Latrodectus Research Articles

Function of structured signalling in the black widow spider Latrodectus hesperus

Many animals communicate using complex signals composed of multiple components. In some, multiple distinct signal components are organized into stereotyped sequences. Few studies, however, have examined how such temporal structure might arise, or how this structural complexity relates to signal function. Male black widow spiders ( Latrodectus hesperus ) intermittently transition from a ‘haphazard’ production of three distinct vibratory signal components to a temporally structured multicomponent display during courtship. In this study, we examined the function of structured signalling during courtship in L. hesperus . More specifically, we examined whether structured signalling rates is predicted by male mass and whether structured signalling rates predict male mating success. Then, we experimentally tested the consequences of removing one of the signal components (abdominal tremulation) for male mating success. Larger males had lower signalling rates, suggesting a trade-off between structured signalling and mass. Males that produced structured signals more frequently mated sooner. Impairment of abdominal tremulation did not affect copulation success, but these ‘muted’ males took significantly longer to mate. Our study demonstrates that the temporal arrangement of signal components is important for male mating success in L. hesperus . • During courtship, males may switch from haphazard displays to structured signalling. • Males that displayed structured signals more frequently (higher rates) mated sooner. • Smaller males produced structured signals more frequently than larger males. • Attenuating one of the signal components increased the latency to copulate.

Siblicide in the city: the urban heat island accelerates sibling cannibalism in the black widow spider (Latrodectus hesperus)

Siblicide in the city: the urban heat island accelerates sibling cannibalism in the black widow spider (Latrodectus hesperus)

28362 Black widow spider bite: A common creature in an uncommon geographic location

The black widow spider is one of the most clinically significant spiders worldwide. Although considered ubiquitous, they are not endemic to the Caribbean. We present the case of a 52-year-old male patient with acute onset of painful erythematous soft tissue inflammation with associated diaphoresis, chills, and ipsilateral periorbital edema after identifying a black widow spider near his bed. Physical examination revealed multiple tense bullae in a violaceous background involving his thenar eminence and left thumb with associated visible fang marks. Notable vital sign and laboratory abnormalities included elevated blood pressure (156/92 mmHg), neutrophilia (16,900 cells/μL), elevated CPK (18,510 U/L), and transaminitis (ALT 91 U/L, AST 236 U/L). The patient was managed with local wound care and supportive treatment. To our knowledge, one similar case has been described in Puerto Rico. Given the scarcity of similar reports in the Caribbean and Latin America, our case highlights the importance of thorough history taking and prompt recognition of early clinical and laboratory features that should alert physicians to consider black widow spider envenomation in the appropriate clinical scenario.

Investigating the Atomic and Mesoscale Interactions that Facilitate Spider Silk Protein Pre-Assembly.

Black widow spider dragline silk is one of nature's high-performance biological polymers, exceeding the strength and toughness of most man-made materials including high tensile steel and Kevlar. Major ampullate (Ma), or dragline silk, is primarily comprised of two spidroin proteins (Sp) stored within the Ma gland. In the native gland environment, the MaSp1 and MaSp2 proteins self-associate to form hierarchical 200-300 nm superstructures despite being intrinsically disordered proteins (IDPs). Here, dynamic light scattering (DLS), three-dimensional (3D) triple resonance solution NMR, and diffusion NMR is utilized to probe the MaSp size, molecular structure, and dynamics of these protein pre-assemblies diluted in 4 M urea and identify specific regions of the proteins important for silk protein pre-assembly. 3D NMR indicates that the Gly-Ala-Ala and Ala-Ala-Gly motifs flanking the poly(Ala) runs, which comprise the β-sheet forming domains in fibers, are perturbed by urea, suggesting that these regions may be important for silk protein pre-assembly stabilization.

New Data on Latrodectus tredecimguttatus Rossi, 1790, the Medically Important Spider Species (Araneae: Theridiidae) from Iran.

Spiders are one of the most important orders of Arachnida comprising more than 48,000 species in the world. Except for families Uloboridae and Holarchaeidae, all others are classified as the venomous spider. However, only about 200 species are medically relevant and cause public health problems or even death. In Iran, there are 51 families and 763 species of spiders, of which the families, Theridiidae and Sicariidae are dangerous for the human being, and the first one is more prevalent. The Latrodectus is considered one of the most poisonous spiders in the world and Iran. This genus has five species in Iran, among which Latrodectus tredecimguttatus (black widow spider or “Dolmak”) is considered one of the most poisonous spiders in Iran. Therefore, this study aimed to investigate this species in the Northwest of Iran (West Azerbaijan, East Azerbaijan, and Ardabil provinces, Iran). Spatial distribution maps were prepared using GIS 9.4. In the current study, five adult female spiders were collected from Germi and Ardabil cities (Ardabil Province), Ahar County (East Azerbaijan province), and Urmia city (West Azerbaijan province) of Iran. These species were first observed in Ardabil province, Iran. Therefore, the presence of Latrodectus species under the rocks in wheat farms in this corner of Iran may be a threat to farms and visitors. People in these areas should wear gloves and avoid any activity that disturbs the spiders and make them aggressive.

Prey availability affects developmental trade-offs and sexual-size dimorphism in the false widow spider, Steatoda grossa

In many spiders, females are significantly larger than males. Several theories have been postulated to explain sexual size dimorphism (SSD), including differential predation risks experienced by each sex early in life (including female cannibalism of males), male-male competition, and the more costly production of eggs than sperm. However, there is considerable intraspecific variation in the relative size of males and females that is reflected in trade-offs on traits such as growth rate and body size. When SSD favors female size, the body mass ratios between the smallest and largest males is expected to be much greater than in females. Here, growth trajectories and body masses of the false widow spider, Steatoda grossa, were compared in male and female spiders fed continually or intermittently. Males provided with unlimited prey (fruit flies and house crickets) took about 15 weeks to attain full size and sexual maturity and grew to a mean of 25 mg. By contrast, males fed only once every three weeks took approximately 6 weeks longer to reach maturity but were only about half as large (mean 13 mg) as males fed constantly. Females fed intermittently took almost twice as long (45 weeks versus 24 weeks) as constantly-fed females to reach maturity, but were almost 90% as large when fully grown. These results reveal that, although both sexes trade-off development time and body size to achieve the optimal phenotype, rapid development is more important than larger body size in males whereas the opposite is true in females. This finding supports life-history theory underpinning sexual-size dimorphism in some spider lineages.

Mediterranean black widow spider (Latrodectus tredecimguttatus) poisoning in a metropolitan city in Turkey

Introduction: Black widow spider bites cause severe poisoning (latrodectism) with symptoms such as muscle spasm, rigidity, pain, vomiting, hypertension, and tachycardia. Although Latrodectus mactans (L. mactans) is the most well-known species to cause latrodectism, it has not been reported in Turkey. We report a poisoning case caused by Latrodectus tredecimguttatus (L. tredecimguttatus) spider a species known to be in Turkey for the first time in the literature.
 Case: A 35-year-old male patient presented with complaints of pain in the lower extremities and excessive sweating due to a spider bite. Discomfort, agitation, a sweaty appearance, tachycardia, and hypertensive attack were observed in the patient. Because black widow antivenom is not available in Turkey and because of the continuation of symptoms despite treatment for 12 hours in the emergency department, the patient was transferred to the intensive care unit, where he was given IV sedoanalgesia. Nicardipine infusion was administered to treat hypertension attack. The patient’s symptoms improved on the fifth day. The dead spider that was brought in was identified by an expert biologist as L. tredecimguttatus.
 Conclusion: It should be considered that latrodectism due to L. tredecimguttatus spider bite may be resistant to emergent treatment and hospitalization may be required.

Venom and Social Behavior: The Potential of Using Spiders to Evaluate the Evolution of Sociality under High Risk.

Risks of sociality, including competition and conspecific aggression, are particularly pronounced in venomous invertebrates such as arachnids. Spiders show a wide range of sociality, with differing levels of cannibalism and other types of social aggression. To have the greatest chance of surviving interactions with conspecifics, spiders must learn to assess and respond to risk. One of the major ways risk assessment is studied in spiders is via venom metering, in which spiders choose how much venom to use based on prey and predator characteristics. While venom metering in response to prey acquisition and predator defense is well-studied, less is known about its use in conspecific interactions. Here we argue that due to the wide range of both sociality and venom found in spiders, they are poised to be an excellent system for testing questions regarding whether and how venom use relates to the evolution of social behavior and, in return, whether social behavior influences venom use and evolution. We focus primarily on the widow spiders, Latrodectus, as a strong model for testing these hypotheses. Given that successful responses to risk are vital for maintaining sociality, comparative analysis of spider taxa in which venom metering and sociality vary can provide valuable insights into the evolution and maintenance of social behavior under risk.

Bites by the noble false widow spider Steatoda nobilis can induce Latrodectus-like symptoms and vector-borne bacterial infections with implications for public health: a case series

Context In recent years, the Noble false widow spider Steatoda nobilis (Thorell, 1875) has expanded its range globally and may represent a potential threat to native ecosystems and public health. Increasing numbers in synanthropic habitats have led to more human encounters and envenomations. Steatoda nobilis bites were previously classed as medically significant with similarities to bites from true black widows of the genus Latrodectus but deemed milder in onset, with symptoms generally ranging from mild to moderate. Case details In this manuscript we present 16 new cases of S. nobilis envenomations bringing the total number of confirmed cases reported in the literature to 24. We report new symptoms and provide discussion on the contributing factors to pathology following bites by S. nobilis. Discussion We report a range of pathologies including necrosis, Latrodectus-like envenomation symptoms that include debilitating pain, tremors, fatigue, nausea, hypotension, and vectored bacterial infections including cellulitis and dermatitis. Symptoms ranged from mild to severe, requiring hospitalisation in some cases.

Case Report: Soldier With Latrodectism After Black Widow Spider Bite During a Field Training Exercise.

Latrodectism from black widow spider (BWS) bites is rare in the United States. Latrodectism is a severe systemic manifestation of the envenomation that includes severe abdominal pain mimicking acute surgical abdomen and, in rare cases, could lead to acute myocarditis and rhabdomyolysis. The BWS typically inhabits dark, low-lying areas such as woodpiles, tree stumps, outdoor storage, outdoor furniture, outdoor toilets, and rock piles and is most active during warm weather months. Military service members often participate in field training exercises during warm weather in wooded areas littered with woodpiles and tree stumps; therefore, they are at an increased risk for bites by arachnids. We report the case of a 26-year-old active duty male soldier evacuated from field training with latrodectism and possible envenomation-induced myocarditis after a suspected BWS bite.

Spiders (Arachnida: Araneae) feeding on snakes (Reptilia: Squamata)

In this paper, 319 incidents of snake predation by spiders are reported based on a comprehensive global literature and social media survey. Snake-catching spiders have been documented from all continents except Antarctica. Snake predation by spiders has been most frequently documented in USA (51% of all incidents) and Australia (29%). The captured snakes are predominantly small-sized with an average body length of 25.9 ± 1.3 cm (median = 27 cm; range: 5.8–100 cm). Altogether >90 snake species from seven families have been documented to be captured by >40 spider species from 11 families. About 60% of the reported incidents were attributable to theridiids (≈0.6–1.1 cm body length), a spider family that uses strong tangle webs for prey capture. Especially the Australian redback spider (Latrodectus hasselti Thorell, 1870), the African button spider (Latrodectus indistinctus O. Pickard-Cambridge, 1904), an Israeli widow spider (Latrodectus revivensis Shulov, 1948), and four species of North American widow spiders (Latrodectus geometricus C.L. Koch, 1841, Latrodectus hesperus Chamberlin & Ivie, 1935, Latrodectus mactans (Fabricius, 1775), and Latrodectus variolus Walckenaer, 1837) – equipped with a very potent vertebrate-specific toxin (α-latrotoxin) – have proven to be expert snake catchers. The use of vertebrates as a supplementary food source by spiders represents an opportunity to enlarge their food base, resulting in enhanced survival capability. Interestingly, the snakes captured by spiders also encompasses some species from the families Elapidae and Viperidae known to be highly toxic to humans and other vertebrates. Not only do spiders sometimes capture and kill snakes, quite often the tables are turned – that is, a larger number of arthropod-eating snake species (in particular nonvenomous species in the family Colubridae) include spiders in their diets.

Functional morphology of immature mating in a widow spider

BackgroundMating generally occurs after individuals reach adulthood. In many arthropods including spiders, the adult stage is marked by a final moult after which the genitalia are fully developed and functional. In several widow spider species (genus Latrodectus), however, immature females may mate a few days before they moult to adulthood, i.e. in their late-subadult stage. While the “adult” mating typically results in cannibalism, males survive the “immature” mating. During both “immature” and “adult” matings, males leave parts of their paired copulatory organs within female genitalia, which may act as mating plugs. To study potential costs and benefits of the two mating tactics, we investigated female genital morphology of the brown widow spider, L. geometricus. Light microscopy, histology and micro-computed tomography of early-subadult, late-subadult and adult females were conducted to determine the overall pattern of genital maturation. We compared genitalia of mated late-subadult and adult females to reveal potential differences in the genitalic details that might indicate differential success in sperm transfer and different environments for sperm storage and sperm competition.ResultsWe found that the paired sperm storage organs (spermathecae) and copulatory ducts are developed already in late-subadult females and host sperm after immature mating. However, the thickness of the spermathecal cuticle and the staining of the secretions inside differ significantly between the late-subadult and adult females. In late-subadult females mating plugs were found with higher probability in both spermathecae compared to adult females.ConclusionsSperm transfer in matings with late-subadult females follows the same route as in matings with adult females. The observed differences in the secretions inside the spermathecae of adult and late-subadult females likely reflect different storage conditions for the transferred sperm which may lead to a disadvantage under sperm competition if the subadult female later re-mates with another male. However, since males mating with late-subadult females typically transfer sperm to both spermathecae they might benefit from numerical sperm competition as well as from monopolizing access to the female sperm storage organs. The assessment of re-mating probability and relative paternity will clarify the costs and benefits of the two mating tactics in light of these findings.

Female control of a novel form of cannibalism during copulation in a South American widow spider

Sexual cannibalism is an extreme form of sexual conflict that may have broad evolutionary effects on mating behaviour. Latrodectus spiders (∼30 “widow” species) could enable comparative tests of the evolution of sexual cannibalism, but most species are poorly-studied. Here we describe the mating and remating behaviour of a species endemic to South America, L. mirabilis, with a focus on the occurrence and consequences of sexual cannibalism. Mating and cannibalistic behaviours were novel relative to other Latrodectus species. Cannibalism started during copulation when females grasped the male’s legs with their chelicerae, and continued as females pulled the male’s abdomen onto their chelicerae, without interrupting copulation. Cannibalism was initiated by females, and not facilitated by males as was observed in other Latrodectus species. Females frequently remated however, so cannibalized males might lose paternity to future rivals. We report high rates of cannibalism, with 70 % of males killed by females during their first mating, and 85 % killed by previously-mated females. We discuss our novel findings in the context of previous observations in other Latrodectus species, proposing that foundational studies in a wider range of species are necessary to support comparative tests about the evolution of sexual cannibalism within this model taxon.

Black widow spiders use path integration on their webs

Many animals store information about their external environment in memory and use this information to facilitate movement and decision-making. The information used to navigate has been described for numerous animals and is dependent on the ecology of the animal. Spider webs make up nearly all of a spider’s physical and sensory environment. Here, we first asked whether black widow spiders form memories of their web and then asked whether the contents of these memories include a path integration vector. Black widows made navigational errors when we rotated their web in their absence and searched about the web upon realizing they made an error. Black widows were able to move on their web without retracing their steps, often taking shortcuts to a goal location without sensory cues to guide navigation. Black widows also began moving back to their retreat on a path parallel to their path out from the retreat, even after being moved on the web, and searched about the web for the retreat after not finding it initially. These results show that black widows use path integration when navigating. These results suggest that using internal representations of an animal’s position within its environment, such as by using path integration, is widespread among animals with varied brain types and sensory ecologies, representing perhaps a convergent solution to common navigational problems. The ability of animals to store information in memory that is then used in decision-making has evolved multiple times, in vertebrates and invertebrate lineages. The information and cognitive mechanism used for representing an animal’s location within its environment vary in complexity, but the methods that have been described rely on vision for at least some of the sensory information used to form representations. Using behavioral assays, we have shown that black widow spiders represent their position relative to their home as a path integration vector. Black widows have poor vision and rely primarily on vibrations transmitted through the web to sense their environment. Our results indicate that internal representations are a general solution to brains’ problem of integrating sensory information, and do not need acute vision to evolve.

North American widow spiders (Araneae: Theridiidae)

Widow spiders belong to the cosmopolitan genus Latrodectus (Araneae: Theridiidae), of which five species are found in North America. In part due to their medical importance and common occurrence, they are ever-more popular study organisms in a wide variety of fields. However, the literature is widely dispersed, and a broad synthesis has not been attempted since 1970. Here, we review and synthesize published information on the five North American Latrodectus species: L. hesperus, L. mactans, L. variolus, L. bishopi, and the introduced L. geometricus. We focus on distribution, ecology, anatomy, physiology, reproduction, ontogeny, behaviour, web structure, silk, venom, genetics, and phylogeny. We also include some of our own observations on L. hesperus. We conclude by highlighting areas where further research would be especially fruitful.

Body Size, Not Personality, Explains Both Male Mating Success and Sexual Cannibalism in a Widow Spider.

Simple SummaryThe role of personality in sexual selection has mostly been investigated on vertebrate species, in which males provide direct benefits to females or offspring. Less is known about the links between behavioral variation and sexual selection in species where males provide only sperm, while the advantages of female-choice are due to male genes that increase offspring fitness. Our study is centered on a sexually-size dimorphic spider species, the Mediterranean black widow, which is ideal to investigate how sexual selection shapes behavior. In this species, a male-biased operational sex-ratio leads to male-male competition, and aggressive and/or large males should have a selective advantage. Females are selected for fecundity, which should correlate with selection for higher voraciousness. Theory predicts that voracity “spills-over” into the mating context, such that voracity towards prey correlates with voracity towards mates. We tested how body size and two behaviors, male aggression toward rivals and female voracity toward prey, influence mating behavior, mating success, and sexual cannibalism. We show that individual variation in aggression does not play a direct role in the mating behavior of this species. Instead, body size affects male mating success and the occurrence of sexual cannibalism in females.Theory suggests that consistent individual variation in behavior relates to fitness, but few studies have empirically examined the role of personalities in mate choice, male-male competition and reproductive success. We observed the Mediterranean black widow, Latrodectus tredecimguttatus, in the individual and mating context, to test how body size measures and two functionally important aggressive behaviors, i.e., male aggression towards rivals and female voracity towards prey, affect mating behaviors, mating success and sexual cannibalism. We specifically selected voracity towards prey in females to test the “aggressive spillover hypothesis”, suggesting that more voracious females are more sexually cannibalistic. Both females and males exhibit consistent individual differences in the examined aggressive behaviors. While larger males win contests more often and achieve more copulations, neither male nor female size measures correlate to aggression. Female voracity does not correlate with aggression towards mates and sexual cannibalism, rejecting the “spillover hypothesis”. However, occurrence of sexual cannibalism positively relates to longer insertion duration. Furthermore, the smaller the ratio between male and female body length the more likely a female attacked and cannibalized a mate. We show that individual variation in aggression levels plays no direct role in the mating behavior of the Mediterranean black widow. Instead, body size affects male mating success and occurrences of sexual cannibalism in females.

Vibratory communication in a black widow spider (Latrodectus hesperus): signal structure and signalling mechanisms

Despite the ubiquity of web-borne vibratory communication among many web-building spiders, few empirical studies, to date, have quantified the characteristics and mechanisms of the signals involved. In this study, we used western black widow spider, Latrodectus hesperus , and examined male signal characteristics, signal production mechanisms and signal transmission efficacy on webs. It is not clear how vibrations are transmitted through the chaotic cobweb typical of this species and relatives, and previous work argued that L. hesperus courtship vibrations lacked structure. We videorecorded courtship and copulation behaviour, and used laser vibrometry to record and characterize web-borne vibrations. We examined signalling mechanisms using synchronous high-speed video and vibrometry recordings. Lastly, we examined signal transmission by measuring transfer functions between body movements and the resulting vibration signal. We found that males displayed three distinct signal types (abdominal tremulation, bounce and web plucks), each of which were generated by a different signal production mechanism. Our results also show that male bounces and web plucks may convey information about male size. Contrary to earlier work, we show that during the later phases of male–female interactions, males intermittently organize individual signal types into stereotyped sequential displays (‘structured signalling’). Moreover, despite the cobweb structure, transfer function analyses showed that female webs transmit male signals with high efficacy. These results suggest that vibratory communication in L. hesperus , previously classified as simple signallers, can comprise emergent forms of signal complexity and lay the foundation for future studies on this mode of communication in other web-dwelling species. • Black widow males produce three different vibration signals during courtship. • These signals can carry important information about male size. • Males display signal elements haphazardly during the early courtship phase. • During later stages, males combine signal elements into a stereotyped sequence.

A NOVEL PEPTIDE MODULATOR OF THE HUMAN CHANNEL NAV1.5 FROM LATRODECTUS TREDECIMGUTTATUS SPIDER VENOM

Spider venom contains a wide repertoire of pharmacologically active compounds, and in the case of some spider species bite, toxins from spider venom can play a fatal role for humans as well as other organisms. Among all the spiders, one could say the bite of Latrodectus tredecimguttatus, known as Black Widow spider, is very dangerous and can even lead to tragic consequences. Especially, voltage-gated sodium channels are responsible for propagating action potentials in excitable cells. NaV1.5 plays a crucial role in the human cardiac muscle, where it enhances the influx of sodium ions via the cell membrane, causing the fast depolarization phase of the cardiac action potential. It is also an important therapeutic target for heart disorders. Various venom-derived peptides have been observed as potential modulators of sodium channels, and these biologically active peptides are an abundant source for pharmacological tools.

Recombinant Silk Proteins with Additional Polyalanine Have Excellent Mechanical Properties.

This paper explores the structures of exogenous protein molecules that can effectively improve the mechanical properties of silkworm silk. Several transgenic vectors fused with the silkworm fibroin light chain and type 3 repeats in different multiples of the ampullate dragline silk protein 1 (MaSp1) from black widow spider with different lengths of the polyalanine motifs were constructed for this study. Transgenic silkworms were successfully obtained by piggyBac-mediated microinjection. Molecular detection showed that foreign proteins were successfully secreted and contained within the cocoon shells. According to the prediction of PONDR® VSL2 and PONDR® VL-XT, the type 3 repeats and the polyalanine motif of the MaSp1 protein were amorphous. The results of FTIR analysis showed that the content of β-sheets in the silk of transgenic silkworms engineered with transgenic vectors with additional polyalanine was significantly higher than that of wild-type silkworm silk. Additionally, silk with a higher β-sheet content had better fracture strength and Young’s modulus. The mechanical properties of silk with longer chains of exogenous proteins were improved. In general, our results provide theoretical guidance and technical support for the large-scale production of excellent bionic silk.

Widow spiders in the New World: a review on Latrodectus Walckenaer, 1805 (Theridiidae) and latrodectism in the Americas.

Humankind has always been fascinated by venomous animals, as their toxic substances have transformed them into symbols of power and mystery. Over the centuries, researchers have been trying to understand animal venoms, unveiling intricate mixtures of molecules and their biological effects. Among venomous animals, Latrodectus Walckenaer, 1805 (widow spiders) have become feared in many cultures worldwide due to their extremely neurotoxic venom. The Latrodectus genus encompasses 32 species broadly spread around the globe, 14 of which occur in the Americas. Despite the high number of species found in the New World, the knowledge on these spiders is still scarce. This review covers the general knowledge on Latrodectus spp. from the Americas. We address widow spiders’ taxonomy; geographical distribution and epidemiology; symptoms and treatments of envenomation (latrodectism); venom collection, experimental studies, proteome and transcriptome; and biotechnological studies on these Latrodectus spp. Moreover, we discuss the main challenges and limitations faced by researchers when trying to comprehend this neglected group of medically important spiders. We expect this review to help overcome the lack of information regarding widow spiders in the New World.