• Login
    View Item 
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    •   Home
    • Massey Documents by Type
    • Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Ecology of Paropsis charybdis Stål (Coleoptera : Chrysomelidae) : a Eucalyptus defoliator in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University

    Icon
    View/Open Full Text
    02_whole.pdf (5.705Mb)
    01_front.pdf (589.1Kb)
    Export to EndNote
    Abstract
    Paropsis charybdis Stål (Coleoptera: Chrysomelidae), misidentified as P.dilatata Er. before 1963, seriously defoliates some Eucalyptus species in New Zealand. This study investigated the life history and phenology, behaviour, growth and development, population dynamics and host-plant interactions of P.charybdis, emphasising those aspects likely to affect biological control programmes. P.charybdis in the central North Island had a bivoltine life history. Adults diapaused during winter. Low temperatures and probably changes in foliage characteristics were sufficient for induction of diapause but no single factor was necessary. Adults emerged in spring to lay eggs. Young Eucalyptus foliage was necessary for oviposition. Activity of adults was increased in the presence of volatiles from E.viminalis leaves but did not differ significantly between mature and young leaf treatments. Egg-laying ceased in midsummer but this was not caused by lack of new growth, nor by high defoliation. The pattern of abundance in summer was driven by oviposition and temperature and enhanced by intra-specific competition among early instars. Density-dependent mortality occurred between eggs and 4th instars during the second generation and appeared to result from intra-specific competition for new growth. This was also the key stage that caused variation in summer morality. Egg survival rates were 93-99%. Survival between eclosion and establishment of 1st instars on new foliage averaged 45% and was independent of density in an experiment where food was in excess. Mortality of the pre-pupal to teneral adult stages in die soil was 90%, but was independent of density in both generations. Development rate-temperature relationships were described for larvae fed E.viminalis young adult foliage, and for eggs and pupae. A method was developed for minimising differences in duration among larvae grown at different temperatures, so that the effects of changes in food quality were obviated. The method appears widely applicable for development-rate studies. Defoliation in a five-year old plantation of Eucalyptus nitens was almost twice as severe in the second P.charybdis generation as in the first. Shoot growth was significantly correlated with rainfall and defoliation intensity. There was a strong inverse relationship between defoliation intensity and deviations from the seasonal trend in rainfall.
    Date
    1989
    Author
    McGregor, Peter Gerard
    Rights
    The Author
    Publisher
    Massey University
    URI
    http://hdl.handle.net/10179/3288
    Collections
    • Theses and Dissertations
    Metadata
    Show full item record

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2023.7-7
     

     

    Information PagesContent PolicyDepositing content to MROCopyright and Access InformationDeposit LicenseDeposit License SummaryTheses FAQFile FormatsDoctoral Thesis Deposit

    Browse

    All of MROCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    LoginRegister

    Statistics

    View Usage Statistics

    Copyright © Massey University
    | Contact Us | Feedback | Copyright Take Down Request | Massey University Privacy Statement
    DSpace software copyright © Duraspace
    v5.7-2023.7-7