European black widow
| European black widow | ||||||||||||
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European black widow female ( Latrodectus tredecimguttatus ); on the right the remains of a spider's exoskeleton that has been stripped off after a molt |
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| Latrodectus tredecimguttatus | ||||||||||||
| ( Rossi , 1790) |
The European or Mediterranean black widow ( Latrodectus tredecimguttatus ), often also called Malmignatte or Karakurt or Karakurte , is a spider from the family of canopy-web spiders (Theridiidae). It is the European representative of the species of real widows ( Latrodectus ) that were previously generally referred to as "black widows" ( Latrodectus mactans in the broader sense). With a body length of up to 15 millimeters, the European black widow is also the largest crested web spider found in Europe and is widely known in Europe for its drawing with thirteen red spots on a glossy black background and reports of its poisonous effects, although the distribution area of the xerophiles ( drought-loving) and spread from the Mediterranean to China , is mainly limited to southern Europe. Like the majority of crested web spiders, the European black widow also creates irregular space nets that contain a hiding place further up as a place to stay for the spider. Here, too, catch threads with sticky droplets actually prevent possible prey from escaping, which, as soon as they get into one of the catch threads, are spun in by the spider before it incapacitates them with a poisonous bite and then consumes them.
As with the other species with this designation and the species of the real widows in general, the designation "black widow" stems from the assumption that the male immediately falls victim to the female after mating, which is often the case with the European black widow This is the case, but occurs with different frequencies in other species of the genus and has not yet been fully clarified. The species, which is often feared just like the other "black widows", has another prominence due to the possible consequences of its poisonous bite for humans. The bite of the European black widow can be associated with serious complications because of its poisonous effects , although deaths from bites of the species are very rarely detectable. It used to be assumed that the bite of the European black widow, like the bite of the Apulian tarantula ( Lycosa tarentula ), could be associated with tarantism or dance anger , which could then be treated therapeutically with the help of the southern Italian folk dance tarantella .
The European black widow, like the other representatives of the real widows known as “black widows”, is increasingly used as a research object, which is due in particular to the composition of the effective poison of these species. Furthermore, the European black widow is seen to be useful in the context of biological pest control and it is occasionally kept as a pet in the field of terraristics .
features
The basic body structure of the European black widow corresponds to that of other species of the genus. The basic color of the species is a glossy black. The entire body of the spider is velvety hairy. The hair is split in two.
The red markings on the opisthosoma (abdomen) of the species are striking . One of these is an arched mark on the front of the opisthosoma. Four more are laid out in a vertical row on the dorsal side of the opisthosoma. This row is flanked on both sides by a further and similar row. These rows contain three spots. On each side there is another spot next to these rows, making the total number thirteen. This also gives rise to the species name tredecimgutattus (Latin for "thirteen spots"). Since these drawing elements can be fused together or partially or completely missing, the number of recognizable spots can vary.
Sexual dimorphism
As with the other species of true widow, the male of the European black widow is much smaller than the female. The sexual dimorphism (difference between the sexes) is also pronounced in different shapes and colors.
female
The larger female reaches a body length of seven to 15 millimeters. Its prosoma (front body) takes up three to 5.2 millimeters of body length. The carapace (breast shield of the prosoma) of the female is covered with small black hairs that are regularly arranged. The sternum (breast shield of the prosoma) is dark brown and contains a few black hairs.
The female's spherical opisthosoma appears shiny and is slightly longer than it is wide. In a female found in 2004 in the area of the port of the Romanian city of Constanța on the Black Sea , the opisthosoma measured a length of 5.57 and a width of 4.71 millimeters. On the ventral side of the opisthosoma of the female there is the red hourglass-shaped drawing that is typical for the real widows ( Latrodectus ), but it can also be reduced to two horizontal stripes.
In terms of color, the female is completely black, apart from the sternum and the spots and the hourglass markings on the opisthosoma. In younger females, the spots are outlined in white, but not in adult females. The legs of the female are longer and stronger than the male.
| Pair of legs | Coxa (hip joint) | Trochanter (thigh ring) | Femur (thigh) | Patella (link between femur and tibia) | Tibia (splint) | Metatarsus | Tarsus (tarsus) | overall length |
| 1 | 1.35 | 0.38 | 5.53 | 1.40 | 3.91 | 5.49 | 2.02 | 20.08 |
| 2 | 1.16 | 0.43 | 3.29 | 1.44 | 2.31 | 3.76 | 1.34 | 13.73 |
| 3 | 0.89 | 0.54 | 2.92 | 1.44 | 2.31 | 3.76 | 1.34 | 13.73 |
| 4th | 1.4 | 1.02 | 5.25 | 1.4 | 3.74 | 5.52 | 1.75 | 20.08 |
male
The significantly smaller and less powerfully built male has a higher-contrast coloration compared to that of the female. As with the female, the basic color is also black, with the male being lightened in individual areas and thus making it appear brownish.
The spots of the opisthosoma of the male are outlined in white, similar to those of younger females. Anterior (previous) there is a white and moon-shaped stripe here. The ventral side of the abdomen is completely black in the male and, unlike in the female, has no sign elements. The male has a significantly narrower opisthosoma compared to that of the female. In a male, also found in 2004 at the same location as the aforementioned female, who was in the female's net at the time of the discovery, an opisthosoma length of 2.64 and a width of 1.22 millimeters could be determined.
The male's legs are reddish brown. The color is darker near the leg joints.
| Pair of legs | Coxa | Trochanter | Femur | patella | Tibia | Metatarsus | tarsus | overall length |
| 1 | 0.66 | 0.32 | 5.31 | 0.87 | 3.61 | 4.68 | 1.61 | 17.12 |
| 2 | 0.57 | 0.2 | 2.6 | 0.66 | 1.92 | 2.95 | 1.04 | 9.94 |
| 3 | 0.41 | 0.18 | 2.21 | 0.37 | 1.44 | 1.86 | 0.87 | 7.43 |
| 4th | 0.66 | 0.22 | 4.99 | 0.63 | 2.96 | 3.82 | 1.4 | 14.86 |
Similar species
The European black widow is occasionally confused with other similar species within the genus of real widows ( Latrodectus ) as well as with those of the genus of fat spiders ( Steatoda ). The latter genus also belongs to the family of the crested web spiders and their representatives are often referred to as "false widows" due to their similarity to the real widows.
The European black widow also has many similarities in terms of the structure of its sexual organs with the closely related southern black widow ( Latrodectus mactans ), which is widespread in North America .
Similarities to Latrodectus lilianae
A common candidate for confusion within the genus of the real widows ( Latrodectus ) is the species Latrodectus lilianae , newly described in 2000 , which occurs on the Iberian Peninsula and shares this range with the European black widow.
Like the European black widow, Latrodectus lilianae has a black-brown to matt black basic coloration, but can be reliably distinguished from the other species by the only sign elements on the front edge of the opisthosoma. This drawing is either fragmented or partially dissolved or only hinted at by fine light lines. Younger females have a median pattern made up of interconnected bright diamonds. These extend lengthways over the opisthosoma. The coloring of the male of Latrodectus lilianae is similar to that of the young female of the species, but here the white color is usually greater.
In addition to the morphological structure of the sexual organs, further differences between the two species lie in the hairiness of the opisthosoma. Latrodectus lilianae is characterized by the fact that, unlike the European black widow, these hairs are divided into two parts (bifid).
Similarities to the False Black Widow
Within the genus of fat spiders ( Steatoda ), the European black widow is often confused with the false black widow ( S. paykulliana ). It resembles the European black widow in the form of the opisthosoma and also has a conspicuous markings, which usually only consist of a red or yellow horizontal stripe in the front part of the abdomen. The very strong resemblance of the false black widow to the actual "black widow" including the European black widow has also led to its common name .
The European black widow is also slightly larger than the false black widow and the two species can be distinguished from one another based on the position of their eyes. As with all fat spiders and thus also with the false black widow, the side eyes are closer together than with the real widows, including the European black widow. The distance between the two side eyes is smaller in the fat spiders than their own diameter (in some species of this genus the side eyes even touch each other). In addition, as with all fat spiders including the false black widow, the chelicerae (jaw claws) are toothed, but this is not the case with the real widows ( latrodectus ) and thus also the European black widow.
The false black widow is also found in the Mediterranean area and prefers similar habitats as the European black widow.
Genital morphological features
The bulbi (male genital organs) of the European black widow are similar to those of Latrodectus lilianae . They have brown colored patellae, tibiae and cymbii (the first sclerites or hard parts of the bulbi) which, like the prosoma of the female, are provided with a few black colored hairs. The cymbii are comparatively small and the emboli (last sclerite and import organs of the bulb) are wound like a spring and each have four loops.
The epigyne (female sexual organ) of the European black widow is also similar to that of Latrodectus lilianae and that of the sister species Latrodectus renivulvatus and has two adjacent spermatheks . These have fertilization ducts with four loops each in all three types. In the European black widow and the Iberian widow, the fourth loop runs between the second and the third, while in L. renivulvatus the fourth loop follows the third. The spermatheks of the European black widow and Latrodectus lilianae can be distinguished from each other by the shape of the third loop in each case, which in Latrodectus lilianae forms an almost completely closed circle, while in the European black widow it is almost semicircular.
toxicology
The toxicity (effect) of the various poisons of the European black widow is recorded by the toxicology , which analyzes their components. The main purpose of existing in almost all spiders spider toxins is the immobilization of prey. In the case of the European black widow, there is also the toxicity of the eggs and young animals that are supposed to protect them.
Spider toxin
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The spider toxin of the European black widow, which has been studied several times due to its effect, consists among other things of 146 toxin-like proteins , which, depending on their function and bioactivity, are divided into the five groups of neurotoxins (nerve toxins ), auxiliary toxins, peptidases ( enzymes that can split proteins or peptides ) , protease inhibitors (molecules that inhibit peptidases) and other toxins whose function is unknown.
The majority of the toxin is made up of the neurotoxins, which, like all real widows ( Latrodectus ), include alpha-latrotoxins (α-LTX), the number of which in this species is 21. These have a size of about five to six picometers and a molecular mass of 110 to 140 kilodaltons and, after binding to certain neuronal receptors, cause a massive release of neurotransmitters from the nerve endings in the group of animals on which the respective neurotoxins (nerve toxins) are supposed to act. Seven of the alpha latrotoxins are latro insectotoxins (LIT), which have a neurotoxic effect on insects. Nineteen other alpha latrodoxins produce this effect in vertebrates. It also contains a component called A-latrocrustatoxin (α-LCT), which causes neurotoxic effects in crustaceans . Other neurotoxins are the four ankyrins (proteins with a pentapeptide repeat) and eight lycotoxins.
The auxiliary toxins probably include the 62 theriditoxins, which apparently serve to increase the effect of the neurotoxins.
The peptidases of the spider toxin are formed from 16 trypsins, which support the maturation of the toxins and the digestion of the prey.
Nine ctenitoxins, which protect neurotoxins and auxiliary toxins from proteolytic degradation of prey, and nine orphan toxins, which block proteases or inhibitors of peptidases and ion channels of prey , serve as protease inhibitors . The latter function is also fulfilled by three so-called SCP peptides.
There are also four other toxins whose function is unknown and whose properties are similar to scorpion toxins .
Studies have shown that the spider toxin of the European black widow is composed similarly to that of the western black widow ( Latrodectus hesperus ), especially with regard to the structure of toxins (poisonous substances), hydrolases and inhibitors (inhibitors). However, the western black widow venom has fourteen ankyrins (repeating proteins), while the number in the European black widow venom is thirteen.
Toxicity of the Eggs
The eggs of the European black widow also have a toxic effect on other organisms, but the same typical proteins were not found in the eggs examined as in the spider toxins from real widows. This means that the eggs have their own toxic mechanism. It is known that the eggs have four different and quite distinct toxins with the names latroegg toxin-I to -IV.
Latroegg toxin-I has a molecular mass of 23.8 kilodaltons. In experiments with mice , it has been found that it reversibly blocks their motor endplates .
Latroegg toxin-II has a molecular weight of 28.7 kilodaltons. Electrophysiological studies with rats showed that the toxin selectively inhibits sodium channels resistant to the nerve toxin tetrodotoxin in the spinal ganglia (nerve nodes in the vertebral canal ) without seriously affecting sodium channels that are resistant to tetrodotoxin.
Latroegg toxin-III has a molecular mass of about 36.0 kilodaltons and was neurotoxic in tests on cockroaches, but not on mice, which, in contrast to the two previous latroegg toxins, probably only shows full effect on insects. In further investigations it was analyzed with the help of the BLAST algorithm that latroegg toxin-III is a protein-degrading toxin and contains vitellogenins .
Latroegg toxin IV differs significantly from the other latroegg toxins in that, in contrast to these, it functions as an antibiotic and this peptide is designed as such. Its molecular mass is 3.6 kilodaltons and it proves to be particularly effective against the staphylococci S. aureus and S. typhimurium , against the bacterium Bacillus subtilis and against the Escherichia coli commonly known as " coli bacterium " as well as against Pseudomonas aeruginosa .
Toxicity of young animals
Like the eggs, the young of the European black widow also have toxic properties. Investigations of the inner workings of newly hatched spiders have shown that they contain 69.42% proteins, which differ in terms of their molecular mass and isoelectric points . Abdominal injections of the extract of the inner life in mice in the amount of 5.30 milligrams per kilogram of body weight of the respective mouse and in cockroaches in the amount of 16.74 micrograms per gram of body weight of the respective cockroach showed clear symptoms of intoxication and also led to death in some specimens.
Electrophysiological studies in mice given the extract at a concentration of 10 micrograms per milliliter showed that it was able to completely block their nerves in the diaphragm within 1.5 to 21 minutes. At an administered dose with an intensity of 100 micrograms per milliliter, this could also be achieved with the supply of tension-activating sodium and the supply of calcium in the ion channels of the spinal ganglion.
Possible reasons for the toxicity of the eggs and young animals
It has not yet been fully clarified why both the eggs and the juveniles in their early stages also have poisonous properties as such. One theory is that this toxicity forms a protection against other predatory arthropods. It was shown that the toxins of the eggs of the European black widow had negative effects on the garden spider ( Araneus diadematus ). Some specimens that received 3-5% of their own body weight in toxins in a laboratory test showed abnormal network building activity, and one that received 1% of their own body weight in toxins died six hours after administration.
Another assumption is that the toxic properties of these stages also serve antibacterial protection. A female of the European black widow usually deposits her egg cocoons higher up in her safety net, where it can occasionally be dark and humid and these rooms therefore also offer good opportunities for microorganisms to develop, although the eggs and young animals are sensitive to their pathogenic effects. The spiders can come into contact with these microorganisms when they eat food.
Happen
The European black widow is found in warmer areas of the Palearctic . The wide range of the species extends over the entire Mediterranean area , the Ukraine , the Caucasus , Russia (from the European part to the south of Siberia ), Kazakhstan , Iran , Central Asia and China . In Europe, the distribution area ends in Istria to the north . The European black widow is also found quite often, for example, on the Mediterranean islands of Sardinia and Corsica .
The Central Asian form of the European black widow has also been described as a separate species under the name Latrodectus lugubris . However, this view is no longer valid today. It is possible that the Central Asian occurrence is a subspecies.
habitat
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The European black widow, like all species of the real widow ( Latrodectus ), is xerophilous (dry-loving) and inhabits predominantly open arid areas , including wastelands . However, it does not avoid grasslands either. In addition, the species has been proven on warm, open ruderal areas and under stones.
Other habitats of the European black widow are dunes and sandy and scree beaches. Finds in close proximity to the sea have also been handed down. When a habitat is covered with bushes , the number of individuals in the population in this area decreases.
frequency
In general, the European black widow is often found in suitable habitats . However, the frequency is highly variable and varies from year to year. In Istria, for example, the species was almost undetectable in some years, while in other years the spider's finding rate was quite high there.
way of life
The European black widow stays close to the ground and, like many crested web spiders, creates a spider web typical of the family for the purpose of catching prey, which consists of several threads that reach to the ground. At the top there is a key-shaped hiding place that serves as the residence of the nocturnal spider. The net is usually laid near the ground in half-height grass or other vegetation. However, places under overhanging rocks or other rocky structures are often used as network construction sites.
Hunting behavior
The hunting strategy of the European Black Widow, like all spiders who hunt exclusively with a safety net, as ambulance hunters corresponds to that of other crested-web spiders who specialize in ground-dwelling prey. The spider remains in its shelter until a prey animal touches one of the taut catching threads with sticky drops of glue and, if it does not escape, is now caught. The thread itself loosens upon contact.
The spider, which locates the position of the prey animal based on its vibrations, now moves to it and begins to immobilize it from above by throwing further catching threads at it. If the prey is unable to move, the spider now uses the chelicerae to bite it poisonously . The spider then lingers for a few minutes and then continues throwing threads at the prey. The intensity depends on the preparedness of the prey.
If the prey now spun in and paralyzed by the spider toxin no longer moves, the spider separates it with its chelicerae from the safety net and transports it attached to a spider thread to the shelter, where it is now consumed. Remnants of sucked-out prey, mainly the exoskeletons of arthropods, remain in the spider's web.
Loot spectrum
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The European black widow has a large range of prey, whereby a passive selection of food is made by the type of network construction. The range of prey also depends on the age of the spider. Various arthropods, especially larger insects, fall into the range of prey. The main component of the prey animals are medium to large arthropods , including various beetles , grasshoppers and other spiders.
Due to the European black widow's effective and, for the spider itself, mostly safe trapping technique, it is also possible for it to successfully capture very large or well-fortified prey. Thus, the prey spectrum of the species also includes male trapdoor spiders who roam around at night in search of females and get caught in the European black widow's nets in the process. There have also been reports of small vertebrate animals , mainly lizards , caught in their webs and preyed on by the spiders.
Younger individuals, whose hunting style is basically the same as that of adult specimens, but who create smaller nets in the process, primarily prey on smaller arthropods . The prey animals of growing specimens include aphids , dwarf leafhoppers and various moths . In experiments with pups of European black widow under laboratory conditions from those in the first and second feeding skin (development stage of spiders), the successful capture of caterpillars (this one also in the first and third stage) of the African cotton worm ( Spodoptera littoralis ) and the third to fourth skin also observed the preying of caterpillars of the great wax moth ( Galleria mellonella ). Already advanced juveniles from the fifth to the eighth-eating skin succeeded under these conditions also imagines to capture (adult specimens) of the African cotton worm.
Life cycle
The life cycle of the European black widow is divided into several phases and also depends on the seasons.
Phenology
The activity time of the European black widow amounts to the period between May and November in adult females. This period is shorter in adult males and adult specimens of this sex can be found between May and September.
Reproduction
A sexually mature male already seeks out a not yet mature female and enters its network, which usually no longer leaves it. As soon as this has completed the last and thus the mature molt, the male spins the female and thus ties her up before she mates. The female frees herself from the threads very quickly and usually consumes the male, which is where the name "black widow" comes from in addition to the visual appearance.
Some time after mating, the female creates up to five egg cocoons , which it deposits in the net. The egg cocoons are fourteen to seventeen millimeters long and twelve to fifteen millimeters wide and also pointy on one side. In terms of color, the cocoons are initially white or cream-colored, but after a short time they take on a yellowish hue before they hatch shortly before hatching, which occurs in examined laboratory conditions with temperatures of 27 ° C after a total of 49 days after the production of one egg cocoon. get darker again. However, it is assumed that the incubation (the young animals mature in the eggs and the time it takes to hatch) in the wild can take significantly more time and that the young animals also hibernate.
An egg cocoon contains around 103 eggs, with the hatching rate in females at a good 57% being slightly higher than that of the males at around 43%. Studies have shown that a single egg of the European black widow has high molecular weight peptides (organic compound that contains peptide bonds between amino acids ) with a molecular mass of less than five kilodaltons and 157 proteins (protein bodies) that are involved in important cellular functions and processes such as catalysis and transport and regulation of metabolic products are involved. In addition, the eggs are poisonous (see section Toxicity of the eggs ), although the composition of the proteins in the eggs is more complex than that of the toxins. The property of poisonous eggs is also present in other species of true widows.
The hatched and poisonous young animals (see section Toxicity of young animals ) initially remain with the mother before they become independent. They grow up by molting over several scavenger skins , the number of which is four to five in males and eight in females. After the scavenger hides, the last moulting takes place, after which the spider is then fully grown and thus sexual maturity occurs.
Life expectancy
The male grows up within about 108 days and can achieve a total lifespan of about 180 days. The female needs a full 215 days to grow and reaches a life expectancy of about 302 days than the male.
Systematics
The European black widow is today the type species of the genus of the real widows ( Latrodectus ). and has seen more and more orders and renaming in its description history, especially since it has been used by different authors under different names.
Description history
The first descriptor and Italian entomologist ( entomologist ) and arachnologist (spider scientist) Pietro Rossi classified the species in the first description in 1790, which is now considered valid, in the genus Aranea , like all spiders back then, and gave the name Aranea 13-guttata . The first description as "short-legged spotted spider" Aranea brevipes , in 1778 by the German naturalists Friedrich Heinrich Wilhelm Martini and Johann August Ephraim Goeze , was suppressed as a forgotten name ( nomen oblitum ) (see the naming section ).
The current scientific name of the European black widow, Latrodectus tredecimguttatus , was first used by Eugène Simon in 1873 and from then on it has increasingly been the name used throughout the species. In 1966, however, under Ion Eduard Fuhn, it became a subspecies of the real widows ( Latrodectus ) and prominent southern black widow ( Latrodectus mactans ) with the designation Latrodectus mactans tredecimguttatus , which was revised in 1983 by Gershom Levy and P. Amitai and thus received its independent species status again.
Internal system
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Within the genus of real widows ( Latrodectus ), the European black widow is most closely related to the species Latrodectus renivulvatus found in Africa . Research has shown that European black widow species found in Spain appear to be more closely related to individuals of this species than to European black widow populations in Israel . The phylogenetic relationships of all species to one another have not yet been finally clarified.
L. tredecimguttatus and L. renivulvatus belong to the clade of the southern black widow ( L. mactans ), one of the two species groups of true widows. This includes the majority of the species in this genus. The other clade is that of the brown widow ( L. geometricus ), which in addition to this only contains the South African species Latrodectus rhodesiensis . These two species are genetically further removed from the other representatives of the true widows, which is also true of the European black widow and Latrodectus renivulvatus .
The more precise relationship of the species mentioned within the genus of real widows shows the following cladogram :
| Real widows ( latrodectus ) |
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Naming
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The specific epithet tredecimguttatus stands for "thirteen spots". The European black widow was already described as Aranea brevipes in 1778 , but this description was ignored by later editors and is now suppressed as a forgotten name (nomen oblitum) in the taxonomy, so that the description of Pietro Rossi , who gave it the name Aranea 13 -guttata in its fauna Etrusca , received validity (see section Systematics ). Rossi already mentions the variability of the species, but later attempts were made to define specimens with a lower number of red markings on the abdomen and other variants as separate species. In 1805, Charles Athanase Walckenaer introduced the spider into the new genus Latrodectus as part of his revision of the genus Aranea . In 1966 it was placed as a subspecies to Latrodectus mactans , but raised again to a species in 1983.
The European black widow is also known today under other names:
Malmignatte
In his first description, Pietro Rossi also mentions the common Italian name "Marmignatto" for this species of spider. The Germanized name "Malmignatte" is derived from this. In 1837 Charles Athanase Walckenaer described a Latrodectus malmignatus in his Histoire naturelle des insectes , which is, however, identical to the European black widow. Mostly, “Malmignatte” refers to the European type of black widow. The name is also transferred to species that live on other continents.
Karakurts
In the southern Russian and Central Asian distribution area of the European black widow, the common name Karakurt , Germanized Karakurte, is used. The meaning of this name, which can be translated as “black wolf”, alludes to the dangerousness of the spider for animals and humans, which the population of these areas rates as highly. Every summer there are reports from Kazakhstan that numerous camels die from the bite of the black widow if they are not treated with an antiserum .
Black widow
The later German-language term "black widow" comes from the assumption that the females eat the smaller males after mating and thereby make themselves "widows". However, this behavior, which can also be observed in other spiders, is not the rule in the majority of species of this order. Even with the so-called "black widows", this phenomenon is not necessarily the rule, although cannibalistic behavior can indeed often be observed in the female of the European black widow compared to the male.
European black widow and human
Because of the medical consequences of their bite, the European black widow is often feared like many other true widows ( Latrodectus ) including the other "black widows" and like the fat spiders ( Steatoda ), which belong to the same family. On the other hand, due to its effective prey capture, the species is also seen as being able to be used in agriculture (see section Use in agriculture ). Due to its properties and not least due to the high toxicity of its various poisons, the spider has also become a research object of science with greater relevance, and it is also occasionally kept as a pet in terraristics (see section on terraristics ).
Bite accidents
As with the other real widows ( Latrodectus ), only the females of the European black widow can penetrate the human skin with the help of their chelicerae (jaw claws), but are not aggressive, but usually try to flee in the event of disturbances and only bite in the greatest need.
Most often farm workers are bitten during harvest, which comes into contact with the spider, which is preferred in rural areas. Bites are correspondingly rare in urban areas, which the species, unlike the closely related southern black widow ( Latrodectus mactans ), predominantly avoids. In the meantime, however, bite accidents are significantly less common in Europe.
The toxicity (poisonous effect) of the spider bite for humans is controversial. While the first describer, Pietro Rossi , one of the leading entomologists of the 18th century, mentioned that the poison of the spider could kill people, the poisonous effect of the spider in France was almost completely denied at the beginning of the 20th century. Sometimes the effect of the bite is described just like that of a wasp sting. Fatal courses after a bite only occur in extreme exceptional cases, around four to five out of 1,000 bites. Still other sources suggest that approximately 5% (50 in 1,000 bites) or 0.2% (2 in 1,000 bites) of untreated bites are fatal.
Symptoms
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A variety of physical complications can be associated with a European black widow bite. Frequent symptoms are sweating in 70% of the registered bite cases and further systemic effects in 20% to 30%. These include nausea, vomiting in less than 20%, fever and neuromuscular effects in 10% and high blood pressure in less than 10% of the cases. These symptoms can linger for one to four days. Two thirds of the reported bite victims suffered severe and long-lasting pain, which is said to prevent a third of the bite victims from sleeping. More than half of the bite victims complained that the intensity of the pain increased within an hour after the bite and that it also radiated into the extremities and abdomen. This pain subsides after a day or two.
In addition, it is not uncommon for the symptoms to be similar to those of the southern black widow ( Latrodectus mactans ) bite , which occurs in the southeastern states of the USA. The alpha-latrotoxin contained in the spider venom causes involuntary neuromuscular discharges that lead to cramping abdominal pain, headache, high blood pressure and, after one to three hours, generalized, rapidly increasing muscle pain and muscle cramps. If left untreated, these symptoms can last for days. Local swelling and reddening appear on the bite wound.
Often the connection between the symptoms and the spider bite cannot be established, since most of the symptoms of this clinical picture, called latrodectism , only become noticeable after 20 minutes to 2 hours. Misdiagnosis and incorrect treatment are often the result, since spider bites are relatively rare in Europe and there is a lack of experience with these symptoms of poisoning as well as antitoxin in hospitals . For example, between 1984 and 1994 there were only twelve cases of victims of European black widow bites in the hospital in Almería in Spain, which is located in a known area of the spider's distribution. Almost all of them were farm workers who had mostly worked in greenhouses. There was hardly any contact with the spider in the wild.
Tarantism
Even today, the bite of the black widow is still seen as the cause of tarantism, a kind of St. Vitus dance , which can lead to hallucinations in addition to convulsions and involuntary jerks. For the people of the Middle Ages, these symptoms of poisoning were difficult to classify and, starting in the city of Taranto in southern Italy, led to downright hysteria that also spread to Spain in the 15th century. Although the symptoms were soon attributed to a spider bite, the Apulian tarantula ( Lycosa tarantula ) was blamed. The tarantula is much less poisonous than the European black widow, but it is much larger than this and also active during the day, so that it could be observed by humans much more often than the nocturnal black widow, who hides under stones during the daytime. Later the name "tarantula" by the Spaniards was also in South America domestic tarantulas transmitted.
The therapy methods of that time included sweating cures or treatment with excrement. The patient was perhaps best served by the tarantella , a piece of music that was originally composed for the purpose of freeing the bite victims from their ailments by dancing quickly. This "healing method" was recommended in 1875 by the Spanish Medical Association. The use of tarantella for the purpose of those affected by tarantism was often used until the 1950s and is still used in isolated cases today. In modern literature, the bite of the European black widow as well as the Apulian tarantula and other poisonous animals widespread in the Mediterranean region, such as various scorpions or snakes , are taken as a symbolic interpretation of tarantism. This is supported by the fact that many patients diagnosed with tarantism did not find any bite or stab wounds from such animals. Instead, the causes can increasingly be traced back to psychological causes, which is reinforced by the crises that occur annually, the non-occurrence of the disease in some villages and the general increase in tarantism among young women. Furthermore, symptoms such as hysteria or melancholy are ascribed to tarantism, which, on the other hand, are not considered to be the result of a bite by the European black widow.
Threat and protection
Due to the generally high population density and thus general frequency in habitats that meet optimal conditions for the species to live, the European black widow is not threatened in its range and therefore does not enjoy any protection status. The population of the species is not recorded by the IUCN .
Use in agriculture
The European black widow has increasingly proven to be an effective beneficial insect in agriculture , as it also prey on a large number of known pests that attack vegetable plants as well as ornamental and fruit trees. Because of this, the interest in using the species as a control agent for said pests in the context of biological pest control has meanwhile increased significantly. For this purpose, individuals of the European black widow are often left at sites within agricultural areas or brought to such areas, where they are then supposed to decimate animals that can damage agriculture and are therefore considered pests.
Terrariums
The European black widow, like some other spiders, is occasionally kept as a pet in terrariums , which is sometimes due to the visual appearance of the spider. For many interested parties, the small amount of space required due to the species' loyal way of life is also viewed positively, which enables it to be kept in comparatively small dwellings (preferably terrariums ). The temperature can and the humidity should be rather low due to the natural habitats of the spider. It is compulsory to set up the spider web and a place to hide that the animal can use and expand as a shelter. Thus, keeping the European Black Widow as such is comparatively easy, but you should be aware of the possible danger it poses before buying one or more specimens (see section bite accidents ).
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q r s t Heiko Bellmann: Der Kosmos Spinnenführer. Over 400 species in Europe. 2nd Edition. Kosmos Naturführer, Kosmos (Franckh-Kosmos), 2016, p. 94, ISBN 978-3-440-14895-2 .
- ↑ a b c d e f g h i j k Latrodectus tredecimguttatus (Rossi, 1790) from araneae - Spiders of Europe, accessed on April 6, 2020.
- ↑ a b c d e f g h i j k l m n o p AS M Metwally, M. A Mohafez, M. A El-Danasory, AA El-Gendy: Notes on the biology of Latrodectus tredecimguttatus (Rossi, 1790) (Araneae: Theridiidae) . Serket (2015), Volume 14 (4), pp. 189–195, accessed on March 6, 2020.
- ↑ a b c d e f g h i j Ioan Duma: Latrodectus tredecimguttatus (Araneae: Theridiidae) in Romania. Distribution and Ecology. Travaux de Muzeul de Istorie Naturalǎ “Grigore Antipa”, 49, pp. 75–81, Bucharest 2006, accessed on August 27, 2020.
- ↑ a b c d e f g h i Latrodectus tredecimguttatus (Rossi, 1790) at the Wiki der Arachnologische Gesellschaft e. V., accessed on August 22, 2020.
- ↑ a b c Latrodectus lilianae (Melic, 2000) at the Wiki der Arachnologische Gesellschaft e. V., accessed on August 26, 2020.
- ↑ SW Hann: Descriptions of four Steatoda species (Araneae, Theridiidae) found in New Zealand , New Zealand Journal of Zoology, Volume 21, 1994, ISSN 0301-4223 (print version), 1175-8821 (online version), p. 225 -238, accessed September 8, 2020.
- ↑ a b Steatoda paykulliana (Walckenaer, 1805) at the Naturwissenschaftlichen Arbeitsgemeinschaft Oberhausen Mosbach eV , accessed on April 6, 2020.
- ↑ Latrodectus lilianae (Melic, 2000) at araneae - Spiders of Europe, accessed on August 27, 2020.
- ↑ a b c d e f g h i j k l m n o p q r S. Yan, X. Wang: Recent Advances in Research on Widow Spider Venoms and Toxins , Toxins, Issue 7 (12), 2015, pp. 5055-5067, accessed March 7, 2020.
- ↑ Victor Ivanovitsch Motschulsky: Note sur deux araignées vénimoux de la Russie méridionale. Bulletin de la Société Imperiale des Naturalists de Moscou, 1st volume, 1849, pp. 289-290.
-
↑ a b c
- B. Knoflach & K. Pfaller: Kugelspinnen - an introduction (Araneae, Theridiidae) , Denisia 12, Serie 14, 2004, pp. 111-160, accessed on August 26, 2020.
- ↑ a b c Latrodectus tredecimguttatus (Rossi, 1790) in the WSC World Spider Catalog , accessed March 8, 2020.
- ↑ a b c JE Garb, A. Gonzalez, RG Gillespie: The black widow spider genus Latrodectus (Araneae: Theridiidae): Phylogeny, biogeography, and invasion history . In: Molecular Phylogenetics and Evolution . tape 31 , no. 3 , 2004, p. 1127–1142 , doi : 10.1016 / j.ympev.2003.10.012 .
- ^ Herbert W. Levi: The three species of Latrodectus (Araneae), found in Israel. Journal of Zoology, 150, pp. 427-432, London 1966.
- ↑ G. Levy and P. Amitai: Revision of the widow-spider genus Latrodectus (Araneae: Theridiidae) in Israel. Zool. J. Linnean Soc., 77, pp. 39-63, 1983.
- ↑ Spiders plague Kazakh camels Friday, BBC News of July 2, 2004 (accessed July 9, 2010).
- ↑ a b Rainer F. Foelix: Biology of the spiders. Georg Thieme Verlag, Stuttgart 1979, ISBN 3-13-575801-X .
- ↑ Rudolf Kobert: Textbook of intoxications . Second part, 2nd edition, Verlag F. Enke, 1906, p. 457.
- ↑ Cleveland P. Hickman: Zoology. 13th edition, Pearson Studium, Munich 2008, p. 576.
- ↑ Toxicological assessment of black widow bites in the Toxinfo database.
- ^ F. Torregiani, C. La Cavera: Differential diagnosis of acute abdomen and latrodectism. Minerva Chir., 45, 5, pp. 303-305, 1990.
- ^ F. Torregiani, C. La Cavera: Review of latrodectism and Malmignatta sting (Latrodectus tredecimguttatus) in Italy. Minerva Med., 81, (7-8 Suppl), pp. 147-154, 1990.
- ↑ F. Díez García, F. Laynez Bretones, M.-C. Gálvez Contreras, H. Mohd, A. Collado Romacho, F. Yélamos Rodríguez: Black widow spider (Latrodectus tredecimguttatus) bite. Presentation of 12 cases. Medicina Clinica, 106, 9, pp. 344-346, Barcelona 1996.
- ↑ Bites and stings from animals in Spain on the pages of Iberia Nature, a guide to the natural history of Spain.
- ↑ Laurence Reuter: The healing ritual of Tarantism from a music therapy perspective . Berlin University of the Arts, accessed on August 22, 2020.
- ^ Latrodectus tredecimguttatus (Rossi, 1790) at Global Biodiversity Information Facility , accessed on March 6, 2020.
- ↑ Latrodectus (Walckenaer, 1805) in Arachnida, accessed on March 8, 2020.
literature
- Heiko Bellmann: The cosmos spider guide. Over 400 species in Europe. 2nd Edition. Kosmos Naturführer, Kosmos (Franckh-Kosmos), 2016, ISBN 978-3-440-14895-2 .
- Pietro Rossi: Fauna Etrusca: sistens insecta quae in Provinciis Florentina et Pisana praesertim collegit . Tomus 1, pp. 126-140, Livorno 1790, p. 136 (first description).
- Charles Athanase Walckenaer: Tableau des aranéides ou caractères essentiels des tribus, genres, familles et races que renferme le genre Aranea de Linné, avec la désignation des espèces comprises dans chacune de ces divisions. Paris 1905, p. 81.
- Heiko Bellmann: Cosmos Atlas Arachnids of Europe. 3rd edition, Franckh-Kosmos, Stuttgart 2006 pp. 76-77, ISBN 3-440-10746-9 .
- AS M Metwally, M. A Mohafez, M. A El-Danasory, AA El-Gendy: Notes on the biology of Latrodectus tredecimguttatus (Rossi, 1790) (Araneae: Theridiidae) , Serket (2015), volume 14 (4), Pp. 189-195.
- S. Yan, X. Wang: Recent Advances in Research on Widow Spider Venoms and Toxins . Toxins, Issue 7 (12), 2015, pp. 5055-5067.
- JE Garb, A. Gonzalez, RG Gillespie: The black widow spider genus Latrodectus (Araneae: Theridiidae): Phylogeny, biogeography, and invasion history , Molecular Phylogenetics and Evolution 31, 3rd volume, 2004, pp. 1127–1142.
- B. Knoflach & K. Pfaller: Kugelspinnen - an introduction (Araneae, Theridiidae) , Denisia 12, Series 14, 2004, pp. 111-160.
- Ioan Duma: Latrodectus tredecimguttatus (Araneae: Theridiidae) in Romania. Distribution and Ecology. Travaux de Muzeul de Istorie Naturalǎ “Grigore Antipa”, 49, pp. 75–81, Bucharest 2006.
Web links
- Latrodectus tredecimguttatus in the World Spider Catalog
- Latrodectus tredecimguttatus at Fauna Europaea
- Latrodectus tredecimguttatus (Rossi, 1790) at Global Biodiversity Information Facility
- Latrodectus tredecimguttatus (Rossi, 1790) at araneae - Spiders of Europe
- Latrodectus tredecimguttatus (Rossi, 1790) at Global Biodiversity Information Facility
- Latrodectus tredecimguttatus (Rossi, 1790) at the Wiki of the Arachnological Society e. V.
- Latrodectus (Walckenaer, 1805) near Arachnida
- Latrodectus (Walckenaer, 1805) at the Hanover Student Council for Biology & Naturopathy (web archive from April 5, 2009)
