Biocontrol introduction
Target pest: Ageratina riparia (Asterales: Asteraceae), mist flower
Agent introduced: Entyloma ageratinae (Tilletiales: Tilletiaceae), mist flower fungus
Imported:
1998
Import source:
Jamaica/Mexico via Hawai'i
Released:
1998
Release details:
Barton et al. (2007), Fowler (2007) - released at nine sites from Northland to Waikato Nov-Dec 1998.
Establishment:
Barton et al. (2007) - established readily and spread throughout the North Island within five years; now common.
Impacts on target:
Barton et al. (2007) - monitored up to 51 sites 1998-2004: live leaves infected rapidly reached nearly 60%, plant height declined significantly and in heavy infestations mean cover of mist flower declined from 81 to 1.5%. This is now considered to be a successful programme.
Fowler (2007) - in 3 years after release mean mist flower ground cover dropped from 90 to 35%.
Hayes et al. (2013) - a preliminary analysis of financial savings from no longer having to control mist flower by conventional means in the upper North Island suggests a cost reduction of $80,000 to $90,000 per year from the introduction of E. ageratinae and the gall fly Procecidochares alani in 1998 and 2001 respectively. The net present value for this is more than $3 million with a benefit:cost ratio of 2.5:1; considered very good over a 13 year period.
Landcare Research (2017g) - often causes severe damage, providing excellent control.
Impacts on non-targets:
Paynter (2007) - mist flower fungus will only attack mist flower (Ageratina riparia). In lab tests, Mexican devil weed (A. adenophora), also an exotic weed, developed slight disease symptoms but the fungus was unable to complete its life cycle on this host. In the field in Hawai'i and South Africa no disease symptoms have been seen on Mexican devil weed, even when growing beside infected mist flower.
Barton et al. ( 2007), Paynter (2007) - as mist flower declined, species richness and cover of native plants increased. While species richness and cover or exotics did not decrease, data to date indicates control of mist flower is benefitting native species more than other weedy exotics.
Waipara et al. (2009) - to assess non-target impacts of pathogenic weed biocontrol agents, including Entyloma ageratinae, introduced to New Zealand, nationwide surveys were conducted 2000-2009, focussing on plants closely related to the target weeds. No non-target damage was observed for E. ageratinae, despite positive infection being observed on many of the host (target) plants at the same sites.
References
Barton J, Fowler SV, Gianotti AF, Winks CJ, de Beurs M, Arnold GC and Forrester G. (2007). Successful biological control of mistflower in New Zealand: agent establishment, impact, and benefit to the New Zealand flora. Biological control 40:370-385
Fowler S (2007). Mist Flower Fungus. 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/
Hayes L, Fowler SV, Paynter Q, Groenteman R, Peterson P, Dodd S, Bellgard S (2013). Biocontrol of weeds: achievements to date and future outlook. In: Dymond JR (ed) Ecosystem services in New Zealand: conditions and trends. Manaaki Whenua Press, Lincoln, pp 375-385 https://www.landcareresearch.co.nz/__data/assets/pdf_file/0005/77054/2_8_Hayes.pdf
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
Waipara NW, Barton J, Smith LA, Harman HM, Winks CJ, Massey B, Wilkie JP, Gianotti AF, Cripps MG (2009). Safety in New Zealand weed biocontrol: a nationwide pathogen survey for impacts on non-target plants. New Zealand Plant Protection 62: 41-49
