New Guinea flatworm, one of the world’s worst invasive species, found in US

New Guinea flatworm invasive species
© Andrew Wee Kien Han

International team says discovery poses a significant threat.

It’s very flat, it’s two inches long and less than a quarter inch wide. It’s black and olive in color with a stripe down its back; it has an elongated head with big black eyes and mouth in the middle of its belly. It’s name is Platydemus manokwari and although on first glance it just seems a harmless ground-dwelling worm, in fact it can climb trees. Which it does to eat snails, and eat them it does. The New Guinea flatworm, as P. manokwari is commonly called, consumes snails with voracity and endangers endemic species. It is considered such a threatening invasive species that it holds the distinction of being the only land planarian (flatworm) to be included in “100 worst invasive alien species” list.

New Guinea flatworm invasive speciesPlatydemus manokwari with white pharynx protruding from the underside, ingesting soft tissues of a specimen of the Mediterranean snail. (Photo: Pierre Gros)/CC BY-NC-SA 4.0
And the species has now been identified in several gardens in Miami.
Already found in 15 territories around the world, mostly in the Pacific area and in France, a group of 14 international experts have undertaken an intensive research effort and have written a paper describing how the little guy has now been identified in six more territories as well: New Caledonia (including mainland and two of the Loyalty Islands, Lifou and Maré), Wallis and Futuna Islands, Singapore, Solomon Islands, Puerto Rico, and Florida.

P. manokwari is a known threat for endemic terrestrial mollusks, and the appearance of the flatworm in Florida is of special concern. Until now, infested areas have been mostly islands, the water surrounding acting as a protective barrier to keep the invasions somewhat contained. However, the flatworms now established in Florida have nothing to hold them back. And not only will they likely spread on their own, but they can be easily spread through human agency and passively spread with infested plants, plant parts and soil.

So what’s the prognosis? The authors conclude that this could be bad, they write: “The species could potentially eventually be spread from Florida throughout the US mainland, and this can be considered a significant potential threat to the whole US, the West Indies and even the rest of the Americas.”

Is it time to start thinking of recipes for New Guinea flatworm? (See why here: Cooking invasive species may be the new ethical food frontier.)

New Guinea flatworm, one of the world’s worst invasive species, found in US
International team of scientists says the discovery poses a significant threat.

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