Population dynamics of clover root weevil (Sitona lepidus) in the Manawatu
New Zealand Plant Protection
Population dynamics of CRW in the Manawatu were observed in the field over a 0 month period (April to January). The aim was to determine whether or not CRW adults in the region had two overlapping generations per year. Overlapping generations will be important for supporting a parasitoid, Microctonus aethiopoides, recently released to control CRW. The population parameters that were sampled included: the number of CRW adults/m²; percentage of reproductively mature females; and the number of CRW
... d the number of CRW larvae and pupae/m². Peak adult numbers were evident in April (8/m²) and January (3/m²). Peak larval numbers were observed during June and July (48.9/m²) and in October and November (66.7/m²). This pattern is similar to that occurring in the Waikato, where CRW has two generations per year. This suggests that CRW also has two generations in the Manawatu, with one generation emerging in late summer or autumn and a second generation emerging in early spring. Pupal numbers indicated that these two generations overlapped in late spring, although adult numbers were very low.