Biocontrol introduction
Target pest: Berberis darwinii (Ranunculales: Berberidaceae), Darwin's barberry
Agent introduced: Berberidicola exaratus (Coleoptera: Curculionidae), Darwin's barberry seed weevil
Imported:
2013, 2014, 2015, 2016, 2017
Import source: Chile
Import notes:
Environment Southland (2012) - Berberidicola exaratus has been collected from 36° 47’ S to 42° 52’ S in Chile and daylength effects are unlikely to limit establishment in New Zealand, even in Southland (46-47° S). The climates in the region of origin broadly match those in New Zealand, and both weevils should be able to colonise Darwin’s barberry populations wherever these occur here.
Landcare Research (2015c, 2016f) - imported adults from Chile spring 2013 and spring 2014; both shipments infected with microsporida. Imported larvae in fruit from Chile later in spring 2014. Larger batch of larvae imported in fruit in spring 2015.
Landcare Research (2018b) - large quantity of infested fruits imported from Chile in November 2016, but only a handful of adults emerged from pupae, possibly due to over-crowding or dehydration in large containers. A further import from Chile in November 2017 yielded several thousand adults.
Released:
2015
Release details:
Landcare Research (2015c, 2015j, 2016f) - Imported larvae in fruit from Chile 2014, 70 subsequent adults released in April 2015 at one site in Southland, South Island, initially in cages for a couple of weeks.
Landcare Research (2016f, 2018a) - 1,260 weevils from larvae imported in fruit in spring 2015 were released in summer 2015-16, at a total of seven sites, in Southland in the South Island, and Wellington and Manawatu-Wanganui in the North Island.
Landcare Research (2018b) - several thousand adults were released at the Southland and Wellington sites in early February 2018.
Landcare Research (2018h) - five releases made in the year Sep 2017 - Aug 2018.
Landcare Research (2023e) - Berberidicola exaratus are currently being redistributed to new sites from Southland sites, where high densities of the weevil have been achieved.
Establishment:
Landcare Research (2017f) - establishment is not yet confirmed.
Landcare Research (2018b) - in early-November 2017 two adults were found at the site of the first ever release in Southland, suggesting the weevil is well on the way to establishing at that site.
Landcare Research (2023e) - establishment of B. exaratus has been confirmed in Southland and the Greater Wellington region. High densities were found only in Southland.
Impacts on non-targets:
Environment Southland (2012) - host range testing was carried out in Chile (the home range of the weed) in 2009/10 and 2010/11 (field surveys and outdoor experiments) and in New Zealand in 2012 (laboratory trials in containment). A total of 17 plant species belonging to families within the order Ranunculales were tested. The results indicate that B. exaratus is able to complete development on several species within the genus Berberis and is not specific to Darwin's barberry. However, is unlikely to attack species outside the subfamily Berberidoideae. Therefore, New Zealand native plants are unlikely to be at risk as there are no native species in this subfamily or even in the family Berberidaceae. It is possible that the foliage and buds of exotic non-target species of Berberis may be slightly damaged by adult weevils.
EPA Applications:
EPA (2012c) - 19 Jun 2012: application by Environment Southland to release two weevils, Anthonomus kuscheli and Berberidicola exaratus, as biological control agents for the weed Darwin's barberry (Berberis darwinii). EPA Application # APP201363, approved without controls 11 Sep 2012.
References
EPA (2012c). Application to EPA (APP201363) to import and release two weevils, Berberidicola exaratus and Anthonomus kuscheli, as biological control agents for Darwin's barberry (Berberis darwinii). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP201363
Environment Southland (2012). Application to EPA (APP201363) to import for release, or release from containment, two weevils, Berberidicola exaratus and Anthonomus kuscheli. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/APP201363/6c1c373a3b/APP201363-Application.pdf
Landcare Research (2015c). Darwin's barberry weevil released. What's new in biological control of weeds? 72: 7 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-72
Landcare Research (2015j). Biocontrol agents released in 2014/15. Weed Biocontrol: What's New? 73: 2 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-73
Landcare Research (2016f). Barberry weevil breakthrough. Weed Biocontrol: What's New? 76: 7 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-76
Landcare Research (2017f). Spring activities Weed Biocontrol: What's New? 81: 8-9 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-81
Landcare Research (2018b). Darwin's barberry; playing the numbers game. Weed Biocontrol: What's New? 83, February 2018 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-83/first-release-of-new-agents
Landcare Research (2018h). Biocontrol agents released in 2017/18. Weed Biocontrol: What's New? 85, August 2018 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-85/biocontrol-agents-released-in-201718
Landcare Research (2023e). Spring activities. Weed Biocontrol: What's New? 105, August 2023. https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/spring-activities-4
