Biocontrol introduction
Target pest: Costelytra zealandica (Coleoptera: Scarabaeidae)
Agent introduced: Various agents
General comments:
Various agents were imported against the New Zealand grass grub, an endemic New Zealand species, from the 1920s to the 1980s. At the time of the importations/releases, New Zealand grass grub was considered to be Costelytra zealandica. However, Coca-Abia & Romero-Samper (2016) renamed New Zealand grass grub Costelytra giveni, reserving the name C. zealandica for a different, also endemic, species [see the Taxonomic note (8 April 2025) entry below].
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).]
See the Costelytra giveni introduction record for details of the biocontrol programme against New Zealand grass grub.
References
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
