Target pest: Cirsium arvense (Asterales: Asteraceae), Californian thistle
Agent introduced: Ceratapion onopordi (Coleoptera: Apionidae) = Apion onopordi, Acanephodus onopordi, Californian thistle stem miner
The 2003 introduction (as Apion onopordi) was into containment for evaluation. The 2007 introduction was for release.
Gourlay (2010) - first releases were made in 2008.
Landcare Research (2014c) - released at limited sites as difficult to rear.
Gourlay (2010), Landcare Research (2014c) - not known if establishment has been successful.
Impacts on non-targets:
Hill (2006a) - in Europe, C. onopordi has been recorded from a wide range of thistle and related species that belong to the tribe Cardueae in the family Asteraceae. New Zealand has no native species in this tribe and almost all imported thistles and knapweeds in this tribe have the potential to become weedy once established in the New Zealand environment. Host range testing in New Zealand confirmed that there is no evidence that species of other tribes belonging to the family Asteraceae would be at risk from this weevil in New Zealand. Ceratapion onopordi could not lay eggs or feed on any of the 11 plants selected to represent the other tribes that are indigenous to New Zealand. There are few species of potential economic importance in New Zealand that fall within the apparent host range of this weevil, e.g. Silybum marianum (variegated thistle) (though this is also a significant pasture weed), Centaurea cyanus (cornflower), C. montana (mountain knapweed), and various ornamental Centaurea cultivars. Centaurea cyanus successfully supported weevil oviposition and development. Related species are known hosts in Europe, and it is likely that these species will be field hosts in New Zealand. Occasional adults emerged in trials from Cynara scolymus (artichoke) and Carthamus tinctoria (safflower), but use of these species was clearly poor compared with attack on thistle species and neither species are recorded as hosts of C. onopordi in Europe.
Gourlay (2010) - prefers nodding (Carduus nutans), Scotch (Cirsium vulgare), and variegated (Silybum marianum) thistles, and Californian thistle if they are infected with rust. It may also attack other thistles to a lesser extent. Plants outside the Cardueae tribe are unlikely to be attacked. Most of the plants in this tribe are unwanted introduced thistles except for globe artichoke (Cynara scolymus) and safflower (Carthamus tinctoria). In laboratory tests the stem miner will attack these plants, but given that there are no records of the beetle ever being a pest on these plants in Europe or the USA, damage to these plants in the field is unlikely.
EPA (2003) - 27 Jan 2003: application by the Californian Thistle Action Group (CalTAG) to import into containment the root and stem boring weevil Apion onopordi [subsequently Ceratapion onopordi], to evaluate its suitability as a control agent for Californian thistle (Cirsium arvense). EPA Application # NOC02004, approved with controls 22 Apr 2003.
EPA (2007b) - 10 Nov 2006: application by the Californian Thistle Action Group (CalTAG) to import for release a weevil, Ceratapion onopordi (Brentidae) and a beetle, Cassida rubiginosa (Chrysomelidae), for the biological control of the weed Californian thistle (Cirsium arvense). EPA Application #NOR06005, approved without controls 17 Apr 2007.
EPA (2003). EPA application NOC02004: to import root and stem boring weevil, Apion onopordi, into containment for assessment as a biocontrol agent of Californian thistle, Cirsium arvense. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/NOC02004
EPA (2007b). Application to EPA (NOR06005) to import and release two insects, Ceratapion onopordi (Brentidae) and Cassida rubiginosa (Chrysomelidae), for biological control of the weed Californian thistle (Cirsium arvense). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/NOR06005
Gourlay H (2010). Californian Thistle Stem Miner. In The Biological Control of Weeds Book (Landcare Research) http://www.landcareresearch.co.nz/research/biocons/weeds/book/documents/Californian_Thistle_Stem_Miner.pdf
Hill R (2006a). Application to EPA (NOR06005) to import and release two insects, Ceratapion onopordi (Brentidae) and Cassida rubiginosa (Chrysomelidae), for biological control of the weed Californian thistle (Cirsium arvense). Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/NOR06005/9287e22698/NOR06005.pdf
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