Biocontrol introduction
Target pest: Paropsis charybdis (Coleoptera: Chrysomelidae), eucalyptus tortoise beetle
Agent introduced: Neopolycystus sp. (Hymenoptera: Pteromalidae)
Imported:
1934, 1987 [the 1934 importation was identified only at the genus level and the 1987 shipment imported as N. insectifurax but subsequently determined to be N. sp. - see Taxonomic note (2 December 2024) entry in 'General comments' section below].
Import source:
Australia
Import notes:
Cameron et al. (1989) - in March 1934 a small consignment of field-collected Paropsis atomaria eggs was imported from Australia; five Neopolycystus adults emerged and one of the females successfully parasitised P. charybdis eggs in the laboratory. No releases were made. In June 1987, approximately 400 adult Neopolycystus [imported as N. insectifurax but later determined to be N. sp. - see Taxonomic note (2 December 2024) entry in 'General comments' section below] were received from Perth, Western Australia. These were successfully cultured in quarantine and the progeny released.
Released:
1987
Release details:
Cameron et al. (1989) - no releases were made from the 1934 importation. Between November 1987 and March 1988, approximately 650 adults, progeny of the 1987 importation, were released at each of three sites in Nelson, South Island (Collingwood, Golden Downs and Richmond), approximately 1,000 at Chertsey (Canterbury, South Island), approximately 1,500 at each of two Bay of Plenty, North Island sites (Kaingaroa and Maketu) and approximately 2,300 near Tokoroa (Waikato, North Island).
Establishment:
Cameron et al. (1989) - so far no recoveries of Neopolycystis have been made.
Toni Withers (Scion, pers. comm. 2014) - extensive monitoring of P. charybdis eggs through the 1990s failed to find Neopolycystus parasitism.
General comments:
Taxonomic note (2 December 2024) - a shipment of Neopolycystus, considered at the time to be N. insectifurax, was imported in 1987 and released in 1987-88 (Cameron et al. 1989). Neopolycystus was first detected in the field in New Zealand in 2001 (Jones & Withers 2003). Comparison of 1987-imported specimens with 2003 New Zealand field specimens showed the former were N. sp., the latter N. insectifurax (Berry 2003). It is possible that N. insectifurax established accidentally, the most probable route being inside eggs of its host on plant material (Berry 2003). Extensive monitoring of P. charybdis eggs through the 1990s failed to find Neopolycystus parasitism, supporting the conclusion that the N. insectifurax field specimens collected in 2003 represented a recent self-introduction and that the Neopolycystus released in 1987-88 failed to establish (Toni Withers, Scion, pers. comm. 2014).
References
Berry JA. (2003). Neopolycystus insectifurax Girault (Hymenoptera: Pteromalidae) is established in New Zealand, but how did it get here? New Zealand Entomologist 26: 113-114
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.
Jones DC, Withers TM (2003). The seasonal abundance of the newly established parasitoid complex of the eucalyptus tortoise beetle (Paropsis charybdis). New Zealand Plant Protection 56: 51-55 https://journal.nzpps.org/index.php/nzpp/article/view/6031/5859
