They were crouched under the collar of the dune plants, out of sight. On October 27, Christian Géry, amateur entomologist from the Linnean Society of Bordeaux, made a shocking discovery, even though he didn’t know it at the time. He fell on Latrodectus tredecimguttatuscommonly called european black widow, or even malmignatte. This venomous spider had never before been observed in New Aquitaine.
The females were installed under the leaves, with their cocoons. “It was total chance, says Christian Géry to 20 minutes. It was while looking for beetles, which are my specialty, in the gray dune near Cap-Ferret (Gironde), that I came across these spider cocoons that I did not know. I immediately sent a photo to a colleague to find out more. »
The colleague, Hervé Thomas, another member of the Linnean society, “immediately recognized the malmignatte” when he saw the photo. It must be said that the little beast with its big black body and its red spots, is easily recognizable for specialists. “And then, she is famous, there are a whole lot of legends around the black widow, because it is a very venomous spider, especially for humans” says Hervé Thomas.
Global warming not necessarily to blame
In France, the European black widow spider is not unknown, since it is found in Corsica and in the Mediterranean arc. “On the Atlantic coast, it had been reported at the end of the 19th century, in 1877 and 1881 in Vendée and in Morbihan, but it has never been found since, continues Hervé Thomas. For my part, I have been working with the ONF since 2006 to carry out surveys on the dunes and beaches, I do a lot of prospecting between the Vendée and the Landes, and I had never seen it. »
Can its presence near Cap-Ferret be the consequence of global warming? “Without these old mentions in Vendée and Morbihan, we would be tempted to say yes, since it is a Mediterranean species. We have examples of arachnids rising in the wake of warming, this is the case of a very large spider, lobed argiope, who arrived in New Aquitaine a few years ago. In the case of the black widow, we do not completely rule out the climatic explanation, but there are other possible hypotheses, and one of the most probable is that it has always more or less existed in the dune environment. , but as it is a very secretive species, it has remained unnoticed so far. »
“Do not fantasize about this spider”
As for the question that everyone is asking, namely should we be worried, the specialists assure that not. But the venomous reputation of the black widow spider, whose female tends to devour the male after mating, usually precedes it. “You should not fantasize about this spider, and there is no reason to panic, insists Hervé Thomas. The black widow has no aggressiveness and does not seek to bite. In addition, it is found on the part of the dune which is very inaccessible, these environments being increasingly protected. “We can continue, a priori, to bask in the pill quietly on the beaches of Cap-Ferret next summer …
“There is a scientific challenge behind this discovery, but no repercussions in society as the emergence of the tiger mosquito and the Asian hornet can have” adds Christian Géry.
Moreover, it should not be confused Latrodectus tredecimguttatus and Latrodectus mactans“the most famous of the black widows, which is the American version” specifies Hervé Thomas, or Latrodectus hassselti, the australian version. “The venom of the black widow spider from America or Australia is much more toxic, we even have fatal cases in humans, this is absolutely not the case for its European cousin whose envenomation is much less severe. »
The fear of attracting “ill-intentioned terrariophiles”
On the other hand, entomologists deliberately remain discreet as to the precise place of their discovery. “We gave an indication, on the side of the Black Crohot, which is not entirely exact, recognizes Hervé Thomas. It’s voluntary, to prevent ill-intentioned terrariophiles from landing to look for the creature. We don’t want the station to be destroyed. »
The Linnean Society of Bordeaux, which is a society of amateur scientists founded in 1818, will soon publish a scientific bulletin