Venom

Black widow venom is dangerous. We know this. What most people do not know, however, is how incredibly complex and finely tuned this molecule of venom is. Widow venom is 15 times more potent than rattlesnake venom, but because so little is injected, it rarely kills humans. There are also a slew of active ingredients found in the venom. The most important active ingredients are a series of toxins called latrotoxins. These are monster-sized molecules (atomic weight >120kDa). Widow venom contains at least 7 different latrotoxins, each of which have a specific function: the first 5 of these toxins work specifically on invertebrates (which makes total sense as bugs make up almost all of their diet); the 6^th, called alpha-latrotoxin (which is the best-studied and most understood of the toxins) works specifically on vertebrates (molecule structure and diagram can be seen below!); the 7^th and final toxin works specifically on crustaceans, which is very interesting because there is only 1 genus of land-based crustacean on earth. These critters have been such an important enough food source to support the evolution of the crustacean-specific latrotoxin.

If you are ever unfortunate enough to be bitten by a Latrodectus, stay calm! But also be aware that you are in for a rough week with some intense suffering. Unless you are a very small child, elderly person, or have a compromised immune system, you have no need to worry, you will not die. But these little gals pack quite a punch (males do not inject venom). The neurotoxic venom will affect your nervous system. Following the bite, symptoms usually start within 20 minutes or so with acute pain at the bite site. Severe muscles cramps and abdominal pain will follow, with weakness and tremors lasting awhile. Large muscle groups are often affected, resulting in considerable pain. In bad cases, victim might even experience nausea, vomiting, dizziness, fainting, chest pain, and respiratory difficulties. When bitten, pain pills will be your best bet- ibuprofen, acetaminophen, or if it were me, something much stronger (morphine!). Hospitalization should be your last resort, as Latrodectus anti-venin can only be administered to an individual once in a lifetime due to its nature. Anti-venin would only be administered if it were a life-threatening case, so by going to the hospital, you would just be purchasing the most expensive bottle of ibuprofen on the planet.

Alpha-Latrotoxin is an enormous tetramer (molecule consisting of 4 monomers). Below, are a ball-and-stick representation of the molecule, followed by a real 3D image.

LD50 values for some of the N.A. Latrodectus species:

Latrodectus geometricus = .43 mg/kg (IV) & .223 mg/kg (IP)

Latrodectus hesperus = .84 mg/kg (IV)

Latrodectus mactans = 1.39 mg/kg (IV) & .90 mg/kg (SC)

Latrodectus bishopi = 2.2 mg/kg (could be IP)

Latrodectus variolus = 1.8 mg/kg (IP)