Invasive Mediterranean Tramp Slug Taking Over the World

The invasive Mediterranean tramp slug, which already inhabits large parts of Europe and Australia as well as North and South America, is now being found in Mexico, Costa Rica and Ecuador, seemingly taking over the world.

"By now, this species of slug can be encountered almost worldwide," Dr. Heike Reise from the Senckenberg Museum of Natural History in Görlitz, Germany said in a statement.

As its scientific name Deroceras invadens implies, this invader has the habit of settling in new areas, mainly in gardens and under debris, but also in greenhouses and out in open nature. The silver lining in this situation is that the three-centimeter-long slug cannot handle extreme hot or cold environments, only residing in perfectly temperate regions.

So how is it that this mollusk is taking over? This particular slug species is introduced through imports, hitching a ride as a stowaway on shipments. Native to the Mediterranean, the first evidence that this slug was voyaging to other unexplored territory came from the British Isles in 1930, and within just 10 years it expanded as far as Denmark, California, Australia and New Zealand, and since has spread throughout the world.

"Today, Deroceras invadens is found across large parts of Europe, Australia, North and South America, and the slug has also made itself at home on several islands, such as the Azores, Madeira and the Canaries," Reise added.

And even though the migrating mollusk doesn't prefer hot or cold extremes, some have been seen to be able to handle these temperatures. For example, they utilize the extensive agricultural irrigation systems in North America and Egypt.

Surprisingly, during the study they detected for the first time this wandering slug in Mexico, Costa Rica and Ecuador as well.

"We tried to determine in which countries the slug has already been established, when it first occurred there, and whether its expansion is correlated to specific climate factors," explained Dr. John M. C. Hutchinson, the paper's lead author.

The study was published in the journal NeoBiota.