Biocontrol introduction
Target pest: Costelytra giveni (Coleoptera: Scarabaeidae), New Zealand grass grub
Agent introduced: Neozeleboria volatilis (Hymenoptera: Thynnidae)
Imported:
1949-51
Import source:
Victoria, Australia
Import notes:
Cameron et al. (1989) - the search for parasitoids as biocontrol agents for C. giveni was carried out in Australia (mainly in southwest Victoria) for six years from 1945. During this time, 97 consignments of [subfamily] Thynninae [Hymenoptera: Thynnidae] were imported to New Zealand. Included in these consignments were 737 N. volatilis imported in 1949-51. Six of the 13 species imported oviposited in C. giveni in laboratory tests, although five of these laid only two to seven eggs.
Released:
Between 1949 and 1951
Release details:
Cameron et al. (1989) - thynnines imported from Australia [see Cameron et al. (1989) entry in ‘Import notes’ section above] were released at nine areas spread over New Zealand [although release sites for individual species are not recorded]. A total of 518 N. volatilis females were released [release dates are not recorded but would have been shortly after importation, as the imported individuals were released rather than reared].
Establishment:
Cameron et al. (1989) - no recoveries of N. volatilis have been made despite extensive sampling and rearing of C. giveni.
General comments:
Taxonomic note (8 April 2025) - a species of scarab beetle was described as Rhizotrogus zealandicus by White in 1846 from two specimens collected in the Wellington region. In 1952 Given described the genus Costelytra with the New Zealand grass grub as the type species, naming it C. zealandica, considering it conspecific with White’s Rhizotrogus zealandicus. However, Coca-Abia & Romero-Samper (2016) found differences between Given’s description of C. zealandica (i.e. New Zealand grass grub) and White’s specimens, and renamed the New Zealand grass grab Costelytra giveni, reserving the name C. zealandica (syn R. zealandicus) for the species described by White, considered by Coca-Abia & Romero-Samper (2016) likely to be a shrubland or forest species from the Wellington region. [All information from Coca-Abia & Romero-Samper (2016).]
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.
Coca-Abia MM, Romero-Samper J (2016). Establishment of the identity of Costelytra zealandica (White 1846) (Coleoptera: Scarabeidae: Melolonthinae) a species commonly known as the New Zealand grass grub. New Zealand Entomologist 39(2): 129-146 https://doi.org/10.1080/00779962.2016.1230254
