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Biocontrol introduction

Target pest: Epiphyas postvittana (Lepidoptera: Tortricidae), light brown apple moth

Agent introduced: Dolichogenidea tasmanica (Hymenoptera: Braconidae) = Apanteles tasmanicus

Imported: 1969

Import source: Australia

Released: 1969

Release details: Cameron et al. (1989) - 244 released at Nelson

Establishment: Cameron et al. (1989) - D. tasmanica was already present in New Zealand prior to the 1969 importation and release.

Impacts on target: Cameron et al. (1989) - levels of parasitism in Nelson by D. tasmanica in 1935 reported to be between 20% and 51%, consistent with reports of percentage parasitism in 1965 and 1984. Charles et al. (1996) - three species of leafroller were recovered from berryfruit orchards in Hawkes Bay: the introduced Epiphyas postvittana and the endemic Planotortrix octo (greenheaded leafroller) and Ctenopseustis obliquana (brownheaded leafroller). More than 90% of parasitoids reared from these were D. tasmanica, which was found throughout the year. Parasitised larvae were not identified to species; it is assumed that all three leafroller species were attacked equally, though there is some evidence that D. tasmanica preferentially attacks E. postvittana. Lo et al. (2018) - a study to measure changes in the abundance and pest status of three leafroller species, Epiphyas postvittana, Planotortrix octo and Ctenopseustis obliquana, in fruit growing areas of Hawke’s Bay between 1976 and 2016, showed populations of all three species decreased substantially; however, P. octo and C. obliquana declined to a much greater extent than E. postvittana. Leafrollers damaged over 20% of apples receiving no insecticides during the 1980s but, subsequent to 2000, damage has been below 2%. Between 1994–1999 and 2008–2011, the numbers of immature leafrollers in searches on fruit crop and non-crop hosts decreased by 55% and the mean percentage of leafrollers parasitised per sample increased from 51% to 70%. The reduction in leafroller populations can be attributed to two key factors: increased biological control and the replacement of broad-spectrum insecticides with selective insecticides. In 1974–1975, parasitism of leafroller larvae on fruit crops was 13%; in the 2000s, 69%. The decline in importance of leafrollers as pests has occurred on managed and unmanaged orchards, vineyards, and on non-crop shelter plants. In the 1970s and 1980s, leafrollers and their associated damage were highly visible on Hawke’s Bay orchards, whereas, currently, they are difficult to find, even on unsprayed trees. From the 1994-1999 and 2008-2011 leafroller larvae collections, 75% of parasitoids reared from three fruit crops (apple, grape, boysenberry), and 17% from oak trees in shelter belts, were Dolichogenidea spp.

Impacts on non-targets: Charles et al. (1996) - D. tasmanica was the dominant parasitoid reared from the New Zealand endemic leafrollers Planotortrix octo (greenheaded leafroller) and Ctenopseustis obliquana (brownheaded leafroller) in berryfruit orchards in Hawkes Bay (see "Target Impact" section above). Munro & Henderson (2002) - a study of the parasitoid guild attacking preimaginal Tortricidae on shrubs and small trees in broadleaf/podocarp forests in the central North Island recorded D. tasmanica from only a single host species: Ctenopseustis obliquana. Lo et al. (2018) - Planotortrix octo and Ctenopseustis obliquana have declined in orchards, vineyards and shelterbelts (where they are pests) in Hawkes Bay, at least partly as a result of parasitism by Dolichogenidea spp. and other introduced biological control agents.

General comments: Cameron et al. (1989) - imported as Apanteles tasmanicus. Austin & Allen (1989) - this species transferred from Apanteles to Dolichogenidea, becoming Dolichogenidea tasmanica.

References

Austin AD, Allen GR. (1989). Parasitoids of Uraba lugans Walker (Lepidoptera: Noctuidae) in South Australia, with description of two new species of Braconidae. Transactions of the Royal Society of South Australia 113 (4): 169-184

Cameron PJ, Hill RL, Bain J and 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, Walker JTS, White V. (1996). Leafroller phenology and parasitism in Hawkes Bay, New Zealand, canefruit gardens. New Zealand Journal of Crop and Horticultural Science 24 (2): 123-131

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

Munro, V.M.W. and Henderson, I.M. (2002). Nontarget effect of entomophagous biocontrol: Shared parasitism between native lepidopteran parasitoids and the biocontrol agent Trigonospila brevifacies (Diptera: Tachinidae) in forest habitats. Environmental Entomology 31 (2). 388-396