Target pest: Cydia pomonella (Lepidoptera: Tortricidae), codling moth
Agent introduced: Glabridorsum stokesii (Hymenoptera: Ichneumonidae) = Gambrus stokesii, Ischnus stokesii
Cameron et al. (1989) - 11 released at Nelson in 1969. Releases were made in 1967-73 at Kerikeri, Hamilton, Kaingaroa Forest, Rotorua, Nelson and Christchurch. In 1972, 1979-80 and 1985 it was redistributed to Christchurch.
Cameron et al. (1989) - established at Appleby, Nelson in 1969-70 and since then in Northland, Auckland, Hamilton and Hawkes Bay. Collected in Christchurch in 1985-86 but its establishment there is uncertain.
Sandanayaka et al. (2017), Charles et al. (2019) - found parasitising codling moth (Cydia pomonella) in Nelson, Central Otago and Hawke's Bay while monitoring for the codling moth biocontrol agent Mastrus ridens.
Impacts on target:
Cameron et al. (1989) - Glabridorsum stokesii has been known as a parasitoid of codling moth in Australia for many years and was occasionally observed to parasitise codling moth after its establishment in Nelson in 1969-70. However, there is no clear evidence that parasitism of this species has been obtained in New Zealand. The best prospects for G. stokesii attacking codling moth may be in the northern regions of the country where this pest is bivoltine/multivoltine.
Charles et al. (2019) - in a trial using sentinel codling moth larvae, sampled monthly between September 2015 and June 2016, G. stokesii parasitised larvae in Hawkeâ€™s Bay (December - March, at rates of up to approximately 8%), Nelson (January - April, up to approximately 7%) and Central Otago (March only, approximately 10%).
Impacts on non-targets:
Cameron et al. (1989) - G. stokesii has been recorded from the New Zealand native torticids Ctenopseustis obliquana in the Bay of Plenty, and Ctenopseustis obliquana sensu latu and Planotortrix excessana sensu latu in Nelson. [These leafrollers are significant orchard pests.] Glabridorsum stokesii is the most common introduced parasitoid of leafroller pupae in Nelson. However, while native hosts are parasitised, at least in some habitats, there is no evidence that this is affecting the population dynamics of these species.
Lo et al. (2018) - the New Zealand endemic leafrollers Planotortrix octo (greenheaded leafroller) and Ctenopseustis obliquana (brownheaded leafroller) have declined in orchards, vineyards and shelterbelts (where they are pests), at least partly as a result of introduced biological control agents. G. stokesii was recorded as a minor component (5%) of the parasitoids reared from leafroller larvae of these species collected from oak trees in shelter belts in Hawke's Bay, though was not reported from larvae collected from fruit crops.
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.
Charles JG, Sandanayaka WRM, Walker JTS, Shaw PW, Chhagan A, Cole LM, Colhoun K, Davis VA, Wallis DR (2019). Establishment and seasonal activity in New Zealand of Mastrus ridens, a gregarious ectoparasitoid of codling moth Cydia pomonella. BioControl 64: 291â€“301 https://doi.org/10.1007/s10526-019-09939-z
Lo PL, Walker JTS, Hedderley DI, Cole LM. (2018). Reduction in leafroller (Lepidoptera: Tortricidae) abundance in orchards and vineyards 1976-2016, in Hawke's Bay, New Zealand. Agricultural and Forest Entomology 20 (4): 505-513
Sandanayaka M, Charles J, Davis V, Chhagan A, Shaw P, Wallis R, Lo P, Cole L, Walker J, Colhoun K. (2017). Establishment of Mastrus ridens (Hymenoptera: Ichneumonidae), an ectoparasitoid of codling moth, in New Zealand. Proceedings of the 5th International Symposium on Biological Control of Arthropods, Langkawi, Malaysia, September 11-15, 2017: 85-87 https://www.cabi.org/cabebooks/FullTextPDF/2017/20173267456.pdf