Target pest: Tradescantia fluminensis (Commelinales: Commelinaceae), wandering willie, wandering jew
Agent introduced: Lema basicostata (Coleoptera: Chrysomelidae), tradescantia stem beetle
Fowler et al. (2013) - in 2012 1,262 L. basicostata were released at 6 sites. Landcare Research (2013a) - total of 10 releases prior to Aug 2013.
Landcare Research (2014c) - releases are continuing. Landcare Research (2015j) - 5 releases 2014/2015.
Landcare Research (2016c) - Northland and Taranaki Regional Councils harvesting beetles from initial release sites to spread around their regions. Wellington Botanic Gardens are breeding the beetles to release in Wellington's parks and reserves; first release made at Mt Victoria.
Landcare Research (2018h) - 5 releases made in the year Sep 2017 - Aug 2018.
Landcare Research (2020h) - 4 releases made in the year Sep 2019 - Aug 2020.
Landcare Research (2014c) - already well established and numbers appear to be building rapidly.
Impacts on target:
Landcare Research (2015a) - caused significant damage in 3 years to tradescantia at Welcome Bay (near Tauranga), reducing coverage to bare ground in places.
Landcare Research (2016c) - the three beetle species introduced for this weed - Neolema abbreviata, N. ogloblini and Lema basicostata are establishing well and starting to knock back the plant at release sites. Site at Waikakaho (Marlborough) showed L. basicostata alone can have a rapid impact; after only 3 years, 10 square metres of weed had collapsed and disappeared at release site, with heavy damage out for another 20m. A trial has been established in forest remnants at Hikurangi flood plain (Northland) to assess tradescantia control and habitat recovery.
Landcare Research (2018f) - the impact of the stem beetle has been monitored at sites in Northland, Auckland and the Bay of Plenty; the damage is encouraging but somewhat patchy. In wetter sites the percentage cover is still quite high, perhaps because tradescantia stems severed by larval feeding are capable of re-establishing, but bare patches are appearing in drier areas.
Landcare Research (2021a) - all three beetle species released against T. fluminensis (L. basicostata, Neolema abbreviata, Neolema ogloblini) have proven effective in controlling tradescantia in multiple regions, most notably Northland and the Waikato.
Impacts on non-targets:
Auckland Council (2011) - there are no New Zealand native plants in the same order as T. fluminensis, and apart from some ornamental house plants, no closely-related valued exotic plants. Host range testing carried out by Landcare Research included the native nikau palm (Rhopalostylis sapida) because it is the most closely related native plant; there was no semblance of attack on this species. Several host plants (all within the tribe Tradescantineae) supported complete development of L. basicostata. Tradescantia albiflora (naturalised in New Zealand) appears to be as good a host as T. fluminensis. The house plants Callisia repens, Gibasis spp. and Cyanotis somaliensis appear to be adequate hosts. The test results indicate that the physiological host range of L. basicostata lies within the Family Commelinacae, and possibly within the Tribe Tradescantineae. Given the extreme taxonomic distance between this tribe and any valued plant, the risk of significant adverse effects on such plants species in New Zealand (whether native or exotic) is considered to be negligible.
Fowler et al. (2013) - Tradescantia albiflora appears to be a fundamental host. This plant is naturalised in New Zealand and a potential future weed. Potential 'spillover' attack on other plant species in the Commelinaceae may be beneficial as well as some are already naturalised in New Zealand and are invasive in other countries. New Zealand has no native or commercially significant exotic plants in this family.
EPA (2011b) - 11 Mar 2011: application by Auckland Council for the importation and release of two beetles, Lema basicostata and Neolema abbreviata, as biological control agents for the weed tradescantia. EPA Application # ERMA200638, approved without controls 29 Jun 2011.
Auckland Council (2011). EPA application [ERMA200683] to release a new organism [Lema basicostata and Neolema abbreviata] without controls. Environmental Protection Authority website https://www.epa.govt.nz/assets/FileAPI/hsno-ar/ERMA200683/8ee858ce25/ERMA200683-FINAL-Application-ERMA200683-2011-03-11.pdf
EPA (2011b). EPA application ERMA200683: to import and release two beetles, Lema basicostata and Neolema abbreviata, as biological control agents for the weed tradescantia. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/ERMA200683
Fowler SV, Barreto R, Dodd S, Macedo DM, Paynter Q, Pedrosa-Macedo JH, Pereira OL, Peterson P, Smith L, Waipara N, Winks CJ and Forrester G (2013). Tradescantia fluminensis, an exotic weed affecting native forest regeneration in New Zealand: Ecological surveys, safety tests and releases of four biocontrol agents from Brazil. Biological Control 64: 323-329
Landcare Research (2013a). Biocontrol agents released in 2012/13. What's new in biological control of weeds? 65: 7 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-65
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 (2015a). Tradescantia beetles make big impression. What's new in biological control of weeds? 72: 2-3 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 (2018f). Tradescantia be gone! Weed Biocontrol: What's New? 84, May 2018 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-84/tradescantia-be-gone
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 (2020h). Further reading and agents released table. Weed Biocontrol: What's New? 93, Aug 2020. https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/further-reading-and-agents-released-table/
Landcare Research (2021a). The more the merrier? Testing efficacy of multiple agents. Weed Biocontrol: What's New? 95, Feb 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/the-more-the-merrier-testing-efficacy-of-multiple-agents