Latrodectus Geometricus Research Articles

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. We investigated the impact of six water-based pesticide sprays and four oil-based aerosol products against egg sacs of brown widow spiders, Latrodectus geometricus C. L. Koch. All water-based spray products except one failed to provide significant mortality to egg sacs, resulting in successful spiderling emergence from treated egg sacs at a similar rate to untreated egg sacs. In contrast to water-based sprays, oil-based aerosols provided almost complete control, with 94-100% prevention of spiderling emergence. Penetration studies using colored pesticide products indicated that oil-based aerosols were significantly more effective in penetrating egg sac silk than were the water-based sprays, delivering the active ingredients on most (>99%) of the eggs inside the sac. The ability of pesticides to penetrate spider egg sac silk and deliver lethal doses of active ingredients to the eggs is discussed in relation to the chemical nature of egg sac silk proteins. Our study suggests that pest management procedures primarily relying on perimeter application of water-based sprays might not provide satisfactory control of brown widow spider eggs. Determination of the most effective active ingredients and carrier characteristics warrant further research to provide more effective control options for spider egg sacs.

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). The brown widow spider was recorded from the island of Moorea in 2006 and, since that discovery, the occurrence of this species has expanded to two of the five archipelagos of French Polynesia including the main island of Tahiti and four of the Cook Islands. Although the tropical climate contributes to the establishment of L. geometricus, a biotic factor, P. latrodecti, may restrain population from demographic explosion. This eurytomid wasp is present in French Polynesia and is a parasitoid that has been used in biological control of the southern black widow Latrodectus mactans (F.) in Hawaii. This wasp could become a significant limiting factor for L. geometricus distribution on these islands, as it was found in 31% of the Tahitian brown widow spider egg sacs that were dissected. However, thus far, the wasp was only found on Tahiti in association with the brown widow spider. Although the brown widow is generally considered to be less toxic than its black widow relatives, it remains of medical concern in French Polynesia because reactions to its bites can, at times, be severe. The spider remains of public concern because it is a novel species; it has the word widow in its name and dark morphs are mistaken as black widows.

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

BackgroundThe 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.MethodsWe 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.ResultsThe 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.ConclusionReports 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.

Venomous Spiders of the Southeastern US: An Unexpected Threat

Background: Environmental health specialists recommend that residents of the Southeastern US, including Georgia, have the ability to identify the three venomous spiders indigenous to this area. It is necessary to recognize the black widow, brown widow, and brown recluse spiders and to be familiar with the likely habitats of these insects and with the symptoms of bites. The primary author, who serves as an Environmental Health Specialist and is a hobbyist who works with distressed wood, frequently encounters all three of these spiders.

Records of brown widow spider, <I>Latrodectus geometricus</I> Koch 1841, (Araneae: Theridiidae) from Gujarat, western India, with notes on its distribution, habitat and natural history

Records of brown widow spider, <I>Latrodectus geometricus</I> Koch 1841, (Araneae: Theridiidae) from Gujarat, western India, with notes on its distribution, habitat and natural history

First record of a brown widow spider Latrodectus geometricus Koch, 1841 (Araneae, Theridiidae) feeding scorpion (Scorpiones, Bothriuridae) in a Brazilian Atlantic forest.

(With 1 figure)Scorpions are generalist predators, capturing a great variety of arthropods including even small vertebrates (Polis, 1990), however, they are also subject to predation, especially by vertebrates such as amphibians, reptiles, birds and mammals (Polis et al., 1981; McCormick and Polis, 1990). Regarding the invertebrates, there are reports of predation by coleopterans, chilopods, solpugids, others scorpions and spiders (Cloudsley-Thompson, 1960; Williams, 1966; Cloudsley-Thompson, 1977; Punzo, 1998; McCormick and Polis, 1990; Melic, 2000 ). There is no record for this phenomenon in the Brazilian Atlantic Forest. To increase knowledge about the natural history these arachnids, this paper reports the first case of scorpion predation by spider for this biome. The observation was reported during field work in Reserva Particular de Patrimonio Natural Nossa Senhora do Oiteiro de Maracaipe (08°31’48”S, 35°01’05”O), Ipojuca, Southern coast of Pernambuco state, Brazil. The reserve area totals 76.2 ha, of these, 29.7 ha occupied by Atlantic forest (22.7%) classified by restinga and 46.5 ha occupied by mangroves. On 15-I-2013 at about 9:00 pm, following the nocturnal collection of a scorpion sample (active search), the second author (Costa, A.) noted on a scorpion (Bothriurus sp.) caught in the web of Latrodectus geometricus Koch, 1841 on a small bush approximately 30 cm above the ground (Figure 1). The scorpion found himself paralyzed, with the spider feeding its fluids. Probably the scorpion was captured while walking through the litter as this type of spider prey capture touching sues capture vertical wires down and quickly injecting its paralyzing venom. Both, the spider and the scorpion were deposited in Arachnological Collection of Universidade Federal de Pernambuco, Recife, Brazil. The present case of predation may be considered as occasional. Latrodectus geometricus is not a regular predator of scorpions, but a generalist hunter that feeds on large diversity of prey like others Latrodectus species (Melic, 2000).

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. L. Koch, to a commercial fumigation event using sulfuryl fluoride directed at termite control. General consensus from the pest control industry is that fumigation is not always effective for control of spiders for a variety of reasons, including insufficient fumigant dosage, particularly, for contents of egg sacs that require a higher fumigant dosage for control. We demonstrated that a sulfuryl fluoride fumigation with an accumulated dosage of 162 oz-h per 1,000 ft(3) at 21°C over 25 h (≈1.7 × the drywood termite dosage) directed at termites was sufficient to kill adult brown recluse and brown widow spiders. The effectiveness of commercial fumigation practices to control spiders, and particularly their egg sacs, warrants further study.

Aggregation Behavior in Spiderlings: a Strategy for Increasing Life Expectancy in Latrodectus geometricus (Araneae: Theridiidae)

Studies on the biology of Latrodectus geometricus are scarce, especially on the behavior and life expectancy of the species. In this study we investigated the importance of the aggregation behavior of juveniles on life expectancy and longevity of the species. Egg sacs were collected in the urban area of Dourados- MS and transferred to the laboratory. The spiderlings hatched were separated into two groups: spiderlings aggregated and isolated, kept in the presence of luminosity. The same tests were run with egg sacs deprived of luminosity. A calculation of entropy was performed for all cases. Individuals grouped held under light exposure showed 14.3 days of life expectancy and 46 maximum longevity and 14.8 days of life expectancy and 32 days of longevity when isolated. For individuals grouped and deprived of light life expectancy was 29.8 days and maximum longevity 85 days and 19.3 days of life expectancy and 26 days of maximum longevity when isolated. The entropy of individuals kept in the presence of light, when grouped was H=0.692 and when isolated H=0.377. For individuals deprived of light, the entropy was H = 0.628 when kept grouped and H = 0.143 when isolated. Therefore it is concluded that the aggregation behavior and luminosity influence the longevity and life expectancy of spiderlings. Cannibalism must be a strategy to acquire food reserves contributing to the survival of a small number of individuals.

Natural Egg Sac Clutch Size of the Brown Widow Spider,Latrodectus geometricus(Araneae: Theridiidae) in Southern California

The brown widow spider, Latrodectus geometricus C. L. Koch, 1841, is a non-native arachnid that became established in peninsular Florida in the 1930s (Pearson 1936). In the first decade of the 21 century, it rapidly spread through the southeastern United States and southern California (Brown et al. 2008; Vincent et al. 2008; Vetter et al. 2012a) and has become a ubiquitous urban pest species in the Los Angeles Basin and San Diego area (Vetter et al. 2012b). One possible reason for its success lies in its fecundity, as it can produce an egg sac every four days during its earliest ovipositions and averages 22 egg sacs in a lifetime (Bouillon and Lekie 1961). We were interested in documenting the seasonal field egg production of brown widows from June to October to determine whether there is a specific peak and subsequent dropoff in productivity or whether it is fairly consistent throughout the summer season. This provided basic biology information that benefitted research involving insecticide bioassays on brown widow egg sacs (Vetter et al, in prep); knowing the phenology of seasonal clutch size helped determine whether lab-produced egg sacs would be temporally comparable with natural oviposition and, hence, whether pesticides tested on egg sacs would have real world relevance. To determine monthly egg clutch size, brown widow egg sacs were collected during the day from several cities in Orange and Riverside counties, California from June through October 2012. Collections were restricted to urban sites such as around homes, in parks, under playground equipment, etc. as documented favored habitats for this spider (Vetter et al. 2012b). We attempted to collect egg sacs primarily from sites that were occupied by female brown widows as this presumedly increased the chances of collecting sacs with freshly laid eggs. The study was terminated at the end of October because temperatures cool considerably in November in southern California. We did not collect egg sacs for the first seven days of any month in order to more accurately assign sacs with eggs to the correct month of oviposition. At 29uC, brown widow eggs hatch in 9 days. Considering that daily high temperatures in many of our collection locales are typically 35 to 40uC, we felt that this was an acceptable estimate to separate clutch size into monthly cohorts. We also received some sacs in the mail from citizen scientists who participated in previous brown widow studies (Vetter et al. 2012a,b); again, no data from sacs collected and received during the first week of the month were used.

Notes on the biology of the wasp, Chalybion spinolae (Hymenoptera: Sphecidae), an obligatory predator of Latrodectus (Araneae: Theridiidae) spiders in South Africa

Some aspects of the biology of the wasp Chalybion spinolae are documented. This includes behaviour relating to life cycles, nesting, mating, oviposition and prey interaction of this wasp. The physical appearance of the wasps and their prey are described and some measurements are given. The prey of C. spinolae are two species of spiders, Latrodectus indistinctus and Latrodectus geometricus (Araneae: Theridiidae). The observations spanned a period of 5 years, and involved approximately 200 wasp nests. This study serves to provide more observational information about the biology of the wasp and its predatory behaviour.

Substrate Preferences for Attaching Gumfoot Lines inLatrodectus geometricus(Araneae: Theridiidae)

Spider web construction is energetically costly, but it plays an important role in survivorship and reproduction. Studies have revealed facultative changes in spider web construction to adjust to available attachment sites. We used rectangular cardboard frames and two contrasting substrates to determine preferences in placement of gumfoot lines. This study demonstrated that mature females and first-instar nymphs of the brown widow spider, Latrodectus geometricus, display preferences for smooth substrates as sites to attach the gumfoot lines of their webs. First-instar nymphs also preferred to attach to the peaks when offered a wrinkled substrate. The preference of first-instar nymphs supports the hypothesis that substrate preferences for gumfoot line attachment may already be a selected behavior and not learned from previous experience.

Recruitment and diversification of an ecdysozoan family of neuropeptide hormones for black widow spider venom expression

Venoms have attracted enormous attention because of their potent physiological effects and dynamic evolution, including the convergent recruitment of homologous genes for venom expression. Here we provide novel evidence for the recruitment of genes from the Crustacean Hyperglycemic Hormone (CHH) and arthropod Ion Transport Peptide (ITP) superfamily for venom expression in black widow spiders. We characterized latrodectin peptides from venom gland cDNAs from the Western black widow spider (Latrodectus hesperus), the brown widow (Latrodectus geometricus) and cupboard spider (Steatoda grossa). Phylogenetic analyses of these sequences with homologs from other spider, scorpion and wasp venom cDNAs, as well as CHH/ITP neuropeptides, show latrodectins as derived members of the CHH/ITP superfamily. These analyses suggest that CHH/ITP homologs are more widespread in spider venoms, and were recruited for venom expression in two additional arthropod lineages. We also found that the latrodectin 2 gene and nearly all CHH/ITP genes include a phase 2 intron in the same position, supporting latrodectin's placement within the CHH/ITP superfamily. Evolutionary analyses of latrodectins suggest episodes of positive selection along some sequence lineages, and positive and purifying selection on specific codons, supporting its functional importance in widow venom. We consider how this improved understanding of latrodectin evolution informs functional hypotheses regarding its role in black widow venom as well as its potential convergent recruitment for venom expression across arthropods.

Susceptibility ofLatrodectus geometricus(Araneae: Theridiidae) to aMucorStrain Discovered in North Central Florida, USA

A population of adult reproductive female brown widow spiders, Latrodectus geometricus Koch (Araneae: Theridiidae) was collected in North Central Florida. Within weeks, the spiders displayed reduced foraging behavior and began to die. A white fungal growth was observed on deceased individuals and others who showed signs of decline. Fungal samples were collected from living spiders as well as from recently deceased specimens. Samples were excised from the spiders and isolated on acidified potato dextrose agar. Morphological characterization was cross referenced with the most recent phenotypic variability studies to confirm probable matches. Molecular identification was rendered using ITS1/5.8S/ITS2 and Mucor fragilis Bainier (Mucorales: Mucoraceae) was indicated with 99% match. Little is documented regarding M. fragilis, and no prior records of pathogenic occurrence are known by the authors. Subsequent bioassay trials supported with 83% mortality that this novel strain of M. fragilis does infect and kill L. geometricus.

Habitat, redescription and distribution of Latrodectus geometricus in Uruguay (Araneae: Theridiidae)

This study provides the first accurate records of Latrodectus geometricus C. L. Koch, 1841 for Uruguay and extends the known distribution of this species to the Southeastern region of South America. Data and figures of the genitalic morphology for the recognition of the species and natural history in this country are indicated. In Uruguay L. geometricus was mainly restricted to urban areas at the west of this country and it is associated with locations with high human activity.

Incidence of Parasitoids and Predators on Eggs of Seven Species of Therididae (Araneae)

Summary Although many characteristics of the egg sacs of spiders likely evolved to reduce the effect of parasites and predators that attack their eggs, many parasite and predator insects have become specialized on spider eggs. Eggs of six of the seven species of Theridiidae included in this study were attacked by wasp parasites (Baeus achaearaneus, Idris sp., and Comastichus zopheros), and two by the specialized spider egg predator (Neuroptera: Zeugomantispa minuta). The incidence of parasites in the egg sacs varied across species. Parasites attacked more than 60% of the egg sacs of Tidarren sisyphoides and Parasteatoda tepidanorum, but none of the sacs of Latrodectus geometricus. The incidence of parasites in the egg sacs was higher during the dry season for T. sisyphoides, and during the rainy season for P. tepidanorum. The proportion of the eggs parasitized per egg sac varied from 0.09 (± 0.19) in Nesticodes rufipes to 0.50 (±0.46) in T. sisyphoides. Differences in the biology of parasites, as well as ...

Predators and parasitoids of egg sacs of the widow spiders, Latrodectus geometricus and Latrodectus hesperus (Araneae: Theridiidae) in southern California

Abstract The brown widow spider, Latrodectus geometricus C. L. Koch 1841, is non-native to North America and has experienced an explosive range expansion in the first decade of the 21st century. Previously restricted to peninsular Florida, it is now well established in the southeastern United States and southern California. In southern California, brown widow spiders have become ubiquitous around urban homes and are well known to the general public because of their high numbers and distinctive spiked egg sacs. Several insects attack egg sacs of the native western black widow, L. hesperus Chamberlin & Ivie 1935, as either parasitoids or egg predators. We investigated whether and to what degree these insects would attack brown widow egg sacs. We dissected 3,739 brown widow egg sacs finding evidence of the chloropid fly, Pseudogaurax signatus (Loew 1876) in 2.0% and wasp parasitoids in 0.4% of the sacs. For comparison, we also dissected 263 western black widow egg sacs with P. signatus showing a higher level...

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. Brown widows and egg sacs were collected within the urban Los Angeles Basin using timed searches. We also collected and compared the abundance and distribution of the native western black widow spider, Latrodectus hesperus Chamberlin & Ivie, to brown widows. Brown widows were very common around urban structures especially outside homes, in parks, under playground equipment, in plant nurseries and landscaping areas, greatly outnumbering native western black widows, and were very rare or nonexistent in garages, agricultural crops, and natural areas. Western black widows predominated in xeric habitats and were less prevalent around homes. Neither species was found in the living space of homes. In southern California, envenomation risk exists because brown widows are now common in urban areas and the spiders hide where people place their fingers and exert pressure to move objects (e.g., under the curled lip of potted plants, in the recessed handle of plastic trash bins). Nonetheless, brown widow spider bites are less toxic than those of native western black widow spiders and, hence, if they are displacing black widows, overall widow envenomation risk may actually be lower than before brown widow establishment.

Activities against hemostatic proteins and adrenal gland ultrastructural changes caused by the brown widow spider Latrodectus geometricus (Araneae: Theridiidae) venom

Brown widow spider (BrWS) ( Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24 h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented α/β-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only α-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by L. geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.

Early development of the anterior body region of the grey widow spider Latrodectus geometricus Koch, 1841 (Theridiidae, Araneae)

We document the early morphogenesis of Latrodectus geometricus, particularly of the anterior body region. Significant changes in the development of the external prosomal structures revealed with scanning electron microscopy (SEM) images include: (1) reorganisation of each pre-cheliceral lobe by subdivision and internalisation of its central area; (2) shortening of the ventro-median bridge connecting the pre-cheliceral lobes and its eventual disappearance; (3) appearance and expansion of a prospective mouth region between the pre-cheliceral lobes with a recessed median area surrounded by lip-like borders, the anterior lip-part developing into the hypostome; (4) reduction of the mouth region to an area around the hypostome and the lip-like latero-posterior border of the mouth opening; (5) change of the position of the mouth region from anterior to the insertions of the chelicerae to posterior to them; (6) eventual shortening of the mouth opening to a slit overhung by the hypostome; (7) origination of the prosomal shield from the anterior margin of the pre-cheliceral lobes and the tergal portions of the four posterior-most prosomal segments; and (8) expansion of a ‘ventral sulcus’ from the cheliceral to the fifth opisthosomal segment separating the sides of these segments. Embryonic features are compared across the Chelicerata and discussed briefly in a phylogenetic context.

Neurotoxic activity and ultrastructural changes in muscles caused by the brown widow spider Latrodectus geometricus venom

Brown widow spider (Latrodectus geometricus) venom (BrWSV) produces few local lesions and intense systemic reactions such as cramps, harsh muscle pains, nausea, vomiting and hypertension. Approximately 16 protein bands under reducing conditions and approximately 14 bands under non-reducing conditions on a 12.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis were observed. Neurotoxic clinical manifestations were confirmed in vivo, while proteolytic activity was demonstrated on gelatine film. Severe ultrastructural damages in mice skeletal muscles were observed at 3, 6, 12 and 24 h postinjection with at total of 45 microg of venom protein. Infiltration of eosinophils and ruptures of the cellular membranes were observed in the muscles along with swelling of the nuclear cover and interruption of the collagen periodicity. Altered mitochondrias and autophage vacuoles, nuclear indentation and mitochondria without cristae, slight increment of intermyofibrillar and subsarcolemic spaces and myelinic figures formation were also observed. In the capillary, endothelial membrane unfolding into the lumen was noticed; along with myelinic figures compatible with a toxic myopathy. Swollen sarcotubular systems with lysis of membrane, intense mitochondria autophagia and areas without pinocytic vesicles were observed. Swollen mitochondria surrounded by necrotic areas, myofibrillar disorganization and big vacuolas of the sarcotubular system, degenerated mitochondrium with formation of myelinic figure was seen. Glycogenosomes with small particulate, muscle type glycogen was noticed. Autophagic vacuole (autophagolysosomes) and necrotic areas were also noticed. These damages may be due to interactive effects of the multifactorial action of venom components. However, Latrodectus geometricus venom molecules may also be utilized as neuro therapeutic tools, as they affect neuronal activities with high affinity and selectivity. To our knowledge, the present study is the first ultrastructural report in the literature of muscle injuries and neurological and proteolytic activities caused by BrWSV.