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Biocontrol introduction

Target pest: Cirsium arvense (Asterales: Asteraceae), Californian thistle

Agent introduced: Urophora cardui (Diptera: Tephritidae), Californian thistle gall fly


1975, 1994, 1996

Import source:

Native to Europe. 1975 Switzerland and Canada (previously introduced as a BCA), 1994 Canada, 1996 USA, 2000 Oregon USA.

Import notes: Cameron et al. (1989) - in Sep 1975, 7,250 U. cardui galls from CIBC European Station in Switzerland, and 66 galls from Regina Station of Agriculture Canada were imported into quarantine at Lincoln, Canterbury.



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. In the same year, 100 pairs were released at a site at Kaikoura (Marlborough).

Hayes (2007c) - progeny of 1994 and 1996 shipments released at a limited number of sites.


Cameron et al.(1989) - did not establish from 1976 releases although it persisted at Kaikoura until 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 1990's 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) - not assessed but as galls are commonly eaten by stock unlikely to have a large impact.

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.

Impacts on non-targets:

Hayes (2007c) - U. cardui will not attack other plants, even other thistle species.

Cripps et al. (2011) - U. 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.


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. 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/

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, 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