Biocontrol introduction
Target pest: Cirsium arvense (Asterales: Asteraceae), Californian thistle
Agent introduced: Urophora cardui (Diptera: Tephritidae), Californian thistle gall fly
Imported:
1975, 1994, 1996, 2000
Import source:
Switzerland (1975), Canada (1975, 1994), USA (1996, 2000)
Import notes:
Cameron et al. (1989) - in September 1975, 7,250 U. cardui galls from the Commonwealth Institute of Biological Control European Station in Switzerland, and 66 galls from Regina Station of Agriculture Canada were imported into quarantine at Lincoln, Canterbury.
Landcare Research (2007a) - specimens of U. cardui from Canada, dated 1975, and Oregon, USA, dated 2000, are present in the Biological Control Voucher Collection of the New Zealand Arthropod Collection [indicating importations from those sources in those years].
Hayes (2007c) - Urophora cardui is native to Europe and was first imported into New Zealand from Switzerland and Canada (where it had also been used as a biocontrol agent) in 1975. Releases from these importations appeared to be unsuccessful and a second attempt was made to establish this agent when Landcare Research imported shipments of flies from Canada in 1994 and the USA in 1996.
Released:
1976
Release details:
Cameron et al. (1989) - in 1976, 12 pairs of first-generation adults (from the 1975 importations) were released at each of 10 sites and 50 pairs at another site in Canterbury, South Island. In the same year, 100 pairs were released at a site at Kaikoura (Marlborough, South Island).
Hayes (2007c) - progeny of the 1994 and 1996 shipments [see Hayes (2007c) entry in 'Import notes' section above] were released at a limited number of sites.
Establishment:
Cameron et al.(1989) - did not establish from 1976 releases although it persisted at Kaikoura until 1985. No adults or galls have been observed since 1985. The releases probably failed because insufficient numbers were released at any one site.
Hayes (2007c) - believed to have established at limited number of sites from 1990s releases but is not common or widespread.
Cripps et al. (2011) - established only at a limited number of sites in New Zealand, and was not detected in a recent survey across the country.
Landcare Research (2014c) - rare, as galls tend to be eaten by sheep.
Impacts on target:
Hayes (2007c) - the impact of U. cardui has not been assessed but as galls are commonly eaten by stock it is unlikely that it will contribute much to C. arvense control in most situations.
Cripps et al. (2011) - even where established overseas, U. cardui generally has a negligible impact under agricultural field conditions since it typically attacks C. arvense after shoot elongation is 80% complete and establishes permanent populations only in riparian ecosystems.
Paynter et al. (2018) - U. cardui is rare and ineffective due to predation.
Paynter (2024) - factors influencing the success of weed biocontrol agents released and established in New Zealand were investigated. Each agent’s impact on the target weed in New Zealand was assessed as ‘heavy’, ‘medium’, ‘variable’, ‘slight’ or ‘none’, where a ‘heavy’, ‘medium’ or ‘variable’ impact have all been observed to reduce populations or percentage cover of their target weed in all or part of their respective target weed ranges in New Zealand. Results showed that: (i) agents that are highly damaging in their native range were almost invariably highly damaging in New Zealand; (ii) invertebrate agents with a closely related ‘native analogue’ species are susceptible to parasitism by the parasitoids that attack their native analogues and failed to have an impact on the target weed, and (iii) agent feeding guild helped predict agent impact - in particular, agents that only attack reproductive parts of the plant (e.g., seed and flower-feeders) are unlikely to reduce weed populations. Damaging impacts of U. cardui, a gall-forming fly, have not been reported in its native range, it does not have a New Zealand native ecological analogue and its impact in New Zealand is assessed as ‘slight’.
Impacts on non-targets:
Hayes (2007c) - Urophora cardui will not attack other plants, even other thistle species.
Cripps et al. (2011) - Urophora cardui has a highly restricted host range, and other than C. arvense, only Cirsium creticum (an aquatic thistle native to the eastern Mediterranean region) and C. setosum (native to the Ural Mountains) are known host plants from field records.
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.
Cripps MG, Gassmann A, Fowler SV, Bourdôt GW, McClay AS, Edwards GR. (2011). Classical biological control of Cirsium arvense: Lessons from the past. Biological Control 57: 165–174
Hayes L (2007c). Californian thistle gall fly: Urophora cardui. The Biological Control of Weeds Book - Te Whakapau Taru: A New Zealand Guide (Landcare Research) https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/projects-agents/biocontrol-agents/californian-thistle-gall-fly-3/
Landcare Research (2007a). New Zealand Arthropod Collection (NZAC) Biological Control Voucher Collection. Landcare Research website [Updated 2020] https://www.landcareresearch.co.nz/tools-and-resources/collections/new-zealand-arthropod-collection-nzac/databases-and-holdings/new-t2-landing-page/
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
Paynter Q (2024). Prioritizing candidate agents for the biological control of weeds. Biological Control, Volume 188, January 2024, Article Number 105396 https://doi.org/10.1016/j.biocontrol.2023.105396
Paynter Q, Fowler SV, Groenteman R. (2018). Making weed biological control predictable, safer and more effective: perspectives from New Zealand. BioControl 63: 427-436 (first published online 8 Aug 2017) https://doi.org/10.1007/s10526-017-9837-5 https://link.springer.com/article/10.1007/s10526-017-9837-5
