Biocontrol introduction
Target pest: Costelytra giveni (Coleoptera: Scarabaeidae), New Zealand grass grub
Agent introduced: Pterostichus unistriatus (Coleoptera: Carabidae) = Trirammatus unistriatus
Imported:
1968-70
Import source:
Argentina
Import notes:
Cameron et al. (1989) - eight hundred and twenty-one P. unistriatus were imported as adults for release from Argentina between 1968 and 1970 and larvae were obtained in laboratory rearing.
Released:
1968
Release details:
Cameron et al. (1989) - five hundred and eighty-seven P. unistriatus were released in the Nelson region of the South Island in 1968-70.
Establishment:
Cameron et al. (1989) - surveys for over a year after releases did not recover any P. unistriatis.
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
