Author
Chantal M Probst
probstc@landcareresearch.co.nz
Bioeconomy Science Institute – Manaaki Whenua group
Auckland, New Zealand
Coauthors
Caroline M Mitchell, Bioeconomy Science Institute – Manaaki Whenua group, Lincoln, New Zealand
Quentin Paynter, Bioeconomy Science Institute – Manaaki Whenua group, Auckland, New Zealand
Chris McGrannachan, Bioeconomy Science Institute – Manaaki Whenua group, Auckland, New Zealand
Simon V Fowler, Bioeconomy Science Institute – Manaaki Whenua group, Lincoln, New Zealand
Lynley Hayes, Bioeconomy Science Institute – Manaaki Whenua group, Lincoln, New Zealand
Abstract
Decalobanthus peltatus (merremia) is a fast-growing vine that smothers native vegetation and disrupts agricultural systems, posing a significant threat to biodiversity and livelihoods in many Pacific Island Countries and Territories. In 2023, it was ranked the ninth highest priority weed for natural enemy development at the Pacific Invasive Learning Network meeting in Apia, Samoa. Native to some Indian Ocean islands, Malesia, northern Australia, and Polynesia, merremia has become increasingly invasive across much of the Pacific. Because merremia has been reported as both native and introduced within the Pacific, molecular studies were undertaken to clarify its status with support from the New Zealand Ministry of Foreign Affairs and Trade (MFAT). These revealed that the population structure is best explained with four genotypic clusters (genotypes), with likely origins in Malesia and Africa. Two genotypes appear to have been present in the Pacific for millennia, while the other two are more recent arrivals. Natural enemy surveys conducted across 11 countries, supported by MFAT, found mainly generalist herbivores and minimal damage, indicating the need to continue the search for an effective biocontrol agent. We will present findings from the genetic studies and natural enemy surveys, discuss the challenges when considering biocontrol for native species, consider regulatory and logistical constraints, and outline next steps and future prospects for the biocontrol of merremia.
keywords
Decalobanthus peltatus
invasive vine
population genetics
natural enemy surveys
Pacific Islands
Highlights
Population genetics of merremia revealed four genotypes in the Pacific
Merremia has been long established in the Pacific with some recent introductions
No biocontrol agents have been identified but the search is not yet over