Biocontrol introduction
Target pest: Ageratina adenophora (Asterales: Asteraceae), Mexican devil weed
Agent introduced: Ragnhildiana perfoliati (Capnodiales: Mycosphaerellaceae) = Passalora ageratinae, Mexican devil weed leaf fungus
Imported:
Accidental introduction, first recorded in New Zealand in 1962, but probably arriving 1958
Import source:
Hawaii, via Queensland, Australia?
Import notes:
Cameron et al. (1989) - Ragnhildiana perfoliati was accidentally introduced to New Zealand [though misidentified at the time as Cercospora eupatorii - see Taxonomic note (1 April 2024) entry in 'General comments' section below]; its origin is not certain, but it was probably introduced from Queensland, Australia along with the biocontrol agent Procecidochares utilis (a tephritid fly introduced against A. adenophora) in 1958. The fungus was first isolated in 1954 in Queensland, and it seems certain had been imported from Hawaii on adult P. utilis. The risk of importing the fungus into New Zealand along with P. utilis had been carefully considered and the consequences thought to be slight because it only attacks Ageratina species and was likely to introduce itself into New Zealand anyway.
Released:
Cameron et al. (1989) - first recorded in New Zealand in 1962, but probably accidentally introduced with the biocontrol agent Procecidochares utilis (Mexican devil weed gall fly) in 1958.
Establishment:
Cameron et al. (1989) - occurs throughout the range of A. adenophora in New Zealand.
Landcare Research (2012) - common in New Zealand.
Impacts on target:
Cameron et al. (1989) - the impact of R. perfoliati on A. adenophora in New Zealand is unknown. The decline in importance of A. adenophora in the 10 years following the release of the biocontrol agent Procecidochares utilis [and likely introduction of R. perfoliati - see the Cameron et al. (1989) entry in 'Import notes' section] may have been caused by P. utilis in conjunction with R. perfoliati, but no detailed evaluation has been carried out and changes in land management may have also played a part.
Landcare Research (2008d) - there is anecdotal evidence that R. perfoliati and Mexican devil weed gall fly (Procecidochares utilis) [deliberately introduced against A. adenophora - see the Procecidochares utilis introduction entry], significantly suppress A. adenophora.
Landcare Research (2012) - almost certainly having an impact on A. adenophora.
Hayes et al. (2013) - Mexican devil weed is not a serious problem today; this can be attributed, at least in part, to biocontrol agents [the gall fly Procecidochares utilis was deliberately released, the fungus R. perfoliati probably accidentally introduced with it].
Landcare Research (2014f) - Ageratina adenophora is generally considered to be a minor weed in New Zealand. It is believed that an introduced gall fly (Procecidochares utilis) and the leaf blight fungus Ragnhildiana perfoliati are exerting some level of control, although this has not been formally measured.
General comments:
Taxonomic note (1 April 2024) - Ragnhildiana perfoliati was first recorded in New Zealand in 1962 [see Landcare Research (2012) entry in ‘Import notes’ section above] and misidentified at the time as Cercospora eupatorii (a fungus subsequently renamed Pseudocercospora eupatorii (Braun & Castañeda-Ruiz (1991)). Ragnhildiana perfoliati at the time was simply known as “Phaeoramularia” sp., but was described in 2009 as Passalora ageratinae, the genus Phaeoramularia being treated as a synonym of Passalora (Crous et al. 2009). Passalora ageratinae was subsequently renamed Ragnhildiana perfoliati (Videira et al. 2017).
References
Braun U, Castañeda-Ruiz RF (1991). Cercospora and allied genera of Cuba (II). Cryptogamic Botany 2(2-3): 289-297 https://www.researchgate.net/publication/255701229_Cercospora_and_allied_genera_of_Cuba_II
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.
Crous PW, Schoch CL, Hyde KD, Wood AR, Gueidan C, De Hoog GS, Groenewald JZ (2009). Phylogenetic lineages in the Capnodiales. Studies in Mycology 64(1): 17-47 https://doi.org/10.3114/sim.2009.64.02
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 (2008d). Parasitism - a major or minor cause of biocontrol failure? What’s New In Biological Control of Weeds? August 2008, 45: 4-5 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew45.pdf
Landcare Research (2012). Who’s who in biological control of weeds? What’s New In Biological Control of Weeds? August 2012, 61: 14-15 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/wtsnew61.pdf
Landcare Research (2014f). International weed biocontrol symposium. What’s New In Biological Control of Weeds? May 2014, 68: 2-4 https://www.landcareresearch.co.nz/assets/Publications/Weed-biocontrol/Whatsnew68.pdf
Videira SIR, Groenewald JZ, Nakashima C, Braun U, Barreto RW, de Wit PJGM, Crous PW (2017). Mycosphaerellaceae - chaos or clarity? Studies in Mycology 87: 257-421 https://doi.org/10.1016/j.simyco.2017.09.003
