First report of brown widow spider sightings in Peninsular Malaysia and notes on its global distribution

Background:The brown widow spider (Latrodectus geometricus Koch, 1841) has colonised many parts of the world from its continent of origin, Africa. By at least 1841, the species had successfully established populations in South America and has more recently expanded its range to the southern states of North America. This highly adaptable spider has been far more successful in finding its niche around the world than its famous cousins, the black widow, Latrodectus mactans, found in the south-eastern states of North America, and the red-back, Latrodectus hasselti, found mostly in Australia, New Zealand and Japan.Methods:We performed an extensive web search of brown widow sightings and mapped the location of each sighting using ArcGIS. Specimens reputedly of the species L. geometricus were collected at three localities in Peninsular Malaysia. The spiders were identified and documented based on an examination of morphological characteristics and DNA barcoding.Results:The spiders found in Peninsular Malaysia were confirmed to be Latrodectus geometricus based on their morphological characteristics and DNA barcodes. We recorded 354 sightings of the brown widow in 58 countries, including Peninsular Malaysia.Conclusion:Reports from the Americas and the Far East suggest a global-wide invasion of the brown widow spider. Herein we report the arrival of the brown widow spider in Peninsular Malaysia and provide notes on the identification of the species and its recently expanded range.(AU)

Microdissection of black widow spider silk-producing glands.

Modern spiders spin high-performance silk fibers with a broad range of biological functions, including locomotion, prey capture and protection of developing offspring. Spiders accomplish these tasks by spinning several distinct fiber types that have diverse mechanical properties. Such specialization of fiber types has occurred through the evolution of different silk-producing glands, which function as small biofactories. These biofactories manufacture and store large quantities of silk proteins for fiber production. Through a complex series of biochemical events, these silk proteins are converted from a liquid into a solid material upon extrusion. Mechanical studies have demonstrated that spider silks are stronger than high-tensile steel. Analyses to understand the relationship between the structure and function of spider silk threads have revealed that spider silk consists largely of proteins, or fibroins, that have block repeats within their protein sequences. Common molecular signatures that contribute to the incredible tensile strength and extensibility of spider silks are being unraveled through the analyses of translated silk cDNAs. Given the extraordinary material properties of spider silks, research labs across the globe are racing to understand and mimic the spinning process to produce synthetic silk fibers for commercial, military and industrial applications. One of the main challenges to spinning artificial spider silk in the research lab involves a complete understanding of the biochemical processes that occur during extrusion of the fibers from the silk-producing glands. Here we present a method for the isolation of the seven different silk-producing glands from the cobweaving black widow spider, which includes the major and minor ampullate glands [manufactures dragline and scaffolding silk], tubuliform [synthesizes egg case silk], flagelliform [unknown function in cob-weavers], aggregate [makes glue silk], aciniform [synthesizes prey wrapping and egg case threads] and pyriform [produces attachment disc silk]. This approach is based upon anesthetizing the spider with carbon dioxide gas, subsequent separation of the cephalothorax from the abdomen, and microdissection of the abdomen to obtain the silk-producing glands. Following the separation of the different silk-producing glands, these tissues can be used to retrieve different macromolecules for distinct biochemical analyses, including quantitative real-time PCR, northern- and western blotting, mass spectrometry (MS or MS/MS) analyses to identify new silk protein sequences, search for proteins that participate in the silk assembly pathway, or use the intact tissue for cell culture or histological experiments.

The first cytogenetic characterization of the poisonous black widow spider Latrodectus gr. curacaviensis from Brazil, with chromosomal review of the family Theridiidae (Arachnida, Araneae)

In this paper we present, for the first time, cytogenetical data on Latrodectus gr. curacaviensis (Theridiidae) from Brazil, as well as the first data on meiosis and sex chromosome system of this genus. Testes were submitted to colchicine, hypotonic, and fixation treatment, and chromosomal preparations were stained with Giemsa solution. The analysis showed 2n=26 telo/acrocentric chromosomes in spermatogonial metaphases. Metaphase I exhibited 12 autosomal bivalents and two sex chromosome univalents (12II+X1X2). All bivalents revealed one terminal chiasma. Metaphases II confirmed the sex chromosome system, showing 12 autosomes or 12 autosomes plus two X chromosomes, respectively. Male karyotype prevailing in theridiids is formed by 2n=22 chromosomes, including sex chromosome system X1X2 in all species. The Latrodectus species of the geometricus clade analyzed until now showed smaller diploid number (2nŠ=16 and 2nŠ=18) than the species of the mactans clade (2nŠ=24 and 2nŠ=26). Thus, according to the chromosome number, the examined Latrodectus species seems to be related to the mactans clade.

Repeated evolution of male sacrifice behavior in spiders correlated with genital mutilation.

According to sexual cannibalism theory, male complicity in terminal mating can be adaptive when the male's future reproductive value is low relative to the benefits of self sacrifice. Spiders and insects that exhibit male sacrifice behavior (either complicity in cannibalism or spontaneous death associated with copulation) often also have male genitalia that stereotypically become broken or disfigured the first time they are used for copulation, potentially lowering his future reproductive value. Theoretical work on monogamy has identified male bias in the effective sex ratio as a precursor to the evolution of monogamy (including male sacrifice) as an adaptive form of paternity protection. Using phylogeny-based statistics and drawing on several phylogenetic studies of araneoid spiders, I investigate relationships between male sacrifice behavior, genital mutilation, extreme sexual size dimorphism, and the accumulation of multiple males in the female web (as an indicator of a male-based effective sex ratio). This investigation focuses on araneoid spiders because several independent origins of sacrifice behavior are known for this group and the phylogenetic structure of the lineage is relatively well studied. I report that male genital mutilation is significantly correlated with sacrifice behavior and argue that this finding is consistent with sexual cannibalism theory. Male sacrifice behavior is also correlated with male accumulation, a result that is consistent with theoretical work on the evolution of monogamy. Male accumulation and extreme sexual size dimorphism are correlated suggesting that sex-based differences in maturation time can lead to a male biased effective sex ratio. Similar patterns of correlated characters may hold for some insect taxa. Studying traits that have appeared independently in multiple lineages is a powerful method for developing general theories about the evolution of biological phenomena.

Ultrastructure of the major ampullate gland of the black widow spider, Latrodectus hesperus.

Silk production in the spider occurs within specialized glands that are capable of the synthesis of large fibrous proteins and the post-translational processing of those proteins to form an insoluble fiber. The major ampullate gland of Latrodectus hesperus (black widow) is similar in morphology to those found in the Araneid spiders. The tail domain of this gland is highly protein synthetic, giving rise to a core, fibrous protein product. In addition to a storage function, the ampulla region also synthesizes and exports an electron dense material that appears to form a 'coat' surrounding the silk generated within the tail. The duct of the gland consists of at least two distinct cell types: one type contains 'honeycomb' vesicles of unknown function, while the other possesses elaborate apical microvilli that may be involved in the reabsorption of water and subsequent dehydration of the silk. As the silk product transits through these various stages of assembly, it can been seen to undergo a condensation or concentration, possibly reflecting the influence of both the shear forces induced by movement into the duct and the dehydration that is thought to occur there.

Black widow spider Latrodectus cinctus (Araneae: Theridiidae) new to Liberia--savanna species in the forest zone.

The first record of the African black widow spider, Latrodectus cinctus Blackwall, 1865 (= L. indistinctus Pickard-Cambridge, 1904) from Liberia is presented. It is a further record of a savanna species in the forest zone of West Africa. Increasing deforestation may cause expansion of the ranges of savanna-inhabiting animal species into the forest zone.

Black and brown widow spider bites in South Africa. A series of 45 cases.

Cases of black widow (Latrodectus indistinctus) and brown widow (L. geometricus) spider bites referred to the Tygerberg Pharmacology and Toxicology Consultation Centre from the summer of 1987/88 to the summer of 1991/92 were entered into this series. Of a total of 45 patients, 30 had been bitten by black and 15 by brown widow spiders. It was evident that black widow spider bites caused a more severe form of envenomation than brown widow bites, characterised by generalised muscle pain and cramps, abdominal muscle rigidity, profuse sweating, raised blood pressure and tachycardia. The symptoms and signs of brown widow bites were mild and tended to be restricted to the bite site and surrounding tissues. Conditions which should be considered in the differential diagnosis include cytotoxic spider bite, scorpion sting, snakebite, acute abdominal conditions, myocardial infarction, alcohol withdrawal and organophosphate poisoning. To prevent the development of complications, the administration of black widow spider antivenom is recommended in severe cases because untreated latrodectism could become protracted, without improvement, for several days.

Black widow spider bites.

Black widow spiders (Latrodectus species) are found worldwide. Envenomation of humans usually occurs as the result of chance intrusion into the spider's domain by the human. The venom is regarded as one of the most potent biologic toxins. The venom acts by destabilization of cell membranes and degranulation of nerve terminals resulting in the release of neurotransmitters. The clinical picture is characterized by painful muscle spasm and hypertension. The very young, the elderly or enfeebled, and those with cardiovascular disease are at greatest risk. While not always necessary, the most effective treatment is specific antiserum. Muscle relaxants, analgesics and intravenous calcium are useful adjuvant treatment.

Structure of the cuticle of the common house cricket with reference to the location of lipids.

Cuticle segments from the thorax, abdomen, and jumping legs of the house cricket, Acheta domesticus, were examined using histological techniques for light microscopy, scanning and transmission electron microscopy, and direct examination of frozen-fractured cuticle. The surface of untreated cuticle is covered by a lipid film which obscures fine surface detail. Standard EM preparative procedures, as well as washing the cuticle with ethanol before examination, remove this film exposing previously covered openings to dermal gland ducts and wax canals. An epicuticle, exocuticle, mesocuticle, endocuticle, and a deposition layer were present in all transverse sections of cuticle. Light microscopy showed that the exocuticle and mesocuticle are heavily impregnated with lipids, whereas there is little lipid associated with the endocuticle. Frozen-fractured cuticle clearly shows the 'plywood' structure of the meso- and endocuticle, while the exocuticle fractures as if it were a solid sheet. The epicuticle is composed of a dense homogeneous layer, cuticulin, outer epicuticle, and the outer membrane. Superficial wax was detected only in cuticle samples prepared using vinylcyclohexane dioxide as a polar dehydrant. The results were used to construct a comprehensive model of the cuticle of A. domesticus.

Review of the medically important spiders in Southern Africa.

Known and suspected medically important Southern African spiders are reviewed in terms of their distribution, identification, action of the venom and treatment of the bite. Simple diagnostic characteristics of each species are provided to assist the non-specialist in identifications.