Clinical consequences of toxic envenomation by spiders.

Spider venom is being researched for its potential use in applications such as insecticides, to better understand the dynamics of neuronal ion channel physiology and as potential remedies to counter antibiotic resistant bacteria. However, spider venom is more widely known for its ability to cause deleterious reactions after toxic envenomations in humans. In this short review, the "dark" side of spider venoms is presented to provide a counterbalance to the investigations of the positive potential that venoms can or might improve our world or its understanding.

Distribution and medical aspects of Loxosceles rufescens, one of the most invasive spiders of the world (Araneae: Sicariidae).

Loxosceles rufescens is a circum-Mediterranean spider species, potentially harmful to humans. Its native area covers the Mediterranean Basin and Near East. Easily spread with transported goods, it is meanwhile an alien and invasive species to nearly all other continents and many islands.

Efficacy of Several Pesticide Products on Brown Widow Spider (Araneae: Theridiidae) Egg Sacs and Their Penetration Through the Egg Sac Silk.

Information on pesticide effects on spiders is less common than for insects; similar information for spider egg sacs is scarcer in the open literature. Spider egg sacs are typically covered with a protective silk layer. When pesticides are directly applied to egg sacs, the silk might prevent active ingredients from reaching the eggs, blocking their insecticidal effect.

Establishment of the Brown Widow Spider (Araneae: Theridiidae) and Infestation of its Egg Sacs by a Parasitoid, Philolema latrodecti (Hymenoptera: Eurytomidae), in French Polynesia and the Cook Islands.

This paper presents two newly established species for French Polynesia: the invasive brown widow spider, Latrodectus geometricus C. L. Koch, and its potential biocontrol agent, the parasitoid wasp, Philolema latrodecti (Fullaway).

Spiders (Araneae) Found in Bananas and Other International Cargo Submitted to North American Arachnologists for Identification.

Spiders found in international cargo brought into North America are sometimes submitted to arachnologists for identification. Often, these spiders are presumed to be of medical importance because of size or a submitter's familiarity with a toxic spider genus from the continent of origin. Starting in 2006, requests were made for spiders found in international cargo brought into North America, in addition to the specimens from similar cargo shipments already in our museum collections.

Exposure of Brown Recluse and Brown Widow Spiders (Araneae: Sicariidae, Theridiidae) to a Commercial Sulfuryl Fluoride Fumigation.

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.

Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity.

This study compiled 33 verified spider bites from the state of Oregon (USA). The initial goal was to amass a series of bites by the hobo spider to assess whether it possesses toxic venom, a supposition which is currently in a contested state. None of the 33 bites from several spider species developed significant medical symptoms nor did dermonecrosis occur.

Distribution of the brown recluse spider (Araneae: Sicariidae) in Illinois and Iowa.

The medical importance of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik, is well known, but there is a need for more accurate information about the distribution of the spider in North America. We gathered information via an Internet offer to identify spiders in Illinois and Iowa that were thought to be brown recluses. We also mined brown recluse locality information from other agencies that kept such records.

Spider envenomation in North America.

In North America, spider envenomation is perceived to be a greater threat than in actuality; however, it still is a valid source of morbidity and, very rarely, mortality. Only 2 groups (widows, recluses) are medically important on this continent. Widow bites affect the neuromuscular junction, have minor dermatologic expression, and are treated with analgesics and antivenom.

The prevalence of brown widow and black widow spiders (Araneae: Theridiidae) in urban southern California.

The brown widow spider, Latrodectus geometricus C. L. Koch, has become newly established in southern California during the first decade of the 21st century.

Envenomation by spiders of the genus Hololena (Araneae: Agelenidae).

Three verified bites from Hololena spiders (Family Agelenidae) are presented here. Two male victims, each over 100 kg weight (bitten by female spiders), experienced headaches and 4-h episodes of vomiting. A female bite victim (bitten by a male spider) experienced minor reaction.

Seasonality of brown recluse spiders, Loxosceles reclusa, submitted by the general public: implications for physicians regarding loxoscelism diagnoses.

Many medically important animals exhibit fluctuating seasonal abundance such that risk from envenomation or disease is not constant throughout the year. As indicated by homeowner submissions, brown recluse spiders, Loxosceles reclusa, show seasonal peaks of activity during summer and paucity in winter. This information should be incorporated as part of the diagnostic algorithm for physicians when considering the probability of loxoscelism in endemic Loxosceles areas especially if a skin lesion occurs when spiders are scarce.

Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider.

Experiments reported in Sandidge (2003; Nature 426: 30) indicated that the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, preferred to scavenge dead prey over live prey and that the spiders were not detrimentally affected when fed insecticide-killed crickets. Extrapolations made in subsequent media coverage disseminating the results of this research made counter-intuitive statements that pesticide treatment in houses would increase brown recluse populations in homes. This information was presented as if the scavenging behavior was specialized in the brown recluse; however, it was more likely that this behavior has not been well studied in other species.

Cobweb management and control of the spider Holocnemus pluchei (Araneae: Pholcidae) on buildings.

The spider Holocnemus pluchei (Scopoli) (Araneae: Pholcidae) is a nonnative species commonly found in the southwestern United States. In urban areas around homes and other structures, it is often the dominant spider species on outside surfaces; requests for control of spiders and their cobwebs are common for the commercial pest management industry. We tested two physical (brushing and vacuuming) and two low-impact chemical (permethrin and botanical insecticide) spray control methods for H.

Tracking a medically important spider: climate change, ecological niche modeling, and the brown recluse (Loxosceles reclusa).

Most spiders use venom to paralyze their prey and are commonly feared for their potential to cause injury to humans. In North America, one species in particular, Loxosceles reclusa (brown recluse spider, Sicariidae), causes the majority of necrotic wounds induced by the Araneae. However, its distributional limitations are poorly understood and, as a result, medical professionals routinely misdiagnose brown recluse bites outside endemic areas, confusing putative spider bites for other serious conditions.

Development of virtual bait stations to control Argentine ants (Hymenoptera: Formicidae) in environmentally sensitive habitats.

A novel bait station referred to as a virtual bait station was developed and tested against field populations of the invasive Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), at White Beach, Camp Pendleton, in Oceanside, CA. White Beach is a nesting habitat for an endangered seabird, the California least tern (Sterna antillarum browni Mearns). The beach is heavily infested with Argentine ants, one of the threats for the California least tern chicks.

Influence of spider silk on refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae).

In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling).

Brown recluse spider (Loxosceles reclusa) envenomation in small animals.

Objective: To provide a comprehensive review of relevant literature regarding the brown recluse spider (BRS) and to define those criteria that must be satisfied before making a diagnosis of brown recluse envenomation.

Etiology: The complex venom of the BRS contains sphingomyelinase D, which is capable of producing all the clinical signs in the human and some animal models.

Diagnosis: There is no current commercially available test.

The ability of spiderlings of the widow spider Latrodectus hesperus (Araneae: Theridiidae) to pass through different size mesh screen: implications for exclusion from air intake ducts and greenhouses.

Experiments tested the ability of newly emerged spiderlings of a black widow spider, Latrodectus hesperus Chamberlin & Ivie (Araneae: Theridiidae), to crawl through brass screen of various mesh size. The purpose was to determine whether immatures of these medically important spiders could be excluded from buildings. In horizontal orientation, black widow spiderlings were able to easily pass through mesh with openings of 0.

Arachnids misidentified as brown recluse spiders by medical personnel and other authorities in North America.

Misidentification of harmless or nearly benign arachnids as Loxosceles spiders by medical personnel and other authorities proliferates misinformation in regard to alleged loxoscelism and leads to decreased health care. This is especially true in areas of North America where Loxosceles spiders are rare or non-existent. A diverse assemblage of such misidentified arachnids is presented here.