Mile-a-minute vine, a Pacific nuisance

Many Pacific farmers call it a nuisance, some call it "mile-a-minute" vine, and scientists call it Mikania micrantha. Whatever you call it, this weed is a big problem in the Pacific and in other parts of the world, where it can grow so quickly that it literally chokes and smothers other plants.

Because the vine grows so quickly, chopping the vine back is only a temporary measure—many farmers and gardeners already spend huge amounts of time fighting this weed. Herbicides can be used to control Mikania more easily, but this would be expensive and potentially harmful for non-target plants if the herbicide applicator was unskilled. What if there was an easy way to control only the Mikania?

A rust pathogen that controls Mikania is an option to make sure that only Mikania is affected. This pathogen, Puccinia spegazzinii, comes from the same place that Mikania first came from in South America and is a natural enemy of Mikania. The main reason Mikania is so invasive in other places is that the natural enemies of Mikania have not been brought to the new places along with the plant. The rust pathogen has already been introduced to control Mikania in five Pacific countries and many countries outside the Pacific. There are potentially 15 other countries in the Pacific that could benefit from introducing this natural enemy.

Mikania-micranthaMikania Micrantha plant. Photo: P. Skelton/SPREP

But introducing a new species is a bad idea, isn't it? Not necessarily.

"Not every introduced species becomes invasive. Before a natural enemy can be responsibly introduced, scientists and environmental experts must study it and consider all the possible effects of introduction. This includes "host specificity testing" to ensure that useful and closely related plants are not at risk of being attacked by the potential natural enemy of the target species," said Mr. David Moverley, the Invasive Species Adviser of the Secretariat of the Pacific Regional Environment Programme (SPREP).

"Such a controlled process is a very different introduction than the accidental spread of invasive species that can eat, kill, or out-compete many native species and different from some of the disastrous intentional releases of natural enemies in the past."

There is one down-side: all that research, experience, and careful analysis takes a lot of time, expertise, and money. One way to help meet those needs is to openly share information through a network of people who all have the same goal of protecting Pacific islands from invasive species.

P3241231 study tourPILN members studying restored sites. Photo: PILN

Sharing news, lessons, and methods like this increases the success of invasive species managers in Pacific nations, and the upcoming PILN2016 meeting is designed to make this sharing happen. The Pacific Invasives Learning Network (PILN), a peer learning network for 22 teams in Melanesia, Micronesia, and Polynesia, connects in-country practitioners to share effective ways to battle invasive species. The PILN2016 meeting on 1–5 August in Samoa, will bring the network together to define priorities and create working relationships.

"Invasive species practitioners are the ones on the ground, taking on the fight against invasive species. They need the support of the region, their peers, and their communities to make this happen. The PILN Meeting is a significant step in this process," said Moverley.

"The practitioners and experts at this meeting have the best regional knowledge, and sharing it helps protect the Pacific."

Meeting outcomes and invasive species efforts will also be shared in Apia, Samoa, during the following week at a workshop to help nations meet Aichi Target nine, part of national obligations to the Convention on Biological Diversity (CBD). The workshop will be co-hosted by SPREP, the Pacific Community (SPC), and CBD.
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