Biocontrol introduction

Target pest: Costelytra giveni (Coleoptera: Scarabaeidae), New Zealand grass grub

Agent introduced: Ithone fusca (Neuroptera: Ithonidae)

Imported:

1921-22

Import source:

Australia

Import notes:

Cameron et al. (1989) - Ithone fusca was imported from Australia sometime in 1921-22 in one shipment of 6,000 eggs, which were released into the field in soil. This introduction can be considered speculative because of the low numbers imported and failure to gain development of the parasitoid on C. giveni.

Released:

1921-22

Release details:

Cameron et al. (1989) - the imported shipment of 6,000 eggs [see Cameron et al. (1989) entry in ‘Import notes’ section above] was released in soil.

Establishment:

Cameron et al. (1989) - no larvae were recovered from the released eggs [see Cameron et al. (1989) entry in ‘Release details’ section above].

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

Tillyard RJ (1923). History of the introduction of beneficial insects into New Zealand. Proceedings of the Pan-Pacific Science Congress, Australia, 383-390.