Biocontrol introduction
Target pest: Clematis vitalba (Ranunculales: Ranunculaceae), old man's beard
Agent introduced: Aceria vitalbae (Acariformes: Eriophyidae), old man's beard gall mite
Imported:
Pre-2019 (numerous importations since 2011), 2019 (hand-delivered importation)
Import source:
Serbia
Import notes:
Landcare Research (2013h) - several attempts have been made to establish an A. vitalbae colony in containment in New Zealand, but earlier shipments of the mites arrived in bad shape after being delayed in transit or were heavily diseased. Mite expert Dr Biljana Vidovic from the University of Belgrade, Serbia, hand-delivered a new shipment in April [2013]. If they produce a successful colony in containment this will be used for host range testing, otherwise the possibility of host-testing in Serbia will be explored [see Landcare Research (2019b) entry in ‘General comments’ section].
Landcare Research (2019b) - establishing a mite colony in containment has so far proved to be difficult. The mites have either arrived from Europe in poor condition or there have been issues with insect pests like aphids and thrips out-competing the mites on potted plants. A fresh attempt to establish a mite population in containment will be made in June 2019, with mite expert Dr Biljana Vidovic from the University of Belgrade, Serbia, hand-delivering the mites to avoid shipping issues.
Landcare Research (2021b) - a mite colony was finally established from the hand-delivered mites [see Landcare Research (2019b) entry above]. The mites were painstakingly transferred on pinheads to fresh plant material and after receiving MPI approval to remove them from containment, the infested plants were transferred to an outdoor shadehouse on Landcare Research's Lincoln, Canterbury campus for mass-rearing.
Cartier (2021b) - Aceria vitalbae is native to Europe from France to Romania. It was first imported into containment in New Zealand by Landcare Research in 2011. However, it was difficult to establish a colony in the laboratory, so host specificity testing was carried out in Serbia.
Landcare Research (2021i) - it has been more than 10 years since the mite was first imported into containment in New Zealand; after numerous failed attempts at establishing a laboratory colony, a starter colony was hand-delivered from Serbia in July 2019 [see Landcare Research (2019b, 2021b) entries above in this section].
Released:
2021
Release details:
Landcare Research (2019i) - it is hoped the first field releases can be made in late-2019.
Landcare Research (2020g) - it is hoped the first field releases can be made in late-2020.
Landcare Research (2021b) - the first official field releases of the old man’s beard mite will go ahead later this year in spring [see 'Import notes' section for details of release from containment for mass-rearing].
Landcare Research (2021i) - the first field release of A. vitalbae took place in Rangitikei District in the lower North Island in September 2021. In the following few weeks more releases were conducted by several regional councils in both the North and South Islands, totalling 14 releases altogether, the most recent being in Timaru.
Landcare Research (2022b) - the 2021 releases [see Landcare Research (2021i) entry above] were made by planting C. vitalba plants heavily infested with A. vitalbae in the field near C. vitalba infestations. Sites included one in the Waipara district of North Canterbury, South Island.
Landcare Research (2022h, 2023f) - 14 releases made in the year Sep 2021 - Aug 2022, 21 in the year Sep 2022 - Aug 2023.
Establishment:
Landcare Research (2021b) - over the past 18 months [up to Feb 2021] the mites have slowly transferred to fresh plants placed alongside the original mite-infested plants removed from containment into a shadehouse [see Landcare Research (2021b) entry in 'Import notes' section]. They have also been found on old man’s beard plants growing in other shadehouses, and even on wild plants growing on the Lincoln campus.
Landcare Research (2022b) - A. vitalbae has been found on C. vitalba at least 800 m from the release site at Waipara, North Canterbury, approximately eight months post-release. The mites have also been found at several other locations in Canterbury, including one at least 65 km from the nearest known established site. In fact, it is becoming difficult to find old man’s beard plants not infested by the mites throughout Canterbury as far as Hanmer Springs.
Landcare Research (2023g) - establishment has been confirmed in several regions of the country.
Impacts on non-targets:
Landcare Research (2018k), EPA (2018b) - host range tests were conducted in Serbia [see Landcare Research (2019c) entry in 'General comments' section below], using host plant material sourced from both New Zealand and Serbia. Seven of the nine New Zealand native Clematis species and a cross incorporating another were tested, along with six exotic Clematis species or hybrids selected to represent commercial interests in New Zealand and to provide representative coverage across the 10 clades described in the genus. The trials showed that small populations of A. vitalbae could persist (and presumably reproduce) in the buds of several test species, including three native species, for over 60 days without causing the leaf galls that typically developed on C. vitalba, although significant leaf damage was only recorded on the exotic C. stans. The persistence of A. vitalbae on native Clematis species without gall damage is unlikely to lead to sustainable populations; without galls, A. vitalbae becomes susceptible to desiccation and predation. On the basis of the test results and host plant records in Europe, A. vitalbae is expected to effectively colonise only C. vitalba in New Zealand with only occasional galls on nontarget exotic Clematis species, e.g. C. stans, which is in the same phylogenetic clade as C. vitalba. The presence of low numbers of mites on non-target plants is unlikely to result in damage.
General comments:
Landcare Research (2019b) - the old man’s beard mite is extremely difficult to rear under laboratory conditions, and after numerous failed attempts at establishing a laboratory colony in New Zealand, host range testing was eventually conducted in its native range of Serbia.
Landcare Research (2024c) - a recent population genetics study identified five distinct C. vitalba genotypes throughout its native range in the UK and Europe, with varying prevalence in different regions. Remarkably, all five genotypes appear to be present in New Zealand, with different regions hosting a mixture of genotypes. This suggests that C. vitalba was introduced into New Zealand on multiple occasions from different sources, followed by deliberate spread across the country. The most prevalent old man’s beard genotype in New Zealand shares similarities with genotypes from the UK and Italy, while other genotypes correspond to those from Germany, Sicily and Serbia, with the least common one originating from other European countries. Identifying this genetic diversity in New Zealand presents both challenges to, and opportunities for, developing tailored biocontrol strategies that account for genotype-specific interactions.
EPA Applications:
EPA (2018b) - 4 Jul 2018: application by Horizons Regional Council to release a leaf-galling mite, Aceria vitalbae, as a biological control agent for old man's beard (Clematis vitalba). EPA Application APP203313, approved without controls 29 Oct 2018.
References
Cartier A (2021b). Old man's beard mite: Aceria vitalbae. 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/old-mans-beard-mite/
EPA (2018b). EPA application APP203313: to release a leaf-galling mite, Aceria vitalbae, as a biological control agent for old man's beard (Clematis vitalba). Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP203313
Landcare Research (2013h). Mite we have found the answer to old man's beard? What’s New In Biological Control of Weeds? August 2013, 65: 8 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/whatsnew65.pdf
Landcare Research (2018k). The host range of the leaf‐galling eriophyid mite Aceria vitalbae, a biological control agent for Clematis vitalba. Landcare Research website https://www.landcareresearch.co.nz/__data/assets/pdf_file/0005/139667/old-mans-beard-host-range-tests.pdf
Landcare Research (2019b). Two agents ready to trim old man's beard. Weed Biocontrol: What's New? 87, February 2019. https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-87/two-agents-ready-to-trim-old-mans-beard
Landcare Research (2019i). Who's who in biological control of weeds? Weed Biocontrol: What's New? 89, August 2019 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/weed-biocontrol-issue-89/whos-who-in-biological-control-of-weeds
Landcare Research (2020g). Who's who in biological control of weeds? Weed Biocontrol: What's New? 93, Aug 2020. https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/status-of-agents/
Landcare Research (2021b). Old man's beard agents show promise. Weed Biocontrol: What's New? 95, Feb 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/old-mans-beard-agents-show-promise
Landcare Research (2021i). The old man's beard mite has finally landed. Weed Biocontrol: What's New? 98, November 2021 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/the-old-mans-beard-mite-has-finally-landed/
Landcare Research (2022b). Two recruits to battle old man’s beard. Weed Biocontrol: What's New? 100, May 2022 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/two-recruits-to-battle-old-mans-beard/
Landcare Research (2022h). Further reading and agents released 2021/22. Weed Biocontrol: What's New? 101, August 2022 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/further-reading-and-agents-released-202122/
Landcare Research (2023f). Further reading and biocontrol agents released in 2022/23. Weed Biocontrol: What's New? 105, August 2023. https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/further-reading-and-agents-released
Landcare Research (2023g). Who's who in the biological control of weeds. Weed Biocontrol: What's New? 105, August 2023 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/whos-who/
Landcare Research (2024c). Old man's beard pathogens. Weed Biocontrol: What's New? May 2024, 108: 6 https://www.landcareresearch.co.nz/publications/weed-biocontrol/weed-biocontrol-articles/old-mans-beard-pathogens/
