Research@Lincoln
    • Login
     
    View Item 
    •   Research@Lincoln Home
    • Theses and Dissertations
    • Theses and Dissertations with Restricted Access
    • View Item
    •   Research@Lincoln Home
    • Theses and Dissertations
    • Theses and Dissertations with Restricted Access
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Intraspecific variation in Microctonus hyperdoae and M. aethipopides (Hymenoptera: Braconidae); significance for their use of biological control agents

    Phillips, Craig B.
    Abstract
    Microctonus aethiopoides Loan and M. hyperodae Loan (Hymenoptera: Braconidae; Euphorinae) are parasitoids introduced to New Zealand to assist suppression of the lucerne pest Sitona discoideus Gyllenhal and the pasture pest Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae) respectively. Morphological variation in adults of M. aethiopoides was examined as a means of measuring genetic variation. The extent of genotypic variation in M. aethiopoides could not be readily ascertained using morphology because morphological variation in adults reared from different host species was not due to genetic differences. Rather, morphological variation in M. aethiopoides was accounted for by effects of factors such as host size and nutritive quality on adult parasitoid morphology. Some previously accepted evidence for the existence of genetic differences between M. aethiopoides populations is, therefore, questionable. Morphological variation in M. hyperodae adults derived from eight diverse South American locations was examined. Morphological differences between M. hyperodae reared from one host species under controlled conditions indicated genetic variation between some of the geographic populations. However, no between-population variation was found during examination of larval morphology, enzyme/non-specific protein electrophoretic banding patterns, and effects of antibiotics on M. hyperodae asexuality. The morphological variation between M. hyperodae adults of known South American origins was exploited using discriminatory function analysis to develop a method of classifying M. hyperodae of unknown South American origins recovered from the field in New Zealand. Rigorous crossvalidation tests indicated that more than 80% of specimens could be classified correctly using this method. In New Zealand, the release in 1991 of equal numbers of M. hyperodae from each South American geographic population led to the hypothesis that, in the absence of between population performance differences, each South American population should be equally represented in samples taken from the field. Analysis of M. hyperodae adults collected in New Zealand during 1992-1994 did not support this hypothesis. Parasitoids derived from east of the South American Andes were significantly more prevalent than expected. A rigorous and quantitative method of analysing Microctonus spp. oviposition behaviour was developed and a definitive description of M. hyperodae and M. aethiopoides oviposition behaviour provided. Variation in M. hyperodae oviposition behaviour was examined as a possible reason for the differential performances of the South American geographic populations in New Zealand. No clear behavioural differences between the geographic populations were identified, but two preliminary possibilities were recognised. First, there is an indication that some M. hyperodae geographic populations derived from Argentina and Uruguay may be better adapted to searching in New Zealand's pastoral habitats. Second, some evidence supports the hypothesis that, in Chile, M. hyperodae parasitises species other than L. bonariensis and is not as specialised to attack L. bonariensis as M. hyperodae from Uruguay, Argentina and Brazil. As shown by morphometric analysis, M. hyperodae genetic variation has been important to its use as a biological control agent. However, reasons why such variation has been important, and to what extent, were not clearly established. The implications of these results for classical biological control practice are discussed and an experimental approach to biological control is advocated.... [Show full abstract]
    Keywords
    Microctonus aethiopoides; Microctonus hyperodae; Sitona discoideus; Listronotus bonariensis; parasitoids; genetic variation; morphological variation; biological control
    Date
    1995
    Type
    Thesis
    Access Rights
    Digital thesis can be viewed by current staff and students of Lincoln University only. If you are the author of this item, please contact us if you wish to discuss making the full text publicly available.
    Collections
    • Department of Pest Management and Conservation [703]
    • Theses and Dissertations with Restricted Access [2368]
    View/Open
    Staff/student login to read
    Staff/student login to read
    Staff/student login to read
    Staff/student login to read
    Staff/student login to read
    Share this

    on Twitter on Facebook on LinkedIn on Reddit on Tumblr by Email

    Metadata
     Expand record
    This service is maintained by Learning, Teaching and Library
    • Archive Policy
    • Copyright and Reuse
    • Deposit Guidelines and FAQ
    • Contact Us
     

     

    Browse

    All of Research@LincolnCommunities & CollectionsTitlesAuthorsKeywordsBy Issue DateThis CollectionTitlesAuthorsKeywordsBy Issue Date

    My Account

    LoginRegister

    Statistics

    View Usage Statistics
    This service is maintained by Learning, Teaching and Library
    • Archive Policy
    • Copyright and Reuse
    • Deposit Guidelines and FAQ
    • Contact Us