Biocontrol introduction
Target pest: Clematis vitalba (Ranunculales: Ranunculaceae), old man's beard
Agent introduced: Monophadnus spinolae (Hymenoptera: Tenthredinidae), old man's beard sawfly
Imported:
1997, 1998, 1999, 2018
Import source:
Austria 1997; Switzerland 1998, 1999; Serbia 2018
Import notes:
Research (2019b) - mass rearing challenges with the 1990s importations resulted in suboptimal numbers of sawflies for release and possibly a sex ratio skewed towards males. A fresh sawfly shipment from Serbia was imported into containment in May 2018. A successful rearing procedure was established the the sawfly reared through three generations, producing good numbers of both males and females.
Released:
1998, 2018
Release details:
Gourlay (2007) - released widely (details unknown) from 1998, but at limited number of sites as difficult to rear.
Landcare Research (2016d) - 16 releases were made at 14 sites from Bay of Plenty to Otago, by far the largest being nearly 3,000 individuals at a site near Nelson in 2002.
Landcare Research (2018g) - the sawfly, using new material sourced from Serbia, will be re-released, in much bigger numbers and with better genetic diversity than previous releases, at a site carefully chosen to be as be safe as possible from disturbance.
Landcare Research (2019b) - due to rearing challenges, releases in the 1990s were suboptimal: probably too small and possibly skewed towards males. The plan this time [with material imported 2018] is to put out a large number of sawflies, with a good sex ratio, at an ideal site (based on observed preferences in Serbia - sunny with sandy soil) to try to establish a sawfly "nursery" that can later be used to supply other M. spinolae-infested areas. Sawflies were released in stages in December 2018 near the Waipara River in North Canterbury as material became available.
Landcare Research (2021b) - in late-2019, thousands of sawfly larvae along with mated adult females were released in Amberley in the Waipara district in the Canterbury Region in the South Island [the same release site as the December 2018 releases].
Establishment:
Gourlay (2007) - no signs of establishment recorded.
Landcare Research (2014c) - probably failed to establish.
Landcare Research (2016d) - surviving release sites checked; found only at Nelson site and rare even there (3 larvae, 1 adult found). Population may be inbred, and predatory vespid wasps are likely to be a limiting factor in New Zealand.
Landcare Research (2017g) - only established in low numbers at one site in Nelson. More material will be imported in 2017 in an attempt to establish this insect more widely.
Landcare Research (2019b) - already [Feb 2019] there is feeding damage starting to appear on plants at the Waipara River site, and three male flies were spotted flying around, probably from larvae released in early December 2018.
Landcare Research (2021b) - in February 2020 some larvae were found feeding on leaves at the late-2019 release site, and adults (which would have been second generation adults) were seen flying around. The site was visited again this summer [2020/21] and both adults and larvae were observed.
Landcare Research (2022b) - the 2018/19 Waipara release site has been monitored closely since early 2019, with the presence of adult males (which fly searching for mates while females remain hidden) consistently being noted. But not until this last season (November 2021 – April 2022) could it be reported that the population was booming, with many males flying and, during the last visits, larvae easily found on C. vitalba leaves and feeding damage obvious.
Impacts on target:
Landcare Research (2016i) - has only established at one site in Nelson where it still appears to be rare and having no obvious impact.
General comments:
Landcare Research (2016d) - the merits of attempting to establish the sawfly again have been considered. The initial step was to check release sites once more (see details under "Establishment"). It is recommended that there are no further releases as vespid wasps likely to be a limiting factor in New Zealand.
Landcare Research (2018g) - further releases will be made with new material sourced from Serbia (see details under "Release details"), with steps taken to ensure that wasps don't impact on the newly released sawflies, although it is thought this is not a key reason for the poor establishment previously, since the larvae readily ooze haemolymph when threatened, which deters predators. The sawfly population in Serbia may have a better climate match with New Zealand than earlier introductions.
References
Gourlay H (2007). Old Man's Beard Saw Fly. In The Biological Control of Weeds Book (Landcare Research) http://www.landcareresearch.co.nz/research/biocons/weeds/book/documents/Old_Mans_Beard_Sawfly.pdf
Landcare Research (2007a). New Zealand Arthropod Collection (NZAC) Biological Control Voucher Collection. http://www.landcareresearch.co.nz/resources/collections/nzac/holdings/biological-control-voucher-collection
Landcare Research (2014c). Who's who in biocontrol of weeds? What's new in biological control of weeds? 69: 10-11 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-69
Landcare Research (2016d). What's happening with old man's beard? Weed Biocontrol: What's New? 76: 4-5 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-76
Landcare Research (2016i). Who's who in biological control of weeds? Weed Biocontrol: What's New? 77: 10-11 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-77
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 (2018g). Old man's beard to face new attack. Weed Biocontrol: What's New? 84, May 2018 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-84/old-mans-beard-to-face-new-attack
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 (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 (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/
