology Impson, F A C Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| thesis_degree_str | Master's |
| title | Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| title_full | Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| title_fullStr | Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| title_full_unstemmed | Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| title_short | Biological control of Acacia cyclops in South Africa : the role of an introduced seed-feeding weevil, Melanterius servulus (Coleoptera: Curculionidae), together with indigenous seed-sucking bugs and birds |
| title_sort | biological control of acacia cyclops in south africa the role of an introduced seed feeding weevil melanterius servulus coleoptera curculionidae together with indigenous seed sucking bugs and birds |
| topic | Zoology |
| url | http://hdl.handle.net/11427/6272 |
| work_keys_str_mv | AT impsonfac biologicalcontrolofacaciacyclopsinsouthafricatheroleofanintroducedseedfeedingweevilmelanteriusservuluscoleopteracurculionidaetogetherwithindigenousseedsuckingbugsandbirds |