By Timothée L’Angevin
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It measures up to 12 centimeters, is yellow and black, and loves woodlice. here is the Caenoplana variegata, a species of flatworm, an invading flatworm, which was spotted in Calvados for the first time in early June 2022.
It is already causing some concern among home gardeners because of the threat it poses to biodiversity.
Arrived from Australia via plant transport
Are these fears justified? If the information available to scientists is still very fragmented and mainly comes from reports from individuals, we know that this worm is one of about ten flatworms, worms qualified in France as an invasive alien species.
“We observed it for the first time in 2013, in the South”, indicates to news.fr Jean-Lou Justine, professor of zoology at the National Museum of Natural History.
It arrived in France from Australia, certainly via the transport of potted plants. Obviously, the climate of France pleases him and he finds a lot of prey there.
A danger for woodlice?
the Caenoplana variegata feeds mainly on woodlice, but also other arthropods, myriapods (centipedes) and spiders. “We currently have no information on the ecological impact of this species”, recognizes the specialist in predatory worms. “It probably has a harmful role, as do invading insects (such as Asian hornets), especially if there are hundreds of them in the same place. »
The danger weighs above all on woodlice, and we know that this small crustacean is essential for the ecology of soils, thanks to their role in the decomposition of organic matter. But from there to seeing them disappear because of this worm? ” VSit has never been quantified. »
However, flatworms can affect other soil animals. This is particularly the case of theobama nungara, which devours earthworms, an animal vital to the soil. This prompted scientists to warn about their proliferation in France (it has to date been spotted in more than 70 departments).
It reproduces on its own
the Caenoplana variegata has been observed for its part in several southern departments (Mediterranean arc, South-West), but also in Brittany, and now in Normandy. It is highly likely that it will develop further. As Jean-Lou Justine points out, “it can reproduce on its own”.
Its reproduction is done by fission: that is to say that a small piece of one centimeter is detached from the back of the body and gives a new animal. The multiplication can go quickly, of the order of several individuals per month!
What if you spotted it?
If you have observed this worm in your garden, make sure it is a flatworm, as the scientist explains on his website: this worm is elongated, has a thin head, a back with a yellow stripe and two thin black lines, and is between 5 and 12 cm long.
Then remember to photograph her and send her your pictures (the whole process is explained here).
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