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Biocontrol introduction

Target pest: Jacobaea vulgaris (Asterales: Asteraceae) = Senecio jacobaea, ragwort

Agent introduced: Botanophila jacobaeae (Diptera: Anthomyiidae) = Pegohylemyia jacobaeae, ragwort seed fly



Import source:


Import notes:

Cameron et al. (1989) - imported as puparia along with the seedfly Botanophila seneciella.



Release details:

Cameron et al. (1989) - adults emerging from imported puparia were released between 1936 and 1940. More recently several attempts have been made to transfer B. jacobaeae from the central North Island to other areas (Kaikoura, 1975 - 200 pupae released; Golden Bay, 1982 - 500 pupae, 1983 - 515 pupae; Nelson, 1984 - 1,630 pupae).

Syrett et al. (1991) - released in the central North Island and Nelson.


Syrett et al. (1991) - 50 years after the original introductions B. jacobaeae still has only limited distribution.

Gourlay (2007d) - established on the central volcanic plateau of the North Island, Bay of Plenty and and southern Waikato.

Impacts on target:

Cameron et al. (1989) - the impact of B. jacobaeae on ragwort is negligible. Only 10-20% of seedheads were infested at two field sites and up to 200 seedheadsper square metre escaped attack.

Gourlay (2007d) - does not impact seed production enough to reduce ragwort populations. A high proportion of first seedheads are infested, but this declines throughout the summer when the majority of plants flower. Studies show 80-90% of seeds escape attack.

Paynter et al. (2018) - asynchrony with host plant limits effectiveness.

Impacts on non-targets:

Paynter et al. (2004) - surveys record no feeding on Senecio bipinnatisectus and S. vulgaris, consistent with lab tests that predicted no non-target feeding.


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.

Gourlay H (2007d). Ragwort Seedfly. In the Biological Control of Weeds Book (Landcare Research) https://www.landcareresearch.co.nz/discover-our-research/biosecurity/weed-management/using-biocontrol/the-biological-control-of-weeds-book/

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

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.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

Syrett P, Grindell JM, Hayes LM, Winks CJ (1991). Distribution and establishment of two biological control agents for ragwort in New Zealand. Proceedings of 44th New Zealand Weed and Pest Control Conference 44: 292-293