Phenology of Listronotus bonariensis (Kuschel) (Coleoptera: Curculinonidae) in Otago

Abstract

Using adult phenology it was shown that Listronotus bonariensis populations in the Southern South Island of New Zealand were restricted to one full generation per year. This was associated with degree day accumulation above 10 degrees C between spring and the onset of reproductive diapause in mid March. In some areas a partial second generation was observed but the influence of this appears minor, and predominantly first generation adults overwintered to lay eggs in spring. It is suggested that the lack of a second generation prevents L. bonariensis from commonly reaching damaging population densities in the southern South Island.