Biocontrol introduction
Target pest: Paropsis charybdis (Coleoptera: Chrysomelidae), eucalyptus tortoise beetle
Agent introduced: Cleobora mellyi (Coleoptera: Coccinellidae), southern ladybird
Imported:
1977, 1979, 1980
Import source:
Tasmania, Australia
Import notes:
Cameron et al. (1989) - approximately 600 C. mellyi adults were imported from Tasmania, Australia in 1977. From these, a few (about 20) F1 adults were reared in the laboratory on P. charybdis eggs. Approximately 400 overwintered adults were imported from Tasmania in August 1979 and improved rearing techniques produced enough F1 adults for releases. In August 1980 a further 400 adults were received from Tasmania.
Released:
1979
Release details:
Cameron et al. (1989) - 7,320 beetles were released in two eucalypt plantations near Tokoroa (Waikato, North Island) over six releases between October 1979 and September 1982; 88 at Whakarewarewa (Rotorua, Bay of Plenty, North Island) in 1980; 2,849 at Maori Bay (Marlbourough Sounds, South Island); 200 at Christchurch (Canterbury, South Island) in 1983 and 200 at Rotoehu (Bay of Plenty) in 1987.
Brown (2007 - in Murray et al. 2008) - recent releases of over 3,000 adults and 1350 eggs have been made at 17 sites in the North Island from Northland to Rotorua (Bay of Plenty) in an attempt to broaden the geographical range of C. mellyi. [See Withers & Bain (2009) entry in 'Impacts on non-targets' section below for context of releases, and Withers & Berndt (2010) entry in this section below for further details.]
Withers & Berndt (2010) - Cleobora mellyi collected in October 2005 from Marlborough Sounds were reared in captivity and released from October to December 2006 and in September 2007 at 19 sites in the North Island [see Brown (2007 - in Murray et al. 2008) entry above in this section], as well as at two sites in Southland in the South lsland.
Establishment:
Cameron et al. (1989) - recovered in the vicinity of a Tokoroa release site in November and December 1981 but not since. However, it appears to have established at Maori Bay, Marlborough Sounds.
Satchell et al. (2004) - specimen found at Havelock (Marlborough Sounds), and plentiful at original Marlborough Sounds release site (Maori Bay).
Murray et al. (2008) - to date no establishments documented from the Brown (2007)-reported North Island releases. C. mellyi still only known to be established close to Marlborough Sounds release site.
Withers & Bain (2009) - following the recent releases of C. mellyi (field-collected from the Marlborough Sounds) at about 18 locations, mainly in the North Island but also in Southland [see Brown (2007 - in Murray et al. 2008) and Withers & Berndt (2010) entries in ‘Release details’ section above], this agent is now known to be established in Northland and Bay of Plenty in the North Island, as well as Marlborough Sounds in the South Island. Further work is planned to determine distribution throughout the country. It is thought that the paucity of psyllids, required by C. mellyi for successful reproduction, was a major factor in the failure of this agent to establish at most original release sites. At the time, only two psyllid species were found on eucalypts in New Zealand; since then, another seven species have established.
Withers & Berndt (2010) - in surveys last summer at most of the recent release sites [see Brown (2007 - in Murray et al. 2008) and Withers & Berndt (2010) entries in ‘Release details’ section above] C. mellyi was found at eight of the 14 sites visited in the North Island, and one of the two Southland sites, indicating it is now widely established in New Zealand. It is established in Northland, Auckland, Coromandel, Waikato and Bay of Plenty in the North Island, and Southland in the South Island, in addition to the previously-established Marlborough Sounds site.
Impacts on target:
Weser et al. (2024) - field studies from Australia and laboratory predation trials from New Zealand led to the conclusion that C. mellyi can have a significant impact on paropsine beetle populations in the field through egg and, to a lesser extent, larval predation. In New Zealand, C. mellyi feeds on P. charybdis eggs and larvae in the field, but its quantitative impact on population levels remains unknown.
Mansfield (2019) - laboratory trial was undertaken to determine the potential for C. mellyi to interfere with the biocontrol of P. charybdis by the egg parasitoids Enoggera nassaui and Neopolycystus insectifurax through intraguild predation (IGP - predation within the same trophic level when the two species also compete for shared prey). Adult and larvae C. mellyi showed a strong preference for unparasitised P. charybdis eggs over parasitised, and also fed readily on acacia and eucalypt psyllids (psyllids are essential prey for C. mellyi reproduction) with some evidence of preference for psyllids over unparasitised P. charybdis eggs. In addition, eucalypt psyllids feed on juvenile foliage, P. charybdis on mature foliage, creating a physical separation reducing competition between C. mellyi and the egg parasitoids when the former is foraging for psyllids (though also reducing the effectiveness of C. mellyi as a biocontrol agent for P. charybdis). These prey preferences and the necessity of psyllid prey for reproduction reduce the likelihood that C. mellyi will disrupt biological control of P. charybdis.
Weser et al. (2025) - a study to identify effective predators of the paropsine pests P. charybdis and the recently invasive in New Zealand Paropsisterna cloelia in a Eucalyptus bosistoana stand in Marlborough in the South Island combined field observations over two eucalypt growth seasons (September-March 2021-22 and 2022-23) and molecular analysis of predators for the presence of paropsine DNA. Cleobora mellyi was one of the two (along with the hemipteran Oechalia schellenbergii) most abundant and/or most active paropsine predators, and these two species appear important for paropsine control in eucalypt plantations in Marlborough. An estimated 87% of C. mellyi individuals tested paropsine positive. This study suggests there is potential for augmentative biocontrol (augmenting existing natural enemy field populations with releases of laboratory-reared individuals) or conservation biocontrol (manipulating the environment to enhance the effectiveness of natural enemies) using C. mellyi and O. schellenbergii (of which 100% of individuals were paropsine positive in this study) as part of an integrated pest management strategy for P. charybdis (and P. cloelia).
Withers (2025) - the impact of C. mellyi on P. charybdis remains uncertain.
Impacts on non-targets:
Withers & Bain (2009) - in the early-2000s, C. mellyi was found feeding on the eggs of the Australian paropsine beetle Dicranosterna semipunctata, first detected in New Zealand in 1996. It was concern about damage by D. semipunctata to commercial eucalypts, particularly Acacia melanoxylon that prompted the relocation of C. mellyi from Marlborough Sounds sites [see Brown (2007 - in Murray et al. 2008) entry in ‘Release details’ section above]. Trials are also underway, with promising initial results, using C. mellyi to control Bactericera cockerelli, the potato-tomato psyllid, first detected in New Zealand in 2006, in tomato and capsicum crops.
Withers et al. (2018) - Cleobora mellyi, along with Enoggera nassaui (another biocontrol agent introduced against P. charybis), attack and kill the eggs of Paropsisterna cloelia [previously known as Paropsisterna variicollis], first detected in New Zealand in Hawke’s Bay in 2016, but have not been effective in halting the rapid population growth of P. cloelia in Hawke’s Bay. Paropsisterna cloelia has the potential to become a significant pest of eucalypts in New Zealand. There is no data yet to suggest how effective C. mellyi might be at controlling P. cloelia.
Mansfield (2019) - eucalypt and/or acacia psyllids are essential food for breeding by C. mellyi in New Zealand. On eucalypts, the foliage types preferred by eucalypt psyllids and P. charybdis contribute to a physical separation that will reduce the effectiveness of C. mellyi as a biocontrol agent for its target pest, P. charybdis [see Mansfield (2019) entry in ‘Impacts on target’ section above]. In contrast, there is no significant physical separation between acacia psyllids and Dicranosterna semipunctata, an invasive paropsine pest of blackwood (Acacia melanoxylon) in New Zealand [see Withers & Bain (2009) entry above in this section]. Thus, it is possible that C. mellyi, now established on blackwood in the North Island, will be a more useful biocontrol agent for acacia pests than eucalypt pests in New Zealand.
Weser et al. (2024) - in New Zealand, C. mellyi feeds on Paropsisterna cloelia [see Withers et al. (2018) entry above in this section] eggs and larvae in the field, but its quantitative impact on population levels remains unknown.
References
Cameron PJ, Hill RL, Bain J, Thomas WP (1989). A Review of Biological Control of Invertebrate Pests and Weeds in New Zealand 1874-1987. Technical Communication No 10. CAB International Institute of Biological Control. DSIR Entomology Division. 424p.
Mansfield S (2019). Intraguild predation and prey preferences influence biological control of Paropsis charybdis by the southern ladybird, Cleobora mellyi. Biological Control 129: 164-170 https://doi.org/10.1016/j.biocontrol.2018.10.013
Murray TJ, Withers TM, Mansfield S and Bain J. (2008). Distribution and current status of natural enemies of Paropsis charybdis in New Zealand. New Zealand Plant Protection 61: 185-190 https://journal.nzpps.org/index.php/nzpp/article/view/6834/6662
Satchell D, Hood I and Bain J. (2004). Cleobora alive and well in the South Island. Forest Health News 140 [accessed 29 August 2014] http://www.scionresearch.com/__data/assets/pdf_file/0019/3835/fhnewsNo140-2004May.pdf
Weser C, Dhami MK, Moltchanova E, Podolyan A, Withers TM, Pawson SM (2025). Predators of the two paropsine leaf beetles Paropsisterna cloelia and Paropsis charybdis in eucalypt plantations in Marlborough, New Zealand. Agricultural and Forestry Entomology 28(2): 137-148. First published online on 19 Sept 2025. https://doi.org/10.1111/afe.70013
Weser C, Withers TM, Pawson SM (2024). Comparison of the biology, ecology and potential pest impacts of the eucalypt-defoliating leaf beetles Paropsisterna cloelia and Paropsis Charybdis (Coleoptera: Chrysomelidae) in New Zealand. New Zealand Journal of Forestry Science, 54 https://doi.org/10.33494/nzjfs542024x317x
Withers TM (2025). Classical biological control of defoliators in Eucalyptus plantations. In: Biological Control of Insect Pests in Plantation Forests (Eds Hurley BP, Lawson SA, Slippers B), Springer 2025, pp 205-221 https://doi.org/10.1007/978-3-031-76495-0
Withers TM, Bain J (2009). Cleobora mellyi - what is it up to these days. Forest Health News No. 193, March 2009 https://cdm20044.contentdm.oclc.org/digital/collection/p20044coll2/id/77/rec/84
Withers TM, Berndt L (2010). Southern ladybird gets a second chance. New Zealand Tree Grower 31(4): 37-38 https://www.nzffa.org.nz/farm-forestry-model/resource-centre/tree-grower-articles/november-2010/southern-ladybird-gets-a-second-chance/
Withers TM, McDougal RL, Harnett M, Murray TJ (2018). Eucalyptus variegated beetle creates concern for eucalypt growers. New Zealand Tree Grower 39(2): 18-21 https://www.nzffa.org.nz/farm-forestry-model/the-essentials/forest-health-pests-and-diseases/Pests/paropsisterna-variicollis-the-eucalyptus-variegated-beetle-evb/eucalyptus-variegated-beetle-creates-concern-for-eucalypt-growers/
