Field evaluation of spinosad for control of the willow sawfly (Nematus oligospilus) in Hawkes Bay
Willow sawfly (Nematus oligospilus (Hymenoptera Tenthredinidae)) a species recently discovered in New Zealand has spread throughout the country In Hawkes Bay it is a threat to willow trees many of which are an important part of river flood control systems A trial was conducted in Napier to test the efficacy of the insecticide Spinosad against sawflies infesting golden willows (Salix alba var vitellina) Insecticide was applied once at each of two sites while a third site was used as an untreated control Larval densities were measured on two trees from each site immediately before the experiment began and for 28 days afterwards At both treated sites 100 mortality occurred within seven days of insecticide application The results showed that Spinosad can provide effective control of willow sawfly