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Biocontrol introduction

Target pest: Graphognathus leucoloma (Coleoptera: Curculionidae), white-fringed weevil

Agent introduced: Pseudelaphroptera brevipilosa (Hymenoptera: Thynnidae)

Imported:

1965-73

Import source:

Argentina

Import notes:

Cameron et al. (1989) - Pseudelaphroptera brevipilosa was reared from field-collected melolonthine Scarabaeidae [i.e. in the same subfamily as New Zealand grass grub, Costelytra giveni, the primary biocontrol target for these introductions of P. brevipilosa] or G. leucoloma in Argentina and 76,178 females or pairs were shipped to New Zealand between 1965 and 1973.

Released:

1965

Release details:

Cameron et al. (1989) - a total of 36,735 mated female P. brevipilosa were released at nine sites in the northern South Island (in the Marlborough and Nelson regions) and at five sites in the northern North Island. Release details by year were as follows: 1965 - 205 released in Marlborough; 1966 - 12,130 in Taupo, Marlborough, Nelson; 1967 - 9,339 in Nelson; 1968 - 1,682 in Nelson; 1970 - 717 in Nelson; 1971 - 7,621 in Waikato, Bay of Plenty, Nelson; 1972 - 4,876 in Auckland, Bay of Plenty, Nelson; 1973 - 165 in Auckland, Bay of Plenty. As a result of thynnine cocoons being obtained from white-fringed weevil (Graphognathus leucoloma) larvae, P. brevipilosa releases from 1970 were partly directed against G. leucoloma [having been primarily imported against New Zealand grass grub, Costelytra giveni].

Establishment:

Cameron et al. (1989) - forty-five P. brevipilosa males emerged from New Zealand grass grub, Costelytra giveni, caged in the field, and thynnine cocoons were also obtained from G. leucoloma larvae. No P. brevipilosa were reared from field-collected larvae of either host, but male thynnines were recalled by attracting them to tethered females 13 days after release in the Marlborough region. No further recoveries were reported and the evidence indicates an early failure to establish.

References

Cameron PJ, Hill RL, Bain J, Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.