14 March 2025, Apia, Samoa - A two-day interactive workshop hosted by Samoa’s Ministry of Natural Resources and Environment (MNRE) in collaboration with Manaaki Whenua - Landcare Research (MWLR) aimed to enhance the capacity and capability of agencies in Samoa to implement a Pacific Regional Invasive Species Management Support Service (PRISMSS) Natural Enemies - Natural Solutions (NENS) project. The workshop reaffirmed the need for coordination, the use of innovative and sustainable methods, and community engagement to sustainably manage invasive weeds.
The workshop facilitated the exchange of information about PRISMSS NENS opportunities, reviewed top priorities identified at a previous workshop, and encouraged collaboration through sharing lessons, stories, and expertise. Participants learned about natural enemies already present in the Pacific, including Samoa, and focused on creating sustainable solutions for emerging weed threats.
While delivering the keynote address at the PRISMSS NENS Workshop, Afioga Lealaisalanoa Frances Brown Reupena CEO of MNRE, commented, “everyone here understands that invasive weed species pose a significant threat to Samoa’s environment, economy and food security as they outcompete native plants leading to biodiversity loss and ecosystems imbalances.”
“They affect agricultural productivity reducing yields which threatens our people’s livelihoods but the problem we face now is, we do not have the capacity, manpower or resources to successfully manage some of these invasive weeds.”
The MNRE CEO informed participants that the PRISMSS NENS programme enables the use of natural enemies of invasive weeds to ensure they are effectively controlled to the point where it is no longer an environmental, agricultural or social well-being concern.
“For now, Samoa will focus on using this initiative to control the African tulip tree which plagues Samoa’s agricultural lands and native forests, once successful, which I have full confidence that it will be, we can move on to other priority weed species”.
“In saying this, there is nothing that comes without risk and the PRISMSS NENS approach comes with its own unique set of challenges, advantages and disadvantages.”
PRISMSS NENS is a programme of the Secretariat of the Pacific Regional Environment Programme (SPREP) led, PRISMSS. The programme supports Pacific Island Countries and Territories to restore ecological balance and offers a safe, self-sustaining solution by introducing highly specific natural enemies from a weed’s native range to curb its growth.
The PRISMSS NENS programme involves identifying natural enemies that specifically target the invasive species in its native habitat. These natural enemies are thoroughly researched and tested to ensure they are safe and effective, without harming native species or the environment. Once approved by national regulatory authorities, the natural enemies are released, and their impact is closely monitored to assess their effectiveness.
The intent is to reduce the population of the invasive species to manageable levels, allowing native ecosystems to recover and thrive.
SPREP Invasive Species Adviser, Mr David Moverley, commented, “in Samoa, as in many Pacific nations, there are a suite of invasive plants that have become naturalised and now occupy significant areas of both natural habitat and productive lands”.
“The resilience of these ecosystems is significantly diminished meaning that they provide less security in times of changing environmental conditions. Natural enemies provide a solution to address this at the large landscape level.”
“Our challenge is to investigate and secure natural enemies for this ever-increasing suite of invasive plants and return a balance that favours natural systems, and we are grateful to our PRISMSS donors and PRISMSS NENS partner Landcare Research for helping the Pacific to utilise natural enemies and improve the future for our member states”.
MWLR, is the PRISMSS partner for the PRISMSS NENS programme, having extensive experience in controlling weeds using natural enemies, including similar successful projects in the Cook Islands, Tonga and Vanuatu.
PRISMSS NENS programme technical lead from MWLR, Ms Lynley Hayes commented that, “weeds will get worse with the increasing CO2, temperatures and disturbance as these conditions favour weeds, and so weeds need to be better managed so Pacific communities can be more resilient to the impacts of climate change.”
“There are many benefits of natural enemies including it being a sustainable and long-term solution, PRISMSS NENS aims for a lasting effect by establishing a natural enemy that regulates the invasive plant population”.
“The use of natural enemies avoids the risk of harming non-target organisms and can be significantly less expensive than other control methods in the long run.”
“By controlling invasive weeds, natural enemies help to restore native ecosystems and their biodiversity.”
Participants of the workshop were largely from the Samoa National Invasives Task Team (SNITT). SNITT, a collaborative group that includes various government ministries, regional organisations, international and national NGOs, and the private sector. They actively participate in the development and revision of the National Invasive Species Strategy and Action Plan (NISSAP) to manage and mitigate the impacts of invasive species in Samoa.
During the workshop session interactions participants learnt that the use of natural enemies is a rigorously tested approach that prioritises safety and effectiveness as prior to any natural enemy being released, it undergoes research to ensure it targets only the problem species without harming beneficial plants or other biodiversity.
The SNITT members were informed that the Koster's curse thrips (Liothrips urichi) have been found in Samoa and is an effective natural enemy for controlling the invasive Koster's curse weed (Miconia crenata previously known as Clidemia hirta) in open habitats.
It is likely the thrips arrived from American Samoa where they were released in 1974. Other successful natural enemies established for weeds in Samoa include the giant sensitive plant (Mimosa diplotricha) psyllid (Heterospylla spinulosa) released in 1997 and the leaf-mining beetle (Uroplata girardi) released against lantana (Lantana camara) in 1975.
Natural enemies for priority weeds for Samoa such as ivy gourd (Coccinia grandis) and African tulip tree (Spathodea campanulata) have been identified and are being deployed elsewhere in the Pacific and are now being evaluated for Samoa.
The workshop facilitated discussions on how various agencies in collaboration with MNRE, SPREP, and the PRISMSS NENS programme will ensure success by working together on using sustainable and cost-effective ways to battle invasive weeds.
Participants were taken on a field trip to observe and familiarise themselves with natural enemies already present on weeds in Samoa. These natural enemies are not widely known about, or particularly obvious as their host weeds are now much less common.
Sessions included discussions on determining the feasibility of the PRISMSS NENS approach, mitigating any biosecurity risks, and testing to ensure no natural enemies are introduced that could become invasive or harm non-target species. A detailed understanding of local flora is crucial to avoid introducing species that could have negative consequences.
A Senior Terrestrial Biodiversity Conservation Officer with MNRE, Mr. Vatapuia Maiava, shared that, "we can reduce and eventually eliminate the spread of invasive weeds in Samoa by integrating effective traditional methods with innovative and sustainable invasive species management techniques.
“This approach not only addresses the issue of invasive weeds but also significantly contributes to strengthening the resilience of our communities and our efforts towards biodiversity conservation.”
A lecturer and a principal scientist at the National University of Samoa, Ms. Aleluia Taise expressed during the workshop that, "involving our community in sustainable invasive species management is essential as our diverse groups hold unique perspectives on invasive species, and their reliance on the land and sea for sustenance provides them with invaluable traditional knowledge and firsthand experiences.”
“Unlike those of us in town offices, they understand the real impact of weeds and by fostering collaboration, we can achieve more effective and sustainable solutions for biodiversity conservation.”
Ms. Fusi Rosie Coffin from the Mothers of Future NGO shared, “implementing sustainable and cost-effective methods to combat invasive weeds is not just a practical solution for our Pacific islands, it's essential.”
“But to truly succeed, we must actively involve and engage our communities. By fostering a deep understanding and commitment among all stakeholders, we can ensure that everyone takes ownership of the efforts to keep our lands free of weeds.”
Mr. Tanumafili Seuao, based with the Biosecurity Division at the Ministry of Agriculture and Fisheries, commented that "leveraging the knowledge of local communities about our natural environment and the behaviour of invasive species can help us implement effective management strategies.”
“By actively engaging and involving our communities in sustainable efforts to battle invasive species, including weeds, we not only protect our environment but also enhance community resilience.”
MNRE, in coordination with PRISMSS and MWLR will continue discussions to ensure priority weeds can be effectively managed using the PRISMSS NENS programme and contribute towards ensuring that communities in Samoa are confident and comfortable about what natural enemies are and why they are a sustainable solution.
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About PRISMSS: The Pacific Regional Invasive Species Management Support Service (PRISMSS) is a coordinating mechanism designed to facilitate the scaling up of operational management of invasive species in the Pacific. PRISMSS brings together experts to provide support within the Pacific region with a focus on protection of indigenous biodiversity and ecosystem function. As a service provider, PRISMSS provides a comprehensive suite of support services in a cohesive, effective, efficient, and accessible manner to Pacific Island countries and territories.
Restoring Island Resilience (RIR): The PRISMSS - Restoring Island Resilience (RIR) is a New Zealand-PRISMSS collaboration project that aims to improve Pacific Island Countries and territories livelihoods and resilience to climate change by reducing the impact of invasive species on natural and agricultural ecosystems through the five PRISMSS programmes.
PRISMSS Powered by: New Zealand Foreign Affairs & Trade, UK International Development, GEF, UNEP & SPREP
PRISMSS Partners: Birdlife International, NZ Department of Conservation, Island Conservation, Manaaki Whenua Landcare Research, Pacific Community and SPREP
For additional information please contact Mr Dominic Sadler, PRISMSS Manager on dominics@sprep.org or Mr Nitish Narayan, PRISMSS Communications & Liaison Officer on nitishn@sprep.org