Platydemus manokwari may not be dangerous to humans, but it could decimate the entire snail and earthworm population of the United States if its spread is not halted.
The worm is native to New Guinea and the Pacific region of the world, but it has accidentally been introduced into the soil of 15 countries, including being found in a hothouse in France in 2014. The predatory worm is so persistent in chasing down its prey, it will even climb up trees to reach snails.
The New Guinea flatworm is rather large, averaging between 40-65 millimeters (1.4 to 3.5 inches) in length and about 4 to 7 millimeters (o.2 to 0.3 inches) in width. Both ends of the worm come to a point, with the head being more pointed than the tail, with two eyes right on the tip of the head. They are generally brown to a murky olive color with a pale underside.
The new Guinea flatworm has a gruesome way of eating its prey. The flatworm’s mouth is in the middle of its belly, so when it wants to eat a snail, a protruding white, cylindrical pharynx is inserted into the body of the prey and it is then sucked into the worm.
It is interesting to note that while the flatworm has been contained in one hothouse in France, it has defied efforts to eradicate it. This tells scientists just how dangerous this land flatworm can be if it is not stopped. It has now showed up in a few gardens in Miami, Florida.
There is the very real danger of it spreading because it has very few known predators. Birds don’t like its strong taste. But the flatworm is not that particular when it comes to snails, any snails, and if they aren’t readily available, earthworms will do. This is important because native snails and earthworms are important to local ecosystems.
Study on the spread of the New Guinea flatworm
Jean-Lou Justine, of the Institute of Systematics, Evolution, and Biodiversity in Paris, France, and the lead author in a study of the New Guinea flatworm says, “This should be considered a significant threat to the whole of the US and even to the rest of the Americas.”
“The record in Florida is of particular concern because it is in mainland America,” the study said. “Until now infested territories were mostly islands and the spread of the species from island to island is limited.”
While the eradication of snails in France would have a detrimental effect on French cooking if the flatworm is not stopped, looking at the broader implications in Europe and the Americas, the spread of these worms would have a devastating effect on the environment.
Earthworms and agriculture
Earthworms provide numerous benefits in supporting agriculture just by their burrowing and feeding activities. The burrowing of earthworms helps with water filtration, soil aeration and porosity of the soil itself. An earthworm population can consume twp tons of dry matter per acre each year, partly digesting and mixing the matter with the soil.
Earthworm casts or excrement have a higher concentration of nitrogen, phosphorus, potassium, and calcium than the surrounding soil. They also have a higher cation-exchange capacity. The gut of the earthworm also has beneficial microbes, and these help in decomposing crop residue.
Snails and their role in the environment
Land snails, semi-slugs, and slugs all play a critical role in the decomposition process in ecosystems, as well as being an important part of the food chain. Land snails are also important environmental indicators and biodiversity predictors.
In our forests, snails provide nutrients by the decomposition of their decaying bodies, shells, and feces. Their shells are also an important source of calcium for other animals where there is a calcium-poor habitat. Snails eat vegetation, helping to keep some plants from becoming overgrown and choking out other plant life.
How worried should we be? Very worried, is the answer. France and the United States now have the flatworm.The study shows us that we are looking at two huge land masses. While before, the flatworm was accidentally introduced onto islands, there is a limit to the spread of the worms. Large land masses are a different story.
Besides disrupting the food chain and having a negative effect on agriculture, we must keep in mind that climate change will also play a role in the spread of these invasive creatures.
The study, entitled The invasive land planarian Platydemus manokwari (Platyhelminthes, Geoplanidae): records from six new localities, including the first in the USA, was published in the journal PeerJ on June 23, 2015.
