Biocontrol introduction
Target pest: Jacobaea vulgaris (Asterales: Asteraceae) = Senecio jacobaea, ragwort
Agent introduced: Tyria jacobaeae (Lepidoptera: Arctiidae), cinnabar moth
Imported:
1926-1931
Import source:
England
Released:
1929
Release details:
Cameron et al. (1989) - between 1929 and 1932 approximately 3.5 million eggs were distributed on ragwort throughout the country. Main liberation areas were Nelson, Auckland, Taranaki and Southland.
Syrett et al. (1991) - the well-established population of T. jacobaeae in the southern North Island was used as a source of insects for rearing and redistribution throughout New Zealand. Between the summers of 1982/83 and 1990/91, 135 releases were made at 106 sites throughout the country. Releases comprised 1,000+ caterpillars.
Establishment:
Cameron et al. (1989) - initial establishment from the 1929-32 releases was very good in some areas, but populations failed to be maintained for more than two or three years. In 1941 it was reported in particularly large numbers at Horahora along the Waikato River and a few years later there were records from the Wairarapa. To date it persists in abundance only in the southern North Island (Wellington, Wairarapa and Manawatu regions). It appears to have extended its range both northwards and southwards from the Wairarapa area where it has persisted since the early liberations.
Syrett et al. (1991) - T. jacobaeae has established at 35% of the 1982/83 - 1990/91 release sites. After 2-3 years moth adults or larvae were recovered on average only 20 m from the release point, although at one site caterpillars were recovered 1 km away. In 5-6 years they were found 200 m away.
Gourlay (2007g) - most of the original populations died out except in the southern North Island. As a result of rearing and redistribution from this population the moth now occurs patchily throughout most areas of New Zealand where ragwort occurs, and is more common in some years than others.
Landcare Research (2014c) - common in some areas.
Landcare Research (2016h) - over 70 L. jacobaeae (ragwort flea beetle) release sites nationwide revisited 20-30 years post-release and density of ragwort now compared to density at the time of release: cinnabar moth was encountered at 68% of sites at some stage over the course of the study and is well spread throughout New Zealand.
Impacts on target:
Syrett et al. (1991) - at two of six release sites (where appropriate data was collected) where T. jacobaeae had been established in 1987 or earlier (and no other biocontrol agents were present), a decline in ragwort abundance was observed. While T. jacobaeae probably has limited value as a control agent, ragwort abundance decreased at all 3 sites where both T. jacobaeae and Longitarsus jacobaeae (ragwort flea beetle) were established, suggesting these two agents may be complementary in their impact on ragwort populations.
Harman et al. (1996) - Tyria jacobaeae alone is not thought to be effective.
Landcare Research (2014c) - often causes obvious damage.
Landcare Research (2016h) - in a nationwide study of ragwort sites, damaging levels of cinnabar moth was only ever noted sporadically, and earlier studies have shown it to be limited by natural enemies.
Paynter et al. (2018) - heavily parasitised by tachinid flies (up to 78% parasitism) to an extent that is likely to significantly influence its efficacy. Larvae are also subject to predation by birds.
Impacts on non-targets:
Fowler et al. (2000) - known to cause minor damage to Cineraria sp., Sonchus oleraceus (sow thistle) and native Senecio spp. The attack on Cineraria sp. was anticipated pre-release; the attack on S. oleraceus (sow thistle) and native Senecio spp. was not.
Fowler et al. (2004), Paynter et al. (2004) - surveys record T. jacobaeae eating native fireweeds such as Senecio minimus and S. biserratus. However adults do not oviposit on these and attack is very sporadic 'spill-over' feeding when target weed completely defoliated. Lab tests had been performed with native Senecio species, but S. minimus and S. biserratus were not placed in this genus at the time and were not tested.
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.
Fowler SV, Syrett P, Hill RL. (2000). Success and safety in the biological control of environmental weeds in New Zealand. Austral Ecology 25: 553–562
Fowler, S.V., Gourlay, A.H., Rill, R.H. and Withers, T. (2004). Safety in New Zealand weed biocontrol: a retrospective analysis of host specificity testing and the predictability of impacts on non-target plants. proceedings of the XI International Symposium on Biological Control of Weeds. Cullen, J.M., Briese, D.T., Kriticos, D.J., Lonsdale, W.M., Morin, L. and Scott, J.K. (Eds). Canberra, Australia, CSIRO Entomology, 27 April - 2 May 2003.
Gourlay H (2007g). Cinnabar Moth. 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/
Harman HM, Syrett P, Hill RL, Jessep CT. (1996). Arthropod introductions for biological control of weeds in New Zealand, 1929 - 1995. New Zealand Entomologist, 19(1): 71-80
Landcare Research (2014c). Who's who in biocontrol of weeds? What's new in biological control of weeds? 69: 10-11 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/WhatsNew69.pdf
Landcare Research (2016h). Comparing ragwort then with now: Part One. Weed Biocontrol: What's New? 77: 4-5 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-77
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 QE, Fowler AH, Gourlay AH, Haines ML, Harman HM, Hona SR, Peterson PG, Smith LA, Wilson-Davey JRA, Winks CJ, Withers TM (2004). Safety in New Zealand weed biocontrol: A nationwide survey for impacts on non-target plants. New Zealand Plant Protection 57: 102-107 https://journal.nzpps.org/index.php/nzpp/issue/view/vol57
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
