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
Import notes:
Cameron et al. (1989) - parasitised E. postvittana larvae were collected in eastern Australia and Tasmania in 1969 and imported into quarantine at Nelson. Two hundred and ninety-five D. tasmanica [then called Apanteles tasmanicus - see Austin & Allen (1989) entry in 'General comments' section] emerged, of which 244 were directly released.
Varela et al. (2010) - Dolichogenidea tasmanica was accidentally introduced to New Zealand [prior to deliberate releases as part of the later biocontrol programme], probably entering the country in parasitised E. postvittana from Australia.
Released:
1969
Release details:
Cameron et al. (1989) - 244 adults that emerged from the 1969 importation of parasitised E. postvittana larvae were released into a field cage 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 were 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.
Suckling et al. (1998) - leafroller populations were sampled from October 1993 to March 1994 on eight known leafroller non-crop host plants in the vicinity of apple orchards in Hawke's Bay, Nelson, Canterbury, and Central Otago. Dolichogenidea tasmanica was consistently the most common larval parasitoid found; 31% of sampled leafrollers were parasitised, of which two-thirds was by D. tasmanica. The abundance of leafrollers on alternative host plants near orchards suggests management of such plants could usefully reduce leafroller pest density on crops.
Suckling et al. (2001) - Dolichogenidia tasmanica is the most abundant parasitoid recorded in the vicinity of orchards in New Zealand. Sampling of leafroller pests - E. postvittana and the New Zealand natives Planotortrix octo and Ctenopseustis herana - at an organic apple orchard in Canterbury, South Island in February 1998 showed no significant difference in rate of parasitism between host species by D. tasmanica (E. postvittana 35%, P. octo 33%, C. herana 32%). In contrast, in an April 1999 trial using potted apple trees in a Canterbury orchard the level of parasitism varied significantly between the three host species (E. postvittana 83.2%, P. octo 25.8 %, C. herana 57.5%).
Rogers et al. (2003) - a study of leafrollers in the summer-autumn (January-May) of 2003 in organic Hawke’s Bay apple orchards recorded an overall mean parasitism rate of leafroller larvae (of which E. postivittana was the dominant species) of 48.8%. Dolichogenidea spp. was the most abundant parasitoid (57.5%), followed by [the New Zealand native] Glyptapanteles demeter (33%), Trigonospila brevifacies (6.3%) and [the accidentally introduced] Meteorus pulchricornis (2.5%). Dolichogenidea spp. was dominant in the apple foliage, G. demeter in the understorey. Nearly half of all leafrollers were located in the understorey, highlighting the importance of understorey and its management for leafroller control. A complex of Dolichogenidea species constitutes the most widespread and abundant leafroller parasitoid in New Zealand.
Varela et al. (2010) - the first reports of natural enemies of E. postivittana in New Zealand, in the 1930s, listed D. tasmanica as the most frequent parasitoid, found in 20-50% of larvae reared. From the 1960s to the 1980s, when control programmes were based on frequent application of broad-spectrum insecticides, leading to the development of resistance to organochlorines, E. postvittana damage in apple crops in New Zealand averaged 8-26% (and was as high as 48%). Over the last two decades damage has decreased to typically less than 2% in unsprayed trees as the result of the introduction of biocontrol agents and the use of selective insecticides. Consequently, New Zealand growers can control E. postivittana and meet the export standards of more than 60 countries that import a variety of fruit crops. Of parasitoids emerging from leafroller larvae and pupae (predominantly E. postvittana) collected from orchards and vineyards in Hawke’s Bay between 1993 and 2009, Dolichogenidea tasmanica was the most abundant, comprising 66-97% of the parasitoids reared from apple and stone fruit trees, berry fruit and grapevines. The next most abundant parasitoids were T. brevifacies (1-27%), [the New Zealand native] Glypapanteles demeter (2-16%) and Goniozus jacintae (2-12%).
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) [both species are orchard pests] in berryfruit orchards in Hawkes Bay [see 'Impact on target' section, and Cameron et al. (1993) entry in 'General comments' section].
Suckling et al. (2001) - field sampling in an apple orchard and a trial with potted apple trees [see Suckling et al. (2001) entry in ‘Impacts on target’ section above] recorded parasitism of the New Zealand native leafrollers (and orchard pests), Planotortrix octo and Ctenopseustis herana, by D. tasmanica, demonstrating conclusively, for the first time, that D. tasmanica parasitises these hosts in the field.
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.
Todd et al. (2018) - larval parasitism of the leafrollers Ctenopseustis obliquana and Cnephasia jactatana was measured in organic and Integrated Pest Management (IPM) kiwifruit orchards in Bay of Plenty in the kiwifruit growing seasons of 2013-14 and 2014-15. The leafrollers, both New Zealand natives, are two of the main economic pests of New Zealand kiwifruit. Four parasitoid species emerged from the leafroller larvae, although average parasitism rates were very low (1-3%), including a single Microgastrinae parasitoid, of uncertain identity but most likely D. tasmanica, which emerged from a C. jactatana larva in 2014-15.
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:
Austin & Allen (1989) - this species transferred from Apanteles (as A. tasmanicus) to Dolichogenidea, becoming Dolichogenidea tasmanica.
Cameron et al. (1993) - native tortricid pest species were included as targets in the 1967-69 programme against E. postvittana. By 1984, changing attitudes to conflicts between conservation and biological control were recognized and more specific consideration was given to the preservation of non-target native species.
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, 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.
Cameron PJ, Hill RL, Bain J, Thomas WP (1993). Analysis of importations for biological control of insect pests and weeds in New Zealand. Biocontrol Science and Technology 3(4): 387-404 https://doi.org/10.1080/09583159309355294
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 https://www.tandfonline.com/doi/pdf/10.1080/01140671.1996.9513944
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 VMW & Henderson IM (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
Rogers D, Walker J, Moen I, Weibel F, Lo P, Cole L (2003). Understorey influence on leafroller populations in Hawkes Bay organic apple orchards. New Zealand Plant Protection 56: 168-173 https://journal.nzpps.org/index.php/nzpp/article/view/6037/5865
Suckling DM, Burnip GM, Gibb AR, Daly JM, Armstrong KF (2001). Plant and host effects on the leafroller parasitoid Dolichogenidia tasmanica. Entomologia Experimentalis et Applicata 100: 253-260 https://doi.org/10.1046/j.1570-7458.2001.00870.x
Suckling DM, Burnip GM, Walker JTS, Shaw PW, McLaren GF, Howard CR, Lo P, White V, Fraser J (1998). Abundance of leafrollers and their parasitoids on selected host plants in New Zealand. New Zealand Journal of Crop and Horticultural Science 26(3): 193-203 https://doi.org/10.1080/01140671.1998.9514055
Todd JH, Poulton J, Richards K, Malone LA (2018). Effect of orchard management, neighbouring land-use and shelterbelt tree composition on the parasitism of pest leafroller (Lepidoptera: Tortricidae) larvae in kiwifruit orchard shelterbelts. Agriculture, Ecosystems & Environment 260: 27-35 https://doi.org/10.1016/j.agee.2018.03.016
Varela LG, Walker JTS, Lo PL, Rogers DJ (2010). New Zealand lessons may aid efforts to control light brown apple moth in California. California Agriculture 64(1): 6-12 https://escholarship.org/uc/item/4qv9b8nw
