IntroductionScorpion venoms are natural sources of neurotoxins that primarily modulate the properties of neuronal ion channels, particularly voltage-gated sodium and potassium channels. However, they also contain a variety of small bioactive molecules that have been largely neglected in the omics era of toxinological research.MethodsIn the present study, we employed a high-throughput FLIPR screen of arthropod venoms against nicotinic acetylcholine receptors (nAChRs) expressed in the human SH-SY5Y neuroblastoma cell line. ResultsThe venom of the Malaysian forest scorpion Heterometrus spinifer (family: Scorpionidae) proved to be an agonist of nAChRs, and the small choline ester senecioylcholine was identified as being responsible for the observed effect. Synthetic senecioylcholine and its isomers tigloylcholine and angeloylcholine were not insecticidal when injected into sheep blowflies. DiscussionBased on previous reports of senecioylcholine being toxic to vertebrates along with the agonistic effect we observed on human nAChRs, we postulate that senecioylcholine in scorpion venom is likely to assist with vertebrate prey capture and defense against vertebrate predators. Since senecioylcholine has only been previously reported in marine gastropods and moths, its presence in scorpion venom seems to represent an unusual case of convergent evolution.
Many people are afraid of spiders and consider them to be both dangerous and disgusting, which can negatively impact their mental well-being as well as their relationship with nature. Very few studies have examined what characteristics draw visual attention toward or away from spiders, or have assessed the impact of arachnophobia and sex on attentional biases. Here, 118 undergraduate students freely viewed single and paired images of spiders and other arthropods in their natural environments while having their eye movements monitored. Participants also completed a survey measuring spider phobia and attitudes toward spiders. Multiple eyetracking metrics (total dwell time, first run dwell time, first fixation time, and run count) were used as indicators of attentional bias. Findings suggest a general avoidance of spider images in the presence of other non-spider arthropod images as well as avoidance of scorpion images in the presence of non-scorpion arachnid images. Presentation of image pairs with two kinds of spiders elicit attention toward spider-specific features. These effects were occasionally, though not often, moderated by sex and phobia levels. Across all metrics, there was a tendency to record longer first fixation times, shorter dwell times, and lesser run counts toward images of spiders. Images of jumping spiders and insects received considerably more and faster attentional allocation relative to other spiders. Understanding how general body form versus specific spider features influence visual attention provides insight into visual factors that may motivate spider phobia, providing evidence-based knowledge that could be useful in treatments. Additionally, knowledge of potentially appealing features of spiders may provide useful perspectives for communicating the usefulness of spiders in our ecosystem.
Conspecific male to female envenomation, though rare, has been documented across venomous taxa. While traditionally interpreted as a coercive mating strategy to enhance male reproductive success and to avoid cannibalism, this explanation may not fully account for the behaviour in scorpions, which exhibit minor sexual size dimorphism and complex courtship rituals. This review explores the possibly multifaceted roles of sexual stinging in scorpions. We highlight potential adaptive strategies, such as venom metering and compositional plasticity, that allow males to subdue females without causing lethal harm. We discuss hypotheses on the evolution of sexual stings, ranging from sexual coercion to chemical seduction and cooperative signalling. Finally, we propose future research directions, including comparative venomics, behavioural assays, and ecological studies, to shed light on the selective pressures that shape this enigmatic behaviour. By integrating insights from physiology, ecology, and evolution, this review advances our understanding of sexual envenomation as a dynamic interplay between conflict and cooperation in scorpion reproductive strategies.
The Gulf-Coast tick (Amblyomma maculatum) is an emerging species whose geographic range is expanding in the United States. Although tick bite-induced paralysis is uncommon, Am. maculatum has been implicated in cases affecting vertebrate hosts. We report a rare case of paralysis in α-Gal-deficient mice following nymphal tick attachment. Notably, the symptoms resolved rapidly after the nymph was removed.
The Chilobrachys tarantula, a genus of Old-World tarantulas, is known for its unique behavior and venomous bites, which have varying effects on humans. This research provides a comprehensive overview of Chilobrachys species distribution, bite incidents, and medical treatment based on bioclimatic modeling and clinical case reports. Chilobrachys species thrive in regions with moderate daily temperature ranges (−7.9°C to 43.3°C), stable climates, and sufficient precipitation (0 mm to 2,325 mm), particularly in Southeast Asia. Key bioclimatic variables such as maximum temperature of the warmest month (BIO5) and precipitation during both warm and cold months (BIO18, BIO19) significantly influence species distribution. Field data from 24 confirmed Chilobrachys bites reveal that most incidents occur between April and July, with bite symptoms ranging from severe localized pain, swelling, and necrosis to systemic effects like fever and hemoglobinuria. Case studies demonstrate the cytotoxic effects of Chilobrachys venom, leading to complications such as cellulitis, necrosis, and compartment syndrome, particularly in untreated or delayed cases. Medical reports indicate that treatment involves immediate first aid (RICE protocol), pain management, antihistamines for allergic reactions, and antibiotics to prevent secondary infections. In severe cases, surgical intervention is required for necrosis and compartment syndrome management. Bioclimatic and clinical data emphasize the need for public awareness, healthcare training, and early intervention to mitigate the risks associated with Chilobrachys bites. This research provides crucial insights into the ecological and medical aspects of these tarantulas, aiding in the prevention and management of envenomation cases.
Spiders have adapted to a wide range of ecological niches, accompanied by the diversification of their silk, which performs various ecological functions under different environmental conditions. This study investigates the physical properties of silk produced by highly mobile linyphiid spiders, whose airborne silken “sails” enable long-distance, high-altitude windborne dispersal. Environmental Scanning Electron Microscopy imaging demonstrated that linyphiid silk interacts with moisture in its surroundings, leading to changes in stiffness and increased torsion at relative humidities greater than 60%. The estimated tensile strength under low moisture conditions is estimated to be up to 1 GPa but drops by the order of a factor of 2 when exposed to moisture (>60% relative humidity) or to short (30 minute) bursts of short wavelength (UV-C) light. In contrast, storage at temperatures ranging from -18°C to 70°C had no significant impact on tensile strength. These findings demonstrate the resilience of linyphiid silk to low temperatures typical of high altitudes, with important implications for understanding wind-assisted dispersal, global spider distribution, and potential responses to climate change. We also show that the silk can withstand exposure to ultraviolet light at intensities that would induce damage or death to living tissue, albeit with an increased likelihood of fracture. Together these findings provide important insights needed to understand ecological processes and explore uses and limitations of synthetic analogues of these biological materials in medicine and engineering.
Kleptoparasitism, broadly defined, is the theft of extrinsic resources resulting in potential cost to the host. The stealing of resources, often food gathered by another, is perhaps best known in birds and mammals, but is even more common and widespread in arthropods like ants, bees, flies and spiders. Spiders are involved in myriad kleptoparasitic interactions, best studied as obligatory kleptoparasites of other spiders. However, less attention has been paid to the critical role of spiders as “superhosts” to commensal and kleptoparasitic organisms, and their variety of facultative kleptoparasitic strategies. To understand obligatory kleptoparasitism in spiders, it is first necessary to examine their role and characteristics as hosts and as facultative kleptoparasites. Most spider kleptoparasites utilize other spiders as hosts, a link that is not coincidental, and facultative resource stealing, in its many forms, is generally assumed to provide an evolutionary bridge to obligate kleptoparasitism. Here, I provide a brief review of these two roles through a summary of literature on all kleptoparasitic spiders and over 200 hosts. The phylogenetic distribution of spider hosts is distinctly non-random, involving about 200 species, in 86 genera, and 23 families. These then pertain to a few select lineages, out of total spider diversity: 23/136 families, 86/4,427 genera, and 200/52,765 known species. The vast majority of argyrodine hosts belong to four Araneoidea families (Araneidae, Nephilidae, Theridiidae, Linyphiidae), while the majority of hosts of mysmenid kleptoparasites are mygalomorphs, mostly Dipluridae and Ischnothelidae. Key spider hosts like Nephila, Trichonephila, Argiope, Cyrtophora, and Linothele, build large, often structurally complex, and persistent webs. Three-dimensionality, often in the form of auxiliary webbing, provides safe refuges for kleptoparasites, and the abundant prey and extended prey handling time of large spiders provide resources and opportunities for theft. Many of the favored hosts either interlink webs or are social. Key host traits to counter kleptoparasitism include web takedown and relocation, food concealment, and direct aggression. Facultative resource stealing in spiders includes web takeover, male kleptoparasitism of females in webs, and opportunistic prey theft. Among these, kleptotany, the facultative abandonment of own web and the invasion of a larger host web, to steal it and/or to prey on the host (araneophagy) are the most likely to link to obligatory kleptoparasitism.
Here, we review the processes involved in producing and assessing the quality of recombinant spider silk proteins (spidroins) and the challenges associated with their synthesis and spinning into robust fibres. We provide an overview of the techniques used to produce the proteins, from gene synthesis to expression in various host organisms. Evidence suggests that the N- and C-terminal regions of spidroins are of utmost importance for fibre assembly and the repetitive domains are responsible for the unique mechanical properties in both native and recombinant versions of spider silks. We describe the role of liquid–liquid phase separation (LLPS) in spidroin assembly and its importance in subsequent fibre formation. Recent developments in recombinant spidroin production and co-expression strategies for improving yield and scalability are highlighted. Techniques such as mass photometry and size exclusion chromatography (SEC) for analysing protein purity and assembly behaviour are thereupon detailed. Finally, we address the role that predictive computational methods play in the future of designing novel and high-performing materials inspired by spidroins.
Arachnid venom peptides receive increasing attention from researchers for possible applications as human therapeutics, as bioinsecticides in agriculture or for targeting vectors of human disease. One commonly perceived disadvantage of peptides in contrast to small molecule drugs is their inability of crossing biological membranes comprised of lipid bilayers, providing a major obstacle for the delivery of peptide-based drugs and bioinsecticides. However, some arachnid venom peptides were reported to cross biological membranes, including cellular membranes, the vertebrate and insect blood brain barrier (BBB) and the insect midgut epithelium. This review will focus on these membrane-permeating arachnid peptides and discuss the underlying mechanisms. Different physico-chemical properties of membrane-permeating arachnid peptides and their contribution to the ability of crossing biological membranes will also be examined. In addition, several methods that facilitate or enable peptides to cross biological membranes will be discussed, which can be employed on peptides with no inherent membrane-permeating capabilities.
Dolomedes may easily be considered to be among the most charismatic spider taxa. Known colloquially as fishing or raft spiders, this clade of dolomedid cursorial hunters is speciose with about 100 valid species names. Most Dolomedes are large spiders that inhabit water bodies across all continents except Antarctica and, interestingly, South America. Dolomedes have captured the attention of researchers and the public alike for their ability to walk on and submerge under water, fish for prey (including small vertebrates), and for their often-bizarre mating behavior that includes examples of male spontaneous death and sexual cannibalism. In this review, we critically evaluate what is known of Dolomedes biology, focusing on their systematics and morphology, ecology, behavior, and conservation. Given their close association with water, Dolomedes may be particularly vulnerable to the impacts of anthropogenic change and provide an important group of indicator species for understanding the effect of pollution, habitat loss and climate change. We outline a roadmap for future studies that, in our view, will consolidate Dolomedes as an ideal model lineage among spiders for addressing a vast array of questions across multiple fields of biology.
SPECIALTY GRAND CHALLENGE article Front. Arachn. Sci., 15 January 2024Sec. Arachnid Genetics and Biomaterials Volume 3 - 2024 | https://doi.org/10.3389/frchs.2024.1356170
Systematics provides the foundational knowledge about the units of biodiversity, i.e., species, and how we classify them. The results of this discipline extend across Biology and can have important impacts on conservation. Here we review the systematic and taxonomic practices within Theraphosidae over the last 260 years. We examine the rate of newly described species and investigate the contemporary practices being used in the description of new genera and species. There have been two large waves of theraphosid taxonomy, with an explosive growth of newly described species and author combinations in the last 60 years. We look back and find that during 2010–2024 contemporary practices in theraphosid systematics and taxonomy have remained largely static, being dominated by morphology-based approaches. Over this period, only 10% of newly described species incorporated DNA data or explicitly stated the species concept used. Similarly for genera, only five of the 37 newly described genera over that time were supported as distinct and monophyletic by DNA. We highlight the taxonomic movement of species among Theraphosidae, Barychelidae, and Paratropididae; however, given the limited molecular sampling for the two latter families, the boundaries of these families remain a significant area of needed research. To promote inclusivity, we provide a copy of this paper in Spanish as supplementary material.
Spiders are ancient and highly successful predators, which use venom for both predation and defense. Their venoms are complex mixtures of potent biological molecules, emerging as a prolific source of biomolecular innovation in agriculture, biomedicine, and bioeconomy. While small cysteine-rich neurotoxins are typically considered the main components of spider venoms, recent research has shown that spider venoms also contain many high-molecular-weight proteins, especially enzymes. To date, very little is known about the diversity, biochemistry and ecology of these components. Here, we provide the first systematic overview of spider venom enzymes, describing all known examples in terms of their properties and functions in the spider venom system. We argue that the sheer diversity of these neglected spider venom compounds offers significant translational potential and holds great potential for the bioeconomy, reflecting a wide range of technical applications such as industrial production, food processing, and waste management.
Phytophagous spider mites, belonging to the subfamily Tetranychinae, have diverse lifestyles. Life type is an important concept for understanding spider mite diversity. There are three basic life types: little web (LW), non-systematic and complicated web (CW), and woven nest (WN), which are characterised by silk production, silk usage patterns, faeces defaecation patterns, and other behavioural outcomes. In this review, we first address the diversity of life types and then discuss the functions of life types as reported by several studies. The primary function of the CW type is to provide a firm footing for residing on the underside of host leaves and to protect mites from the deleterious effects of solar radiation. Next, we discuss how spider mites have evolved various defence mechanisms through life types to avoid their natural enemies. We observed that the life type can affect the results of interspecies competition. Faeces manipulation behaviours observed in the CW and WN type mites may be an adaptation to keep a clean habitat. The CW species showed a significantly higher intrinsic rate of natural increase (rm) than LW and WN species, and such differences may be associated with host plant stability. Although there was no apparent relationship between sex ratio and life type, the extremely female-biased sex ratio in several WN species appears to contribute to local mate competition. In contrast, WNs strongly affect the aggressiveness of males because they provide a recognisable domain that they should defend. Furthermore, the WN type enhances mite aggregation in nests, and their iteroparous reproduction causes generation overlapping. Such traits may lead some WN species to develop advanced sub-sociality (cooperative sociality).
Introduction The design of biological structures and the materials composing those structures are intimately connected to performance in biological systems. Spider webs present an excellent example of how design and materials interact during their function in capturing prey. Major shifts in how spider webs capture prey have occurred due to evolutionary changes in both web architecture and silk properties. However, these shifts are mostly described for long timescales deep within the spider’s tree of life. Hawaiian Tetragnatha presents an opportunity to ask if such shifts can occur at much shorter timescales because web design diverges significantly among closely related species on the same island while also converging with more distant relatives on other islands. Here, we provide an initial test of whether or not silk properties diversified during the recent adaptive radiation of Hawaiian Tetragnatha . Methods We obtained radial and capture spiral silk from orb webs for spiders on two islands and tested their tensile and adhesive properties. We also used solution-state NMR to compare the composition of low molecular weight compounds in the glue because of their influence on capture spiral stickiness. Results Results showed differences in the stiffness of radial silk among four populations of Hawaiian Tetragnatha , while extensibility remained unchanged. Although not statistically different, radial strength and toughness varied twofold among species. Stickiness varied threefold among the four populations of orb weavers. No conspicuous qualitative differences in the low molecular weight compound composition of aggregate glue were found, suggesting that differences in capture spiral stickiness were due to the amount or arrangement of glue droplets on threads. Discussion While our sampling is modest, our data provide the first evidence that silk properties can evolve measurably over the relatively short timescales of the adaptive radiation of Hawaiian Tetragnatha spiders.
Silk of the water spider Argyroneta aquatica (Clerck, 1757) was obtained in the laboratory in the form of a capturing web irrespective of the formation of a diving bell and egg cocoon. Silk threads were examined by light microscopy, scanning (SEM), and transmission electron microscopy (TEM) as well as by atomic force (AFM) microscopy. Based on the diameter and internal organization, the silk threads have been divided into five types—a-, b-, c-, d-, and e-types interlaced freely in the thread bundles taken for examinations. Threads of all types are infinitely long, non-branched, round in shape, uniform in width through their course, and rarely found to be ruptured. Threads of the a-type are mostly straight, up to 1,000 nm in diameter, and composed of a fibrillary wall enveloping an electron-dense vacuolated core, which may be occasionally absent. The wall may also become lost, leaving a single core substance surrounded by a slightly wrinkled double membrane. Threads of the b-, c-, and d-types are organized nearly identical, being composed of a fine granular electron-light uniform material enveloped by a fine membrane. The diameter of these threads varies from max. 500 nm in the b-type and 120 nm in the c-type to around 50 nm in the d-type. Threads of these types are more convoluted and more numerous than threads of the a-type. Threads of the last kind, the e-type, occur rarely and are significantly larger with a diameter of around 3.5–4.5 µm. They possess the layered membranous wall surrounding a uniformly dense core. The silk of the water mites Limnochares aquatica (L., 1758) and Limnesia maculata (O.F. Müller, 1776) is composed of threads of only one type that closely corresponded to the a-type threads of A. aquatica . Conversely, the silk of the two-spotted spider mite Tetranychus urticae (C.L. Koch, 1836) consists of threads highly correlated with the d-type threads of A. aquatica . This finding shows that in different phylogenetic lineages of arachnids, the mechanisms of silk production are quite similar.
Visual signal, mechanical reinforcement, protein storage, or non-functional stress response? Web decorations constructed by a number of orb web spider species puzzle behavioural ecologists. While some species use a variety of construction materials, it seems particularly difficult to solve the issue for silk decorations. The visual pattern of decoration structures has sparked the researchers’ imagination, and the conclusion that they act as signals is unsurprising. For over a century, however, we have not found a conclusive answer on a specific signal function of silk decorations. More recent studies even suggest that the construction mode of web decorations may render a specific signal function rather unlikely. In this review, I discuss reasons for the continuous struggle to find conclusive answers and what could be alternative routes for unravelling their adaptive significance. Based on my own experience in the field, I present a personal viewpoint, which I hope will be inspiring at a stage where research in this field seems to have reached a dead end. We are faced with a controversial debate, inconclusive and sometimes contradicting results; and an interest in new studies is fading. I draw the attention to three trouble areas, covering research gaps, logical inconsistencies and conceptual misunderstandings. More specifically: 1) Web decorations should be treated more as the dependent variable. 2) Experimental setups of several earlier studies appear flawed in retrospect, and their results thus overinterpreted. 3) We have not understood the evolutionary origin of web decoration. We may look at a signal that is still in an early phase of shaping, and inconclusive results may thus be inevitable. Finally, if web decorations do not act as signals, studies that look for exactly that cannot find conclusive results. In discussing these issues critically, I argue, we can open new routes for progress in finding a satisfying solution of the riddle of the silk decoration function.
