LABORATORY NONTARGET HOST-RANGE OF THE INTRODUCED PARASITOIDS MICROCTONUS AETHIOPOIDES AND M-HYPERODAE (HYMENOPTERA, BRACONIDAE) COMPARED WITH FIELD PARASITISM IN NEW-ZEALAND

Laboratory host specificity of 2 biological control agents, already in troduced in New Zealand, was compared with actual field parasitism. Th e parasitoids were Microctonus aethiopoides Loan and Microctonus hyper odae Loan, braconids imparted to control the curculionid forage pests Sitona discoideus Gyllenhal and Listronotus bonariensis (Kuschel). res pectively. The nontarget weevil species tested included native, introd uced, and beneficial species. M. aethiopoides oviposited in 11 of the 12 species to which it was exposed and successfully parasitized 9 spec ies. M. hyperodae oviposited in 5 of the 11 species to which it was ex posed and developed successfully in 4 species. Higher percentage paras itism was recorded with M. aethiopoides than with M, hyperodae. Field collections of weevils from Otago, Canterbury, and Waikato indicated t hat 10 New Zealand native species and 3 other nontarget species, inclu ding the weed biological control agent Rhinocyllus conicus (Froehlich) , were parasitized by M. aethiopoides. M. hyperodae has been found par asitizing 1 native species, as well as Sitona lepidus Gyllenhal, which was accidentally introduced to New Zealand recently. In nontarget spe cies, parasitism levels in the field of >70% have been recorded for M. aethiopoides and <5% for M. hyperodae. The results of this study sugg est that laboratory host range testing is indicative of nontarget para sitism in the field.