Biocontrol introduction

Target pest: Araujia hortorum (Gentianales: Apocynaceae) = Araujia sericifera?, moth plant

Agent introduced: Puccinia araujiae (Pucciniales: Pucciniaceae), moth plant rust

Import notes:

Landcare Research (2016) - approved for release in 2015 but no releases made as yet as waiting for export permit to be granted by the Argentinian authorities.

Landcare Research (2017g) - still waiting for export permit.

Landcare Research (2019g) - still no permit to export from Argentina. The rust could be potentially be sourced from Uruguay but this is not straightforward. In the native range the rust is attacked by a hyperparasitic fungus (Cladosporium uredinicola) and is not easy to find. An Argentinian collaborator has retained a culture of the rust that is free of the hyperparasite, achieved after much painstaking effort. If the rust could be collected in Uruguay it would be a massive undertaking to repeat all this work, let alone the host-range testing, but this option will be explored with the project funders in the near future.

Paynter et al. (2025) - Puccinia araujiae was approved for release in December 2015 [see EPA (2015c) entry in ‘EPA applications’ section below]. However, export permits to allow shipment of P. araujiae to New Zealand from Argentina have not yet been applied for because of the great difficulties encountered during the exportation process of another rust fungus [biocontrol agent] from Argentina (Uromyces pencanus), associated with the Convention on Biological Diversity (CBD) and Access and Benefit Sharing (ABS) legislation. It was decided to keep the paperwork for the exportation of P. araujiae on hold until the application to export U. pencanus was successfully completed, something that happened only recently [2021], indicating that a system to allow ABS with New Zealand is now in place. It is hoped that an application for an export permit for P. araujiae will proceed soon. No attempts were made to source P. araujiae from elsewhere in South America (e.g. Uruguay) because of the presence of a hyperparasitic fungus in the wild (while a culture free of this fungus is held in Argentina) and the work that would be required to repeat host range testing with a new culture [see Landcare Research (2019g) entry above in this section].

Impacts on target:

Paynter et al. (2025) - field surveys in Argentina indicate P. araujiae is generally uncommon and may sometimes be heavily parasitized by Cladosporium species such as C. uredinicola and C. sphaerospermum. Cladosporium uredinicola is also present in New Zealand where it might reduce the impact of P. araujiae, if the New Zealand population of this parasitic fungus can attack P. araujiae. Nevertheless, experimental work carried out in Argentina to compare the effect of P. araujiae on plant growth in the presence and absence of C. sphaerospermum showed that although this hyperparasite is capable of reducing the rust’s negative effect on plant growth, the effect was still significant, indicating that should the rust be attacked by hyperparasites in its new environment, it would still be an effective biocontrol agent.

Impacts on non-targets:

Anderson et al. (2016) - moth plant belongs to the family Apocynaceae, subfamily Asclepiadoideae, tribe Asclepiadeae, subtribe Oxypetalinae. Host specificity testing was carried out on members (all present in New Zealand) of three subfamilies and six tribes in the family Apocynaceae. Puccinia araujiae caused disease only to species in the same subtribe (Oxypetalinae) as moth plant. [See Paynter et al. (2025) entry in 'General comments' section below regarding the taxonomic nomenclature of moth plant.] These results are consistent with the host range of the fungus reported in the literature and in previous experimental results. There are no members of the Oxypetalinae native to New Zealand. Oxypetalum caeruleum (tweedia), an exotic ornamental species in New Zealand, belongs in the Oxypetalinae. Although this species was not tested, it would almost certainly be susceptible to P. araujiae because it belongs to the same subtribe as the other susceptible plant species. The only indigenous taxa in the Apocynaceae are three species of Parsonia, which belong to a different subfamily from moth plant. Five individuals of one species of Parsonia were tested and all were immune.

General comments:

Paynter et al. (2025) - most countries with invasive moth plant populations follow Forster and Bruyns (1992), who considered Araujia hortorum Fourn. to be synonymous with A. sericifera. Nevertheless, there are consistent differences between the two taxa, suggesting that A. hortorum and A. sericifera are either two separate species, as was proposed by Meyer (1944), or two sub-specific entities within the same species. In New Zealand, moth plant is currently referred to as A. hortorum although the Landcare Research New Zealand Plants website states that “A. sericifera and A. hortorum are very closely related entities and probably do not deserve recognition at the species level”. Nevertheless, it notes that “specimens from Australia and New Zealand and those conserved in the main herbaria of Argentina and Uruguay clearly belong to the taxon here considered as A. hortorum Fourn.”

EPA Applications:

EPA (2015c) - 17 Aug 2015: application by the Northland Regional Council to import and release the moth plant rust fungus, Puccinia araujiae, as a biocontrol agent for the weed moth plant, Araujia hortorum. EPA application # APP202529, approved without controls 15 Dec 2015.

References

Anderson FE, Santos López SP, Sánchez RM, Reinoso Fuentealba CG, Barton J (2016). Puccinia araujiae, a promising classical biocontrol agent for moth plant in New Zealand: Biology, host range and hyperparasitism by Cladosporium uredinicola. Biological Control 95: 23-30 https://doi.org/10.1016/j.biocontrol.2015.12.015

EPA (2015c). EPA application APP202529 to import and release the moth plant rust fungus, Puccinia araujiae as a biocontrol agent for the weed moth plant. Environmental Protection Authority website https://www.epa.govt.nz/database-search/hsno-application-register/view/APP202529

Landcare Research (2016i). Who's who in biological control of weeds? Weed Biocontrol: What's New? 77: 10-11 http://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/issue-77

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

Landcare Research (2019g). Moth plant beetle misconception cleared up. Weed Biocontrol: What's New? 89, August 2019 https://www.landcareresearch.co.nz/publications/newsletters/biological-control-of-weeds/weed-biocontrol-issue-89/moth-plant-beetle-misconception-cleared-up

Paynter Q, Anderson FE, Barton J, Bianchinotti MV, Bownes A, Carpintero D, Delgado S, Delhey R, Gourlay AH, Hayes L, Kiehr M, McGrath Z, Ramírez GH, Testoni D, Villamil CB, Villamil SC (2025). Moth plant Araujia sericifera, an exotic smothering vine in New Zealand: Surveys for candidate biocontrol agents in South America, agent prioritization and safety testing. Biological Control, Vol. 210, November 2025, Article No. 105901 https://doi.org/10.1016/j.biocontrol.2025.105901