Biocontrol introduction
Target pest: Ligustrum spp. (Lamiales: Oleaceae), privet
Agent introduced: Leptoypha hospita (Hemiptera: Tingidae), privet lace bug
Imported:
2013
Import source:
China
Import notes:
Paynter (2021c) - Leptoypha hospita is native to China. It was first imported into New Zealand for study in 2013. It has not been used as a biocontrol agent anywhere else in the world before [i.e. it was imported into New Zealand from China].
Released:
2015
Release details:
Landcare Research (2016e) - eleven releases made spring/early summer 2015-16 in the Auckland, Bay of Plenty, Waikato and Wellington regions.
Landcare Research (2017g) - widespread releases continuing.
Landcare Research (2018h, 2019j, 2021e) - 11 releases made in the year Sep 2017 - Aug 2018; 16 in the year Sep 2018 - Aug 2019; three in the year Sep 2020 - Aug 2021.
Establishment:
Landcare Research (2016e) - at Mt Richmond (Auckland), autumn 2016, seedling plants of Chinese privet (Ligustrum sinense) in the shade were clearly showing signs of attack, with much bleaching of the leaves, only a few months after release; augers well that the lace bug will establish and be able to cause considerable damage to Chinese privet.
Landcare Research (2017g) - establishment success not yet known, but promising early damage seen.
Landcare Research (2018i) - establishment confirmed at Auckland and Waikato.
Impacts on target:
Landcare Research (2018i) - some promising early damage seen at Auckland and Waikato.
Landcare Research (2021f) - damage seen at Auckland and Waikato in shaded sites.
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 L. hospita, a piercing/sucking insect, have not been reported in its native range, it does not have a New Zealand native ecological analogue and its impact in New Zealand is assessed as ‘slight’.
Impacts on non-targets:
Landcare Research (2014e) - Ligustrum and Syringa (lilacs) form a clade within the tribe Oleeae in the family Oleaceae. The native New Zealand genus Nestegis also belongs to the tribe Oleeae, but resides within a different subtribe to Ligustrum. No-choice laboratory tests in USA (reported in 2012) indicated that the fundamental host-range (plants on which development can be completed) of L. hospital is confined to the tribe Oleeae, although within this tribe, of the genera tested, Olea (olives) and Osmanthus were not fundamental hosts. Development to adult occurred in three genera of the Oleeae that are of relevance to the New Zealand nursery industry, namely Fraxinus (ashes), Chionanthus (fringetrees) and Syringa. However, poor oviposition rates and low development success in the laboratory, and lack of host records in the field, suggests these genera are unlikely to be field hosts. No species in the genus Nestegis were tested in USA. Additional host-range testing was carried out in New Zealand to investigate the risk to Nestegis species and ornamental Syringa cultivars grown in New Zealand. The results indicated that Nestegis species are not fundamental hosts and can be discounted as potential field hosts, and L. hospital is most unlikely to be able to persist on Syringa species in the absence of nearby Ligustrum plants. The potential for spill-over attack to occur on ornamental Syringa cannot be completely ruled out, but any such attack is likely to be minor.
Landcare Research (2016e) - in its native range (China) the lace bug is reported to attack a range of privet species in addition to Chinese privet. Host-range testing has indicated that other Ligustrum species present in New Zealand, such as the larger tree privet (L. lucidum) are also potential, but less-preferred hosts.
EPA Applications:
EPA (2015b) - 16 Jan 2015: application by the Waikato Regional Council to release privet lace bug (Leptoypha hospita) as a biological control agent for the weed privet (Ligustrum spp.). EPA Application # APP202262, approved without controls 15 May 2015.
References
EPA (2015b). EPA application [APP202262] to introduce the privet lace bug (Leptoypha hospita) as a biological control agent for the weed privet (Ligustrum spp.). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP202262
Landcare Research (2014e). Host range testing of Leptoypha hospita. Landcare Research website https://www.landcareresearch.co.nz/science/plants-animals-fungi/plants/weeds/biocontrol/approvals/completed/privet/host-range-testing
Landcare Research (2016e). Privet lace bug shows early promise Weed Biocontrol: What's New? 76: 5 http://www.landcareresearch.co.nz/__data/assets/pdf_file/0010/120160/Issue-76.pdf
Landcare Research (2017g). Who's who in biological control of weeds? Weed Biocontrol: What's New? 81: 10-11 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-81
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 (2018i). Who's who in biological control of weeds? Weed Biocontrol: What's New? 85, August 2018 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-85/whos-who-in-biological-control-of-weeds
Landcare Research (2019j). Biocontrol agents released in 2018/19. Weed Biocontrol: What's New? 89, August 2019 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/weed-biocontrol-issue-89/biocontrol-agents-released-in-201819
Landcare Research (2021e). Further reading and agents released. Weed Biocontrol: What's New? 97, August 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/further-reading
Landcare Research (2021f). Who's who in biological control of weeds? Weed Biocontrol: What's New? 97, August 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/whos-who-in-biological-control-of-weeds
Paynter Q (2021c). Privet lace bug: Leptoypha hospita. The Biological Control of Weeds Book - Te Whakapau Taru: A New Zealand Guide (Landcare Research) https://www.landcareresearch.co.nz/discover-our-research/biodiversity-biosecurity/weed-biocontrol/projects-agents/biocontrol-agents/privet-lacebug/
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
