A PROSPECTIVE MODEL FOR THE PHENOLOGY OF MICROCTONUS-HYPERODAE (HYMENOPTERA, BRACONIDAE), A POTENTIAL BIOLOGICAL-CONTROL AGENT OF ARGENTINESTEM WEEVIL IN NEW-ZEALAND

A predictive phenological model is described for the parasitoid Microc tonus hyperodae, introduced to New Zealand as a potential biological c ontrol agent against Argentine stem weevil Listronotus bonariensis. Th e model is based on development/temperature relationships obtained fro m experiments on the parasitoid in quarantine prior to its release, al lowing early predictions of its phenology in different parts of the ta rget pest's New Zealand range. In particular the model was used to pre dict the number of parasitoid generations each year, the degree of tem poral synchrony between parasitoid adults and the susceptible adult pe st stage, the order of parasitism and reproduction in the pest's life cycle as a possible basis for a simplified, discrete host/parasitoid p opulation model, and the likely significance of ecotypic differences i n development and diapause characteristics of the parasitoid. These ap plications demonstrate the potential for simple models to help in clim ate matching of classical biological control agents and estimation of their interaction with pest dynamics, using data obtainable prior to t heir introduction and release. In addition the model proved useful as a decision aid during the release programme, by indicating the likely effects of unusual weather and the need or otherwise for further paras itoid releases.