Biocontrol introduction
Target pest: Costelytra giveni (Coleoptera: Scarabaeidae), New Zealand grass grub
Agent introduced: Microphthalma michiganensis (Diptera: Tachinidae)
Imported:
1926-28
Import source:
Canada
Import notes:
Cameron et al. (1989) - from 1926 to 1928 M. michiganensis was imported from Canada as 2,860 infested June beetle (Phyllophaga sp.) larvae. A total of 106 M. michiganensis adults emerged from the material and were released in the field. This introduction can be considered speculative because of the low numbers imported and failure to gain development of the parasitoid on C. giveni.
Released:
1926-28
Release details:
Cameron et al. (1989) - one hundred and six adult M. michiganensis that emerged from imported, parasitised host larvae [see Cameron et al. (1989) entry in ‘Import notes’ section above] were released in the field near Wellington [in the North Island] and Canterbury [in the South Island].
Establishment:
Cameron et al. (1989) - no recoveries of M. michiganensis were recorded.
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
