Redback Spider Research Articles

Update of antivenom supply for redback spider bites in Japan.

In autumn 2014, with great effort by the Ministry of Health, Labour and Welfare, the research group will obtain several vials of redback spider (RBS) antivenom for emergency use. However, these small amounts of antivenom are insufficient to cover the demands from majority of hospitals in Japan. The research group carefully discussed the domestic RBS antivenom production by themselves for this emergency. We have now entered the second stage for large-scale antivenom production. Although the domestic production of RBS antivenom has started, great caution is required as we move forward with this plan.

Contact pheromones mediate male preference in black widow spiders: avoidance of hungry sexual cannibals?

Males often exercise mate choice when mating frequency is constrained, costs of choice are low and variation in female quality and/or expected paternity can be reliably detected. Across invertebrates, males use sex pheromones to discern female mating status, but there are few demonstrations that information about expected fecundity (‘quality’) is encoded in pheromones alone. Here we examine whether females' sex pheromones allow males to detect differences in female food intake and mass in two species of widow spiders (Latrodectus hesperus and Latrodectus hasselti) in which chemicals are deposited by females in silk. Recent work shows that male L. hesperus prefer well-fed females, and that these females produce more silk than hungry females. Thus, changes in diet could be mechanistically linked to changes in silk-bound pheromonal signals. We show that unmated females of both species lose more than half of their mass when food is withheld, and silk production is reduced by 48% (L. hesperus) to 67% (L. hasselti). Males had a significant sexual response to pheromones extracted from the females' silk in both species, although this response was not directly correlated with silk or female mass. In L. hesperus, but not in L. hasselti, males were less responsive to sex pheromones from food-deprived females compared to well-fed females. While females on good diets provide the benefit of higher fecundity in both species, the risk of being cannibalized by hungry females during courtship exists only in L. hesperus. We conclude that sex pheromones alone can provide information about recent female feeding history, possibly reducing the costs of males expressing choice in the field. The species difference in male response also suggests that male preferences in these spiders may depend less on the benefit of seeking a highly fecund female and more on avoiding the cost of risky mating attempts with a likely cannibal.

Metabolic efficiency in courtship favors males with intermediate mass in the Australian redback spider, Latrodectus hasselti

Recent studies have suggested that metabolic efficiency may be an important factor in male mating success when females require vigorous and/or prolonged courtship. In capital breeding animals in which a male’s resource pool is fixed at adulthood the relationship between energy expenditure and courtship performance may be especially important, as males are expected to utilize their finite resources efficiently when soliciting mates. Males may benefit from being efficient, i.e., achieving a sufficiently high level of courtship signaling at low energetic cost, if it enables them to acquire mates before their limited energy reserves are depleted. We investigated the relationship between metabolic efficiency and courtship vibrational signaling in the Australian redback spider, Latrodectus hasselti, a semelparous capital breeder where males invest heavily in courtship to secure a mating. We assessed metabolic rate in a sample of males and measured two courtship components (duty cycle and amplitude) that reflected the energy content of web-borne vibrations. We then calculated two indices of metabolic efficiency for these courtship properties. There was a quadratic relationship between mass and duty cycle such that the highest duty cycle signals were performed by males having intermediate mass. Furthermore, intermediate-mass males were also the most metabolically efficient. Prolonged courtship is necessary in L. hasselti for successful mating, and the results of this study suggest that intermediate-mass males are superior courters because they utilize their finite resource pool most efficiently to produce high energy vibrational signals.

Clinical characteristics of redback spider bites.

BackgroundRedback spiders (Latrodectus hasselti) (RBSs) are venomous spiders that have recently spread to Asia from Australia. Since the first case report in 1997 (Osaka), RBS bites have been a clinical and administrative issue in Japan; however, the clinical characteristics and effective treatment of RBS bites, particularly outside Australia remains unclear. This study aimed to elucidate the clinical characteristics of RBS bites and to clarify the effectiveness of the administration of antivenom for treatment.MethodsWe performed a retrospective questionnaire survey from January 2009 to December 2013 to determine the following: patient characteristics, effect of antivenom treatment, and outcomes. To clarify the characteristics of patients who develop systemic symptoms, we compared patients with localized symptoms and those with systemic symptoms. We also examined the efficacy and adverse effects in cases administered antivenom.ResultsOver the 5-year study period, 28 patients were identified from 10 hospitals. Of these, 39.3% were male and the median age was 32 years. Bites most commonly occurred on the hand, followed by the forearm. Over 80% of patients developed local pain and erythema, and 35.7% (10 patients) developed systemic symptoms. Baseline characteristics, vital signs, laboratory data, treatment-related factors, and outcome were not significantly different between the localized and systemic symptoms groups. Six patients with systemic symptoms received antivenom, of whom four experienced symptom relief following antivenom administration. Premedication with an antihistamine or epinephrine to prevent the adverse effects of antivenom was administered in four patients, which resulted in no anaphylaxis. One out of two patients who did not receive premedication developed a mild allergic reaction after antivenom administration that subsided without treatment.ConclusionsApproximately one third of cases developed systemic symptoms, and antivenom was administered effectively and safely in severe cases. Further research is required to identify clinically applicable indications for antivenom use.

Carbon dioxide versus cold exposure for immobilising live redback spiders Latrodectus hasseltii Thorell, 1870 (Araneae: Theridiidae)

Studying live spiders often involves non-lethally immobilising them. The use of CO2 and refrigeration were investigated, both alone and combined, as methods for immobilising redback spiders (Latrodectus hasseltii). Specimens of L. hasseltii were exposed separately to CO2 and cold temperatures (4.2°C) for time intervals ranging from 5 to 12 s and 4 to 45 min, respectively. Subsequent behaviour exhibited by the spiders was described as either positive or negative: if handling and removal from the container were possible without risking escape or injury this was described as a positive reaction. Conversely, if the spider was too active to be handled the reaction was counted as negative. Two minute CO2 exposure had a significant positive effect on spider response; refrigeration and combining the two treatments did not produce significant effects. Carbon dioxide was the most successful method of immobilising spiders; however, we caution using it for endangered species until further research has been conducted into long-term effects.

Randomized Controlled Trial of Intravenous Antivenom Versus Placebo for Latrodectism: The Second Redback Antivenom Evaluation (RAVE-II) Study

Latrodectism is the most important spider envenomation syndrome worldwide. There remains considerable controversy over antivenom treatment. We aimed to investigate whether antivenom resulted in resolution of pain and systemic effects in patients with latrodectism who received standardized analgesia. In a multicenter randomized placebo-controlled trial of redback spider antivenom for latrodectism, 224 patients (>7 years) with a redback spider bite and severe pain, with or without systemic effects, were randomized to receive normal saline solution (placebo) or antivenom after receiving standardized analgesia. The primary outcome was a clinically significant reduction in pain 2 hours after trial medication compared with baseline. A second primary outcome for the subgroup with systemic features of envenomation was resolution of systemic features at 2 hours. Secondary outcomes were improved pain at 4 and 24 hours, resolution of systemic features at 4 hours, administration of opioid analgesics or unblinded antivenom after 2 hours, and adverse reactions. Two hours after treatment, 26 of 112 patients (23%) from the placebo arm had a clinically significant improvement in pain versus 38 of 112 (34%) from the antivenom arm (difference in favor of antivenom 10.7%; 95% confidence interval -1.1% to 22.6%; P=.10). Systemic effects resolved after 2 hours in 9 of 41 patients (22%) in the placebo arm and 9 of 35 (26%) in the antivenom arm (difference 3.8%; 95% confidence interval -15% to 23%; P=.79). There was no significant difference in any secondary outcome between antivenom and placebo. Acute systemic hypersensitivity reactions occurred in 4 of 112 patients (3.6%) receiving antivenom. The addition of antivenom to standardized analgesia in patients with latrodectism did not significantly improve pain or systemic effects.

Efficacy of Australian red-back spider (Latrodectus hasselti) antivenom in the treatment of clinical envenomation by the cupboard spider Steatoda capensis (Theridiidae)

We describe the first Steatoda capensis envenomation treated with CSL red-back spider antivenom (RBSAV). The patient, a 51-year-old female, developed acute local pain, swelling, redness, and diaphoresis in association with tender lymphadenopathy and hypertension. These features responded, in a dose-dependent manner, to RBSAV. In vitro studies confirmed that RBSAV could neutralize S. capensis venom at equivalent concentrations required to neutralize red-back spider (Latrodectus hasselti) venom. Similar data were obtained using Mexican Latrodectus mactans antivenom (Aracmyn®). Although S. capensis yielded similar quantities of venom protein as L. hasselti, pooled S. capensis and Steatoda grossa venom was more rapidly toxic to insects than either L. hasselti or Latrodectus tredecimguttatus venom. By contrast, both Latrodectus venoms were more potent than S. capensis venom in contracting rat isolated mesenteric arteries. Size-exclusion and anion-exchange chromatography was used to purify a 130 kDa fraction from S. capensis venom that induced contracture and loss of twitch tension in chick isolated biventer cervicis nerve-muscle preparations in a manner similar to α-latrotoxin. This activity was abolished by pre-incubation with RBSAV. We conclude that ‘steatodism’ may overlap more closely with latrodectism than previously recognized and that this bite should be managed in the same way as for Australian red-back envenomation.

Sibling cannibalism in a web-building spider: Effects of density and shared environment

Sibling cannibalism occurs across diverse taxa and can affect population size and structure, as well as the fitness of parents and the cannibal, via density effects and variation in individual propensity to cannibalize. We examined these effects on sibling cannibalism in juveniles of a web-building spider (Latrodectus hasselti, Australian redbacks). Adult redbacks are solitary, but juveniles live in clusters of variable density for a week after hatching. We confined newly hatched siblings from a singly-mated female to a low or high density treatment in a split-clutch design, then left spiderlings unfed for a week. Our results showed no effect of density on overall cannibalism levels, but a strong correlation between cannibalism counts from the same maternal lines across densities. Unlike web-bound sit-and-wait predators, wandering spiders that are active hunters have been shown to experience density-dependent cannibalism. In contrast, we suggest sibling cannibalism in web-building spiders may be density independent because early cohabitation on the web selects for elevated tolerance of conspecifics. We conclude that, rather than being linked to density, cannibalism of siblings in these species may be controlled more strongly by variation in individual propensity to cannibalize.

Mating system does not predict permanent sperm depletion in black widow spiders

Variation in sperm production is strongly influenced by mating system across taxa. Recent work in spiders suggests that males of some species show termination of spermatogenesis before their adult molt and thus an inability to produce sperm after maturation. This permanent sperm depletion (PSD) has been hypothesized to co-occur with monogyny, genital mutilation, or sexual cannibalism because the maintenance of continual sperm supplies is not necessary for species where males can expect only one mating opportunity. Here we test this hypothesis in two congeners exhibiting genital mutilation: the sexually cannibalistic, monogynous Australian redback spider Latrodectus hasselti and the polygynous Western black widow Latrodectus hesperus. We report that PSD does not occur in adult males of either species, and show that males transfer sperm into their copulatory organs multiple times as adults. These data suggest evolutionary links between mating system and investment in sperm production may be more complex than currently appreciated.

Molecular Evolution of α-Latrotoxin, the Exceptionally Potent Vertebrate Neurotoxin in Black Widow Spider Venom

Black widow spiders (members of the genus Latrodectus) are widely feared because of their potent neurotoxic venom. α-Latrotoxin is the vertebrate-specific toxin responsible for the dramatic effects of black widow envenomation. The evolution of this toxin is enigmatic because only two α-latrotoxin sequences are known. In this study, ∼4 kb α-latrotoxin sequences and their homologs were characterized from a diversity of Latrodectus species, and representatives of Steatoda and Parasteatoda, establishing the wide distribution of latrotoxins across the mega-diverse spider family Theridiidae. Across black widow species, α-latrotoxin shows ≥94% nucleotide identity and variability consistent with purifying selection. Multiple codon and branch-specific estimates of the nonsynonymous/synonymous substitution rate ratio also suggest a long history of purifying selection has acted on α-latrotoxin across Latrodectus and Steatoda. However, α-latrotoxin is highly divergent in amino acid sequence between these genera, with 68.7% of protein differences involving non-conservative substitutions, evidence for positive selection on its physiochemical properties and particular codons, and an elevated rate of nonsynonymous substitutions along α-latrotoxin’s Latrodectus branch. Such variation likely explains the efficacy of red-back spider, L. hasselti, antivenom in treating bites from other Latrodectus species, and the weaker neurotoxic symptoms associated with Steatoda and Parasteatoda bites. Long-term purifying selection on α-latrotoxin indicates its functional importance in black widow venom, even though vertebrates are a small fraction of their diet. The greater differences between Latrodectus and Steatoda α-latrotoxin, and their relationships to invertebrate-specific latrotoxins, suggest a shift in α-latrotoxin toward increased vertebrate toxicity coincident with the evolution of widow spiders.

Developmental plasticity in metabolic rates reinforces morphological plasticity in response to social cues of sexual selection

Developmental plasticity allows individuals to match their phenotype to the competitive environment they are most likely to encounter. Although there are numerous studies that demonstrate adaptive shifts in life-history and metric traits, we still have a poor understanding of whether internal physiological processes demonstrate plasticity and whether this plasticity supports life-history and metric traits. Here we use the Australian redback spider (Latrodectus hasselti), a species that demonstrates adaptive developmental shifts in response to the availability of females and the density of males, to examine the relationship between the routine metabolic rate (RMR) and the expression of size, body-condition and development rate. We reared immature males in three diet treatments, and in social environments that varied the presence/absence of females and the density of males and measured their RMR, weight, size and developmental rate at maturity. We show that although RMR decreased with decreasing resource abundance, RMR was positively correlated with the density of rivals. Moreover, RMR was not correlated with size or body-condition at maturity. Our results demonstrate that plasticity in the RMR supports plasticity in metric and life-history traits to create an integrated phenotype that matches the competitive environment.

Effect of web-substrate on male courtship vibration transmission and female reception in web-building spiders

Event Abstract Back to Event Effect of web-substrate on male courtship vibration transmission and female reception in web-building spiders Senthurran Sivalinghem1* and Andrew Mason1 1 University of Toronto Scarborough, Ecology and Evolutionary Biology, Canada In many communication systems, the signaling environment has been shown to impose significant influence on signal characteristics, signaling behaviour, and sensory physiology. Recently, substrate-propagated vibratory communication has received increased attention, and spiders have emerged as ideal model organisms to study this mode of communication. In spiders, vibrations have been shown to play an important role during mate attraction, mate choice, mate/prey localization, and predator avoidance. Despite the purported importance of signaling substrate on vibration transmission, studies looking at the effect of substrate on the efficacy of vibration transmission have primarily focused on solid-surfaces such as small rocks, leaf and pine litter, sand, and red clay, which are generally substrates of ‘land-dwelling’ spiders. To date, however, similar studies are lacking in web-building spiders, which, unlike land-dwellers, only communicate through one substrate-type – the web – and may have signals and receptors that are adapted to the filtering and attenuation characteristics of their respective webs. Understanding these influences has important implications for understanding the function and evolution of solid substrate-borne vibratory communication. In this study, we used the Australian redback spider, Latrodectus hasselti, and the western black widow spider, L. hesperus, to examine if web-substrates influence signal characteristics and transmission properties, and receptor sensitivity. The specific goals of this study were to: 1) quantify vibration transmission properties of web-threads; 2) characterize male courtship vibrations; and 3) determine sensory physiology of vibration reception in female receivers. Vibrations (frequency sweeps from 1 to 2000 Hz) were generated with a piezoelectric actuator, and individual strands were stimulated at increasing distances. The propagated vibrations were measured using a laser Doppler vibrometer – vibrations were measured 1 cm from the female – and transfer functions were then calculated for each distance (dB gain relative to input). We then conducted mating trials and recorded and analyzed male courtship vibrations (1 cm from the female). Lastly, we conducted neurophysiological experiments. Adult females were mounted ventral side up onto a Plexiglas holder, and the front legs were mechanically vibrated at varying frequencies at varying intensities. Tungsten electrodes were inserted into the leg nerve, and extracellular nerve responses to vibrations were recorded. We determined threshold sensitivity at each frequency, and the number of action potentials as a function of stimulus intensity to obtain frequency-response and intensity-response curves, respectively. Our results contribute novel information on the influence of web-substrate on male courtship signals, and female vibration reception. These results elucidate possible functions and evolution of vibratory signals and reception in web-building spiders. Keywords: Sensory Physiology, Signal Transmission, Substrate-borne vibration Conference: Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012. Presentation Type: Poster (but consider for student poster award) Topic: Communication Citation: Sivalinghem S and Mason A (2012). Effect of web-substrate on male courtship vibration transmission and female reception in web-building spiders. Conference Abstract: Tenth International Congress of Neuroethology. doi: 10.3389/conf.fnbeh.2012.27.00366 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 01 May 2012; Published Online: 07 Jul 2012. * Correspondence: Mr. Senthurran Sivalinghem, University of Toronto Scarborough, Ecology and Evolutionary Biology, Toronto, Ontario, M1C 1A4, Canada, s_sen24@hotmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Senthurran Sivalinghem Andrew Mason Google Senthurran Sivalinghem Andrew Mason Google Scholar Senthurran Sivalinghem Andrew Mason PubMed Senthurran Sivalinghem Andrew Mason Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Systematics of Australian Agenioideus Ashmead (Hymenoptera: Pompilidae) with the first record of a spider wasp parasitizing Latrodectus hasselti Thorell (redback spider)

AbstractThe Australian members of the spider wasp genus Agenioideus are revised, and its two constituent species, Agenioideus expulsus Turner and A. nigricornis (Fabricius), are redescribed. A third species, Agenioideus ultimus (Turner), is transferred to Spuridiophorus Arnold, a genus that is newly recorded here from the Australian continent. Diagnoses and criteria to facilitate the identification of the two genera are provided, along with information on the distribution and host biology of Agenioideus species. The first records of a pompilid utilising Latrodectus hasselti Thorell (redback spider) as a host at multiple locations across southern Australia are presented, along with a brief synopsis of insect parasitoids and predators of L. hasselti in Australia.

Cloning and activity of a novel α-latrotoxin from red-back spider venom

The venom of the European black widow spider Latrodectus tredecimguttatus (Theridiidae) contains several high molecular mass (110–140 kDa) neurotoxins that induce neurotransmitter exocytosis. These include a vertebrate-specific α-latrotoxin (α-LTX-Lt1a) responsible for the clinical symptoms of latrodectism and numerous insect-specific latroinsectoxins (LITs). In contrast, little is known about the expression of these toxins in other Latrodectus species despite the fact that envenomation by these spiders induces a similar clinical syndrome. Here we report highly conserved α-LTX, α-LIT and δ-LIT sequence tags in Latrodectus mactans, Latrodectus hesperus and Latrodectus hasselti venoms using tandem mass spectrometry, following bioassay-guided separation of venoms by liquid chromatography. Despite this sequence similarity, we show that the anti-α-LTX monoclonal antibody 4C4.1, raised against α-LTX-Lt1a, fails to neutralize the neurotoxicity of all other Latrodectus venoms tested in an isolated chick biventer cervicis nerve–muscle bioassay. This suggests that there are important structural differences between α-LTXs in theridiid spider venoms. We therefore cloned and sequenced the α-LTX from the Australian red-back spider L. hasselti (α-LTX-Lh1a). The deduced amino acid sequence of the mature α-LTX-Lh1a comprises 1180 residues (∼132 kDa) with ∼93% sequence identity with α-LTX-Lt1a. α-LTX-Lh1a is composed of an N-terminal domain and a central region containing 22 ankyrin-like repeats. The presence of two furin cleavage sites, conserved with α-LTX-Lt1a, indicates that α-LTX-Lh1a is derived from the proteolytic cleavage of an N-terminal signal peptide and C-terminal propeptide region. However, we show that α-LTX-Lh1a has key substitutions in the 4C4.1 epitope that explains the lack of binding of the monoclonal antibody.

Letter: Transmitter release by red back spider venom.

Letter: Transmitter release by red back spider venom.

Red back spider venom and inhibitory transmission.

Red back spider venom and inhibitory transmission.

An Irritable Infant and the Runaway Redback: An Instructive Case

The envenomation syndrome of Redback spider bites, lactrodectism, is distinctive. However diagnosis can be difficult due to an atypical presentation. We describe the case of a 1 year old boy with irritability, diaphoresis and reduced oral intake, in whom a diagnosis was made of redback spider bite. Successful resolution of symptoms was achieved following treatment with antivenom. The symptoms and management of redback spider bites is discussed.

Longevity cost of remaining unmated under dietary restriction

Summary 1. Increases in longevity from dietary restriction (DR) have been linked to the evolution of physiological strategies for maintaining lifetime reproductive output despite periods of nutritional deficiency. If this is the case, then reproductive life history and mating status should determine whether or not dietary restriction increases longevity. 2. We investigate the effects of DR and mating status (mated or unmated) on longevity and lifetime reproductive output and explore mechanisms underlying these patterns by measuring resting energetic rates and changes in mass over time. We study iteroparous female Australian redback spiders (Latrodectus hasselti), which are known to tolerate periods of starvation (ecologically relevant DR) in nature. 3. Mated DR females had the highest longevity of any experimental group, in strong contrast to results for semelparous males of this species [M.M. Kasumovic, M.C.B. Andrade & R.C. Brooks (2009), Biology Letters,5, 636]. Most strikingly, mated females (whether DR or not) had higher longevity than unmated females. 4. Mated females rapidly decreased their resting energetic rates and stopped egg production under DR. Once feeding returned to normal, resting energetic rates of mated females increased immediately, egg sac production continued and there was no net decrease in lifetime reproductive output relative to mated females without DR. 5. This shows DR increases longevity for mated females, but there is a longevity cost of remaining unmated, which may arise because unmated females (regardless of diet) maintained high energetic rates. This may be an evolved pattern of physiological support for reproductive readiness which exerts a fitness cost when mating is delayed. Taken together, these results suggest positive effects of DR on longevity critically depend on reproductive life history (iteroparity or semelparity) and individual mating status.

The invasive Australian redback spider, Latrodectus hasseltii Thorell 1870 (Araneae: Theridiidae): current and potential distributions, and likely impacts

Populations of the Australian redback spider, Latrodectus hasseltii Thorell 1870, were first recorded in New Zealand in the early 1980s and in Osaka, Japan in 1995. Reliable records suggest that naturalised populations of L. hasseltii in New Zealand are present only in Central Otago and New Plymouth. In Central Otago, L. hasseltii feeds on endangered invertebrates, such as Prodontria modesta (Broun 1909). Latrodectus hasseltii is also a hazard to the New Zealand endemic L. katipo through interbreeding and competitive displacement. CLIMEXTM was used to model the potential global distribution of L. hasseltii based on current climate, and using ArcGIS® 9.2, areas of suitable climate in New Zealand were overlaid with favourable habitats to identify areas most suitable for L. hasseltii establishment. In addition, shelter that urban areas offer L. hasseltii were modelled in CLIMEX and incorporated into ArcGIS to produce maps indicating cities and built up areas where the species could establish. The presence of L. hasseltii in New Zealand and Japan, and its possible spread to other areas, is of human health significance, and the species may also impact on native biodiversity.

Acylated Serine Derivatives: A Unique Class of Arthropod Pheromones of the Australian Redback Spider, Latrodectus hasselti

Acylated Serine Derivatives: A Unique Class of Arthropod Pheromones of the Australian Redback Spider, <i>Latrodectus hasselti</i>