Biocontrol introduction
Target pest: Clematis vitalba (Ranunculales: Ranunculaceae), old man's beard
Agent introduced: Phytomyza vitalbae (Diptera: Agromyzidae), old man's beard leaf miner
Imported:
1994, 1996 (?)
Import source:
Switzerland and Germany
Released:
1996
Release details:
Gourlay (2007) - released throughout New Zealand in the summer of 1996/97.
Establishment:
It established and dispersed readily and quickly became common throughout the country.
Impacts on target:
Gourlay (2007) - some damaging outbreaks have been observed, but the agent seems to be limited by parasitism.
Landcare Research (2016d) - while mining of leaves is now common, six native and two exotic parasitoids generally keep the leaf miner populations too low to impact on growth. However, damaging outbreaks do sometimes occur e.g. heavy mining this autumn at Ashburton and on Banks Peninsula.
Paynter et al. (2018) - impacts have been trivial, with P. vitalbae heavily parasitised and predated by eulophid parasitoids (the adults of which feed on P. vitalbae larvae within leaf mines). Combined parasitism and predation rates average at least 58%.
Impacts on non-targets:
Paynter et al. (2004), Gourlay (2007), Paynter et al. (2008) - P. vitalbae has been collected from the native species Clematis foetida and can complete it is life cycle on this host but levels of attack are very low. A single specimen has been collected from C. forsteri, also a native species. Non-target attacks shown to be a "spillover" effect, unlikely to have a major detrimental effect on plants. P. vitalbae needs to feed on C. vitalba before it can lay eggs and can probably only persist on C. vitalba. Phytomyza vitalbae mines have been recorded from introduced ornamental species C. connata DC., C. orientalis L., C. rehderiana Craib., and C. serratifolia Rehder and probably C. montana.
References
Gourlay H (2007). Old Man's Beard Leaf Miner. In The Biological Control of weeds Book (Landcare Research) http://www.landcareresearch.co.nz/research/biocons/weeds/book/documents/Old_Mans_Beard_Leaf_Miner.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 (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
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, Q., Martin, N., Berry J., Hona, S., Peterson ,P., Gourlay ,A.H., Wilson-Davey, J., Smith, L., Winks, C. and Fowler, S.V. (2008). Non-target impacts of Phytomyza vitalbae a biological control agent of the European weed Clematis vitalba in New Zealand Biological Control 44: 248-258
Paynter, Q.E., Fowler, A.H., Gourlay, M.L., Haines, M.L., Harman, H.M., Hona, S.R., Peterson, P.G., Smith, L.A., Wilson-Davey, J.R.A., Winks, C.J. and Withers, T.M. (2004). Safety in New Zealand weed biocontrol: A nationwide survey for impacts on non-target plants. New Zealand Plant Protection 57: 102-107
