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PubMedDate not supplied

Vulnerability representation: the role of perceived dangerousness, uncontrollability, unpredictability and disgustingness in spider fear.

It was proposed that cognitive vulnerability representations relating to the perceived uncontrollability, unpredictability, dangerousness and disgustingness of spiders are important factors in the fear of spiders. One-hundred and ninety-two first-year psychology students completed a questionnaire measuring the four vulnerability variables, spider fear and learning history. It was found that fear of spiders was highly correlated with each of the four vulnerability variables. In addition, greater fear of spiders was found for females in comparison with males and this was associated with differential perceptions of spiders as uncontrollable, unpredictable, dangerous and disgusting. Finally, the vulnerability variables accounted for significantly more variance in fear scores than the experience of a number of classical conditioning, vicarious and informational learning events. It is argued that there is value in considering a person's perception of the uncontrollability, unpredictability, dangerousness and disgustingness of spiders in order to better understand individual differences in spider fear.

Adolescent↗

PubMed1996

Disgust and spider phobia.

Twenty-four women with spider phobia and 45 nonphobic women completed the Disgust Questionnaire (DQ; P. Rozin, A. E. Fallon, & R. Mandell, 1984) and the Spider Phobia Questionnaire (SPQ; R. Klorman, T. C. Weerts, J. E. Hastings, B. G. Melamed, & P. J. Lang, 1974). Participants also underwent behavioral tests concerning disgust sensitivity and fear of spiders. Spider phobic women showed stronger disgust sensitivity than nonphobic women, and spiders were found to have a disgust-evoking status that was related to participants' fear of spiders. The relationship between DQ and SPQ was independent of neuroticism and introversion. DQ scores were not associated with a global measure of phobic complaints (i.e., Fear Questionnaire; I. M. Marks & A. Mathews, 1979). Results are consistent with a disease-avoidance model of spider phobia (G. Matchett & G. C. L. Davey, 1991), which emphasizes the role of disgust in spider phobia.

Adult↗

PubMed1999

Spiders and Borrelia burgdorferi: no evidence of reservoir occurrence in central Arkansas.

BACKGROUND: Although Ixodes ticks are considered the chief vector for Borrelia burgdorferi in the USA, B. burgdorferi has also been identified in mosquitoes, horse flies, and deer flies. We examined the possibility of these organisms being harbored in two species of spider in central Arkansas. METHODS: Ten wolf spiders (Lycosa gulosa) and two brown recluse spiders (Loxosceles reclusa) were collected in central Arkansas during early summer and fixed in formalin. Paraffin-embedded sections of the spiders were examined for spirochetes using the modified Steiner spirochete staining method and examined for B. burgdorferi using immunohistochemistry. RESULTS: All 12 spiders from both species were found to be negative for all spirochetes including B. burgdorferi. CONCLUSIONS: Spiders in our sample appeared not to harbor B. burgdorferi. Further studies utilizing larger sample sizes, more sensitive testing measures, or spiders from an area more endemic with B. burgdorferi may further prove or disprove that spiders are capable of harboring this organism.

Animals↗

PubMedDate not supplied

Suspected white-tail spider bite and necrotic ulcers.

AIM: To describe the clinical features, investigation, diagnosis and treatment of ulcers attributed to white-tail (WT) spider bites or necrotic arachnidism. METHODS: The study was a prospective case series of patients referred to the Hunter Area Toxicology Service (a tertiary referral toxicology unit servicing a population of 500 000) with an ulcer or skin lesion that had been attributed to either a suspected WT spider bite or necrotic arachnidism. Eleven patients with skin lesions or necrotic ulcers were referred between January 2000 and June 2002. RESULTS: In two patients that were inpatients in other hospitals, investigation and follow up was not possible. In both cases there was no history of spider bite and Staphylococcus aureus was cultured. In nine patients, a diagnosis other than spider bite was made following appropriate investigation and follow up, including: (i) two cases of dermatophytoses, (ii) three staphylococcal infections, (iii) one case of pyoderma gangrenosum, (iv) one case of cutaneous polyarteritis nodosa, (v) one case of Nocardia braziliensis and (vi) one infected diabetic ulcer. There was only one case where the person recalled seeing a spider bite them, but the patient did not collect the spider for identification. The median time to diagnosis was 3 weeks (interquartile range: 3-9 weeks) and 3.5 years in one case. Appropriate treatment was initiated once the correct diagnosis was made and all cases resolved. CONCLUSIONS: In this series, all cases initially referred as WT spider bites or necrotic arachnidism were found to have alternative diagnoses with appropriate investigations. This demonstrates that spider bites are an unlikely cause of necrotic ulcers and that all ulcers should be properly investigated with bacterial, fungal and mycobacterial cultures and skin biopsy for histopathology.

Adult↗

PubMed2005

Electrophysiological correlates of threat processing in spider phobics.

The electrocortical correlates of the processing of feared/fear-relevant and neutral stimuli were investigated in a pictorial emotional Stroop paradigm with spider phobic, social phobic, and nonphobic subjects. Subjects identified either the color of red or blue pictures of spiders, birds, or flowers (emotional Stroop task) or the object itself (identification task) by pressing different buttons. No emotional Stroop interference was found for spider phobic subjects when identifying the color of spiders as opposed to neutral stimuli. However, in the object identification task, spider phobic subjects identified spiders significantly faster than birds or flowers. Parietal P300 and P400 amplitudes were enhanced independent of task in spider phobic but not in nonphobic subjects when viewing pictures of spiders, which is consistent with previous studies showing that highly unpleasant and arousing pictures affect parietal late positive potentials.

Adult↗

PubMed2005

Effects of spider Macrothele raven venom on cell proliferation and cytotoxicity in HeLa cells.

AIM: To examine the effect of venom from the spider Macrothele raven on cell proliferation and cytotoxicity in human cervical carcinoma, HeLa cells. METHODS: Morphological and biochemical signs of apoptosis appeared using acridine orange-ethidium bromide (AO/EB) staining. Marked morphological changes in HeLa cells after treatment with spider venom were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cell proliferation and cytotoxicity were determined by [methyl-3H] thymidine assay ([3H]TdR) and lactate dehydrogenase (LDH) release, respectively. DNA fragmentation and cell cycle distribution were monitored using flow cytometry. In addition, Western blot analysis was used to evaluate the level of caspase-3 expression. In vivo examination of the inhibition of the size of tumors in nude mice treated with spider venom was measured. RESULTS: Marked morphological changes were observed using AO/EB staining, SEM and TEM assay. Spider venom at concentrations of 10-40 mg/L caused dose- and time-dependent inhibition of HeLa cell proliferation. The ratio of apoptosis and necrosis increased. The activity of caspase-3 was upregulated after spider venom treatment. In vivo study of tumor size revealed that tumors significantly decreased in size from controls to tumors treated for 3 weeks with spider venom (P<0.05). CONCLUSION: The inhibition of HeLa cells by the venom of the spider Macrothele raveni was carried out in three ways: induction of apoptosis, necrosis of toxicity damage and direct lysis. Spider venom is a novel anti-tumor material both in vitro and in vivo.

Animals↗

PubMed2003

Early patterning of the spider embryo: a cluster of mesenchymal cells at the cumulus produces Dpp signals received by germ disc epithelial cells.

In early embryogenesis of spiders, the cumulus is characteristically observed as a cellular thickening that arises from the center of the germ disc and moves centrifugally. This cumulus movement breaks the radial symmetry of the germ disc morphology, correlating with the development of the dorsal region of the embryo. Classical experiments on spider embryos have shown that a cumulus has the capacity to induce a secondary axis when transplanted ectopically. In this study, we have examined the house spider, Achaearanea tepidariorum, on the basis of knowledge from Drosophila to characterize the cumulus at the cellular and molecular level. In the cumulus, a cluster of about 10 mesenchymal cells, designated the cumulus mesenchymal (CM) cells, is situated beneath the epithelium, where the CM cells migrate to the rim of the germ disc. Germ disc epithelial cells near the migrating CM cells extend cytoneme-like projections from their basal side onto the surface of the CM cells. Molecular cloning and whole-mount in situ hybridization showed that the CM cells expressed a spider homolog of Drosophila decapentaplegic (dpp), which encodes a secreted protein that functions as a dorsal morphogen in the Drosophila embryo. Furthermore, the spider Dpp signal appeared to induce graded levels of the phosphorylated Mothers against dpp (Mad) protein in the nuclei of germ disc epithelial cells. Adding data from spider homologs of fork head, orthodenticle and caudal, we suggest that, in contrast to the Drosophila embryo, the progressive mesenchymal-epithelial cell interactions involving the Dpp-Mad signaling cascade generate dorsoventral polarity in accordance with the anteroposterior axis formation in the spider embryo. Our findings support the idea that the cumulus plays a central role in the axial pattern formation of the spider embryo.

Amino Acid Sequence↗

PubMed2004

Colourful orb-weaving spiders, Nephila pilipes, through a bee's eyes.

Many orb-weaving spiders in the tropics forage in open sites during the day and some of them have both bright and dark colourations. The conspicuous UV-reflective colour markings of these spiders have been reported to be attractive to visually oriented prey and thus could increase the spiders' foraging success. Using a combination of field and laboratory studies, we examine whether or not the body colouration of orb-weaving spiders exhibits optical properties that are attractive to insect prey from the viewpoint of insect visual physiology. We compared the prey interception rates and colour contrasts of the typical and melanic morphs of the giant wood spider, Nephila pilipes. Results of the field study showed that the typical morph caught significantly more insects than the melanic morph. Colour contrasts calculated from spectral reflectances of the background and body surface of spiders showed that the brightly coloured body parts of the typical morph exhibited rather high values, but those of the dark body parts were below the discrimination threshold. The differential colour contrasts of body parts generated a visual signal unlike that of a spider but rather like certain forms of food resources. On the other hand, the melanic morphs did not have bright colouration and the colour contrasts of every part of the body were significantly higher than the threshold, making the contour of spiders quite clear to bees.

Animals↗

PubMed2006

Bird-spiders (Arachnida, Mygalomorphae) as perceived by the inhabitants of the village of Pedra Branca, Bahia State, Brazil.

This paper deals with the conceptions, knowledge and attitudes of the inhabitants of the county of Pedra Branca, Bahia State, on mygalomorph spiders locally known as 'caranguejeiras' (bird-spiders). It is launched here a new filed within ethnozoology: ethnoarachnology, which is defined as the transdisciplinary study of the relationships between human beings and bird-spiders. Data were collected from February to June 2005 by means of open-ended interviews carried out with 30 individuals, which ages ranged from 13 to 86 years old. It was recorded some traditional knowledge regarding the following items: taxonomy, biology, habitat, ecology, seasonality, and behavior. Results show that bird-spiders are classified as "insects". The most commented aspect of the interaction between bird-spiders and inhabitants of Pedra Branca is related to their dangerousness, since they said these spiders are very venomous and can cause health problems. In general, the traditional zoological knowledge of Pedra Branca's inhabitants concerning these spiders is coherent with the academic knowledge.

Adolescent↗

PubMed1997

Spider bite. A rational approach.

BACKGROUND: Spider bite is one of the most common envenomation problems in Australia. Australia is home to two spiders of major medical importance; the Sydney funnel web spider and the redback spider. OBJECTIVE: This paper describes the features of envenomation and discusses treatment for bites by the Sydney funnel web spider and the redback spider. Bites by other spiders are also discussed, as is the problem of necrotising arachnidism. DISCUSSION: It is hoped that the information contained within this article will be of help to medical practitioners dealing with spiderbite throughout Australia. There is, as yet, a great deal to be learned about spiderbite, particularly necrotising arachnidism.

Animals↗

PubMed2000

Web damage and feeding experience influence web site tenacity in the orb-web spider Argiope keyserlingi Karsch.

For orb-web spiders, the decision to remain at a particular site or to relocate elsewhere will ultimately depend on the quality of the site. In the past, the quality of the site has been measured in terms of prey availability; spiders experiencing large numbers of prey items are less likely to relocate. However, regular web damage caused by larger nonprey animals may also contribute to the quality of a particular site. Laboratory experiments revealed that the frequency and extent of web relocation by the orb-web spider Argiope keyserlingi was influenced by the feeding regime and the rate of nonprey web damage. Daily movement patterns were influenced by web damage, and these movements were in the direction away from the source of damage. However, the cumulative distance moved during the 7 days of the experiment was influenced by the frequency with which spiders were fed. Spiders that were not given prey moved further than spiders that obtained prey. These data indicate that spiders respond to web damage on a daily basis, but the cumulative movement of spiders over a longer period is influenced mostly by the history of prey ingestion rate. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed2001

Morphological and membrane characteristics of spider and spindle cells isolated from rabbit sinus node.

This study reports the comparative quantitative, morphological, and electrophysiological properties of two pacemaker cell types, spider and spindle-shaped cells, isolated from the rabbit sinoatrial node. Isolated nodal cells were studied with perforated and ruptured patch whole cell recording techniques. The basic spontaneous cycle length of the spider cells was 381 +/- 12 ms, and the basic spontaneous cycle length of the spindle cells was 456 +/- 17 ms (n = 12, P < 0.05). The spider cells had a more positive maximum diastolic potential (-54 +/- 1 mV) compared with the spindle cells (-68 +/- 1mV, P < 0.05). The overshoot and action potential amplitudes were also smaller in the spider cells. The hyperpolarization-activated inward (I(f)) current density, measured from their tail currents, was 15 +/- 1.3 pA/pF for the spider cells and 9 +/- 0.7 pA/pF for the spindle cells (P < 0.01). I(f) current activation voltage was more positive in the spider cells than the spindle cells. Isoproterenol (1 microM) decreased the spontaneous cycle length of the spider cells by 28 +/- 3% and the spindle cells by 20 +/- 1.5% (P < 0.05). Acetylcholine (0.5 microM) hyperpolarized the membrane potential of the spider cells to -86 +/- 0.7 mV and the spindle cells to -76 +/- 0.8 mV (P < 0.05). In summary, there are at least two distinct pacemaker cell types in the sinus node with different electrophysiological characteristics.

Acetylcholine↗

PubMed1998

Spider angiomas are not found in the retina of patients with cirrhosis.

To determine the prevalence of spider angiomata in patients with cirrhosis, the factors influencing them and whether or not they are present in the retina of patients with cirrhosis, 93 cirrhotics were studied. Cutaneous spider angioma were seen in 19 (20%) patients. All patients with spiders had at least one episode of variceal bleeding and had grade III or IV oesophageal varices. Spiders were seen more commonly in patients with alcoholic cirrhosis than in those with non-alcoholic cirrhosis (53.5% vs 6%, p < 0.001), in patients with Child's C cirrhosis than those with Child's A and B cirrhosis (67% vs 4%, p < 0.001). However, although spiders were seen more often in patients undergoing sclerotherapy than those not, the difference was statistically not significant (23% vs 19%, p = NS). Spiders had no association with presence or absence of portal hypertensive gastropathy or gastric varices. None of the patients showed any abnormality or presence of spiders in the retina. It is concluded that spider angiomas are seen more commonly in patients with alcoholic cirrhosis, those with more severe liver disease and patients having large oesophageal varices and they are not seen in the retina of patients with cirrhosis.

Adult↗

PubMed2003

Control of the two-spotted spider mite (Tetranychus urticae Koch) in glasshouse roses.

Populations of the two-spotted spider mite, Tetranychus urticae, can increase rapidly in glasshouse production, especially during summer. Both chemical and biological control must start at low densities for effective control. The combined efficacy of Phytoseiulus persimilis and the predatory midge, Feltiella acarisuga to control T. urticae on roses was evaluated in 2002. A second year rose crop (Rosa hybrida cv. First Red) was used for this experiment. Two glasshouse compartments of 200 m2 each were used, one was assigned for integrated control and the other for chemical control. The mite populations were monitored by bi-weekly analysis of 12 randomly selected harvestable flower stems, extracted on the Berlese funnel. Sticky plates (3 yellow and 3 blue/200 m2) were used for monitoring the Feltiella adults. End of January a population of +/- 2 spider mites/flower was present in both compartments. In the integrated control, the first Phytoseiulus were released on February the 7th, while the first release of Feltiella was on February the 20th. From week 7 till 13 the population of T. urticae increased exponentially to 90 spider mites/flower stem, while Phytoseiulus population was below one/flower stem. A treatment of fenbutatinoxide + hexythiazox (Torque + Nissuron) was necessary to reduce the spider mite population. A maximum number of predatory mite (4/flower stem) and predatory midge (106 adults/sticky plate) was found only 4 weeks later. A second increase of spider mite population occurred in week 27. Although 2 weeks later 3 predatory mites/flower stem were present, additional chemical treatment was necessary to control. A third and last increase of spider mite occurred in week 39. This last raise could be controlled effectively by Phytoseiulus and Feltiella. Chemical control in the second compartment was effective all-year-round with the exception of week 23 when a major increase up to 60 spider mites/flower stem was found. The applied biocontrol agents could not efficiently control spider mite in glasshouse rose. However, combined with selective insecticides they offer possibilities for IPM in glasshouse roses.

Acari↗

PubMed1988

Cutaneous vascular spiders in cirrhotic patients: correlation with hemorrhage from esophageal varices.

Ninety-two consecutive male cirrhotic patients had esophagoscopy to determine the presence and size of varices, and a concomitant skin examination for assessment of cutaneous vascular spiders. Thirty-one subjects bled from varices within 10 days of the spider evaluation, and this group was compared to 61 individuals who never bled. Our results show that incidence of spiders (90%) and varices (91%) is nearly identical, that frequency of variceal bleeding is higher among subjects with spiders compared with those who lack these lesions (36% vs 11%, p less than 0.05), and that the spider profile may be useful to identify individuals who are at increased risk for variceal hemorrhage. Frequency of bleeding was 50% (p less than 0.01) when greater than 20 spiders were present and 63% (p less than 0.01) when multiple atypically located lesions were detected. Large spiders (greater than 15 mm) correlate best with large varices and have the strongest association with bleeding (80%, p = 0.0002). If evidence of benefit from prophylactic treatment of esophageal varices can be established, then elements of the spider profile may serve as a discriminating marker to assist in selection of appropriate patients for therapy.

Adult↗

PubMed2004

The global epidemiology, syndromic classification, management, and prevention of spider bites.

Spiders are carnivorous arthropods that coexist with humans and ambush or ensnare prey. Unlike other arthropods, spiders rarely transmit communicable diseases, and play a critical role in the ecosystem by consuming other arthropods that frequently transmit human diseases, such as mosquitoes and flies. There are more than 30,000 species of spiders, most of which are venomous, but they cannot inflict serious bites due to delicate mouthparts and short fangs. The differential diagnosis of spider bites is extensive and includes other arthropod bites, skin infections, and exposure to chemical or physical agents. However, approximately 200 species from 20 genera of spiders worldwide can cause severe human envenomings, with dermonecrosis, systemic toxicity, and death. Spider bites can usually be prevented by simple personal and domestic measures. Early species identification and specific management may help prevent serious sequelae of spider bites.

Animals↗

PubMed2005

Brown recluse spider bites: a complex problem wound. A brief review and case study.

Brown recluse spiders (Loxosceles reclusa) are responsible for virtually all documented cases of spider bites leading to significant necrosis. The actual spider bite often goes unnoticed for as long as 4 to 6 hours, which makes diagnosis and, therefore, appropriate treatment, difficult. The spider bite generally results in either a necrotic wound or systemic symptoms that can lead to hemolysis. The patient described in this article experienced both complications. Dapsone and hyperbaric oxygen therapy brought the adverse response to the bite under control. The patient was hospitalized for 7 days during treatment for hemolysis and an extensive, necrotic wound. Efforts are underway to develop an assay to provide a definitive diagnosis for the brown recluse spider bite, but none is yet commercially available. Antivenom is scarce; capture of the offending spider appears to be most helpful in the diagnosis and proper treatment of spider bites.

Adult↗

PubMed2006

Lyriform slit sense organs on the pedipalps and spinnerets of spiders.

Lyriform slits sense organs (LSSO) are a precise assembly of stress detecting cuticular slit sensilla found on the appendages of arachnids. While these structures on the legs of the wandering spider Cupennius salei are well studied in terms of morphology, function and contribution to behaviour, their distribution on pedipalps and spinnerets of spiders is not well explored. A study was therefore carried out to observe the distribution of LSSO on pedipalps and spinnerets of some spider species. Haplogyne spiders belonging to family Pholcidae have a simple complement of LSSOs represented by one or two LSSOs on their femur. The entelegyne spiders possess a complex assembly of LSSOs on the distal segments of their pedipalps. Various types of LSSOs are found on the pedipalps indicating a capacity for analysis of complex cuticular stress. It is suggested that the complexity of LSSOs on pedipalps of entel-egyne spiders relates to courtship and spermatophore transfer and may help in reproductive isolation. Lack of LSSOs on the distal segments of pedipalps leads us to infer that unlike legs, pedipalps are less likely to receive vibratory input through their distal segments. Spinnerets have a relatively simple complement of LSSOs. One LSSO is found only on anterior spinnerets and it is a common feature observed among spiders, irrespective of the variations in web building behaviour. The orb-weaving araneid Argiope pulchella, however, has two LSSOs on the anterior spinneret. As non-web builders and orb weavers do not differ markedly in terms of LSSOs on the spinnerets and LSSOs are simple in nature (type A), it is likely that spinning and weaving are not largely regulated by sensory input from LSSOs on the spinnerets.

Animals↗