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Spiders were collected from Mango greenhouse at Giza Governorate. There were 27 species belonging to 13 families found on ground and 11 species belonging to 6 families found on foliage. There were 22 species recorded as new locality records of Giza governorate and one species as a new record in Egypt, i.e. Theridion hannoniae. From these species, there are two species in terms of toxicity: Loxosceles rufescens and Latrodectus geometricus. Most families found on mango trees do not spin webs to catch their prey, they are active hunter spiders: Dysderidae, Gnaphosidae, Lycosidae, Oonopidae, Philodromidae, Salticidae, and Cheiracanthiidae. These families play an important role in reducing the pest below the economic threshold level, whereas their predators are more specialised and good hunters. Photos of external genitalia of several species are added to facilitate identification. [ABSTRACT FROM AUTHOR]

The Brown Widow spider (Latrodectus geometricus) is an invasive species whose geographic range has been expanding worldwide. It is a relative species of the Black Widow and Red-backed spiders of the genus Latrodectus. Despite its broad geographic distribution cases of Brown Widow envenomation have rarely been documented. The venom of L. geometricus is similar to the venom of L. mactans with the primary venom component being alpha-latrotoxin, and consequent envenoming by L. geometricus to humans has resulted in symptoms similar to those reported for other Latrodectus spp. Specific FDA approved Latrodectus antivenom (IgG) available in North America has been effectively used in treating venom-induced symptoms following L. mactans envenoming. The patient reported here involved a confirmed L. geometricus envenoming who was efficaciously treated with an alternately available F(ab') 2 antivenom from Mexico. • Brown Widow geographic range is spreading in the USA, yet envenoming reports are rare. • Latrodectus geometricus is a medically important invasive spider species in the USA. • Rapid and profound pain developed following L. geometricus envenoming. • Latrodectus species antivenom, Acramyn Plus®, rapidly resolved envenoming symptoms. [ABSTRACT FROM AUTHOR]

Mating generally occurs with adult females, which undergo a suite of changes in morphology, physiology and behaviour during maturation. In the brown widow spider, Latrodectus geometricus , however, males can mate with immature females during a short period before they moult to the adult stage. Mating with immature females seems beneficial for males, because they are not at risk of being cannibalized, whereas cannibalism inevitably occurs in matings with adult females. We conducted choice experiments to elucidate male preference, courtship and mating behaviour with immature and adult females of different ages. We controlled for age of the females' webs to provide males with potential web-borne attractants of similar age. We tested whether males distinguish immature females that are ready to mate (late subadult stage) from adult females and from immature females that do not mate (early subadults), and we examined male response to young versus old adult females. Males approached and mated with adult females more frequently than late subadult females, but there were no differences in the frequencies of approach to early and late subadults or to adult females of different ages. Once on the web, however, males attempted to mate with the late subadults. We suggest that web-borne volatile cues, typical of adult females, may be reduced or lacking in late subadult females, yet less volatile cues may indicate receptivity. • Mating with immature females is an alternative tactic for brown widow males. • Adult females cannibalize mating males, but immature females do not. • Males approached and preferred to mate with adult females over receptive immatures. • Males did not show a preference for unreceptive versus late-stage receptive immatures. • Close-range cues in webs of immatures may indicate receptivity. [ABSTRACT FROM AUTHOR]

The brown widow spider, Latrodectus geometricus Koch 1841, is a toxic spider that is widespread in Thailand, where it has recently been reported on by various media outlets, causing wide concern among the public. However, very little is currently known about the ecology of this species in this country. Therefore, the aim of this research was to investigate the microhabitat use, morphology, and life cycle under laboratory conditions of L. geometricus inhabiting community housing in Samut Songkhram Province. We collected 152 adult spiders between January and August 2017, the majority of which were female (85.53%) and were found on motorcycles (87.50%). Females were much larger than males, with a total body length from the top of the cephalothorax to the bottom of the abdomen of 6.92 ± 0.67 mm, compared with 3.27 ± 0.99 mm in males. In addition, the morphological differences between males and females were significant (p<0.05). Adult females also had a longer life span than males (56.40 ± 11.52 vs. 31.00 ± 2.45 days).The results of this study give us a greater understanding of the biology and morphology of L. geometricus and will be useful for the future monitoring of this species. [ABSTRACT FROM AUTHOR]

Males of the brown widow spider, Latrodectus geometricus (Theridiidae), invest energy in courtship displays and are often cannibalized after mating; accordingly, partial sex role reversal is expected. In this species, subadult females are able to mate and produce viable offspring. In contrast to mature females, these subadult females do not cannibalize their mates after copulation. Nevertheless, when given a choice, males preferred mature over subadult females and older over young mature females. We found no benefit for males in mating with the females of their choice. Older females were significantly less fecund than young mature females, and were not more fecund than subadult females. We tested possible advantages in mating with cannibalistic (mature) females, such as an increased probability of plugging the female's genital duct or longer copulations, or disadvantages in mating with subadult females, such as higher remating risk. None of these explanations was supported. Thus, we lack an adaptive explanation for male preference for mature older females. We suggest that older females produce more pheromone to attract males and that males are thus misled into mating with older, more aggressive and less fecund females. [ABSTRACT FROM AUTHOR]

AbstractBackground: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.

Studies related to communication on spiders show that, as in other invertebrates, the interactions between conspecifics are also made through chemical signals. Therefore, in order to assess whether the composition of cuticular compounds might be involved in interactions that occur during the days after the emergence of juveniles in Latrodectus geometricus , we conducted behavioral and cuticular chemical profiles analysis of females and juveniles of different ages. The results show that females, regardless of their reproductive state, tolerate juveniles of other females with up to 40 days post-emergence and attack juveniles of 80 days post-emergence. Cuticlar chemical analysis shows that while the profile of juveniles is similar to adult’s profile, they can remain in the web without being confused with threat or prey. Also, cuticular chemical profiles vary between different populations probably due to genetic and environmental differences or similarities between them. Finally, females in incubation period are able to detect the presence of eggs within any egg sac, but cannot distinguish egg sacs produced by conspecifics from the ones they had produced. [ABSTRACT FROM AUTHOR]

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 oilbased 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 waterbased 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. [ABSTRACT FROM AUTHOR]

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 ft3 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 of predation (6.1%). Other brown widow sac inhabitants included larvae and adults of dermestid beetles, psocids. and lepidopterans, which are probably scavengers or incidental occupants. The overall impact of the recorded predators and parasitoids is too low to explore the possibility of a biological control program. Additionally, due to the relatively low number of predators/parasitoids in brown widow egg sacs and the entanglement of small arthropods on the outer surface, we speculate that the spiked egg sac surface might serve as an effective barrier to most predators and parasitoids. [ABSTRACT FROM AUTHOR]

Abstract: 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 24h. 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Sexual cannibalism may represent an extreme form of male monogamy. According to this view, males gain reproductive success by sacrificing themselves to females. We studied the occurrence and timing of sexual cannibalism in the brown widow spider Latrodectus geometricus and compared male courtship and mating behavior with virgin and with previously mated females . We found that events of sexual cannibalism are frequent, that they occur during copulation and that males initiate cannibalism by placing the abdomen in front of the female’s mouth-parts during copulation (somersault behavior). Both the somersaults and mating occurred more frequently with virgins than with previously mated females. Our results support the hypothesis that sexual cannibalism is a male strategy in this species. The somersault behavior was previously known only from the redback spider, Latrodectus hasselti. It is as yet unknown whether self-sacrifice has evolved more than once in this genus. [ABSTRACT FROM AUTHOR]

Understanding factors affecting male mate choice can be important for tracking the dynamics of sexual selection in nature. Male brown widow spiders ( Latrodectus geometricus ) mate with adult as well as immature (subadult) females. Mating with adults involves costly courtship with a repertoire of signaling behaviors, and typically ends with cannibalism ("self-sacrifice" initiated by male somersault). Mating with subadults involves brief courtship with behavioral repertoire reduced to one component (vibration) and no cannibalism. We examined male mate choice as a function of risks associated with different types of mates and the cues available to courting males. Previous studies showed male preference for adults based on air-borne pheromones, but it was unclear whether that preference is maintained after males reach female's webs. We show that males prefer adults also based on silk-borne contact cues. To determine which types of cues trigger different courtship components, we swapped adults and subadults between webs. We showed that contact with adult females' webs triggers two courtship behaviors from the repertoire, with adult female's bodies triggering additional behaviors. However, vibrational signals occur regardless of the web origin or female developmental stage. We conclude that males recognize subadult females as potential mates, but are more likely to invest in costly courtship behaviors and mating attempts with adults. In our experiments, subadults were less likely to mate than adults. We conclude that mating with adults could be the preferred option for males because of the higher likelihood of copulation, even at the cost of a higher risk of cannibalism., (© The Author(s) 2022. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology.)

The article discusses a study to document the seasonal field egg production of brown widow spiders from June to October. In the research, brown widow egg sacs were collected during the day from Southern California. Results of the study found that brown widow egg production was fairly steady for a 5-month period, hence there was a constant monthly rate of egg productivity.

The article presents a case study of a 20-year-old male patient who was bitten by the brown widow spider, or Latrodectus geometricus. The patient exhibited to a serious reaction to the spider bite and required hospitalization after exhibiting symptoms like fasciculations in the pectoral and quadriceps muscles, cramps, severe pain and nausea and vomiting.

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., (© The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)