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In this study, Latrodectus revivensis Shulov, 1948 is recorded for the first time from Iran based on female specimens. This species was previously recorded from the eastern Mediterranean region. As a result, the number of Latrodectus species recorded from Iran is raised to six. A comparative diagnosis is provided for this species and other widow spiders previously recorded from the country. Latrodectus revivensis can be easily distinguished from its congeners by colouration, genitalic characters and the shape of the nest. This record represents the easternmost distribution limit of L. revivensis. An updated distribution map of Latrodectus species is also provided. [ABSTRACT FROM AUTHOR]

Objective: The Mediterranean black widow spider; Latrodectus tredecimguttatus (Rossi, 1790) could reasonably be regarded by many health practitioners as living solely in Southern Europe. However, its range extends well beyond the Mediterranean, into central Asia, and reaches parts of China. In this article, we detected this species in Jordan for the first time and confirmed the diagnosis by DNA barcoding. This is also the first clinically significant envenomation case in Jordan. Materials and Methods: The spider was identified using DNA analysis which was extracted using a Qiagen DNeasy Blood and Tissue Kit following the standard protocol. PCR reactions were conducted in 20 µL volumes using 1 µL of DNA template, a final concentration of 0.5 µM of each primer. Cycling conditions consisted of an initial activation at 95°C for 15 min, then 35 cycles of denaturation at 95°C for 30 s, annealing at 45°C for 30 s and elongation at 72°C for 1 min with a final elongation at 72°C for 10. Successful PCR reactions were cleaned using Clean NA Clean PCR magnetic beads (GC Biotech) using the standard PCR cleanup protocol. Bi-directional sequencing was conducted at Genewiz UK. Results: The species was identified using morphological and molecular data. The clinical process was evaluated including the symptoms, medical treatment, and the use of Ferula assa-foetida as self-medicated traditional medicine. Discussion: The first record of this spider is very important for the contribution of the biodiversity of Jordan. In addition, due to its medical importance, the envenomation case and its treatment with Freula are important for local practitioners. Such medically important animals and related cases need to be documented for public health. It is necessary to recognize the existence of venomous spiders in Jordan, and to study their patterns of bites. We also propose a set of recommendations for communities and local hospitals including the necessity of hospitalization and antivenin administration for patients exhibiting serious symptoms. Conclusion: It is important to document envenomation accidents, symptoms, and treatment protocol. Furthermore, traditional medicine practices should be reported as they can interfere with or even hinder medical treatment. The results of this article will certainly apply to a wider range of countries in the region. [ABSTRACT FROM AUTHOR]

Latrodectus tredecimguttatus (Rossi, 1790) of family Theridiidae is recorded from Jordan for the first time. Four individuals of this species were collected from different localities in 2019 and 2021 in Jordan. [ABSTRACT FROM AUTHOR]

Abstract Background Microbiomes can have profound impacts on host biology and evolution, but to date, remain vastly understudied in spiders despite their unique and diverse predatory adaptations. This study evaluates closely related species of spiders and their host-microbe relationships in the context of phylosymbiosis, an eco-evolutionary pattern where the microbial community profile parallels the phylogeny of closely related host species. Using 16S rRNA gene amplicon sequencing, we characterized the microbiomes of five species with known phylogenetic relationships from the family Theridiidae, including multiple closely related widow spiders (L. hesperus, L. mactans, L. geometricus, S. grossa, and P. tepidariorum). Results We compared whole animal and tissue-specific microbiomes (cephalothorax, fat bodies, venom glands, silk glands, and ovary) in the five species to better understand the relationship between spiders and their microbial symbionts. This showed a strong congruence of the microbiome beta-diversity of the whole spiders, cephalothorax, venom glands, and silk glands when compared to their host phylogeny. Our results support phylosymbiosis in these species and across their specialized tissues. The ovary tissue microbial dendrograms also parallel the widow phylogeny, suggesting vertical transfer of species-specific bacterial symbionts. By cross-validating with RNA sequencing data obtained from the venom glands, silk glands and ovaries of L. hesperus, L. geometricus, S. grossa, and P. tepidariorum we confirmed that several microbial symbionts of interest are viably active in the host. Conclusion Together these results provide evidence that supports the importance of host-microbe interactions and the significant role microbial communities may play in the evolution and adaptation of their hosts.

Strategic responses to invasive Latrodectus widow spiders are a global challenge due to the risks they pose to health and ecosystems. Chemical strategies involving the use of pyrethroids are effective against adult spiders, but as their populations rebound, chemical control becomes costly and unsustainable for eradication. A major obstacle is the inefficacy of insecticides against eggs, which are covered by a protective silk egg sac. Eradication of invasive spiders must focus on destroying progeny. Here, the responses of eggs in egg sacs of two invasive Latrodectus spiders in Japan (Latrodectus hasseltii (Thorell) and Latrodectus geometricus (C.L. Koch)) to short-term dry-heat exposure were examined. To test whether the dry-heat tolerance of the egg sacs of both spider species differed, lethal temperature (LT) was determined based on the hatching rate of eggs from egg sacs subjected to a range of temperatures. Hatching in both species failed completely when the egg sacs were exposed to temperatures of 55°C and above for 10 min, but the LT to reduce hatching by 90% (LT90) differed significantly between L. hasseltii (50. 9°C) and L. geometricus (52. 8°C). Our study highlights the efficacy of dry heat in suppressing hatching and thus shows the possibility for effective extermination of these noxious invasive pests. Further exploration and investigation of the effects of humidity and heat exposure time on egg sacs under field conditions are needed to guide Latrodectus spider control strategies. [ABSTRACT FROM AUTHOR]

Abstract 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.

Widow spiders are among the few spider species worldwide that can cause serious envenoming in humans. The clinical syndrome resulting from Latrodectus spp. envenoming is called latrodectism and characterized by pain (local or regional) associated with diaphoresis and nonspecific systemic effects. The syndrome is caused by α-latrotoxin, a ~130 kDa neurotoxin that induces massive neurotransmitter release. Due to this function, α-latrotoxin has played a fundamental role as a tool in the study of neuroexocytosis. Nevertheless, some questions concerning its mode of action remain unresolved today. The diagnosis of latrodectism is purely clinical, combined with the patient’s history of spider bite, as no analytical assays exist to detect widow spider venom. By utilizing antibody phage display technology, we here report the discovery of the first recombinant human monoclonal immunoglobulin G antibody (TPL0020_02_G9) that binds α-latrotoxin from the Mediterranean black widow spider (Latrodectus tredecimguttatus) and show neutralization efficacy ex vivo. Such antibody can be used as an affinity reagent for research and diagnostic purposes, providing researchers with a novel tool for more sophisticated experimentation and analysis. Moreover, it may also find therapeutic application in future.

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Widow spiders are among the few spider species worldwide that can cause serious envenoming in humans. The clinical syndrome resulting from Latrodectus spp. envenoming is called latrodectism and characterized by pain (local or regional) associated with diaphoresis and nonspecific systemic effects. The syndrome is caused by α-latrotoxin, a ~130 kDa neurotoxin that induces massive neurotransmitter release. Due to this function, α-latrotoxin has played a fundamental role as a tool in the study of neuroexocytosis. Nevertheless, some questions concerning its mode of action remain unresolved today. The diagnosis of latrodectism is purely clinical, combined with the patient's history of spider bite, as no analytical assays exist to detect widow spider venom. By utilizing antibody phage display technology, we here report the discovery of the first recombinant human monoclonal immunoglobulin G antibody (TPL0020_02_G9) that binds α-latrotoxin from the Mediterranean black widow spider (Latrodectus tredecimguttatus) and show neutralization efficacy ex vivo. Such antibody can be used as an affinity reagent for research and diagnostic purposes, providing researchers with a novel tool for more sophisticated experimentation and analysis. Moreover, it may also find therapeutic application in future. [ABSTRACT FROM AUTHOR]

Highlights • LCV induces intense and dose-related nociception in mice. • TRPV1 channels contribute to LCV-induced nociception. • Local inflammation does not seem to play a relevant role in LCV-induced nociception. Abstract The present study was undertaken to characterize the behavioral manifestations of nociception and the local mechanisms involved with the nociceptive response elicited by Latrodectus curacaviensis venom (LCV) in mice. After the intraplantar LCV inoculation, spontaneous nociception, mechanical and thermal nociceptive thresholds, motor performance, edema and cytokine levels were evaluated using von Frey filaments, hot/cold plate, rota-rod, plethismometer and ELISA, respectively. Analysis of LCV was performed by SDS-PAGE and chromatography. Intraplantar injection of LCV (1–100 ng/paw) induced intense and heat-sensitive spontaneous nociception, mediated by serotonin and bradykinin receptors, TRPV1 channels, as well as by transient local inflammation. LCV (0.1–10 ng/paw) induced mechanical allodynia, which was reduced by the local pretreatment with H1 receptor or TRPV1 antagonists. Corroborating the TRPV1 involvement, in thermal nociception assays, LCV induced a similar response to that of capsaicin, a TRPV1 agonist, facilitating the response to noxious hot stimuli and inhibiting the response to cold noxious stimulation. LCV promoted mast cell degranulation, increased IL-1β paw levels, but did not produce a relevant edematogenic effect. Analysis of LCV components showed a predominance of high molecular weight proteins. This work provides the first mechanistic hypothesis to explain the local pain induced by LCV, the most frequent clinical symptom of human envenomation. [ABSTRACT FROM AUTHOR]

In spiders, sex pheromones are often associated with silk produced by females, and function in mate attraction, recognition, and evaluation. Silk-bound pheromones typically elicit courtship behaviour in web-building spiders. Here we (1) describe courtship interactions of Steatoda grossa males with virgin or mated females, and (2) show that silk and methanol extracts of silk produced by virgin females trigger courtship behaviour (silk production) by males, whereas silk of mated females does not. Our results indicate that (1) virgin females produce a silk-bound sex pheromone, (2) males discriminate between virgin and mated females based on silk cues, and (3) male silk likely functions in sexual communication. [ABSTRACT FROM AUTHOR]

The widow spider, Latrodectus, (Araneae: Theridiidae) comprise about 31 currently recognized species, some species are very hard to distinct; in this study morphological and molecular method has been used to confirm the diagnosis of the spiders. Phylogenetic tree was constructed using the neighbor-joining of some other Latrodectus sp. sampled, including taxa occurring in the Middle East, Australia, New Zealand, North and South America and Europe, and with the two genera Steatoda Sundevall, 1833 and Asagena Sundevall, 1833 outgroup. The results of the analysis show the highest identity (90%) for Latrodectus thoracicus Nicolet 1849 represented by three specimens and for L. pallidus O.P.-Cambridge, 1872 represented by one specimen in addition to (85%) for the false widow Asagena phalerata (Panzer, 1801) represented by one specimen, these three species is recorded in Iraq for the first time. [ABSTRACT FROM AUTHOR]

Eggs of black widow spiders in the genus Latrodectus Walckenaer, 1805 (Theridiidae) are known to be toxic when injected into mammals. We surveyed eggs from 39 species of spiders in 21 families to determine if spider egg toxicity is a unique property of widow spiders, or if spider egg toxicity is associated with other spider taxa. Eggs from 13 species of spiders in three families were determined to be highly lethal to mice, eggs from four species in four families were moderately lethal, and eggs from 22 species in 17 families lacked detectable lethality. Egg lethality appears to have evolved multiple times in spiders within the Araneidae, Theridiidae, and Agelenidae, and possibly also within the Tetragnathidae, Pimoidae, and Linyphiidae. These toxins in the various spiders may have differing chemical structures and could represent new sources of toxins that may be of future research interest. [ABSTRACT FROM AUTHOR]

“Black widow” spiders belong to the genus Latrodectus and are one of the few spiders in the world whose bite can cause severe envenomation in humans and domestic animals. In Argentina, these spiders are distributed throughout the country and are responsible for the highest number of bites by spiders of toxicological sanitary interest. Here, we studied the toxicity and some biochemical and immunochemical characteristics of eighteen venom samples from Latrodectus spiders from eight different provinces of Argentina, and the neutralization of some of these samples by two therapeutic antivenoms used in the country for the treatment of envenomation and by a anti- Latrodectus antivenom prepared against the venom of Latrodectus mactans from Mexico. We observed important toxicity in all the samples studied and a variation in the toxicity of samples, even in those from the same region and province and even in the same Latrodectus species from the same region. The therapeutic antivenoms efficiently neutralized all the venoms studied. [ABSTRACT FROM AUTHOR]

Latrodectism or envenomation by widow-spiders is common and clinically significant worldwide. Alpha-latrotoxin is the mammalian-specific toxin in the venom that results in toxic effects observed in humans. Symptoms may be incapacitating and include severe pain that can persist for days. The management of mild to moderate latrodectism is primarily supportive while severe cases have variously been treated with intravenous calcium, muscle relaxants, widow-spider antivenom and analgesic opioids. The object of this systematic review is to examine the literature on the clinical effectiveness of past and current treatments for latrodectism. MEDLINE, EMBASE and Google Scholar were searched from 1946 to December 2016 to identify clinical studies on the treatment of latrodectism. Studies older than 40 years and not in English were not reviewed. There were only two full-publications and one abstract of placebo-controlled randomised trials on antivenom use for latrodectism. Another two randomised comparative trials compared the route of administration of antivenom for latrodectism. There were fourteen case series (including two abstracts), fourteen case reports and one letter investigating drug treatments for latrodectism with the majority of these also including antivenom for severe latrodectism. Antivenom with opioid analgesia is often the major treatment reported for latrodectism however; recent high quality evidence has cast doubt on the clinical effectiveness of this combination and suggests that other treatments need to be investigated. [ABSTRACT FROM AUTHOR]

Background: Nowadays use of specific antivenin for latrodectism is considered as the most effective treatment in the world. This study was undertaken to investigate the efficacy of specific antivenom against histopathological complications caused by Latrodectus dahli venom on liver, heart and kidneys tissues within 72h. Methods: Two groups were selected, each one contained 6 male New Zealand rabbits weighing 2±0.5kg. The ani- mals were anesthetized with 0.5ml ketamine and 0.5ml xylazine by intramuscular route. The L. dahli venom (0.5mg/kg) was injected subcutaneously to both the groups. The second group of rabbits 24h after the venom injection received specific antivenom by intravenous route. Seventy-two hours after the venom and antivenom injections, the rabbits were dissected to obtain heart, liver and kidney tissues. The tissues were stained by hematoxylin and eosin stains and histopathological studies were examined by optical microscope. Results: In group one, the venom induced myocytolysis, myocarditis, coagulation necrosis in the heart tissue and the liver tissue showed central vein congestion, congested vessels, dilated sinusoids and inflammation. However, no significant histopathological complications were observed in kidney tissues. In the second group, antivenom injection greatly prevented escalation of the complications on foresaid tissues. Conclusion: Latrodectus dahli venom induces histopathological complications on vital organs. Specific antivenom injection, 24h after the venom injection, could protect the tissues from incidence and intensification of histopathological complications. Future studies in human beings should be conducted to assess the protection against the spe- cific-Latrodectus antivenin. [ABSTRACT FROM AUTHOR]

The genus Latrodectus has not been studied in Colombia even though it is medically important worldwide; there are three species for the country, this study focused on a non-identified species found in the Tatacoa Desert in the Huila Department. This research is the first approximation to the extraction, composition analysis and toxicity evaluation of the venom of a species of the genus Latrodectus in Colombia; and aims to evaluate the toxicity by the initial characterization of its venom. The venom extraction was accomplished with electrostimulation and total protein concentration was determined by the Lowry method and BCA assays from crude venom; with these methods, high protein concentration of the samples was measured. Bioassays on mice were also made to evaluate the toxicity and compare the symptoms produced by this Colombian spider to the Latrodectism Syndrome. Finally, an SDS-PAGE electrophoresis was used to separate the main components of high molecular weight from the samples and compared to a control of the venom of Latrodectus mactans to determine if the venom composition is different between these two species. [ABSTRACT FROM AUTHOR]

Latrodectus tredecimguttatus is a kind of highly venomous black widow spider, with toxicity coming from not only venomous glands but also other parts of its body as well as newborn spiderlings and eggs. Up to date, although L. tredecimguttatus eggs have been demonstrated to be rich in proteinaceous toxins, there is no systematic investigation on such active components at transcriptome level. In this study, we performed a high-throughput transcriptome sequencing of L. tredecimguttatus eggs with Illumina sequencing technology. As a result, 53,284 protein-coding unigenes were identified, of which 14,185 unigenes produced significant hits in the available databases, including 280 unigenes encoding proteins or peptides homologous to known proteinaceous toxins. GO term and KEGG pathway enrichment analyses of the 280 unigenes showed that 375 GO terms and 18 KEGG pathways were significantly enriched. Functional analysis indicated that these unigene-coded toxins have the bioactivities to degrade tissue proteins, inhibit ion channels, block neuromuscular transmission, provoke anaphylaxis, induce apoptosis and hyperalgesia, etc. No known typical proteinaceous toxins in L. tredecimguttatus venomous glands, such as latrotoxins, were identified, suggesting that the eggs have a different toxicity mechanism from that of the venom. Our present transcriptome analysis not only helps to reveal the gene expression profile and toxicity mechanism of the L. tredecimguttatus eggs, but also provides references for the further related researches. [ABSTRACT FROM AUTHOR]

1. Developmental experience, for example food abundance during juvenile stages, is known to affect life history and behaviour. However, the life history and behavioural consequences of developmental experience have rarely been studied in concert. As a result, it is still unclear whether developmental experience affects behaviour through changes in life history, or independently of it. 2. The effect of developmental experience on life history and behaviour may also be masked or affected by individual condition during adulthood. Thus, it is critical to tease apart the effects of developmental experience and current individual condition on life history and behaviour. 3. In this study, we manipulated food abundance during development in the western black widow spider, Latrodectus hesperus, by rearing spiders on either a restricted or ad lib diet. We separated developmental from condition-dependent effects by assaying adult foraging behaviour (tendency to attack prey and to stay on out of the refuge following an attack) and web structure multiple times under different levels of satiation following different developmental treatments. 4. Spiders reared under food restriction matured slower and at a smaller size than spiders reared in ad lib conditions. Spiders reared on a restricted diet were more aggressive towards prey and built webs structured for prey capture, while spiders reared on an ad lib diet were less aggressive and built safer webs. Developmental treatment affected which traits were plastic as adults: restricted spiders built safer webs when their adult condition increased, while ad lib spiders reduced their aggression when their adult condition increased. The amount of individual variation in behaviour and web structure varied with developmental treatment. Spiders reared on a restricted diet exhibited consistent variation in all aspects of foraging behaviour and web structure, while spiders reared on an ad lib diet exhibited consistent individual variation in aggression and web weight only. 5. Developmental experience affected the average life history, behaviour and web structure of spiders, but also shaped the amount of phenotypic variation observed among individuals. Surprisingly, developmental experience also determined the particular way in which individuals plastically adjusted their behaviour and web structure to changes in adult condition. [ABSTRACT FROM AUTHOR]

Background: Latrodectism, a syndrome caused by Latrodectus genus, is one of the clinical problems that occur predominantly in north east of Iran. Nowadays antivenom therapy has become the most useful treatment for animal bites; however there is still a controversy about route and time of antivenom administration in spider bite. The aim of the present study was to determine the efficacy of specific antivenom in neutralizing hepatic and renal symptoms 24 h after Latrodectus dahli envenomation. Methods: We selected a group of male New Zealand white rabbits, weighing 2±0.3 kg. The L. dahli venom (0.5 mg/kg) was injected subcutaneously. Specific antivenom (2.5 ml, I.V) was injected 24 h following venom injection. Blood sampling was performed before and 24 h after venom injection, as well within 24, 48 and 72 h after antivenom administration. Serum levels of (aspartate amino transferase (AST) alanine amino transferase (ALT), alkaline phosphatase (ALP), urea, bilirubin, creatinine and albumin were determined in all the sam. Results: Latrodectus dahli venom caused significant increase (P< 0.05) in all foresaid serum parameters. Antivenom reversed the AST, ALP, creatinine, urea and bilirubin to normal levels, but failed about ALT level, also nonsignificant decrease was observed in albumin levels. Conclusion: Antivenom administration 24 h after venom injection can greatly reverse symptoms caused by venom. Future studies in human beings should be conducted to assess the protection against the specific-Latrodectus antivenom. [ABSTRACT FROM AUTHOR]

Aspects of the natural history of the black widow spider Latrodectus thoracicus (Nicolet, 1849) are poorly known. The first observation of predation on L. thoracicus egg sacs is presented here, and we describe the predatory wasp ( Philolema sp.) as a natural enemy for this species. [ABSTRACT FROM AUTHOR]

Gene duplication and positive selection can be important determinants of the evolution of venom, a protein-rich secretion used in prey capture and defense. In a typical model of venom evolution, gene duplicates switch to venom gland expression and change function under the action of positive selection, which together with further duplication produces large gene families encoding diverse toxins. Although these processes have been demonstrated for individual toxin families, high-throughput multitissue sequencing of closely related venomous species can provide insights into evolutionary dynamics at the scale of the entire venom gland transcriptome. By assembling and analyzing multitissue transcriptomes from the Western black widow spider and two closely related species with distinct venom toxicity phenotypes, we do not find that gene duplication and duplicate retention is greater in gene families with venom gland biased expression in comparison with broadly expressed families. Positive selection has acted on some venom toxin families, but does not appear to be in excess for families with venom gland biased expression. Moreover, we find 309 distinct gene families that have single transcripts with venom gland biased expression, suggesting that the switching of genes to venom gland expression in numerous unrelated gene families has been a dominant mode of evolution. We also find ample variation in protein sequences of venom gland-specific transcripts, lineage-specific family sizes, and ortholog expression among species. This variation might contribute to the variable venom toxicity of these species. [ABSTRACT FROM AUTHOR]

Widow spiders have received much attention due to the frequently reported human and animal injures caused by them. Elucidation of the molecular composition and action mechanism of the venoms and toxins has vast implications in the treatment of latrodectism and in the neurobiology and pharmaceutical research. In recent years, the studies of the widow spider venoms and the venom toxins, particularly the-latrotoxin, have achieved many new advances; however, the mechanism of action of the venom toxins has not been completely clear. The widow spider is different from many other venomous animals in that it has toxic components not only in the venom glands but also in other parts of the adult spider body, newborn spiderlings, and even the eggs. More recently, the molecular basis for the toxicity outside the venom glands has been systematically investigated, with four proteinaceous toxic components being purified and preliminarily characterized, which has expanded our understanding of the widow spider toxins. This review presents a glance at the recent advances in the study on the venoms and toxins from the Latrodectus species. [ABSTRACT FROM AUTHOR]

Background: The longstanding canonical model of spider gastrulation posits that cell internalization occurs only at a unitary central blastopore; and that the cumulus (dorsal organizer) arises from within the early deep layer by cell-cell interaction. Recent work has begun to challenge the canonical model by demonstrating cell internalization at extrablastoporal sites in two species (Parasteatoda tepidariorum and Zygiella x-notata); and showing in Zygiella that the prospective cumulus internalizes first, before other cells are present in the deep layer. The cell behaviors making up spider gastrulation thus appear to show considerable variation, and a wider sampling of taxa is indicated. Results: We evaluated the model in three species from two families by direct observation of living embryos. Movements of individual cells were traced from timelapse recordings and the origin and fate of the cumulus determined by CM-DiI labeling. We show that there are two distinct regions of internalization: most cells enter the deep layer via the central blastopore but many additional cells ingress via an extra-blastoporal ring, either at the periphery of the germ disc (Latrodectus spp.) or nearer the central field (Cheiracanthium mildei). In all species, the cumulus cells internalize first; this is shown by tracing cells in timelapse, histology, and by CM-DiI injection into the deep layer. Injection very early in gastrulation labels only cumulus mesenchyme cells whereas injections at later stages label non-cumulus mesoderm and endoderm. Conclusions: We propose a revised model to accommodate the new data. Our working model has the prospective cumulus cells internalizing first, at the central blastopore. The cumulus cells begin migration before other cells enter the deep layer. This is consistent with early specification of the cumulus and suggests that cell-cell interaction with other deep layer cells is not required for its function. As the cumulus migrates, additional mesendoderm internalizes at two distinct locations: through the central blastopore and at an extra-blastoporal ring. Our work thus demonstrates early, cell-autonomous behavior of the cumulus and variation in subsequent location and timing of cell internalization during gastrulation in spiders. [ABSTRACT FROM AUTHOR]

The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). [ABSTRACT FROM AUTHOR]

Chemical communication is common in spiders but few pheromones have been identified. Female widow spiders in the genus Latrodectus spin webs that disseminate an attractive sex pheromone, and a contact pheromone on the silk elicits courtship behavior by males. The methyl ester of N-3-methylbutanoyl- O-( S)-2-methylbutanoyl- L-serine is a contact pheromone of the Australian redback spider Latrodectus hasselti. We hypothesized that the contact pheromone of congeneric L. hesperus resembles that of L. hasselti. The silk of virgin L. hesperus females was extracted with methanol, and analyses by gas chromatography-mass spectrometry (GC/MS) provided evidence for the presence of N-3-methylbutanoyl- O-methylpropanoyl- L-serine methyl ester (MB-MP-S), a lower homologue of the L. hasselti contact pheromone. Behavioral responses of L. hesperus males to test stimuli were assayed on T-shaped rods with the end sections of the horizontal arm enveloped in filter paper. Males spent 40 % longer in contact with paper bearing female silk than with blank paper, and 39 % longer in contact with paper treated with silk extract than with solvent controls. Contact with silk and silk extract induced courtship behavior by 96 % and 80 % of males, respectively, indicating that there was a methanol-soluble courtship-eliciting contact pheromone on the silk. Males responded less strongly to synthetic MB-MP-S than to silk or silk extract. Paper impregnated with synthetic MB-MP-S (10 or 100 μg) induced courtship behavior in 3-16 % of males, and prompted males to stay 10-16 % longer than on control paper. Our data support the conclusion that MB-MP-S is part of a multi-component contact pheromone of L. hesperus. [ABSTRACT FROM AUTHOR]

Males often exercise mate choice when mating frequency is constrained, costs of choice are low and variation in female quality and/or expected paternity can be reliably detected. Across invertebrates, males use sex pheromones to discern female mating status, but there are few demonstrations that information about expected fecundity (‘quality’) is encoded in pheromones alone. Here we examine whether females' sex pheromones allow males to detect differences in female food intake and mass in two species of widow spiders ( Latrodectus hesperus and Latrodectus hasselti ) in which chemicals are deposited by females in silk. Recent work shows that male L. hesperus prefer well-fed females, and that these females produce more silk than hungry females. Thus, changes in diet could be mechanistically linked to changes in silk-bound pheromonal signals. We show that unmated females of both species lose more than half of their mass when food is withheld, and silk production is reduced by 48% ( L. hesperus ) to 67% ( L. hasselti ). Males had a significant sexual response to pheromones extracted from the females' silk in both species, although this response was not directly correlated with silk or female mass. In L. hesperus , but not in L. hasselti , males were less responsive to sex pheromones from food-deprived females compared to well-fed females. While females on good diets provide the benefit of higher fecundity in both species, the risk of being cannibalized by hungry females during courtship exists only in L. hesperus . We conclude that sex pheromones alone can provide information about recent female feeding history, possibly reducing the costs of males expressing choice in the field. The species difference in male response also suggests that male preferences in these spiders may depend less on the benefit of seeking a highly fecund female and more on avoiding the cost of risky mating attempts with a likely cannibal. [ABSTRACT FROM AUTHOR]

The body of pesticide research on spiders is sparse with most studies using topical or residual applications to assess efficacy. Data on the effects of fumigation on spider survivorship are scarce in the scientific literature. In this study, we exposed adult male and female brown recluse spiders, Loxosceles reclusa Gertsch & Mulaik, and female brown widow spiders, Latrodectus geometricus C. L. Koch, to a commercial fumigation event using sulfuryl fluoride directed at termite control. General consensus from the pest control industry is that fumigation is not always effective for control of spiders for a variety of reasons, including insufficient fumigant dosage, particularly, for contents of egg sacs that require a higher fumigant dosage for control. We demonstrated that a sulfuryl fluoride fumigation with an accumulated dosage of 162 oz-h per 1,000 ft3 at 21°C over 25 h (≈1.7× the drywood termite dosage) directed at termites was sufficient to kill adult brown recluse and brown widow spiders. The effectiveness of commercial fumigation practices to control spiders, and particularly their egg sacs, warrants further study. [ABSTRACT FROM AUTHOR]

During the summer period 2011-2012, seven widow spider bites in Greece were reported to the Hellenic Center for Disease Control and Prevention. Widow spiders (in the genus Latrodectus) are found all over the world, including Europe, Asia, Africa, Australia, and the US. Alpha-latrotoxin (main mammalian toxin) causes the toxic effects observed in humans. Victims should receive timely medical care to avoid suffering. Latrodectus bites are very rarely fatal. All the patients reported having an insect bite 30 minutes to 2 hours before they arrived at the Emergency Department of the local hospital. Severe muscle cramps, weakness, tremor, abdominal pain, and increased levels of creatinine phosphokinase were present in all patients. The Emergency Operation Center of the Hellenic Center for Disease Control and Prevention was informed immediately in all cases. Antivenin was administered to four patients upon the request of their physicians. All patients recovered fully. It is essential that health care workers recognize early the symptoms and signs of Latrodectus bites to provide the necessary care. The management of mild to moderate Latrodectus envenomations is primarily supportive. Hospitalization and possibly antivenin should be reserved for patients exhibiting serious systemic symptoms or inadequate pain control. The most important thing for all of these patients is early pain relief. [ABSTRACT FROM AUTHOR]

Some aspects of the biology of the waspChalybion spinolaeare documented. This includes behaviour relating to life cycles, nesting, mating, oviposition and prey interaction of this wasp. The physical appearance of the wasps and their prey are described and some measurements are given. The prey ofC.spinolaeare two species of spiders,Latrodectus indistinctusandLatrodectusgeometricus(Araneae: Theridiidae). The observations spanned a period of 5 years, and involved approximately 200 wasp nests. This study serves to provide more observational information about the biology of the wasp and its predatory behaviour. [ABSTRACT FROM PUBLISHER]

Spatial associations between the invasive tree lupin (Lupinus arboreus), the New Zealand endemic widow spider Latrodectus katipo (katipo), and the introduced South African spider Steatoda capensis (false katipo) were examined within the nationally significant Kaitorete Spit dune system in Canterbury, New Zealand. These dunes are considered to be a stronghold for L. katipo, but with the decline in preferred vegetation for capture-web attachment as a result of tree lupin invasion, a decline in the spider's population was expected. On other New Zealand dune systems a decline in L. katipo abundance has corresponded with an increase in the abundance of the introduced S. capensis. Spider population data collected over a 6-year period and vegetation data collected in 2008 and 2009 were used to examine the spatial associations at Kaitorete Spit. The abundance of S. capensis was not significantly related to the abundance of L. katipo. The ratio of S. capensis to L. katipo declined annually over the 6 years. The 2008 and 2009 vegetation surveys found that S. capensis was not located in areas where tree lupin was present. Latrodectus katipo was found in areas with up to 40% tree lupin cover. The abundance of L. katipo recorded in areas dominated by tree lupin was not significantly different from the abundances recorded in association with native plant cover. The presence of L. arboreus at Kaitorete Spit is not considered to be a direct threat to the population of L. katipo; Kaitorete Spit is still a stronghold. [ABSTRACT FROM AUTHOR]

Sibling cannibalism occurs across diverse taxa and can affect population size and structure, as well as the fitness of parents and the cannibal, via density effects and variation in individual propensity to cannibalize. We examined these effects on sibling cannibalism in juveniles of a web-building spider (Latrodectus hasselti, Australian redbacks). Adult redbacks are solitary, but juveniles live in clusters of variable density for a week after hatching. We confined newly hatched siblings from a singly-mated female to a low or high density treatment in a split-clutch design, then left spiderlings unfed for a week. Our results showed no effect of density on overall cannibalism levels, but a strong correlation between cannibalism counts from the same maternal lines across densities. Unlike web-bound sit-and-wait predators, wandering spiders that are active hunters have been shown to experience density-dependent cannibalism. In contrast, we suggest sibling cannibalism in web-building spiders may be density independent because early cohabitation on the web selects for elevated tolerance of conspecifics. We conclude that, rather than being linked to density, cannibalism of siblings in these species may be controlled more strongly by variation in individual propensity to cannibalize. [ABSTRACT FROM AUTHOR]

Background: In order to describe the patients and evaluate the effectiveness of treatments for widow spider envenomation, investigators require a reliable assessment tool. In this paper, the development of a clinical index for measuring the widow spider bite severity, Latrodectus Envenomation Severity Score (LESS), is described. Methods: According to the valid methods for index development, a Delphi group process was applied. A panel of 13 experienced medical toxicologists and physician experts in treatment of black widow spider bites was assembled in December 2013. The participants were asked to score clinical manifestations of Latrodectus envenomation based on their importance on the severity and patients' prognosis. Hence, an initial draft of the severity index was developed and in the second phase of study, the draft was discussed in a focus group of experts to finally comment on each variable and vote about the final scores. Results: The proposed version of LESS comprises of 34 clinical items categorized in 8 organ systems. The index includes definition of each clinical variable to help users of the index how to ascertain or rule out the clinical finding. The maximum theoretical score according to LESS is 87. Acute renal failure, myocarditis, pulmonary edema and ileus received the highest scores in this index . Conclusion: The LESS is a new assessment tool that is designed to more objectively evaluate the severity and progression of envenomation in victims of widow spider bite. The prognostic-ability, reliability and sensitivity to change of the index should be investigated in future studies. [ABSTRACT FROM AUTHOR]

The red widow spider, Latrodectus bishopi Kaston, is a species of conservation concern because it is narrowly endemic to threatened palmetto scrub found only on ancient sand ridges in peninsular Florida. We hypothesized that this spider might feed extensively on insects that also are scrub specialists. To ascertain the prey of red widow spiders, we collected arthropods trapped in webs of adult females ( n = 30 per season) located in native oak-palmetto scrub at the Archbold Biological Station after dawn and before dusk for 5 consecutive days in early spring (Mar 1989) and in late spring (May 2003). We identifed a total of 42 species among the 98 specimens collected. Using published regression equations, we converted the size of each specimen to dry mass. We found that 5 species of scarab beetles endemic to Florida scrub accounted for 65% of prey by weight even though their numbers were modest (22% of prey items). In early spring red widow spiders fed predominantly on nocturnally captured coleopterans (78% of prey items), but in late spring when palmetto flowers were blooming near webs day-active hymenopterans were added to the diet. Frequency analysis showed that temporal patterns of prey capture by individual spiders were infrequent (≤ 0.4 prey per day) and statistically random. [ABSTRACT FROM AUTHOR]

Strong male mate preferences have been documented in species with otherwise conventional sex roles in the laboratory, and across taxa, male preferences generally focus on indicators of female fecundity and sperm competition risk. However, the few field studies of male choice rarely show equally strong effects. This suggests that costs of choice in nature may make the expression of preferences unlikely, or that interacting assessment cues may lead to unpredictable and variable outcomes in the wild. Field studies are therefore critical for testing whether or not male mate choice is sufficiently strong to exert sexual selection on females. Here we examine male choice in nature in response to two experimentally manipulated cues of female reproductive value. We recorded the attraction of male black widow spiders, Latrodectus hesperus, to females in a field enclosure and in a unconstrained natural setting. Stimulus females varied in two ways: sperm competition risk (low–unmated; high–mated) and fecundity (high–fed; low–unfed). Females and their silk were caged to prevent behavioural interactions while allowing the spread of airborne pheromones that attract males. Males in both experiments showed strong, nearly unanimous choice for unmated, well-fed females. In field enclosures, 80% of males made this choice, and wild males made the same choice in 94% of trials. We conclude that male choice in L. hesperus is mediated by detection of airborne pheromones, is strong and consistent despite natural costs of mate searching, and is not affected by natural interactions between (sometimes conflicting) cues of female reproductive value. Thus, universal mate choice may exist among males in nature. We propose general features of systems in which this may be likely and discuss implications for the study of sexual selection on females under conventional sex roles. [ABSTRACT FROM AUTHOR]

Following the hospitalization of 195 individuals due to the spider bite in 1995 and three cases of recorded death in the year of 1993 which were referred to Emam Reza Hospital in Mashad, the present study was undertaken on bionomics and medical importance of Lathrodectus spp in Khorasan Province, during 1995-2005. A total cases of 195 bites were studied composing of 70.8 % males and 29.2% females. The most prevalence cases were observed in mid age (20-55 years old) and par¬ticularly among farmers (36.4%). A total number of 216 adult widow spiders and 258 egg sacs were collected from their habitats in different localities of 15 counties in the province. The following species have been recognized: Lathrodectus tredecimgottatus (62%), L. dahli (32%), L. geometricus (5%) and L. pallidus (1%). Here is the first report on the occurrence of males of L. pallidus as well as both sexes of L. trdecimgottatus and L. geometricus in the country. The sex ratio among collected specimens was 88% and 12% female and male, respectively. Summer provides the most suitable and favorable climatic condition for the activities of these spiders. However 65% of spiders were collected in this season. Among different cit¬ies, Mashad had (60%) the most reported cases in the study area. Foot was more injured than other parts. 96.5% of pa¬tients exhib¬ited localized pain from which only 2% had no pain in the bitten part and 87% had a generalized pain in whole body.

Fluorescent dust marking is commonly employed to identify and track small arthropods for studies of ecology, demography, and behavior. Despite its widespread use, no study to date has empirically tested the suitability of dust marking for studies of spider behavior. Here, we test the effects of fluorescent dust marking on proximity of cohabitation, sibling cannibalism, and non-cannibalistic mortality of western black widow spiderlings, Latrodectus hesperus Chamberlin & Ivie ( Araneae: Theridiidae). Results indicate that dust-marked spiderlings cohabitated at closer proximities and died sooner than undusted spiderlings due to a greater incidence of cannibalism in the dust-marked group. Thus, we conclude that fluorescent dust marking significantly affected the cohabitation and cannibalistic behavior of L. hesperus spiderlings. Although few studies have reported adverse effects of dust marking on arthropods, our results should serve as a warning to future studies that normal behavior may be disrupted by the use of these fluorescent dust markers. Therefore, preliminary testing should be routine when determining the suitability of any marking technique for not only new species, but also new life stages and behaviors. [ABSTRACT FROM AUTHOR]

The article presents a study on the feeding ecology of the black widow spider Latrodectus mirabilis in wheat and oat fields of central Argentina to examine their diet composition and capture rate of leaf-cutting ants. The study identified 1,004 prey items that had been captured by the spiders. It was found that the spiders prey mainly on the ants Formicidae and Hymenoptera. Their diet is said to be polyphagous because they prey upon varied arthropods but with a high proportion of one item.

Three Threidiid spiders of the genus Latrodectus occur in Khorasan province: L.tredecimguttatus, L.pallidus, L.dahli. The three are described, their diagnostic features are illustrated, and taxonomic notes are given where possible. Spider bites are very common in these regions, so, further notes about the medical importance of these species are given. A dichotomic key to the species of the genus Latrodectus is presented.

The article focuses on the clinical profile of spider bite in southern Africa, citing that the diagnosis can be difficult particularly if the patient is unaware of having been bitten. The medically important spiders are classified into two groups including the neurotoxic, belonging to the genus Latrodectus (button or widow spiders), and the cytotoxic, belonging to the genus Cheiracanthium (sac spiders) and Laxosceles (violin or recluse spiders).

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The article presents the first report of the widow spider Theridiidae from the genus Latrodectus elegans from India. It notes that the comb-foot spider species has clinical significance due to the three species being reported from India. It also explores the variability within the 31 spider species in their different stages of growth.

What happens to citizenship when the nation and the state are no longer assumed to be the inevitable starting points from which politics is defined? This paper considers how a refusal of the nation as political community and a questioning of the state as guarantor of rights and responsibilities reconfigure our understandings of citizenship. We do this by taking as a metaphor and analytical entry point an art installation developed by artist Tomás Saraceno titled 14 Billions (Working Title). Forming an exaggerated version of a black widow spider's web, this installation offers us a way of engaging politics in relational terms. Inspired by this installation, we ask: how are the categories of citizenship and community troubled or reconfigured when we address sociality and politics from a relational perspective? In which ways does 14 Billions prompt us to address questions of spatiality, power, coexistence, and contestation differently from those accounts of citizenship that remain wedded to the state as a contained geographical unit and to the nation as an imaginary of political community? And finally, how might this web installation suggest an intervention into the broader problematic of 'citizenship without community' that forms the focus of this theme issue? We address these questions by way of an engagement with the 'lines', 'gaps', and 'tension points' presented by 14 Billions and argue that an understanding of citizenship as based upon membership appears inadequate when we address politics through a web. In so doing, we contend that the provocation of citizenship without community presents a challenge that does not simply demand a shift from the nation to the state or the reaffirmation of a rights-bearing subject; rather, this provocation leads us to argue that politics involves more than a search for inclusion and recognition, whilst the web installation offers us a way in to thinking about politics through heterogeneous sites and moments of encounter. [ABSTRACT FROM AUTHOR]

Objectives. Following widow spider ( Latrodectus sp.) envenomation, local pain, erythema, abdominal pain, rigidity, hypertension, and diaphoresis can be seen. While an effective specific antivenom (AV) is available, its use is limited due to concern of possible severe allergic reaction. We performed the current study to determine rate of adverse effects and the efficacy of AV in patients treated for widow spider envenomation. Methods. Observational case series of the California Poison Control System electronic database from January 1999 to December 2009. All cases of widow spider envenomation treated with AV were included. Age, gender, signs, and symptoms, adjunctive therapy, number of vials of AV given, and adverse reaction to AV were recorded. Descriptive statistical methods were used. Results. Ninety-six patients received AV, mean age 26 years (0.12-74 years), 76% male. Following widow spider envenomation generalized pain was reported in 91%, erythema at site in 57%, hypertension (≥ 140/90 mmHg) in 43%, muscle rigidity/cramping in 43%, abdominal pain in 41%, tachycardia (≥ 100 bpm) in 23% and diaphoresis in 21%. No patient required more than one vial of AV. One patient developed urticaria to AV halfway through infusion which was immediately discontinued. Another patient developed generalized flushing following completion of infusion but had no other effects. Two other patients reported myalgia and paresthesia. There were no deaths in any patients receiving AV. There was no shortness of breath or respiratory distress, no hypotension or chest pain following AV administration. All patients reported pain relief with AV and did not require additional AV doses. Conclusions. Our results suggest that Black Widow Spider Antivenin® (Merck) administration is relatively safe with mild to moderate adverse effects seen in only a small percentage of patients. There were no deaths, or severe allergic reactions identified. The retrospective use of poison control system data is a limitation of our study. Further prospective studies are needed to validate our findings and elucidate the full safety profile on this antivenom. [ABSTRACT FROM AUTHOR]

In many mating systems, males strive for securing paternity through monopolizing females. As male monopolization attempts often contradict female interests, this conflict may fuel an evolutionary arms race. In the widow spider genus Latrodectus, females are commonly polyandrous, whereas males are monogynous, hence restricted to mate with a single female, making paternity protection particularly important. Potential mating plugs (specialized embolus sclerites of male copulatory organs) have been discovered in the complex female genital tracts of several Latrodectus species. In this study, we investigated mating strategies in the Mediterranean black widow spider Latrodectus tredecimguttatus and tested the adaptive value of female attacks against male monopolization efforts. In a double mating experiment, we manipulated the number of insertions (=copulations) for first and second males to assess female behaviour and male embolus sclerite placement success. Our results indicate that first males′ embolus sclerites inside the females′ sperm stores physically block sclerites of subsequent males. While female attacks did not affect the deposition of potential mating plugs, they significantly reduced copulation duration. Irrespective of female aggression, male sclerite placement failure occurred frequently, but large males were more successful than smaller competitors. We suggest that the complex genital morphology in both sexes may have co-evolved antagonistically and female morphology could serve to favour large males for fertilization. [ABSTRACT FROM AUTHOR]