Latrodectus Geometricus Research Articles

Envenomation caused by Latrodectus geometricus in São Paulo state, Brazil: a case report

Widow spiders (Latrodectus spp.), also known as "black widows", have a worldwide distribution and can cause latrodectism. To the best of our knowledge, in Brazil, only one case of Latrodectus geometricus (Koch, 1841) envenomation in a human has been reported. The aim of the present report is to describe a spider bite caused by Latrodectus geometricus in a patient who lives in Paranapanema, São Paulo state, Brazil.

Severe Reaction from Envenomation by the Brown Widow Spider, Latrodectus geometricus (Araneae: Theridiidae)

The brown widow, Latrodectus geometricus, is one of five species of Latrodectus in the United States, and is reported to be one of the least dangerous. However, we report a previously healthy patient bitten by a brown widow, resulting in a serious reaction requiring hospitalization. Symptoms included severe pain, cramps, nausea/vomiting, and fasciculations in the pectoral and quadriceps muscles. This report signals a need to re-evaluate previously held ideas that brown widow bites are of minor consequence.

Additions to the Known U.S. Distribution of <I>Latrodectus geometricus</I> (Araneae: Theridiidae)

The range of the brown widow spider Latrodectus geometricus C. L. Koch includes much of Africa and South and Central America. This medically important spider has been recently introduced to Japan, Indonesia, Papua New Guinea, Australia, Hawaii, and California. After the identification of the brown widow spider in New Orleans, LA, and southern Mississippi, surveys in the southeastern United States were conducted from the fall of 2006 through February 2008. We found populations of brown widow spiders in Georgia, Texas, and multiple localities in southeastern Louisiana and Mississippi. In Mississippi, specimens were collected as far north as a county bordering Tennessee. In New Orleans, the brown widow spider has been commonly collected from various locations where human contact is likely.

Additions to the Known U.S. Distribution ofLatrodectus geometricus(Araneae: Theridiidae)

The range of the brown widow spider Latrodectus geometricus C. L. Koch includes much of Africa and South and Central America. This medically important spider has been recently introduced to Japan, Indonesia, Papua New Guinea, Australia, Hawaii, and California. After the identification of the brown widow spider in New Orleans, LA, and southern Mississippi, surveys in the southeastern United States were conducted from the fall of 2006 through February 2008. We found populations of brown widow spiders in Georgia, Texas, and multiple localities in southeastern Louisiana and Mississippi. In Mississippi, specimens were collected as far north as a county bordering Tennessee. In New Orleans, the brown widow spider has been commonly collected from various locations where human contact is likely.

Vestiges of an orb-weaving ancestor? The “biogenetic law” and ontogenetic changes in the webs and building behavior of the black widow spider Latrodectus geometricus (Araneae Theridiidae)

Young juveniles of L. geometricus fit the strong trend for “ontogeny to repeat phylogeny” previously documented in other web-building spiders; younger spiders were less likely to build the derived silk retreats that occur at the edges of webs of adults. Younger individuals also consistently built more highly organized webs, with radial lines that converge on a central, horizontal disc and that support regularly spaced, sticky “gumfoot“ lines. Some details of how radial and gumfoot lines were built suggest that the radial and gumfoot lines and the behavior involved in their construction may be homologous with traits associated with radii and sticky spirals in aranoid orb webs. The numerous convergences between the webs and building behavior of young L. geometricus and the highly modified webs and building behavior of genera of the orb weaving families Theridiosomatidae (Wendilgarda) and Anapidae (Comaroma), which have independently replaced orbs with webs designed to capture prey on surfaces near the web, suggest a new hypothesis for how gumfoot theridiid webs may have evolved from orbs.

First case of human latrodectism in Venezuela

The first case of envenoming by Latrodectus geometricus in Venezuela is described. The accident occurred at the victims home, in Aragua de Barcelona, Anzoátegui State. The 31-year-old female victim was bitten twice on the left scapular region, in quick succession (within seconds). She developed a hyperactive state of the central, autonomic and peripheral nervous systems with minor local symptoms.

Sexual Cannibalism in the Brown Widow Spider (Latrodectus geometricus)

AbstractSexual cannibalism may represent an extreme form of male monogamy. According to this view, males gain reproductive success by sacrificing themselves to females. We studied the occurrence and timing of sexual cannibalism in the brown widow spiderLatrodectus geometricusand compared male courtship and mating behavior with virgin and with previously mated females.We found that events of sexual cannibalism are frequent, that they occur during copulation and that males initiate cannibalism by placing the abdomen in front of the female’s mouth‐parts during copulation (somersault behavior). Both the somersaults and mating occurred more frequently with virgins than with previously mated females. Our results support the hypothesis that sexual cannibalism is a male strategy in this species. The somersault behavior was previously known only from the redback spider,Latrodectus hasselti.It is as yet unknown whether self‐sacrifice has evolved more than once in this genus.

Multiple Recombining Loci Encode MaSp1, the Primary Constituent of Dragline Silk, in Widow Spiders (Latrodectus: Theridiidae)

Spiders spin a functionally diverse array of silk fibers, each composed of one or more unique proteins. Most of these proteins, in turn, are encoded by members of a single gene family thought to have arisen through duplication and divergence of an ancestral silk gene. Because of its remarkable mechanical properties, orb weaver dragline silk, a composite of 2 proteins (MaSp1 and MaSp2), is the best studied. Here, we demonstrate that multiple loci encode MaSp1 in widow spiders (Latrodectus). Because these copies may be the result of more recent duplication events than those leading to the currently recognized silk gene paralogs, they offer insight into the early evolutionary fate of silk gene duplicates. In addition to 3 presumed functional MaSp1 loci in Latrodectus hesperus (Western black widow) and Latrodectus geometricus (brown widow) genomes, we find a MaSp1 pseudogene in L. hesperus, demonstrating the potential for unrecognized extinction of silk gene paralogs. We also document recombination events among L. hesperus MaSp1 loci and between Latrodectus MaSp1 loci and MaSp2. This result supports the hypothesis that concerted evolution occurs not only within an individual silk gene but also among silk gene paralogs. One of the L. geometricus MaSp1 copies encodes a protein that has diverged in amino acid composition and potentially converged on the secondary structure of MaSp2. Based on the presence of multiple MaSp1 loci and the phylogenetic distribution of MaSp1 versus MaSp2, we propose that MaSp2 is derived from an ancestral MaSp1 duplicate. Finally, divergence has occurred in the upstream flanking sequences of the L. hesperus MaSp1 loci, the region most likely to contain regulatory motifs, providing ample opportunity for differential expression. However, the benefits associated with increased protein production may be the primary mechanism maintaining multiple functional MaSp1 copies in widow genomes.

Analysis of the Conserved N-Terminal Domains in Major Ampullate Spider Silk Proteins

Major ampullate silk, also known as dragline silk, is one of the strongest biomaterials known. This silk is composed of two proteins, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2). Only partial cDNA sequences have been obtained for these proteins, and these sequences are toward the C-terminus. Thus, the N-terminal domains have never been characterized for either protein. Here we report the sequence of the N-terminal region of major ampullate silk proteins from three spider species: Argiope trifasciata, Latrodectus geometricus, and Nephila inaurata madagascariensis. The amino acid sequences are inferred from genomic DNA clones. Northern blotting experiments suggest that the predicted 5' end of the transcripts are present in fibroin mRNA. The presence of more than one Met codon in the N-terminal region indicates the possibility of translation of both a long and a short isoform. The size of the short isoform is consistent with the published, cDNA based, N-terminal sequence found in flagelliform silk. Analyses comparing the level of identity of all known spider silk N-termini show that the N-terminus is the most conserved part of silk proteins. Two DNA sequence motifs identified upstream of the putative transcription start site are potential silk fibroin promoter elements.

The black widow spider genus Latrodectus (Araneae: Theridiidae): phylogeny, biogeography, and invasion history

The spider genus Latrodectus includes the widely known black widows, notorious because of the extreme potency of their neurotoxic venom. The genus has a worldwide distribution and comprises 30 currently recognized species, the phylogenetic relationships of which were previously unknown. Several members of the genus are synanthropic, and are increasingly being detected in new localities, an occurrence attributed to human mediated movement. In particular, the nearly cosmopolitan range of the brown widow, Latrodectus geometricus, is a suspected consequence of human transport. Although the taxonomy of the genus has been examined repeatedly, the recognition of taxa within Latrodectus has long been considered problematic due to the difficulty associated with identifying morphological features exhibiting discrete geographic boundaries. This paper presents, to our knowledge, the first phylogenetic hypothesis for the Latrodectus genus and is generated from DNA sequences of the mitochondrial gene cytochrome c oxidase subunit I. We recover two well-supported reciprocally monophyletic clades within the genus: (1) the geometricus clade, consisting of Latrodectus rhodesiensis from Africa, and its is sister species, the cosmopolitan L. geometricus, and (2) the mactans clade containing all other Latrodectus species sampled, including taxa occurring in Africa, the Middle East, Iberian Peninsula, Australia, New Zealand, and North and South America. Recovery of the geometricus and mactans clades is consistent with previous designations of species groups within the genus based on female genitalic morphology. All L. geometricus sampled, consisting of specimens from Africa, Argentina, North America, and Hawaii, were recovered as a strongly supported monophyletic group with minimal amounts of genetic divergence, corroborating the hypothesis that human transport has recently expanded the range of this species.

Webs of theridiid spiders: construction, structure and evolution

Understanding the web construction behaviour of theridiid (comb-footed) spiders is fundamental to formulating specific evolutionary hypotheses and predictions regarding the reduction of orb-webs. We describe for the first time in detail the web construction behaviour of Achaearanea tepidariorum, Latrodectus geometricus, Theridion sisyphium and T varians as well as webs of a range of other theridiids. In our survey we distinguish four major web types. Among webs with gumfooted lines, we distinguish between webs with a central retreat (Achaearanea-type) and those with a peripheral retreat (Latrodectus-type). Among webs without gumfooted lines, we distinguish between those which contain viscid silk (Theridion-type) and those with a sheet-like structure, which do not (Coleosoma-type). Theridiid gumfoot-webs consist of frame lines that anchor them to surroundings and support threads which possess viscid silk. Building of gumfooted lines constitutes a unique stereotyped behaviour and is most probably homologous for Nesticidae and Theridiidae. Webs remained in place for extended periods and were expanded and repaired, but no regular pattern of replacement was observed. We suggest that the cost of producing and maintaining viscid silk might have led to web reduction, at least in theridiids. (C) 2003 The Linnean Society of London.

Entomological fauna from Reserva Biológica do Atol das Rocas, RN, Brazil: I. Morphospecies composition.

Atol das Rocas, the unique atoll in the South-western Atlantic, is located 144 nautical miles (266 Km) northeast from the city of Natal, NE Brazil and 80 nautical miles from Arquipélago de Fernando de Noronha, with geographic co-ordinates 3 masculine51'S and 33 masculine49"W. It's of volcanic origin and coralline formation. The reef is ellipsoid, its largest axis (E-W) is approximately 3.7 km long, and the shortest (N-S) is 2.5 km. Inside the lagoon, there are two islands: the Ilha do Farol and Ilha do Cemitério, which comprehend 7.2 Km2 of emerged area. The Atol das Rocas lodges 143,000 birds, mainly by Sula dactilatra, S. leucogaster, Anous stolidus, A. minuta and Sterna fuscata. Due to their remote location, the islands remain largely undisturbed by the human activities. Aiming to a first characterization of the entomological diversity and the general trophic niches of atoll's entomofauna, three collects were made (1994, 1995 and 1996) utilizing several methods for a wide sample. One thousand six hundred and six insect specimens were collected belonging to eight orders: 1. Coleoptera - 333 individuals of Dermestidae (Dermestes cadaverinus); Tenebrionidae (Phaleria testacea and morphospecies) and Curculionidae (one morphospecies); 2. Dermaptera - 50 individuals of Carcinophoridae (Anisolabis maritima); 3. Diptera - 281 individuals of Ephydridae (Scatella sp. and Hecamede sp.) and Hippoboscidae (one morphospecies); 4. Hymenoptera - 45 individuals of Formicidae (Brachymyrmex sp.); 5. Lepidoptera - 111 individuals of Microlepidoptera (one morphospecies); 6. Mallophaga - 18 individuals in birds (two morphospecies); 7. Orthoptera - 237 individuals of Acrididae (Schistocerca cancellata), Tridactylidae (one morphospecies) and Blattidae (three morphospecies); 8. Thysanoptera -531 individuals (one morphospecies). Also were collected 112 individuals of Arachnida. The taxa of the Order Araneae were represented by the families: 1. Miturgidae (Cheiracanthium inclusum); 2. Salticidae (two morphospecies) and 3. Segestriidae (Ariadna sp.); 4. Theridiidae (Achaearanea sp. and Latrodectus geometricus). For the Order Scorpionida, only samples of Buthidae (Isometrus maculatus) were collected. Through field observations, it was concluded the most insects are detritophagous and/or necrophagous. It is suggested that which the dimension of ecological niches of the insects are a function of the droppings, trash and corpses of birds. A low diversity in the entomofauna of atoll, with its 25 morphospecies, was ascertained.

20 ハイイロゴケグモの生態 (3) : 秋・冬期の室内飼育

20 ハイイロゴケグモの生態 (3) : 秋・冬期の室内飼育

11 ハイイロゴケグモの 1 産卵期における産卵数

11 ハイイロゴケグモの 1 産卵期における産卵数

9 ハイイロゴケグモの生態 : (1) 室内飼育

9 ハイイロゴケグモの生態 : (1) 室内飼育

10 ハイイロゴケグモの生態 : (2) 生存競争

10 ハイイロゴケグモの生態 : (2) 生存競争

日本へのゴケグモ類の侵入

The redback spider, Latrodectus hasseltii, is a common venomous spider in Australia. This species had not been recorded in Japan until late 1995. Large numbers of redback spiders were collected in Osaka City and in Yokkaichi City, Mie Prefecture, in November 1995. Another species of widow spiders, namely, the brown widow spider L. geometricus, was also collected in various ports : Yokohama, Tokyo, Nagoya, Osaka and in Okinawa. The author has reviewed current available information on widow spiders including the life cycle, reproduction, hunting behavior, systematics and distribution of each species, etc. The invasion route of these species into Japan is also discussed. The invasion of redback spiders into Japan apparently dates back several years as frequently old, empty egg sacs have been found. There is no information on how the redback spiders survived the winter season in Japan. Fortunately, so far in Japan no biting cases have been reported.

Records of Latrodectus geometricus(Araneae: Theridiidae) from Japan.

The brown widow spider, Latrodectus geometricus C. L. KOCH, 1841, is recorded from Japan for the first time. Some females with egg sacs and numerous spiderlings were collected in the winter season in an urban park adjoining the container wharf at the port of Yokohama. According to the information received from colleagues by personal communication, spiders of this species were also found at the ports of Tokyo, Nagoya, Osaka and Okinawa, and some other dominant trade ports in Japan.

Action of brown widow spider venom and botulinum toxin on the frog neuromuscular junction examined with the freeze‐fracture technique.

1. Structural changes which normally accompany transmitter release at frog neuromuscular junctions are visualized with the freeze-fracture technique. The effects of brown widow spider venom and botulinum toxin were evaluated in terms of their ability to block or produce these structural changes. Changes produced by these neuropoisons were correlated with their known effects on neurotransmitter release. 3. Fusion of synaptic vesicles with the presynaptic plasmalemma, normally evoked by electrical stimulation, was abolished at neuromuscular junctions from frogs treated with botulinum toxin. 3. The concentration of large intramembranous particles in the presynaptic plasmalemma, an indication of the excess of synaptic vesicle fusion over recovery of synaptic vesicle membrane, was increased by treatment with brown widow spider venom, even in the presence of botulinum toxin. 4. When external calcium was present, sites of vesicle fusion induced by brown widow spider venom, as well as by electrical stimulation, were located mainly in the active zone. In the absence of external calcium, many plasmalemmal deformations, also though to be sites of vesicle fusion, were more evenly dispersed over the presynaptic surface of nerve terminals. 5. Botulinum toxin decreased the number of vesicle fusion sites in the active zone induced by spider venom in the presence of external calcium but had little effect on the number of fusion sites induced by spider venom in the absence of external calcium. 6. Nerve terminals soaked in a sodium-free Ringer solution were partially depleted of vesicles. Addition of spider venom to this Ringer did not cause additional depletion of vesicles. 7. Formation of cation-permeable channels in the presynaptic membrane could account for these effects of spider venom on the frog neuromuscular junction. Botulinum toxin blocks vesicle fusion by some means which is not yet understood.

Discrete and discontinuous action of brown widow spider venom on the presynaptic nerve terminals of frog muscle.

1. A study was made of the effects of the venom of the brown widow spider (Latrodectus geometricus) on end-plates of the frog sartorius muscle. 2. The increase in the frequency of the minature end-plate potentials (m.e.p.p.s), elicited by the venom in normal-"Ca2+" Ringer solution, occurs in discrete volleys having a sharp onset and end. The frequency of the m.e.p.p.s is high (up to 300 sec-1) and relatively constant during the volley. 3. The volleys recur at intervals during a period from 5 to 10 min after addition of the venom until the onset of electrical silence, up to 4 hr later. The activity occurs in groups containing volleys of loing and short duration. 4. Simultaneous intracellular and extracellular recording from single end-plates indicates that the volleys originate at highly localized areas of the nerve terminals. The high-frequency release of m.e.p.p.s in hypertonic sol solutions, which was studied for comparison purposes, occurs randomly over the entire end-plate. Volleys originating simultaneously at different sites are often superimposed in the intracellular recordings. 5. In high-"Ca2+" Ringer solution, the initial frequency of the m.e.p.p.s in a volley is comparatively higher. However, the frequency drops to one half its value in a few seconds. The volley then terminates or else the frequency of m.e.p.p.s remains high for some time and the volley has no sharp end. Activity occurs in groups containing both long and short volleys. Many more short (less than 5 sec) and long (greater than 30 sec) volleys occur in high-"Ca2+" solution than in normal-"Ca2+" solutions. 6. In low-"Ca2+", high-"Mg2+" Ringer solution, the volleys of m.e.p.p.s are fewer in number and much longer in duration. Intra- and extra-cellular recording of uninterruped activity during long periods suggests that in this solution the m.e.p.p.s originate diffusely rather than at discrete areas of the nerve terminals. 7. Implications of the above data on possible modes of action of the venom are discussed.