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Biocontrol introduction

Target pest: Ulex europaeus (Fabales: Fabaceae), gorse

Agent introduced: Pempelia genistella (Lepidoptera: Pyralidae) = Oncocera genistella, gorse colonial hard shoot moth


1995, 1996, 1999

Import source:

Portugal (1995, 1999), Spain (1996)

Import notes:

Landcare Research (2007a) - specimens of P. genistella from Spain, dated 1996, are present in the Biological Control Voucher Collection of the New Zealand Arthropod Collection [indicating an importation from Spain in that year].

Gourlay (2011c) - Pempelia genistella was first imported from Portugal in 1995, though not released in the field until 3 years later as it proved difficult to mass-rear in the laboratory. An additional shipment was imported in 1999 to boost rearing stocks.



Release details:

Landcare Research (2000a) - due to difficulties mass-rearing P. genistella, it has only been released at three sites (Lincoln and Christchurch [the Redcliffs site referred to in other entries] in Canterbury, South Island and Auckland, North Island) so far.

Landcare Research (2003a) - Pempelia genistella was initially released, in 1998, at two sites in Canterbury, South Island (Lincoln and Redcliffs) and one site in Auckland, North Island. Subsequently there have been five releases in 2001 (Manawatu-Whanganui, Northland, Taranaki and Wellington in the North Island, and Canterbury in the South Island) and six in 2002 (Bay of Plenty, Manawatu-Whanganui, Taranaki and two sites in Wellington in the North Island, and Southland in the South Island).

Landcare Research (2003b, 2004b, 2005b, 2006a, 2007c) - Pempelia genistella was released in 2002-03 at two sites, in 2003-04 at one site, 2004-05 at seven sites, 2005-06 at three sites and 2006-07 at five sites.

Gourlay (2011c) - released in 1998 from the 1995 importation. A further importation in 1999 to boost rearing stocks allowed widespread but still limited releases to be made [see Landcare Research (2003b, 2004b, 2005b, 2006a, 2007c) entry above].


Landcare Research (2000a) - follow up visits to the three release sites to date have failed to find any trace of P. genistella, until the discovery this autumn of larvae at the Lincoln site.

Landcare Research (2003a) - in spring this year, P. genistella was found thriving at the Redcliffs, Canterbury site; previous checks at this 1998 release site had shown no sign of the moth, indicating that it might take four or more years for moths to be easily found at release sites. The moths are already more abundant at Redcliffs than they typically are in their native Portugal, which bodes well for the future. Prior to the find at Redcliffs, P. genistella could only be found on a tiny patch of gorse at Lincoln, another initial release site.

Landcare Research (2005c) - Pempelia genistella is going from strength to strength at the Redcliffs site in Canterbury and has also been found at Lansdowne Valley in Canterbury, almost 14 km from the nearest release site, indicating it is dispersing faster than initial impressions suggested.

Gourlay (2011c) - only known to have established at sites in Canterbury so far.

Gourlay (2020c) - Pempelia genistella has only established in the South Island and is quite commonly found in parts of Canterbury. It is uncertain why it did not establish in the North Island.

Impacts on target:

Landcare Research (2005c) - at the Redcliffs, Canterbury release site, noticeable damage to gorse is showing up next to P. genistella webs due to larval feeding; the whole gorse patch has a slight brown tinge due to dead and dying branches.

Gourlay (2011c) - no studies of the impact of gorse colonial hard shoot moth have been undertaken in New Zealand. Where outbreaks have occurred the damage to gorse has been noticeable, but the overall effect on plant growth is unknown.

Landcare Research (2014c) - obvious damage seen at several sites but impact unknown.

Paynter et al. (2018) - Pempelia genistella is localised and impacts appear to be minor; it is parasitised by a native ichneumonid.

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 P. genistella, a defoliating moth, have not been reported in its native range, it does have a New Zealand native ecological analogue and its impact in New Zealand is assessed as ‘slight’.

Impacts on non-targets:

Landcare Research (2003a) - prior to the importation of P. genistella from Portugal in 1995, extensive testing showed that it could only survive on gorse and was extremely unlikely to damage any other plant species.

Landcare Research (2006b) - surveillance this year supports the prediction from host-testing that P. genistella would not attack non-target species in the field.

Gourlay (2011c) - extremely unlikely to attack plants other than gorse in New Zealand. Overseas it also attacks Ulex minor, which is not present in New Zealand.

Paynter et al. (2015) - surveys of potential non-target hosts Cytisus proliferus (tree lucerne, tagasaste) and Laburnum anagyroides (common laburnum, golden chain) report no feeding.


Gourlay H (2011c). Gorse colonial hard shoot moth: Pempelia genistella. The Biological Control of Weeds Book - Te Whakapau Taru: A New Zealand Guide (Landcare Research) [Updated 2020] https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/projects-agents/biocontrol-agents/gorse-colonial-hard-shoot-moth/

Gourlay H (2020c). Gorse colonial hard shoot moth: Pempelia genistella. The Biological Control of Weeds Book - Te Whakapau Taru: A New Zealand Guide (Landcare Research) [Update of Gourlay (2011c)] https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/projects-agents/biocontrol-agents/gorse-colonial-hard-shoot-moth/

Landcare Research (2000a). Local hot gossip. What’s New In Biological Control of Weeds? May 2000, 15: 8 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew15.pdf

Landcare Research (2003a). Moth hogs the limelight. What's New In Biological Control of Weeds? February 2003, 23: 1-2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew23.pdf

Landcare Research (2003b). Control agents released in 2002/03. What’s New In Biological Control of Weeds? Annual Review. August 2003, 25: 2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew25.pdf

Landcare Research (2004b). Control agents released in 2003/04. What’s New In Biological Control of Weeds? Annual Review. August 2004, 29: 2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew29.pdf

Landcare Research (2005b). Control agents released in 2004/2005. What's New In Biological Control of Weeds? Annual Review, August 2005, 33: 2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew33.pdf

Landcare Research (2005c). Outbreak! What’s New In Biological Control of Weeds? February 2005, 31: 1-2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew31.pdf

Landcare Research (2006a). Control agents released in 2005/06. What’s New In Biological Control of Weeds? Annual Review. August 2006, 37: 11 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew37.pdf

Landcare Research (2006b). Are they behaving themselves? What’s New In Biological Control of Weeds? Annual Review. August 2006, 37: 6-7 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew37.pdf

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 (2007c). Control agents released in 2006/07. What's New In Biological Control of Weeds? August 2007, 41: 2 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew41.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

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

Paynter QE, Fowler SV, Gourlay AH, Peterson PG, Smith LA and Winks CJ (2015). Relative performance on test and target plants in laboratory tests predicts the risk of non-target attack in the field for arthropod weed biocontrol agents. Biological Control 80: 133-142 https://doi.org/10.1016/j.biocontrol.2014.10.007