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PubMed2004

Brown spiders and loxoscelism.

Accidents caused by brown spiders (Loxosceles genus) are classically associated with dermonecrotic lesions and systemic manifestations including intravascular haemolysis, disseminated intravascular coagulation and acute renal failure. Systemic reactions occur in a minority of cases, but may be severe in some patients and occasionally fatal. The mechanisms by which Loxosceles venom exerts these noxious effects are currently under investigation. The venom contains several toxins, some of which have been well-characterised biochemically and biologically. The purpose of the present review is to describe some insights into loxoscelism obtained over the last ten years. The biology and epidemiology of the brown spider, the histopathology of envenomation and the immunogenicity of Loxosceles venom are reviewed, as are the clinical features, diagnosis and therapy of brown spider bites. The identification and characterisation of some toxins and the mechanism of induction of local and systemic lesions caused by brown spider venom are also discussed. Finally, the biotechnological application of some venom toxins are covered.

Animals↗

PubMed2001

Neutralization of Latrodectus mactans and L. hesperus venom by redback spider (L. hasseltii) antivenom.

OBJECTIVE: To test the effectiveness of L. hasseltii (redback spider) antivenom in neutralizing the lethal effects of L. hesperus and L. mactans (North American black widow) venoms. METHODS: LD50 values for the L. hesperus and L. mactans venom preparations were determined. A prospective, randomized, double-blind antivenom efficacy experiment was then performed for each venom using a mouse envenomation model. The following treatments were premixed and incubated at 25 degrees C for 1 hour prior to intraperitoneal injection: 1) saline control + protein control, 2) saline control + L. hasseltii antivenom, 3) L. hesperus or L. mactans venom + protein control, and 4) L. hesperus or L. mactans venom + L. hasseltii antivenom. The study endpoints were time elapsed until death and survival at 24 hours. RESULTS: The mouse LD50 values for L. hesperus and L. mactans venoms were 0.64 mg/kg and 0.26 mg/kg, respectively. In the efficacy trial, all mice in group 3 (L. hesperus or L. mactans venom and protein control) died. In both experiments, all mice in group 4 (L. hesperus or L. mactans venom + antivenom) survived (p < 0.0001). CONCLUSION: This is the first study to derive mouse LD50 values for L. hesperus and L. mactans venom obtained by electrical stimulation of live adult spiders. Redback spider antivenom is effective in neutralizing the lethal effects of L. hesperus and L. mactans venoms in a mouse envenomation model. While this study is limited by the optimized premixing of antigen with antibody, it generates the hypothesis that redback antivenom would be effective in the treatment of latrodectism in humans caused by the two clinically relevant species of North American widow spiders.

Animals↗

PubMed1998

When to worry about spider bites. Inaccurate diagnosis can have serious, even fatal, consequences.

Almost all species of spiders are capable of biting people, but the bites of only a few are medically significant. Physicians need to be able to recognize the clinical signs and symptoms of common venomous spider bites and administer appropriate therapy. This may be difficult, since the offending spider is rarely seen or recovered for identification. Knowledge of life cycles, habits, and toxicity of venomous spiders enables physicians to provide more comprehensive medical care of bite victims. It is hoped that study of immunologic mechanisms and inflammation mediators will lead to the development of new treatments.

Animals↗

PubMed1987

Spider bites.

Spiders are a ubiquitous component of the fauna of North America. At least 50 to 60 species in the United States are known to bite humans, although in most cases, the diagnosis is never suspected nor is treatment necessary. A few species of spiders are capable of causing necrotic wounds and, occasionally, death. This review is intended to provide an overview of the recent advances in the diagnosis and treatment of spider bites, as well as a compilation of the many species of spiders that have been reported to give clinically important bites.

Animals↗

PubMed2002

Treatment of spider leg veins with the KTP (532 nm) laser--a prospective study.

BACKGROUND AND OBJECTIVES: Spider leg veins are telangiectasias located intracutaneously. This condition poses a cosmetic problem. STUDY DESIGN/PATIENTS AND METHODS: The purpose of this study was to determine what influence the KTP (532 nm) laser has on spider leg veins dependent on the vascular diameter and to what extent the skin has been affected. Seventy female patients were treated in three laser sessions. Analysis was done 30 weeks after the last laser treatment session. RESULTS: Fifty-six patients completed the study. In group 1 (vascular diameter < or = 0.6 mm), spider leg veins were no longer visible in 33%; in 40%, a decrease in vascular diameter could be observed; in 27%, no change in size occurred. In group 2 (vascular diameter 0.7-1.0 mm), laser-treated spider leg veins were visible in all patients. Hyperpigmentation occurred in 13 patients. CONCLUSIONS: The KTP (532 nm) laser is an effective for treating spider leg veins having a vascular diameter under 0.7 mm.

Adolescent↗

PubMed1998

Mating behaviour in the cellar spider, Pholcus phalangioides, indicates sperm mixing.

In insects and spiders, the pattern of sperm priority is often attributed to the shape of the spermathecae and should entail marked consequences for mating behaviour. Since last-male priority is assumed to occur in haplogyne spiders such as the cellar spider, females of this species are predicted to be more attractive to males shortly before, than shortly after, egg laying and males may guard females after copulation until oviposition. To test these predictions, I individually marked spiders of a natural population and recorded their position and the distance between potential mating partners twice a day over 100 days. The distance between female and male was taken as a measure of the female's attractiveness. The behaviour of cellar spider males was not in accordance with the predictions; females were visited throughout the observation period with no significant increase in attractiveness before egg laying and there was no evidence for mate guarding. However, female attractiveness was correlated with female size, which was correlated with the number of eggs laid. Behaviour and genital morphology suggest sperm mixing occurs in this species. This is discussed in the light of conflicting data on sperm priority. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1999

Competitive foraging in the social spider Stegodyphus dumicola.

Reproductive skew models have greatly enhanced the study of sociality but are applicable only to societies where the aim of the members of the group is to reproduce. In 'foraging societies', where the aim of the members of the group is to grow, quite different parameters will govern the form that the societies take. We examined factors that influence the structure of foraging groups in the social spider Stegodyphus dumicola (Eresidae). In particular, we examined food distribution and consumption within groups, and how this related to predictions derived from two models. One model indicates that colonies in which individuals compete for resources via interference competition are more likely to survive than those in which individuals divide resources using scramble competition. The second model predicts the proportions of hunters, cheaters and scavengers expected in foraging groups. We found that food was not distributed evenly among group members, and that spiders that fed primarily on the head and thorax of the prey during the middle of a feeding event gained the most body mass. Spiders even lost mass if they fed only in the last hour of a foraging event. Large spiders had a competitive advantage (via interference competition) in obtaining preferred positions, and could ingest food faster than small spiders. Distributing food among colony members in this manner could cause large size differences between colony members, as predicted by the models. The implications of competitive foraging for sociality are discussed. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1997

Cognitive bias in spider fear and control children: assessment of emotional interference by a card format and a single-trial format of the stroop task.

The aim of the study was to clarify whether fear in children is related to a distorted cognitive processing of fear-related information. In anxious children, only a few studies of this bias were performed which yielded inconsistent results. Martin, Horder, and Jones (1992. Cognition and Emotion, 6(6), 479-486) found a bias for spider words in spider-fear children, using a card format of the Stroop task. However, by using a single-trial format of the Stroop task, we previously found that both anxious and control children favored the processing of threatening information (Kindt, Brosschot, & Everaerd, 1997. Journal of Experimental Child Psychology, 64, 79-97). In the present study, we administered both a card format and a single-trial format of the Stroop task to spider-fear and control children. In line with our previous results, a bias for spider words was observed in spider fear but also in control children, regardless of the format used. Furthermore, the processing biases assessed by the two formats did not correlate, which suggests that they measure different mechanisms and/or that one or both mechanisms are unstable. It is speculated that certain cognitive developmental deficits in regulating emotions may be a vulnerability factor in the etiology of anxiety disorders.

Affect↗

PubMed1996

Metal body burdens and detoxifying enzymes in spiders from industrially polluted areas.

Detoxifying enzymes have been assayed and metal concentrations have been monitored in four species of spiders from differently contaminated localities in Southern Poland. A behavioural feeding activity and the life style decide on sensitivity and vulnerability of spiders. Wolf-spiders, more active than the web-spinners, cumulate higher amounts of metals, reflecting quantitatively and qualitatively the pollution level in their environment. Detoxifying systems in spiders appeared inducible and efficient to maintain normal physiological responses. Within web-spinning spiders the linyphiids seem to be the most effective regulators of metal burdens. Their detoxifying capabilities correlate well with increased industrial contaminants. The analysis of biochemical biomarkers of exposure confirmed earlier ecological findings that species of the family Linyphiidae are more favoured than the Araneidae. Differences in their feeding activity, behaviour of web-spinning and the size of animals would explain alterations in detoxifying abilities between Meta segmentata and Araneus diadematus.

Journal Article↗

PubMed2006

Testing for non-target effects of spinosad on twospotted spider mites and their predator Phytoseiulus persimilis under greenhouse conditions.

The compatibility of the selective insecticide spinosad (Conserve SC), at rates recommended for thrips control in greenhouses, with release of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) to control spider mites, was investigated in a crop of ivy geranium Pelargonium peltatum, cultivar 'Amethyst 96.' Plants were inoculated with twospotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae), 2 weeks before treatments were applied. There were three treatment variables, each at two levels: predators (released or not), spray application (water or Conserve SC at 2 ml/3.79 l), and timing of spray (1 day before or after predators were released). Twospotted spider mite populations then were sampled twice each week over a three-week period. The application or timing of spinosad had no effect on the ability of the predator to reduce the population of spider mites. Spider mite populations in the no-predator treatment continued to expand over the course of the experiment, while those in the predator-release treatment declined. We conclude that P. persimilis can be used in conjunction with spinosad on ivy geraniums without causing obvious detrimental effects to this predator or leading to a reduction in biological control.

Animals↗

PubMed2003

Multiple-cue probabilistic learning in spider-fearful and in panic-prone individuals.

Probabilistic learning was studied in spider-fearful and in panic-prone individuals. Participants learned to predict the occurrence of aversive outcomes on the basis of relevant and irrelevant stimuli. The salience of irrelevant stimuli was manipulated by the use of threat-related objects, i.e. pictures of spiders and pictures of emergency situations. In spider-fearful individuals, the presence of irrelevant pictures of spiders interfered with the adequate acquisition of the association between neutral relevant stimuli and aversive outcomes. Salient, i.e. threat-related, irrelevant stimuli exerted competitive effects on the accruing of associative strengths between neutral stimuli and aversive outcomes in spider-fearful, but not in panic-prone, individuals.

Adolescent↗

PubMed1998

Treatment of spider veins with the 595 nm pulsed-dye laser.

BACKGROUND: Previous attempts to treat spider veins with the conventional 585 nm pulsed-dye laser with a 0.5-ms pulse duration have been relatively ineffective. Recently, a new pulsed-dye laser that is tunable from 585 to 600 nm with a pulse duration 3 times longer than previously available lasers has preliminarily been shown to be effective for treatment of spider veins. OBJECTIVE: Our purpose was to evaluate the effectiveness of multiple treatments with the tunable long-pulse dye laser in treatment of spider veins of the lower extremity. METHODS: Ten female volunteers were treated in two separate areas containing blue or red linear spider veins less than 1.5 mm in diameter. Treatments were administered with the pulsed-dye laser with a 1.5-ms pulse duration and 595-nm light at fluences of 15 and 20 J/cm2, and each subject received a total of 3 treatments at each site, administered at 6-week intervals. Photographs were taken before and 6 weeks after the last treatment. RESULTS: Computer-based image analysis showed clearing of more than three fourths of veins after 3 treatments with 15 or 20 J/cm2. Side effects were minimal and the treatments were well tolerated. CONCLUSION: The 595 nm, 1.5 ms pulse duration, pulsed-dye laser is safe and effective for treating blue or red spider veins of the lower extremities less than 1.5 mm in diameter in nontanned patients with Fitzpatrick skin types I and II. Multiple treatments improve on the results obtained after a single treatment.

Adult↗

PubMed2002

Role of environmental exposure to spider mites in the sensitization and the clinical manifestation of asthma and rhinitis in children and adolescents living in rural and urban areas.

BACKGROUND: Spider mites such as the citrus red mite and the two-spotted spider mite have been demonstrated to be important allergens for fruit cultivating farmers. OBJECTIVE: To evaluate the role of environmental exposure to spider mites in the sensitization and the clinical manifestations of asthma and rhinitis in children and adolescents living in urban and rural areas. METHODS: A total of 16,624 subjects (aged 7 to 18 years) living in urban (metropolitan and non-metropolitan) and rural areas (apple orchards and citrus orchards) in Korea were evaluated by questionnaire and skin prick test for 11 common aeroallergens, including citrus red mite (CRM) and two-spotted spider mite (TSM). RESULTS: The positive skin response rates to TSM were 4.2% of 1,563 metropolitan subjects, 3.8% of 5,568 non-metropolitan subjects and 6.5% of 1,464 subjects living nearby apple farms, and that to CRM 15.6% of 8,029 living nearby citrus farms. The prevalence of current wheeze and rhinitis as reported on a questionnaire was higher among those with a history of visiting fruit farms once or more per year than among those without it (10% vs. 7.1%, 32.8% vs. 26.7%, for wheezing and rhinitis, respectively). Among those with wheezing or rhinitis, the positive skin responses to TSM or CRM were also higher among those with a history of visiting fruit farms than among those without one (11.2% vs. 6.6%, 13.0% vs. 6.6%, respectively), although the positive skin responses to house dust mites were similar in the both groups. CONCLUSION: Spider mites are common sensitizing allergens in children and adolescents exposed to them, and environmental exposure to these mites may represent an important risk factor in the sensitization and the clinical manifestations of asthma and rhinitis in children and adolescents living in rural and urban areas.

Adolescent↗

PubMed2002

Studies in long-pulsed potassium tritanyl phosphate laser for the treatment of spider naevi and perialar telangiectasia.

Utilization of a 1-10 msec vascular laser to treat facial vessels to limit purpura has become available in recent years. Its efficacy and morbidity in the treatment of common vascular lesions require exploration. We have assessed the relative outcomes and morbidity from a single treatment session of two patterns of 'difficult to treat' facial telangiectasia - perialar vessels and spider naevi - with such a system. Two prospective clinical studies with long pulse 532 nm potassium tritanyl phosphate (KTP) laser were performed with subjective and independent objective assessment at 3 days, 1 week and 4 weeks in both studies. Perialar vessels showed good to excellent improvement subjectively at 4 weeks in 53% (8/15), spider naevi in 83% (20/24). Pain of treatment was substantially greater treating perialar telangiectasia than when treating spider naevi (P < 0.01). Morbidity was low in both groups with no long-term complications. Despite the clinical end-point of vessel disappearance at time of treatment and good early improvement in the appearance of perialar vessels, the failure rate was significant at 1 month follow up. It would appear that spider naevi behave more predictably, with vessel disappearance at time of treatment most often forecasting a successful outcome. Although not statistically significant, spider naevi probably respond better than perialar vessels to a single treatment with this laser.

Adult↗

PubMed1999

Treatment of spider veins using a 10 millisecond pulse-duration frequency-doubled neodymium YAG laser.

BACKGROUND: The pulsed dye laser has been the standard for treating vascular lesions. Although quite effective for treating facial vessels and port-wine stains, spider veins of the lower extremities are more difficult to treat. Recent studies have shown that lasers with longer pulse durations are more effective at treating spider veins. A new long-pulse frequency-doubled Neodymium:YAG laser has been developed with a 10-ms pulse duration and sufficient energy to enable treatment with a 3- or 4-mm diameter treatment beam. OBJECTIVE: To determine the effectiveness of the long pulse Neodymium:YAG laser for treating spider veins of the lower extremities. METHODS: Spider veins less than 0.75 mm in diameter on the legs of 15 female volunteers were treated in 1 or 2 areas. Treatments were administered through a water-cooled chill tip using the frequency-doubled Neodymium:YAG laser with a 10-ms pulse duration. A dose of 16 J/cm2 was administered, completing 3 passes over each visible vein during each session, for a total of 2 sessions administered 6 weeks apart. Photographs of treatment areas were digitally analyzed for degree of vessel clearance. RESULTS: Computer-based image analysis revealed clearing of over 75% of veins following 2 treatments with 16 J/cm2. Side effects were minimal, and the treatments were well tolerated. CONCLUSIONS: The 532 nm, 10 ms pulse duration, frequency-doubled Neodymium:YAG laser is safe and effective for treating spider veins of the lower extremities less than 0.75 mm in diameter, in patients with Fitzpatrick skin Types I-III.

Adult↗

PubMed2006

Olfactory sensitivity for enantiomers and their racemic mixtures--a comparative study in CD-1 mice and spider monkeys.

Using a conditioning paradigm, the olfactory sensitivity of six CD-1 mice for the enantiomers of carvone and of limonene as well as for their racemic mixtures was investigated. With all six stimuli, the animals significantly discriminated concentrations <or=0.1 ppm (parts per million) from the odorless solvent, and with five of the six stimuli, the best-scoring animals were even able to detect concentrations <or=1 ppb (parts per billion). Five spider monkeys tested in parallel were found to detect the same stimuli at concentrations <1 ppm, and with two of the stimuli, they were also able to discriminate concentrations <1 ppb from the solvent. The results showed 1) both CD-1 mice and spider monkeys to have a well-developed olfactory sensitivity for the stimuli tested, with no systematic difference in performance between species; 2) the effect of chirality on detectability of the enantiomers to be substance specific; 3) no systematic effect of the presence (carvone) or absence (limonene) of a functional carbonyl group on detectability of the enantiomers; and 4) that spider monkeys detected the racemic mixtures of both carvone and limonene at lower concentrations compared to the unmixed compounds, whereas the mice failed to do so. These findings lend support to the growing body of evidence suggesting that between-species comparisons of the relative size of olfactory brain structures do not allow us to reliably predict olfactory sensitivity. As mice and spider monkeys are thought to share a similar number of functional olfactory receptor genes, the findings further suggest that differences in the relative abundance of chiral-specific olfactory receptor types might account for the observed difference in mixture additivity at threshold level between the two species. These threshold data may provide useful information for the choice of adequate stimulus concentrations in electrophysiological or imaging studies of the olfactory system or investigations of the discriminative abilities of mice and spider monkeys.

Animals↗

PubMed2005

The true identity of the supposed giant fossil spider Megarachne.

Megarachne servinei from the Permo-Carboniferous Bajo de Véliz Formation of San Luis Province, Argentina (32 degrees 17'S, 65 degrees 25'E), was described as a giant mygalomorph spider ('tarantula') and, with its body length of 339mm, the largest known spider ever to have lived on Earth. Its identification as a spider was based on interpretations of the shape of the carapace, the position of the eye tubercle, the anterior protrusion of the carapace as a pair of chelicerae, and the posterior circular structure as the abdomen. X-radiography revealed possible morphology hidden in the matrix: cheliceral fangs, sternum, labium and coxae, and so a reconstruction of Megarachne as a giant spider was presented. Difficulties with the interpretation (unusual cuticular ornament, suture dividing the carapace and spade-like anterior border of the chelicera), together with non-preservation of synapomorphies of Araneae, provoked debate about its interpretation as a spider. Now, the holotype and a new specimen have become available for study. Megarachne is shown to be a bizarre eurypterid ('sea-scorpion'), similar to rare forms known from Carboniferous rocks of Scotland and South Africa, and is the most complete eurypterid so far recorded from Carboniferous strata of South America.

Animals↗

PubMed2004

Jasmonic acid is a key regulator of spider mite-induced volatile terpenoid and methyl salicylate emission in tomato.

The tomato (Lycopersicon esculentum) mutant def-1, which is deficient in induced jasmonic acid (JA) accumulation upon wounding or herbivory, was used to study the role of JA in the direct and indirect defense responses to phytophagous mites (Tetranychus urticae). In contrast to earlier reports, spider mites laid as many eggs and caused as much damage on def-1 as on wild-type plants, even though def-1 lacked induction of proteinase inhibitor activity. However, the hatching-rate of eggs on def-1 was significantly higher, suggesting that JA-dependent direct defenses enhanced egg mortality or increased the time needed for embryonic development. As to gene expression, def-1 had lower levels of JA-related transcripts but higher levels of salicylic acid (SA) related transcripts after 1 d of spider mite infestation. Furthermore, the indirect defense response was absent in def-1, since the five typical spider mite-induced tomato-volatiles (methyl salicylate [MeSA], 4,8,12-trimethyltrideca-1,3,7,11-tetraene [TMTT], linalool, trans-nerolidol, and trans-beta-ocimene) were not induced and the predatory mite Phytoseiulus persimilis did not discriminate between infested and uninfested def-1 tomatoes as it did with wild-type tomatoes. Similarly, the expression of the MeSA biosynthetic gene salicylic acid methyltransferase (SAMT) was induced by spider mites in wild type but not in def-1. Exogenous application of JA to def-1 induced the accumulation of SAMT and putative geranylgeranyl diphosphate synthase transcripts and restored MeSA- and TMTT-emission upon herbivory. JA is therefore necessary to induce the enzymatic conversion of SA into MeSA. We conclude that JA is essential for establishing the spider mite-induced indirect defense response in tomato.

Animals↗