Biocontrol introduction
Target pest: Costelytra giveni (Coleoptera: Scarabaeidae), New Zealand grass grub
Agent introduced: Steinernema glaseri (Rhabditida)
Imported:
1955, 1981
Import source:
Tasmania, Australia (1981)
Import notes:
Jackson et al. (1981) - a small sample of S. glaseri was imported from Tasmania, Australia in early-1981, freshly extracted from culture medium or infected larvae of the greater wax moth (Galleria mellonella) and trialled as a potential biocontrol agent against C. giveni, porina (Wiseana sp.), white-fringed weevil (Graphognathus leucoloma and black beetle (Heteronychus arator).
Cameron et al. (1989) - the importation of S. glaseri was reported in 1955 [the source country was not recorded]. A 1982 publication reported a further importation from Australia [this importation took place in 1981 - see Jackson et al. (1981) entry above in this section]. Both importations were used in field trials against C. giveni.
Released:
1955, 1981
Release details:
Cameron et al. (1989) - the S. glaseri populations imported in both 1955 and 1981 were used in field trials [see Cameron et al. (1989) entries in ‘Establishment’ and ‘Impacts on target’ sections below.]
Establishment:
Cameron et al. (1989) - it was reported that the S. glaseri imported in 1955 could survive in soil plots for four-and-half years. The S. glaseri imported from Australia in 1981 was recovered from field trials against C. giveni. [Note that Cameron et al. (1989) comment that S. glaseri is a native New Zealand species.]
Impacts on target:
Cameron et al. (1989) - the introduction of S. glaseri has been restricted to its application in the form of a biological insecticide rather than its release for establishment. Steinermema glaseri and Heterorhabditis bacteriophora (another pathogenic nematode) imported from Australia in 1981 were both recovered from trials in which infected C. giveni populations were shown to decline. In another trial, reported in 1982, field applications of S. glaseri in December caused considerable C. giveni mortality, but mid-summer and autumn applications were less successful, attributed to unfavourable soil moisture and temperature conditions. While some good results have been achieved with pathogenic nematodes against C. giveni, storage problems, the lack of low temperature infective strains and low soil moisture conditions are serious limitations to their widespread use.
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
Jackson TA, Bedding RA, Trought TET, Kain WM, East R (1981). The potential use of nematodes for the control of pasture pests. Proceedings of the New Zealand Weed and Pest Control Conference 34: 170-172 https://journal.nzpps.org/index.php/pnzwpcc/article/view/10641/10473
