Latrodectus Geometricus Research Articles

Challenges in the diagnosis and management of brown widow spider (Latrodectus geometricus) envenomation in dogs

This study reports two cases of araneism in dogs caused by the bite of the brown widow spider (Latrodectus geometricus), one of which resulted in death. The first case presented mild signs, successfully treated with medication and ice packs. The second case, more severe, involved exacerbated local signs such as extensive edema and ecchymosis, and diffuse cutaneous hemorrhage in the affected limb, as well as systemic signs, including vomiting, tetraparesis, ataxia, and epileptic seizure, culminating in renal and hepatic failure, circulatory collapse, and death. The treatments employed were based on the symptoms and included the use of analgesics and anti-inflammatories. The study highlights the importance of early diagnosis and appropriate treatment, including the use of specific antivenoms in more severe cases. It emphasizes the importance of preventive measures, such as the use of insecticides, to prevent future accidents. Awareness of the clinical signs of poisoning and the available treatment options is crucial for healthcare professionals and veterinarians to ensure proper management of these incidents and minimize their consequences.

Endosymbiont diversity across native and invasive brown widow spider populations

The invasive brown widow spider, Latrodectus geometricus (Araneae: Theridiidae), has spread in multiple locations around the world and, along with it, brought associated organisms such as endosymbionts. We investigated endosymbiont diversity and prevalence across putative native and invasive populations of this spider, predicting lower endosymbiont diversity across the invasive range compared to the native range. First, we characterized the microbial community in the putative native (South Africa) and invasive (Israel and the United States) ranges via high throughput 16S sequencing of 103 adult females. All specimens were dominated by reads from only 1–3 amplicon sequence variants (ASV), and most individuals were infected with an apparently uniform strain of Rhabdochlamydia. We also found Rhabdochlamydia in spider eggs, indicating that it is a maternally-inherited endosymbiont. Relatively few other ASV were detected, but included two variant Rhabdochlamydia strains and several Wolbachia, Spiroplasma and Enterobacteriaceae strains. We then diagnostically screened 118 adult female spiders from native and invasive populations specifically for Rhabdochlamydia and Wolbachia. We found Rhabdochlamydia in 86% of individuals and represented in all populations, which suggests that it is a consistent and potentially important associate of L. geometricus. Wolbachia was found at lower overall prevalence (14%) and was represented in all countries, but not all populations. In addition, we found evidence for geographic variation in endosymbiont prevalence: spiders from Israel were more likely to carry Rhabdochlamydia than those from the US and South Africa, and Wolbachia was geographically clustered in both Israel and South Africa. Characterizing endosymbiont prevalence and diversity is a first step in understanding their function inside the host and may shed light on the process of spread and population variability in cosmopolitan invasive species.

Microhabitat use and artificial-light related occurrence of the brown widow spider <i>Latrodectus geometricus</i> in a newly invaded area of the inland Kanto region, Japan

Microhabitat use and artificial-light related occurrence of the brown widow spider <i>Latrodectus geometricus</i> in a newly invaded area of the inland Kanto region, Japan

Pre-copulatory choices drive post-copulatory decisions: mechanisms of female control shift across different life stages

BackgroundThe ‘wallflower’ hypothesis proposes females mate indiscriminately to avoid reproductive delays. Post-copulatory mechanisms may then allow ‘trading up’, favouring paternity of future mates. We tested links between pre- and post-copulatory choice in Latrodectus geometricus female spiders paired sequentially with two males. These females copulate as adults or as subadults and store sperm in paired spermathecae. Choosy adults have a higher risk of delays to reproduction than subadults.ResultsWe predicted low pre-copulatory, but high post-copulatory choice at first matings for adults and the opposite for subadults. At second matings, we expected all females would prefer males superior to their first. We found all females mated indiscriminately at their first pairing, but in contrast to subadults, adults usually allowed only a single insertion (leaving one of their paired spermatheca empty); a mechanism of post-copulatory choosiness. Adult-mated females were more likely to remate than subadult-mated females when they became adults, showing a preference for larger males, while subadult-mated females tended to prefer males of greater size-corrected mass.ConclusionsOur results show that the ‘wallflower’ effect and ‘trading up’ tactics can be utilized at different life stages, allowing females to employ choice even if rejecting males is costly.

Spider bite envenomation on Reunion Island

AbstractSpiders are the most abundant group of predators within the Earths ecosystems. On Reunion Island, there are up to 200 known species of spiders. However, the description of the envenomation by the bites of some local spiders have never performed. The objective of this study was to describe the representation of the health risks associated to the six spider species present on the island. The following species were described within the local arachnofauna: Latrodectus geometricus C. L. Koch, 1841 (Theridiidae), Steatoda grossa (C. L. Koch, 1838) (Theridiidae), Loxosceles rufescens (Dufour, 1820) (Sicariidae), Cheiracanthium insulare (Vinson, 1863) (Cheiracanthiidae), Cheiracanthium africanum Lessert, 1921 (Cheiracanthiidae) and Heteropoda venatoria (Linnaeus, 1767) (Sparasidae). This study constituted a first approach to the pathologies encountered by local venomous spider bites. To date, no recorded cases of envenomation linked to these species have been made so far. Some of the species or close species were documented in international literature as responsible for envenomation cases, however, future research should be taken in order to better inform and prepare healthcare professionals within the Reunion Island hospital services to deal with patients with spider bite cases.

Invasive brown widow spiders avoid parasitism despite high densities.

Invasive species are sometimes less susceptible to natural enemies compared to native species, but the mechanism is often unclear. Here we tested two potential mechanisms for lower parasitism of invasive species: density-dependent parasitism and preference for human-dominated habitats. We investigated how variation in host density and habitat type affect egg sac parasitismintwo widow spider species (family Theridiidae). We compared parasitism on the egg sac of the brown widow,Latrodectus geometricus, an urban invasive species, and the white widow,Latrodectus pallidus, a species native to Israel. To investigate variation in host and parasitoid density, we measured nearest-neighbor distance between spider webs and parasitism rates in 16 sites, and in a single site monthly throughout a year. In L. pallidus, denser sites were more heavily parasitized (up to 55%) and parasitism rate increased with population density throughout the season. Extremely dense L. geometricus populations, however, had very low rates of parasitism (0-5%). We then conducted an egg sac transplant experiment in human-dominated and natural habitats. We found no parasitism of either species in the human-dominated habitat, compared to 30% parasitism of both species in the natural habitat. In addition, we found evidence for higher predation of L. pallidus than of L. geometricus egg sacs, particularly in the natural habitat. These combined results suggest that the human-dominated habitats inhabited by L. geometricus have a lower abundance of predators and parasites. We conclude that lower parasitism and predation in human-dominated habitats could contribute to the invasion success of L. geometricus.

Thermal tolerances of different life stages, sexes, and species of widow spiders (Araneae: Theridiidae)

Temperature strongly shapes the physiology and distributions of ectotherms. Environmental extremes and the range of temperatures encountered can limit persistence. Further, thermal tolerance limits are thought to be one of the factors limiting the distributions of invasive species. The critical thermal maximum (CTMax) and critical thermal minimum (CTMin) are metrics frequently applied for defining upper and lower thermal tolerances, respectively. Temperatures contained within the boundaries of the CTMax and CTMin comprise the thermal tolerance range. In this study, we tested whether thermal tolerances differed between two native (Latrodectus hesperus Chamberlin & Ivie, 1935 and L. mactans (Fabricius, 1775)) and one invasive (L. geometricus CL Koch, 1841) widow species (Latrodectus Walckenaer, 1805). We separately tested if thermal tolerances differed by life stage and sex. Using species distribution modelling, we also tested if thermal extremes or temperature range most accurately correspond with current species occurrences in the United States. We hypothesized that Latrodectus geometricus would have lower thermal tolerance range and that minimum temperatures would most influence their present distributions since they presumably originated from a more equatorial climate. We found that CTMin did not vary by developmental stage, but was highest in males. We found that the CTMin and CTMax of L. geometricus (3.2, 51.5 °C) and L. mactans (1.9, 52.4 °C) were higher than L. hesperus (-1.9, 49.6 °C). Males also had the narrowest thermal tolerance range in the three species examined. Lastly, we found that the highest performing distribution model was the one correlating minimum temperature with L. geometricus occurrences.

Predation by the Introduced Brown Widow Spider (Araneae: Theridiidae) May Explain Local Extinctions of Native Black Widows in Urban Habitats

Abstract Invertebrates that successfully colonize new habitats often share life history characteristics including high fertility, rapid development, and early maturation. Since its introduction into Florida, USA, the non-native Brown Widow, Latrodectus geometricus (Kock 1841, Araneae: Theridiidae), has rapidly expanded its range into urban areas as far north as Kansas and as far west as California. During its expansion, the Brown Widow has displaced Florida’s Southern Black Widow, L. mactans (Fabricius 1775, Araneae: Tjerodoodae) and California’s Western Black Widow, L. Hesperus (Chamber lin & Ivie 1935, Araneae: Theridiidae). Here, based on a field survey and controlled laboratory experiments, we report possible causes for the rapid disappearance of Florida’s Southern Black Widows. Our field survey revealed that Brown Widows have twice the fertility potential as Southern Black Widows. In experiments comparing development, we show that sub-adult Brown Widows grew faster and matured earlier relative to Southern Black Widows. In our experiments on cohabitation with neighbors, bold Brown Widows were six times more likely to kill and consume shy Southern Black Widows than bold cobweb spiders and three times more likely to cohabitate with bold cobweb spiders than with shy Southern Black Widows. Our model of maternal risk-management revealed that competition for scarce prey was not a significant cause of offspring mortality for Latrodectus species. Hence, Brown Widows are not predating Black Widows or other cobweb spiders because prey is scarce. To our knowledge, this study is the first to suggest that aggressive predation by Brown Widows is a significant factor contributing to the local extinction of the shy Southern Black Widow in urban structures.

A history of accidental widow spider (genus Latrodectus ) introductions on the island of Ireland with a new irish record for Latrodectus hesperus (Chamberlin and Ivie, 1935), and additional records of Latrodectus geometricus (C.L. Koch, 1841).

ABSTRACT: The widow spiders of the genus Latrodectus (Araneae: Theridiidae) have a well-documented global medical significance due to the potent venom many of them possess. This medical importance partially stems from the global range expansion the genus has undergone, facilitated in part by human trade. This expansion has had an impact on human health in countries where Latrodectus spiders establish populations. Ireland has a detailed report history of accidental widow spider introductions, spanning over 30 years, which assists in understanding the potential such species have for establishing. Here we present three additional cases: a second and third record of Latrodectus geometricus (C.L. Koch, 1841) and the first record of Latrodectus hesperus (Chamberlin and Ivie, 1935). We also review all published reports of Latrodectus introductions in Ireland and discuss the potential for populations to establish. While case histories suggest that L. hesperus and L. geometricus can survive Irish winters, it is not certain that they can complete an egg-to-egg life cycle or even reproduce. Nevertheless, it seems possible they could do so in favourable micro-habitats in anthropogenic habitats such as hot houses. Identification of instances of Latrodectus introductions into Ireland is essential to prevent potential establishments that could lead to envenoming cases.

First Records of Black Widow Spider Latrodectus Walckenaer (Araneae: Theridiidae) in Oman

The present communication deals with a faunistic study on two species of Latrodectus Walckenaer with medically important issues from Oman. Several specimens of Latrodectus have been collected at various localities in Sultanate of Oman. This study records two species of Latrodectus from Oman, of which Latrodectus cinctus Blackwall only from northern Oman and Latrodectus geometricus C.L. Koch from both northern and southern Oman.

Cover Image

EthologyVolume 128, Issue 9 p. i-i COVER IMAGEFree Access Cover Image First published: 11 August 2022 https://doi.org/10.1111/eth.13187AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Graphical Abstract Front Cover The image shows newly-emerged juveniles of the brown widow spider, Latrodectus geometricus. In our study, we found that invasive brown widow spiderlings disperse aerially under an unusually broad range of conditions, including wind speed, temperature, humidity, and time of day. This increased propensity and ability to disperse may partially explain the species' global invasive spread. Photo credits: Alfred Daniel J. Volume128, Issue9September 2022Pages i-i RelatedInformation

Invasive brown widow spiders disperse aerially under a broad range of environmental conditions

AbstractSpiders commonly disperse on silk lines as juveniles by means of rappelling or ballooning. These modes of dispersal, especially long‐distance dispersal via ballooning, can greatly increase the distance an individual can move and, at the population level, the speed of range expansion and likelihood of gene flow. Nevertheless, few studies have examined how spiders disperse under field conditions, and which environmental and meteorological conditions may affect their decision to disperse. We tested dispersal by spiderlings of the invasive brown widow (Latrodectus geometricus) under field conditions in the Negev Desert of Israel. We documented pre‐dispersal (climbing and tiptoeing) and dispersal (short‐distance dispersal by rappelling and long‐distance dispersal by ballooning) behaviours during the day (n = 147 spiders) and night (n = 171 spiders), while recording wind speed, temperature and humidity. We found that spiders ballooned significantly more during the day (14.3%) compared with 1.8% of spiders ballooning at night. At night, spiders were more likely to disperse in conditions of higher wind speeds, lower temperature and higher humidity, whereas during the day, environmental factors were less predictive of dispersal behaviour. In addition, we found significant differences in the proportion of spiderlings showing pre‐dispersal and dispersal behaviour depending on family line. In conjunction with human‐mediated dispersal, ballooning and rappelling may be an important mechanism of range expansion in the brown widow spider. Understanding the environmental and genetic factors affecting dispersal may lead to better management of invasive species.

Risky business: males choose more receptive adults over safer subadults in a cannibalistic spider.

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.

Differential parasitism of native and invasive widow spider egg sacs

AbstractDuring colonization, invasive species establish and spread to new locations, where they may have an advantage over native species. One such advantage may be avoidance of predators or parasites by means of better defenses or due to lower suitability as a host. We conducted field surveys and lab behavioral experiments to investigate the differential susceptibility of two widow spider species—one native to Israel, the white widow spider Latrodectus pallidus, and one invasive species, the brown widow spider, Latrodectus geometricus—to an egg sac parasitoid wasp, Philolema latrodecti. In collections of egg sacs from six paired sites of L. geometricus and L. pallidus populations in the Negev Desert, Israel, we found higher parasitism rates on the egg sacs of the native L. pallidus. In no-choice trials, we found that wasps were more likely to parasitize and oviposited longer on L. pallidus egg sacs than on L. geometricus egg sacs. In two-choice tests with spider webs and egg sacs, parasitoids made first contact with L. pallidus webs more often and faster. After developing inside of L. pallidus egg sacs, more parasitoids emerged and were larger than those emerging from L. geometricus egg sacs. Potentially better defense of the L. geometricus egg sacs as well as the parasitoid’s fitness advantages gained from parasitizing L. pallidus egg sacs may explain the higher parasitism rate in the native species. Our results suggest that the invasion and establishment success of L. geometricus is due, in part, to its ability to escape parasitism.

Dispersal and life history of brown widow spiders in dated invasive populations on two continents

Theory and empirical work suggest that behaviours such as dispersal and exploration are predictors of invasive success, and that behaviours may shift predictably after invasive populations have established and spread. However, there are limited data on temporal patterns in the distribution of behavioural traits linked to the timeline of establishment of invasive species. We examined dispersal and exploration, along with life history traits that may be linked to behaviour, across multiple invasive populations of the brown widow spider, Latrodectus geometricus. This global invader has established populations across the United States and Israel. Using this temporal and spatial variation, we tested predictions about changes in suites of traits over establishment time. We compared trait distributions of four U.S. populations of L. geometricus to patterns in four populations in Israel. We predicted that selective filters during the invasion process would result in more dispersive, more exploratory spiders that are larger and more fecund in recently established populations, but, if trade-offs occur, dispersal would be favoured at the expense of fecundity and size in recent populations. We found more frequent and faster dispersal in more recently established populations in Israel, but not the United States. Spiders in more recently established populations in Israel were larger than those in older populations, but there were no consistent patterns across U.S. populations. However, there was evidence in both the U.S. and Israel for differing trade-offs among fecundity, dispersal and size. In more recently established populations, spiders were more variable in resource allocation to eggsacs. The results suggest that in some populations, trade-offs underlying dispersal, fecundity and body size are shaped by the time interval, and thus the number of generations, since establishment, with implications for the role of evolutionary processes in invasion success.

Predation strategy of the brown widow spider Latrodectus geometricus Koch, 1841 against prey with different defensive mechanisms

Predation strategy of the brown widow spider Latrodectus geometricus Koch, 1841 against prey with different defensive mechanisms

New Record of Brown Widow Spider (Latrodectus geometricus Koch, 1841) in Ha’il Region, Saudi Arabia

Brown Widow Spider (Latrodectus geometricus) is recorded for the first time in Hail Region of Saudi Arabia .Three specimens of brown widow spider (L. geometricus ) were found and collected on October, 2021 from inside a beehive in Al Hait city (Southern of Ha’il region of Saudi Arabia). The specimens were collected and submitted to Biology department of Hail University for the identification of morphological characters and DNA barcode sequence analysis of the specimen. Phylogenetic analysis was performed to compare the DNA sequence of the newly discovered female brown widow spider with the other species of Latrodectus genus.

De Novo Transcriptome Analysis of the Venom of Latrodectus geometricus with the Discovery of an Insect-Selective Na Channel Modulator.

The brown widow spider, Latrodectus geometricus, is a predator of a variety of agricultural insects and is also hazardous for humans. Its venom is a true pharmacopeia representing neurotoxic peptides targeting the ion channels and/or receptors of both vertebrates and invertebrates. The lack of transcriptomic information, however, limits our knowledge of the diversity of components present in its venom. The purpose of this study was two-fold: (1) carry out a transcriptomic analysis of the venom, and (2) investigate the bioactivity of the venom using an electrophysiological bioassay. From 32,505 assembled transcripts, 8 toxin families were classified, and the ankyrin repeats (ANK), agatoxin, centipede toxin, ctenitoxin, lycotoxin, scorpion toxin-like, and SCP families were reported in the L. geometricus venom gland. The diversity of L. geometricus venom was also uncovered by the transcriptomics approach with the presence of defensins, chitinases, translationally controlled tumor proteins (TCTPs), leucine-rich proteins, serine proteases, and other important venom components. The venom was also chromatographically purified, and the activity contained in the fractions was investigated using an electrophysiological bioassay with the use of a voltage clamp on ion channels in order to find if the neurotoxic effects of the spider venom could be linked to a particular molecular target. The findings show that U24-ctenitoxin-Pn1a involves the inhibition of the insect sodium (Nav) channels, BgNav and DmNav. This study provides an overview of the molecular diversity of L. geometricus venom, which can be used as a reference for the venom of other spider species. The venom composition profile also increases our knowledge for the development of novel insecticides targeting voltage-gated sodium channels.

Urban Environments Aid Invasion of Brown Widows (Theridiidae: Latrodectus geometricus) in North America, Constraining Regions of Overlap and Mitigating Potential Impact on Native Widows

Urbanization is a major cause of biotic homogenization and habitat fragmentation for native communities. However, the role of urbanization on the success of biological invasions on a continental scale has yet to be explored. Urbanization may facilitate the establishment success of invasive species by minimizing niche differentiation between native and invaded ranges. In such cases, we might expect anthropogenic variables to have stronger influence on the geographic distribution of invasive compared to native populations. In this study, we use ecological niche modeling to define the distribution of non-native brown widow spider (Latrodectus geometricus) and three native black widows (L. hespersus, L. mactans, L. variolus) in North America and gauge the importance of urbanization on the geographic ranges of widows at a continental scale. We also quantify the geographic overlap of L. geometricus with each native widow to assess potential species and regions at risk of ecological impact. Consistent with our hypothesis, we find that the distribution of L. geometricus is strongly constrained to urban environments, while native widow distributions are more strongly driven by climatic factors. These results show that urbanization plays a significant role in facilitating the success of invasion, weakening the significance of climate on the realized niche in its invaded range.

Don't put all your eggs in small baskets: Ineffective guardians, incidence of parasitoids and clutch size of Latrodectus geometricus (Araneae, Theridiidae) along an urban gradient

Maternal care is common in spiders, but the effects of egg protection by mothers on offspring survival remains understudied for most species, especially against parasitoids. Parasitoid incidence can also be modulated by host clutch size (since larger egg masses provide the opportunity of producing larger clutches for the parasitoids) and urbanization (by creating conditions that may restrict the occurrence of less tolerant species). In this study, we conducted field experiments with the brown widow spider Latrodectus geometricus to investigate the following hypothesis: (1) females are effective in the defense of eggs against parasitoids; (2) large clutch sizes are attacked more often by parasitoids than the smaller ones; and (3) the incidence of parasitoids in egg sacs decreases in a gradient from a preserved area to an urbanized one. The presence of caring females reduced by three times the incidence of two parasitoids, Baeus latrodecti (Hymenoptera, Scelionidae) and an unidentified Eulophidae wasp, compared to unattended egg sacs, but this distinction did not differ from a random distribution. Parasitoids were most often found in egg sacs containing few eggs. The incidence of B. latrodecti in egg sacs was highest in the area with an intermediate degree of urbanization, but Eulophidae wasps were unaffected by the urbanization gradient. We concluded that (1) females are generally ineffective at protecting their egg sacs against parasitoids, that (2) egg sacs containing small clutch sizes are usually more vunerable to parasitoid attacks, and that (3) urbanization does not reduce the incidence of the egg parasitoids identified here. Our study provides an important step towards our understanding of the interactions between spiders with parental care and egg parasitoids, suggesting new aspects to be investigated in future studies.