Title page for ETD etd-10232010-133746


Document Type Doctoral Thesis
Author Hurley, Brett Phillip
Email bret.hurley@fabi.up.ac.za
URN etd-10232010-133746
Document Title Factors influencing the control of the Sirex woodwasp in South Africa
Degree PhD
Department Zoology and Entomology
Supervisor
Advisor Name Title
Prof M J Wingfield Co-Supervisor
Prof B Slippers Supervisor
Keywords
  • biological control
  • Pinus plantations
  • Sirex noctilio
  • woodwasp
Date 2010-09-02
Availability unrestricted
Abstract
The woodwasp Sirex noctilio is one of the most serious invasive pests of Pinus plantations in the southern hemisphere. Extensive control programs have been developed to manage this pest, of which biological control has been a major component. This thesis examined the factors that could influence the control of S. noctilio in South Africa. A critical comparison of S. noctilio infestations and control efforts throughout the southern hemisphere revealed that control has not been uniformly effective, and local adaptation of control strategies is likely required as S. noctilio moves to new areas. The parasitic nematode Deladenus siricidicola is considered the primary biological control agent of S. noctilio. This nematode also feeds on the fungal symbiont of S. noctilio, Amylostereum areolatum. Possible factors influencing the success of this nematode in the summer rainfall areas of South Africa were examined. Data from a field trial revealed that moisture content of the wood influences inoculation success and this is influenced by the time of inoculation and the section of the tree inoculated. Laboratory-based assays revealed that incompatibility between the strain of A. areolatum and D. siricidicola was unlikely to be the cause of low inoculation success with the nematode, but that artificial inoculations could be affected by competition of A. areolatum with sapstain fungi. The parasitic wasp Ibalia leucospoides is another biological agent for S. noctilio. Mitochondrial and nuclear DNA sequence data reflected the extensive introduction of I. leucospoides into the southern hemisphere, followed by genetic bottlenecks that fixed only a few haplotypes in the introduced populations. Promoting awareness of S. noctilio in the forestry community has also been an important component of the control strategy. Data from a survey questionnaire showed that the awareness campaign had been generally successful, but the lack of basic knowledge to identify S. noctilio and its symptoms and the poor reach of the awareness media to some sectors of the forestry community, was of concern. This thesis has contributed towards understanding the factors that influence the control of S. noctilio in South Africa, with relevance to other regions where S. noctilio has been introduced.

2010 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.

Please cite as follows:

Hurley, BP 2010, Factors influencing the control of the Sirex woodwasp in South Africa , PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10232010-133746/ >

D10/714/ag

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