Several Araignée S of the kind Latrodectus is called black Veuve . The most dangerous species is Latrodectus mactans , one finds it on all the American continent, in areas hot, moderate or cold, dry or wet, downtown or in the countryside, and between 0 and 3500 meters of altitude. Although nonaggressive, the subspecies Lactrodectus mactans mexicanus called capulina or chintatlahua in Mexico ( chintatlahua drift of the word náhuatl tzintlatlauhqui ), is the most dangerous spider of the world because of its venom. It is very abundant in the towns of Guadalajara and Aguascalientes. Under European species Latrodectus mactans tredecimguttatus (Rossi) is present on the Mediterranean circumference, in Corsica, Arabia and until the the Caucasus. In France, this under species Malmignatte is called and meets especially in the south of the country but goes up also it length of the Atlantic littoral as far as the Vendée and in Morbihan . It is, with Steatoda nobilis , the only species of dangerous spider present in France .
Latrodectus mactans is a species of small size (length of the body: 15 mm) which one can easily recognize thanks to a drawing in the shape of perfectly symmetrical sand glass bright red located on the globulous abdomen of a brilliant black of the females. Under species tredecimguttatus this drawing is replaced by a variable number of red spots sharp. The sexual dimorphism is marked enough, the males are small (length: 7 to 9 mm) and less coloured. One allots his name to the fact that the female eats the male after the coupling. But this is not systematic at this species.
The envenimation by bite of spider is called araneism and the specific bite by a species of the kind Latrodectus is called Latrodectisme .
Alpha-latrotoxine contained in the venom of these species, 15 times more powerful than that of the Rattlesnake, destroyed the synaptic blisters, it confer on this venom a neurotoxic action more dangerous than that of the venom of a Cobra. Fortunately the quantity injected in the event of bite is much weaker.
The principal symptoms are disorders neurovégétatifs (variations in the temperature (perspiration and cold sweats) and blood pressure), cephalgias, spasms muscular (contraction of the thoracic, abdominal and facial muscles), mental health disorders (intense state of anxiety, fear of dying, even hallucinations), nauseas, an erythema and a local edema.
The fatalities are very rare, the most sensitive people are the infants, the elderly or having cardiac problems. One on average enters only one death for 200 cases of bites. The treatment is based on the calcium IV gluconate injection which removes the muscular contractions and the muscular pains, then of a specific anti-latrodecte serum: fraction Fab de Latrodectus. In the absence of this serum, one practices an injection of one releasing muscular, like the Dantrolène. This treatment is very effective if it is managed in the 24 hours following the bite.
Research and developmentIn 2007, a team of biologists of the the University of California (the United States) finally identified two major genes of the silk synthesis at the black widow. Having properties coveted (elasticity, resistance and lightness), this silk finds applications in the armours of war (waistcoats avoid-ball) or materials surgical. The industrial production can be done by the addition of these genes to that of a bacterium (E. Coli or Escherichia coli) which is then put to synthesize required protein. The university already deposited an patent application with this industrial application.
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