Biocontrol introduction
Target pest: Jacobaea vulgaris (Asterales: Asteraceae) = Senecio jacobaea, ragwort
Agent introduced: Platyptilia isodactyla (Lepidoptera: Pterophoridae), ragwort plume moth
Imported:
2005
Import source:
Europe via Australia
Released:
2006
Release details:
Hayes (2007a) - released at a limited number of sites nationwide since autumn 2006.
Landcare Research (2013d) - released at 47 sites on the West Coast (where the ragwort flea beetle, Longitarsus jacobeaea, is ineffective due to high rainfall) and releases here are continuing.
Establishment:
Gourlay (2011b) - appears to be establishing readily.
Landcare Research (2013d) - established at around 85% of West Coast release sites.
Landcare Research (2014c) - well established.
Landcare Research (2016h) - over 70 L. jacobaeae (ragwort flea beetle) release sites nationwide revisited 20-30 years post-release and density of ragwort now compared to density at the time of release: the plume moth was present at 7 sites; on the West Coast the plume moth has self-colonised at least three of the flea beetle release sites, including the wettest site in the study (Whataroa, with a mean annual rainfall of 5305 mm).
Impacts on target:
Gourlay (2011b) - is reducing ragwort as was hoped.
Landcare Research (2013d) - some release sites have been active for seven years and are showing a significant reduction in ragwort populations, such that farmers only have to spot spray instead of boom or helicopter spraying. Good results with plume moth also reported in other parts of New Zealand.
Landcare Research (2014c) - quickly reducing ragwort noticeably at many sites.
Landcare Research (2016g) - three to five years after release ragwort populations started disappearing. Between the plume moth and the flea beetle (Longitarsus jacobeaea), which is effective in drier areas, almost throughout New Zealand ragwort has become relatively rare.
Landcare Research (2016h) - study of ragwort flea beetle release sites: data showed the plume moth may already be causing some declines in ragwort at wet sites on the West Coast, supporting other observations of the impact of this agent.
Fowler et al. (2023), Landcare Research (2023h) - a cost-benefit analysis of all weed biocontrol programmes in New Zealand showed that in 2022 investment in weed biocontrol in the productive sector (targeting agricultural as opposed to environment weeds) was NZ$0.69 million, with the three most economically successful weed biocontrol programmes in New Zealand - against ragwort (Jacobaea vulgaris), St John’s wort (Hypericum perforatum) and nodding thistle (Carduus nutans) - yielding a combined annual benefit of NZ$84.7 million.
Impacts on non-targets:
Gourlay (2011b) - extremely unlikely the moth will damage plants other than ragwort and marsh ragwort (Senecio aquaticus), which is also a minor weed in New Zealand, and hybrids of the two species.
Paynter et al. (2015) - surveys of potential non-target host the exotic ornamental Jacobaea maritima (=Senecio cineraria) (dusty miller) report no feeding.
EPA Applications:
EPA (2005b) - 1 Jul 2005: application by West Coast Ragwort Control Trust to import for release two new moths, Cochylis atricapitana (Tortricidae) and Platyptilia isodactyla (Pterophoridae), for the biological control of the pasture weed ragwort. EPA Application # NOR05002, approved without controls 15 Dec 2005.
References
EPA (2005b). EPA application NOR05002 to import for release two new moths, Cochylis atricapitana (Tortricidae) and Platyptilia isodactyla (Pterophoridae), for the biological control of the pasture weed ragwort. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/NOR05002
Fowler SV, Groenteman R, Paynter Q (2023). The highs and the lows: a cost benefit analysis of classical weed biocontrol in New Zealand. BioControl (2023) https://doi.org/10.1007/s10526-023-10225-2
Gourlay H. (2011b). Ragwort Plume Moth. In The Biological Control of Weeds Book (Landcare Research) https://www.landcareresearch.co.nz/discover-our-research/biosecurity/weed-management/using-biocontrol/the-biological-control-of-weeds-book/
Hayes L (2007a). Status of weed biocontrol agents in Southland. A report prepared for Environment Southland Sept 2007. Landcare Research Contract Report: LC0708/022
Landcare Research (2013d). West Coast ragwort control - a successful community project. What's new in biological control of weeds? 66: 2-3 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-66
Landcare Research (2014c). Who's who in biocontrol of weeds? What's new in biological control of weeds? 69: 10-11 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/WhatsNew69.pdf
Landcare Research (2016g). Farmer grateful for tiny beetle. Weed Biocontrol: What's New? 76: 8 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-76
Landcare Research (2023h). The highs and lows of cost-benefit analyses. Weed Biocontrol: What's New? 106, August 2023 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/the-highs-and-lows-of-costbenefit-analyses/
Paynter QE, Fowler SV, Gourlay AH, Peterson PG, Smith LA and Winks CJ (2015). Relative performance on test and target plants in laboratory tests predicts the risk of non-target attack in the field for arthropod weed biocontrol agents. Biological Control 80: 133-142 https://doi.org/10.1016/j.biocontrol.2014.10.007
