Latrodectus mactans

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Latrodectus mactans
Latrodectus mactans eating.JPG
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Chelicerata
Class: Arachnida
Order: Araneae
Infraorder: Araneomorphae
Family: Theridiidae
Genus: Latrodectus
Species:
L. mactans
Binomial name
Latrodectus mactans
(Fabricius, 1775) [1]

Latrodectus mactans, known as southern black widow or simply black widow, and the shoe-button spider,[ citation needed ] is a venomous species of spider in the genus Latrodectus . The females are well known for their distinctive black and red coloring and for the fact that they will occasionally eat their mates after reproduction. The species is native to North America. The venom can cause pain and other symptoms, but is rarely fatal to healthy humans. [2]

Contents

Taxonomy

Latrodectus mactans was first described by Johan Christian Fabricius in 1775, placing it in the genus Aranea . [1] [3] It was transferred to the genus Latrodectus in 1837 by Charles Walckenaer and is currently placed in the family Theridiidae of the order Araneae. [1] The species is closely related to Latrodectus hesperus (western black widow) and Latrodectus variolus (northern black widow). Members of the three species are often confused with the genus Steatoda , the false widows. Prior to 1970, when the current taxonomic divisions for North American black widows were set forth by Kaston, [4] all three varieties were classified as a single species, L. mactans. As a result, there exist numerous references which claim that "black widow" (without any geographic modifier) applies to L. mactans alone. Common usage of the term "black widow" makes no distinction between the three species.

Description

The body length (excluding legs) of the mature female is 8–13 mm (0.31–0.51 in), and 3–6 mm (0.12–0.24 in) for males. Legs are long in proportion to body. [5] Females are shiny and black in color, with a red marking in the shape of an hourglass on the ventral (under) side of her very rounded abdomen. [6] There is much variation in female size, particularly in egg-carrying (gravid) females. The abdomen of a gravid female can be more than 1.25 cm (0.5 in) in diameter. Many female widows also have an orange or red patch just above the spinnerets on the top of the abdomen. [7] Juveniles have a distinctly different appearance from the adults; the abdomen is grayish to black with white stripes running across it and is spotted with yellow and orange. [7] Males are either purple, or closer to the appearance of the juveniles in color.

The web of the black widow spider is a three-dimensional tangled cobweb of exceptionally strong silk. [8]

The distinctive red hourglass marking Adult Female Black Widow.jpg
The distinctive red hourglass marking

Range

The southern widow is primarily found in (and is indigenous to) the southeastern United States, ranging as far north as Ohio and as far west as Texas. [9] The northern black widow (L. variolus) is found primarily in the middle Atlantic states, though its range overlaps with that of L. mactans. In the Dominican Republic L. mactans is found throughout the whole country. [10] [11] L. mactans is also found throughout Mexico where its range overlaps with that of Latrodectus hesperus and Latrodectus geometricus . [12]

L. mactans, along with L. hesperus and L. geometricus, is established in the Hawaiian Islands (USA). [13] [14] One pathway of entry into Hawaii for at least one of these black widow species is imported produce [15] (which is also considered an important potential pathway for widow spiders elsewhere). [16]

Reproduction

When a male is mature, he spins a sperm web, deposits semen on it, and charges his palpal bulbs with the sperm. Black widow spiders reproduce sexually when the male inserts his palpal bulbs into the female's spermathecal openings. The female deposits her eggs in a globular silken container in which they remain camouflaged and guarded. A female black widow spider can produce four to nine egg sacs in one summer, each containing about 100–400 eggs. Usually, eggs incubate for twenty to thirty days. It is rare for more than a hundred to survive this process. On average, thirty will survive through the first molting due to cannibalism, lack of food, and/or lack of proper shelter. It takes two to four months for black widow spiders to mature enough to breed; however, full maturation typically takes six to nine months. The females can live for up to three years, while a male's lifespan is about three to four months. [17] The female may eat the male after mating.[ citation needed ]

Prey

Black widow spiders typically prey on a variety of insects, with a preference for fire ants if extant,[ citation needed ] but they also feed on woodlice, diplopods, and chilopods when they are young, and occasionally other arachnids. [18] The spider's web is even strong enough to catch animals as large as mice.[ citation needed ] When the prey is entangled by the web, Latrodectus mactans quickly comes out of its retreat, wraps the prey securely in its strong web, then bites and envenoms its prey. The venom takes about ten minutes to take effect; in the meantime, the prey is held tightly by the spider. When movements of the prey cease, digestive enzymes are released into the wound. The black widow spider then carries its prey back to its retreat before feeding. [19]

Natural enemies

There are various parasites and predators of widow spiders in North America, though apparently none of these have ever been evaluated in terms of augmentation programs for improved biocontrol. Parasites of the egg sacs include the flightless scelionid wasp Baeus latrodecti, [20] and members of the chloropid fly genus Pseudogaurax . Predators of the adult spiders include the brown widow spider, Latrodectus geometricus , [21] wasps, most notably the blue mud dauber Chalybion californicum , and the spider wasp Tastiotenia festiva .[ citation needed ] Other organisms including mantises or centipedes also will occasionally and opportunistically take widows as prey, but the preceding all exhibit some significant specific preference for Latrodectus .[ citation needed ]

The brown widow appears to be competing for territory with, and ultimately displacing black widows in areas where they occur together, including predation on black widows. [21] [22]

Toxicology

Although the reputation of these spiders is notorious and their venom does affect humans, only mature females are capable of envenomation in humans; their chelicerae—the hollow, needle-like mouthparts that inject venom—are approximately 1 mm, or .04 in. in length, making them long enough to inject venom into humans, unlike those of the much smaller males. The actual amount injected, even by a mature female, is variable. The venom injected by the female black widow is known as alpha-latrotoxin which binds to receptors at the neuromuscular motor end plate of both sympathetic and parasympathetic nerves, resulting in increased synaptic concentration of catecholamines. The symptoms are caused by lymphatic absorption and vascular dissemination of the neurotoxin. The symptoms that result from a black widow spider bite are collectively known as latrodectism . Deaths in healthy adults from Latrodectus bites are exceedingly rare, with no deaths despite two thousand bites yearly, and studies within the past several decades have been unable to confirm any fatalities from this or any of the other U.S. species of Latrodectus (e.g. zero fatalities among 23,409 documented Latrodectus bites from 2000 through 2008). [23] On the other hand, the geographical range of the widow spiders is vast. Epidemics of mostly European widow spider bites had been recorded from 1850 to 1950, and during that period deaths were reported from 2 per 1000 bites to 50 per 1000 bites. Deaths from the western black widow had been reported as 50 per 1000 bites in the 1920s. At that same time, antivenom was introduced. [24] The LD-50 of L. mactans venom has been measured in mice as 1.39 mg/kg, [25] and separately as 1.30 mg/kg (with a confidence interval of 1.20–2.70). [26] In 1933, Allan Blair allowed himself to be bitten by the spider in order to investigate the toxicity of its venom in humans and as a means of convincing skeptics at the time who thought that the spider's venom might not be dangerous to humans.

There are a number of active components in the venom:

The venom is neurotoxic.

Related Research Articles

<i>Latrodectus</i> Genus of spiders

Latrodectus is a broadly distributed genus of spiders with several species that are commonly known as the true widows. This group is composed of those often loosely called black widow spiders, brown widow spiders, and similar spiders. However, the diversity of species is much greater. A member of the family Theridiidae, this genus contains 34 species, which include several North American "black widows". Besides these, North America also has the red widow Latrodectus bishopi and the brown widow Latrodectus geometricus, which, in addition to North America, has a much wider geographic distribution. Elsewhere, others include the European black widow, the Australian redback spider and the closely related New Zealand katipō, several different species in Southern Africa that can be called button spiders, and the South American black-widow spiders. Species vary widely in size. In most cases, the females are dark-coloured and can be readily identified by reddish markings on the central underside (ventral) abdomen, which are often hourglass-shaped.

<span class="mw-page-title-main">Redback spider</span> Species of spider

The redback spider, also known as the Australian black widow, is a species of highly venomous spider believed to originate in South Australia or adjacent Western Australian deserts, but now found throughout Australia, Southeast Asia and New Zealand, with colonies elsewhere outside Australia. It is a member of the cosmopolitan genus Latrodectus, the widow spiders. The adult female is easily recognised by her spherical black body with a prominent red stripe on the upper side of her abdomen and an hourglass-shaped red/orange streak on the underside. Females usually have a body length of about 10 millimetres (0.4 in), while the male is much smaller, being only 3–4 mm (0.12–0.16 in) long.

<i>Latrodectus bishopi</i> Species of spider

Latrodectus bishopi is the scientific name for the red widow spider, which is endemic to certain habitats of central and southern Florida, where it lives primarily in sand dunes dominated by sand pine, Pinus clausa – a type of vegetation found only in peninsular Florida.

<span class="mw-page-title-main">Katipō</span> Species of arachnid native to New Zealand

The katipō is an endangered species of spider native to New Zealand. It is one of many species in the genus Latrodectus, such as the Australian redback, and the North American black widow. The species is venomous to humans, capable of delivering a potentially dangerous bite. It is a small to medium-sized spider, with the female having a round black or brown pea-sized body. Red katipō females found in the South Island and the lower half of the North Island, are always black, and their abdomen has a distinctive red stripe bordered in white. In black katipō females found in the upper half of the North Island, this stripe is absent, pale, yellow, or replaced with cream-coloured blotches. These two forms were previously thought to be separate species. The male is much smaller than the female and quite different in appearance: white with black stripes and red diamond-shaped markings. Katipō are mainly found living in sand dunes close to the seashore. They are found throughout most of coastal New Zealand except the far south and west. Katipō feed mainly on ground dwelling insects, caught in an irregular tangled web spun amongst dune plants or other debris.

<i>Latrodectus geometricus</i> Species of spider

Latrodectus geometricus, commonly known as the brown widow, brown button spider, grey widow, brown black widow, house button spider or geometric button spider, is one of the widow spiders in the genus Latrodectus. As such, it is a 'cousin' to the more infamous Latrodectus mactans. L. geometricus has black and white patterns on the sides of its abdomen as well as an orange-yellow colored hourglass shape marking. Their eggs are easily identified by points that project from all over the egg sacs. L. geometricus are found all over the world, but are believed to originate in Africa or South America. Their bites, though painful, are not considered to be dangerous.

Button spider is a common name used in Southern Africa to refer to local members of the spider genus, Latrodectus, the family Theridiidae. There are both black and brown button spiders in Southern Africa, that are known elsewhere as widow spiders. Seven Latrodectus species can be found in Southern Africa; six of them are native, one is possibly imported.

<i>Latrodectus tredecimguttatus</i> Species of spider

Latrodectus tredecimguttatus, also known as the Mediterranean black widow or the European black widow, is a species in the genus Latrodectus of the widow spiders. It is commonly found throughout the Mediterranean region, ranging from southern Iberia to southwest and central Asia, hence the name. Specimens from central Asia are also known by the binomial name Latrodectus lugubris; that name, however, is now considered improper, though it is still commonly found in the literature. Latrodectus tredecimguttatus was previously considered a subspecies of Latrodectus mactans.

<i>Steatoda</i> Genus of spiders

The spider genus Steatoda, in the family Theridiidae, includes about 120 recognized species, distributed around the world. One common name is cupboard spider, for many species build their webs in dark, sheltered, undisturbed places around the house or garden, in sheds and garages, under garden, compost bins, and the like. Signs of the cupboard spider include small white spots of spider droppings, like small splashes of paint, on the floor underneath the web.

<span class="mw-page-title-main">Spider bite</span> Bite caused by a spider

A spider bite, also known as arachnidism, is an injury resulting from the bite of a spider. The effects of most bites are not serious. Most bites result in mild symptoms around the area of the bite. Rarely they may produce a necrotic skin wound or severe pain.

<i>Steatoda grossa</i> Species of spider

Steatoda grossa, commonly known as the cupboard spider, the dark comb-footed spider, the brown house spider, or the false widow or false black widow, is a common species of spider in the genus Steatoda.

<i>Latrodectus variolus</i> Species of spider

Latrodectus variolus, the northern black widow spider or northern widow, is a venomous species of spider in the genus Latrodectus of the family Theridiidae. The population is closely related to the southern black widow, Latrodectus mactans, and the western black widow, Latrodectus hesperus, of the genus.

<i>Latrodectus hesperus</i> Species of spider

Latrodectus hesperus, the western black widow spider or western widow, is a venomous spider species found in western regions of North America. The female's body is 14–16 mm in length and is black, often with an hourglass-shaped red mark on the lower abdomen. This "hourglass" mark can be yellow, and on rare occasions, white. The male of the species is around half this length and generally a tan color with lighter striping on the abdomen. The population was previously described as a subspecies of Latrodectus mactans and it is closely related to the northern species Latrodectus variolus. The species, as with others of the genus, build irregular or "messy" webs: unlike the spiral webs or the tunnel-shaped webs of other spiders, the strands of a Latrodectus web have no apparent organization.

<i>Steatoda nobilis</i> Species of spider

Steatoda nobilis is a spider in the genus Steatoda, known in the United Kingdom as the noble false widow, as it superficially resembles and is frequently mistaken for the black widow and other spiders in the genus Latrodectus. It is often referred to as thefalse widow, although "false widow" is a more general term applied to a wider group of species with this resemblance. It is a moderately medically significant spider, with most bites resulting in symptoms similar to a bee or wasp sting. Some bites may cause more significant harm, partly due to pathogenic bacteria from the spiders.

<i>Latrodectus indistinctus</i> Species of spider

Latrodectus indistinctus is a species of spider in the family Theridiidae, found in Namibia and South Africa. It is one of six species of Latrodectus found in southern Africa, four of which, including L. indistinctus, are known as black button or black widow spiders. Like all Latrodectus species, L. indistinctus has a neurotoxic venom. It acts on nerve endings, causing the very unpleasant symptoms of latrodectism when humans are bitten.

<span class="mw-page-title-main">Latrodectism</span> Medical condition

Latrodectism is the illness caused by the bite of Latrodectus spiders. Pain, muscle rigidity, vomiting, and sweating are the symptoms of latrodectism.

<i>Steatoda capensis</i> Species of spider

Steatoda capensis is a spider originating from South Africa. Its common names include the black cobweb spider, brown house spider, cupboard spider and due to its similarities to the katipō spider it is commonly known as the false katipō in New Zealand. Common throughout Southern Africa, it has been introduced into other countries and is now present in Australia and throughout New Zealand. It is a small spider, usually an all-over shiny black. It may have a small bright red, orange, or yellow patch near the tip of the abdomen along with a crescent shaped band near the front of the abdomen.

<span class="mw-page-title-main">Spider</span> Order of arachnids

Spiders are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude silk. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms. Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every land habitat. As of November 2023, 51,673 spider species in 136 families have been recorded by taxonomists. However, there has been debate among scientists about how families should be classified, with over 20 different classifications proposed since 1900.

<i>Latrodectus curacaviensis</i> Species of spider

Latrodectus curacaviensis is a species of black widow spider, that belongs to the genus Latrodectus. It is known as the South American black widow, Brazilian black widow or Araña del trigo.

Latrodectus revivensis, also known as the desert widow, is a species of venomous spider belonging to the Latrodectus genus and located in the Negev desert and the Arava valley (Arabah).

References

  1. 1 2 3 "Taxon details Latrodectus mactans (Fabricius, 1775)", World Spider Catalog, Natural History Museum Bern, retrieved 28 January 2016
  2. ↑ "Black Widow Spider, HYG-2061A-04". Archived from the original on 21 August 2011. Retrieved 19 July 2008.
  3. ↑ Fabricius, J. C. 1775. Systema entomologiae, sistens insectorum classes, ordines, genera, species, adiectis, synonymis, locis descriptionibus observationibus. Flensburg and Lipsiae, 832 pp. (Araneae, pp. 431–441). [432]
  4. ↑ Kaston, B. J. (1970). "Comparative biology of American black widow spiders". Transactions of the San Diego Society of Natural History. 16 (3): 33–82.
  5. ↑ "Latrodectus mactans (Southern Black Widow) – Spider Identification & Pictures". spiderid.com. Retrieved 7 February 2023.
  6. ↑ "Southern black widow spider". Insects.tamu.edu. Archived from the original on 9 March 2009. Retrieved 10 March 2009.
  7. 1 2 "Widow Spiders". Ext.vt.edu. Archived from the original on 18 October 2008. Retrieved 18 February 2009.
  8. ↑ "Black Widows Spin Super Silk. Science News". 31 December 1996. Retrieved 8 January 2016.
  9. ↑ "Southern black widow". entnemdept.ufl.edu. Retrieved 7 February 2023.
  10. ↑ Marion H., Luis (3 February 1980). "Aracnoidismo en la Republica Dominicana" (PDF). Medicina al Dia (in Spanish). BVS. Archived from the original (PDF) on 3 November 2013. Retrieved 8 October 2012.
  11. ↑ Inirio, Juan Ramon (6 November 2009). "Detectan la peligrosa viuda negra". El Nacional (in Spanish). Retrieved 8 October 2012.
  12. ↑ Cabrera-Espinosa, Luis A.; Valdez-Mondragón, Alejandro (18 October 2021). "Distribución y modelaje de nicho ecológico, comentarios biogeográficos y taxonómicos del género de arañas Latrodectus (Araneae: Theridiidae) de México". Revista Mexicana de Biodiversidad. 92: e923665. doi: 10.22201/ib.20078706e.2021.92.3665 .
  13. ↑ Tenorio, Joanne M., and Gordon M. Nishida. 1995. What's Bugging Me? Identifying and Controlling Household Pests in Hawaii. University of Hawaii Press (Honolulu). 184+7 pp. illus. (publisher's listing Archived 23 July 2009 at the Wayback Machine )
  14. ↑ Scott, Susan, and Craig Thomas, M.D. 2000. Pest of Paradise: First Aid and Medical Treatment of Injuries from Hawaii's Animals. University of Hawaii Press (Honolulu). 190+xii pp. illus. (publisher's listing Archived 5 March 2012 at the Wayback Machine )
  15. ↑ Honolulu Star-Bulletin. 6 November 2008. Creepy critter caught in grapes.
  16. ↑ Import Health Standard Commodity Sub-class: Fresh Fruit/Vegetables Table grapes, (Vitis vinifera) from the United States of America—State of California Archived 6 March 2012 at the Wayback Machine (Issued pursuant to Section 22 of the (New Zealand) Biosecurity Act 1993; Date Issued: 18 August 2005).
  17. ↑ "Black Widow Spiders". DesertUSA.
  18. ↑ McCorkle, Matthew (17 October 2002). "Latrodectus mactans". Animal Diversity Web. Retrieved 7 February 2023.
  19. ↑ Foelix, R. (1982). Biology of Spiders, pp. 162–163. Harvard University, U.S.
  20. ↑ Bibbs, Christopher; Buss, Lyle (August 2015) [2012]. "Widow Spider parasitoids Philolema latrodecti" (PDF). University of Florida. Retrieved 16 March 2017.
  21. 1 2 Louis A Coticchio, Richard Vetter, Deby L Cassill (2023) Predation by the introduced Brown Widow Spider (Araneae: Theridiidae) may explain local extinctions of native Black Widows in urban habitats. Annals of the Entomological Society of America https://doi.org/10.1093/aesa/saad003
  22. ↑ Vetter, RS; Vincent, LS; Danielsen, DW; Reinker, KI; Clarke, DE; Itnyre, AA; Kabashima, JN; Rust, MK (2012). "The prevalence of brown widow and black widow spiders (Araneae: Theridiidae) in urban southern California". J. Med. Entomol. 49 (4): 947–51. doi: 10.1603/me11285 . PMID   22897057.
  23. ↑ Monte AA, Bucher-Bartelson B, Heard KJ (2011). "A US perspective of symptomatic Latrodectus spp. envenomation and treatment: a National Poison Data System review". Annals of Pharmacotherapy 45(12):1491–8. doi : 10.1345/aph.1Q424.
  24. ↑ Bettini, S (1964). "Epidemiology of latrodectism". Toxicon. 2 (2): 93–101. doi:10.1016/0041-0101(64)90009-1. PMID   14301291.
  25. ↑ Rauber, Albert (1 January 1983). "Black Widow Spider Bites". Clinical Toxicology. 21 (4–5): 473–485. doi:10.3109/15563658308990435. PMID   6381753.
  26. ↑ McCrone, J. D. (1 December 1964). "Comparative lethality of several Latrodectus venoms". Toxicon. 2 (3): 201–203. doi:10.1016/0041-0101(64)90023-6. PMID   14298228.
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