Web Silk Research Articles

Integrating Passive Biomonitoring and Active Monitoring: Spider Web Silk and Portable Instruments for Air Quality in Urban Areas

Urban areas worldwide face significant challenges from increasing air pollution, posing health risks and environmental concerns. Lahore, a major city in Pakistan, is particularly affected by severe air pollution due to rapid industrial growth, high vehicle emissions, and various human activities. Traditional air quality monitoring methods, while effective, are often costly and complex, limiting their widespread use. This study investigates a dual monitoring system combining passive biomonitoring with spider web silk and active measurements using portable instruments to assess airborne pollutants in urban environments. Spider webs, collected from various sites in Lahore, were analyzed for heavy metals, while portable instruments simultaneously measured PM2.5, PM10, total volatile organic contents, formaldehyde, and carbon monoxide at the same locations. A spatial distribution analysis using GIS and statistical analysis revealed a pattern with significant changes as per land use in the urban environment related to anthropogenic activities. The Principal Component Analysis revealed three distinct clusters of pollutants origins consisting of: I) effluent drains and landfills, II) construction sites, and III) residential areas. The concentrations of Hg in spider silk (average ~ 2.66 mg/kg) were found to be significantly higher in the northeastern part of Lahore, with a similar trend observed in Cd, Cu, Ni, and As levels (average ~ 15.45, 102.87, 31.72, and 6.64, respectively). Several-fold changes in levels and spatial distribution of Pb (15.12 to 356.41 mg/kg) showed a higher concentration in the northern and northeastern parts of Lahore. The spatial variation pattern of Cr (average~ 57.04 mg/kg) registered a higher concentration in southwestern Lahore. Ambient air levels of measured pollutants followed almost similar patterns in spatial distribution. PM2.5 and PM10 measured higher levels (195 and 226 μg/m3, respectively) in the southwestern and northwestern areas, with a similar pattern of variation observed in TVOC (average ~ 0.14 μg/m3). The concentration of HCHO (average ~ 0.003 μg/m3) was higher in the southwest of Lahore. All measured pollutants registered higher values than air quality standards. Particulate matter is the most dominant pollutant contributing to air pollution (up to 20x higher than WHO guidelines). The findings support the use of a dual monitoring system, integrating passive spider web silk biomonitoring and active portable instruments, as a scalable and sustainable solution for air quality management. This approach holds potential for global application in diverse urban environments, with future research focusing on further validation and integration with advanced remote sensing technologies to enhance air quality monitoring and contribute to improved public health and environmental management worldwide. Hence, this research work points to the potential use of spider silk as a biomonitoring tool in combination with instrumental measurement of ambient air pollutants.

Insight into the molecular basis of the soluble storage-state to fibrous-state structural transformation of spider pyriform silk

Pyriform (or piriform) silk is a fibrous spider silk used in a composite material to attach web silks to substrates and disparate silk types together. Argiope argentata pyriform silk is formed from a protein with a central repetitive region consisting of a 234-amino acid unit (the "Py unit") repeated 21 times. We have previously shown that the Py unit behaves modularly, with a structured core of 6 α-helices that retains its structuring upon truncation of N- and C-terminal intrinsically disordered segments. Here, we apply solution-state nuclear magnetic resonance (NMR) spectroscopy to investigate the structured core of the Py unit. Based on 15N spin relaxation measurements and reduced spectral density mapping at two field strengths, the α-helical core of the Py unit exhibits minimal backbone motion beyond the tumbling of the globular domain except for one interhelical linker that exhibits a notably higher degree of dynamics. Evaluation of rotational diffusion based on 15N spin relaxation and translational diffusion by pulsed field gradient diffusion NMR demonstrates that the core of the Py unit behaves as a compact structure, with hydrodynamic behaviour consistent with a well-packed protein. Pyriform silk protein undergoes a structural transformation upon conversion from the soluble-state to the fibrous-state, with a loss of αhelical content and gain of β-sheet content. The more dynamic segment we observe midway through the structured core of the Py core, especially in the context of the intrinsically disordered segments that flank the core, would provide an initiation point for decompaction, structural transformation, and/or intermolecular interactions.

Conspecific cues mediate habitat selection and reproductive performance in a haplodiploid spider mite

Abstract Selection of a suitable habitat by animals before settlement is critical for their survival and reproduction. In silk-spinning arthropods like spider mites, denser webs offer protection from predation and serve as a dispersal mode. Settling in habitats with the presence of conspecifics and silk webs can benefit the habitat-searching females. Silk and conspecifics usually coexist, but their distinct effects on female colonization have received little attention. In this study, we used a haplodiploid spider mite, Tetranychus ludeni Zacher (Acari: Tetranychidae), to examine the impact of conspecific cues, including cues from ovipositing conspecifics and silk, on habitat selection and subsequent reproductive performance of females. Results show that females significantly preferred habitats with cues from neighboring conspecifics and silk and neighboring conspecifics induced additive effect to that of silk on habitat selection. Conspecific cues did not boost female reproduction but facilitated females laying larger eggs that were more likely to be fertilized and to develop into daughters. When given a choice between silk-covered and clean habitats, females preferred silk-covered habitats, laid a similar number of eggs with similar size, but produced more daughters, suggesting that T. ludeni females can adjust the size threshold for fertilization in response to the current social environment. Knowledge of this study improves our understanding of spider mite habitat selection and post-settlement reproductive performance behaviors.

Preliminary In Vitro Assessment of Antimicrobial and Haemostatic Activity of Spider Web Silk Extract

Preliminary In Vitro Assessment of Antimicrobial and Haemostatic Activity of Spider Web Silk Extract

Ecological strategies of Hyphantria cunea (Lepidoptera: Arctiidae) response to different larval densities

Population density is an essential factor affecting the life history traits of insects and their trade-off relationships, as increasing density intensifies intraspecific competition. It decreases the average resources available to individuals within a population, affecting their morphology, physiology, behavior, and fitness. The fall webworm, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), has been an invasive pest of forest trees, ornamental plants, and fruit trees in China for many years. The larvae have a typical aggregation habit before the fourth instar and keep spitting silk to gather the damaged leaves into silk webs. However, the fitness of H. cunea in response to population density remains unclear. In this study, the critical biological parameters, food utilization, and population parameters of H. cunea in response to different rearing densities were investigated. The results showed that under high population density, H. cunea larvae showed better performance, with faster development, higher survival rates, and shorter generation time, but pupal weight and female fecundity decreased as population density increased. In contrast, for larvae raised in low density, the developmental period was prolonged, and mortality was increased, while higher food utilization, greater body size, and female fecundity were observed. Both males and females had similar development strategies in response to the density, but females may be more resistant to crowding than males. In conclusion, H. cunea could adopt different ecological strategies against the stress of density. High population densities result in shorter generation cycles and higher survival rates. Conversely, the low-density generation period becomes longer but with greater fecundity. The results may help determine the possible outbreak mechanism and develop effective population monitoring and forecasting measures for H. cunea.

Water webbing: Long‐jawed spider (Araneae, Tetragnathidae) produces webs that touch the surface of ephemeral waterbodies

AbstractFew spiders are known to construct silk webs that physically contact water, despite it being both a surface and medium that can be exploited for web construction. Herein, we report on an Australian long‐jawed spider from the Tetragnatha genus (Tetragnatha cf. nitens) that frequently produces aerial webs that touch the surface of ephemeral waterbodies. Field observations revealed webs that were built by these spiders at varying heights above water in emergent vegetation stands around the edge of ephemeral waterbodies. Approximately, 15 of the 100 webs recorded were constructed immediately above the water with their lower sections making physical contact with the water's surface. We observed water striders becoming stuck within these low‐lying webs, suggesting that associating webs with surface water allows the spiders to exploit prey types that cannot be passively filtered from the environment in purely aerial webs. This could suggest that some species of long‐jawed spider select the positioning of their webs above water, which would be adaptive if it allows them to target different and possibly multiple prey communities.

Spider silk as a potential antibiotic substitute

Studies were undertaken on the antibacterial activity of spider silk against bacterial strains, using egg case silk of Parawixia dehaani (Doleschall, 1859) and web silk of Pholcus phalangioides (Fuesslin, 1775). Both silk types inhibited gram negative bacteria more than gram positive bacteria. The egg case silk of P. dehaani showed more antimicrobial activity than the web silk of P. phalangioides. The egg case silk brought about 26.05 per cent inhibition against E. coli, compared to a 22.7 per cent inhibition for B. subtilis. A linear association was found between the volume of silk extract and the percentage of inhibition.The percentage of inhibition against E. coli increased from 5.13 to 26.05 per cent as the volume rose from 20 to 100 µl. in P. dehaani.

Population level variation in silk chemistry but not web architecture in a widely distributed orb web spider

Abstract Spider webs are iconic examples of extended phenotypes that are remarkably plastic across different environments. Orb webs are not only effective traps for capturing prey, but can also provide information to potential mates and, in some cases, potential predators and prey through silk-based chemicals. As with regular phenotypic traits, variability in the properties of spider webs is thought to be mediated by a combination of genetic and environmental effects. Here, we examined variation in several key features of the webs of the orb-weaving spider Argiope keyserlingi across five geographically disparate populations. We documented variation in web architecture and chemical properties of webs collected directly from the field. We then probed the potential for the underlying environmental driver of local insect abundance to explain this variation, by analysing the properties of orb webs constructed by the spiders from these different populations, but under identical laboratory conditions. We found no evidence of variation across populations in the architecture of webs constructed in the laboratory, despite the large geographic distances. Nonetheless, we discovered between population variation in the composition of chemicals found on the surface of silk and in the taxonomic distribution of available prey. Furthermore, there was a positive correlation between the quantity of nitrogenous compounds in web silks and female body condition. When combined, these findings suggest that environmental mechanisms can drive variation in web traits across spider populations.

FERN-ARTHROPOD INTERACTIONS FROM THE MODERN UPLAND SOUTHEAST ATLANTIC RAINFOREST REVEALS ARTHROPOD DAMAGE INSIGHTS TO FOSSIL PLANT-INSECT INTERACTIONS

ABSTRACTFerns were among the first broadleaved plants in the fossil record. We assessed fern-arthropod interactions in modern ferns (Monilophyta) as a model for comparison with damage on ferns in the fossil record. We found that the functional feeding groups of margin feeding, hole feeding, surface feeding, piercing and sucking, oviposition, mining, and galling was present on 13 species of ferns at elevations ranging from 750 to 900 meters along mountain slopes of the Brazilian Atlantic Rainforest. We recognized 17 damage types (DTs), including one new DT, and provide implications for interpreting damage on leaves in the fossil record. Nine fossil DTs with modern analogues were found on ferns. Evaluation of damage on modern ferns demonstrate that the variation in the abundance and damage signatures of external feeding, piercing and sucking, galling, and mining enhances understanding of damage patterns on fossil leaves. The taphonomic implications to fossil plant-insect interactions are provided based on the sampling of modern arthropod damage and the preservation biases on ferns. Arthropod remains that are poorly attached to ferns, such as silk webs, eggs, and spider egg sacs, as well as insect exuviae, pupae, and body parts, might provide an important feature for arthropod preservation associated with fern leaves in the plant fossil record. This integrative method demonstrates that DT signatures on modern ferns indicate that ferns are an important host plant for herbivorous arthropods. Consequently, the same importance of ferns as host plants of arthropod herbivores likely was present in deep time.

Novel Descriptions of Immature Stages of the Forestry Insect Pest, Yponomeuta meguronis (Lepidoptera: Yponomeutidae), with New Records of Its Natural Enemies

The genus Yponomeuta is widely known as a forestry insect pest group; however, it is extremely difficult to identify it at the species level because of its small size and morphological complexity. Thus far, only a few major species and host plants, as well as natural enemy information, are known through European research within the limited eastern Palearctic region. In this study, Yponomeuta meguronis Matsumura is revealed to be a severe forestry insect pest for Euonymus japonicus Thunb. (Celastraceae) in Korea, which constitutes part of the western Palearctic region. We observed that numerous tiny larvae caused serious damage to its leaves and partially or entirely covered the tree by making communal silk webs. To rapidly and accurately identify this insect pest in the future, new descriptions of immature stages, including larva and pupa, were provided, along with their adult forms, based on ecological photographs and morphological illustrations. Two natural enemies of Y. meguronis were also recognized for the first time in this study: Herpestomus brunnicornis (Gravenhorst) (Hymenoptera: Ichneumonidae) was revealed as a parasitoid, and Xanthandrus comtus (Harris) (Diptera: Syrphidae) was presented as a predator.

American fall webworm in China: A new case of global biological invasions

American fall webworm in China: A new case of global biological invasions

Effect of Relative Humidity on the Electrospinning Performance of Regenerated Silk Solution.

Recently, the electrospun silk web has been intensively studied in terms of its biomedical applications, including tissue engineering scaffolds, due to its good biocompatibility, cytocompatibility, and biodegradability. In this study, the effect of relative humidity (RH) conditions on the morphology of electrospun silk fiber and the electrospinning production rate of silk solution was examined. In addition, the effect of RH on the molecular conformation of electrospun silk web was examined using Fourier transform infrared (FTIR) spectroscopy. As RH was increased, the maximum electrospinning rate of silk solution and fiber diameter of the resultant electrospun silk web were decreased. When RH was increased to 60%, some beads were observed, which showed that the electrospinnability of silk formic acid solution deteriorated with an increase in RH. The FTIR results showed that electrospun silk web was partially β-sheet crystallized and RH did not affect the molecular conformation of silk.

Effects of Fabrication Conditions on Structure and Properties of Mechanically Prepared Natural Silk Web and Non-Woven Fabrics.

In this study, natural silk web and natural silk non-woven fabric were prepared mechanically using the binding character of the sericin in silk. The effect of process variables on the preparation, structure, and properties of the silk web and the non-woven fabric was examined. The reeling velocity affected the morphology and mechanical properties of the web but had almost no influence on the crystalline structure of the silk. From the viewpoint of reel-ability and the mechanical properties (work of rupture) of silk web, a reeling velocity of 39.2 m/min represented the optimal processing velocity. The porosity and swelling ratio of the silk web decreased slightly with increasing reeling velocity. Furthermore, the reeling bath temperature had a significant effect on the reel-ability of silk filaments from a silkworm cocoon. Bath temperatures ≥50 °C yielded good reel-ability (>900 m reeling length). The porosity, swelling ratio in water, and mechanical properties of the silk web and silk non-woven fabric changed only slightly with the reeling bath temperature but changed significantly with the hot press treatment. The hot-pressed silk web (i.e., silk non-woven fabric) exhibited higher tensile strength as well as lower elongation at break, porosity, and swelling ratio than the silk web.

Investigating Atomic Level Structure in Pyriform Silk Proteins

Spider silks are biomaterials used for many diverse adaptations by spiders, with mechanical properties comparable to Kevlar and high strength steel. Orb-weaver spiders create up to seven distinct types of silk, including pyriform silk. Pyriform silk is a major constituent of spider attachment discs, which connect web silks to each other and also to disparate materials using glue-coated fibres. Although filling a critical role in web formation, prior to our work neither the structural nor mechanical properties of pyriform silk had been widely investigated. Based on the central pyriform silk repetitive domain from Argiope argentata, we successfully engineered recombinant pyriform silk-based proteins. Using these proteins, we showed that, in contrast to mechanical extremes of strength at the expense of extensibility or vice versa that are seen in most silks, recombinant pyriform silk is both strong and extensible. To understand the structure-function relationships for this distinctive class of silk, we are performing solution and fibre-state structural studies. Our initial studies have implied distinct regions of order and disorder in the repetitive unit based on the observation of differing degrees of NMR spectroscopy chemical shift dispersion that correlate to the sign of heteronuclear 1H-15N nuclear Overhauser effect enhancements, consistent with a sequence that has segregated regions of disordered and ordered tertiary structuring. Through backbone and side chain chemical shift assignment, we expanded on this, with current data suggesting a central 5-6 helix bundle with long disordered linkers at each end of the bundle that shows no structural perturbation upon the addition of extra repeat blocks, indicating that this protein is likely to behave in a “beads-on-a-string” manner. Current investigation into structural transitions upon fibrillogenesis have shown an anticipated shift from predominantly α-helix in solution to β-sheet in fibres, with further studies ongoing.

Chemical Species Recognition in a Tetragnatha Spider (Araneae: Tetragnathidae).

Much of our knowledge regarding the role of chemicals in species recognition in arthropods is based on a few taxonomic groups, predominantly insect pest species. To investigate the chemical underpinnings of species recognition cues in other arthropods, we conducted mate choice experiments and analyzed the chemical profiles of two species in the long-jawed spider genus Tetragnatha from allopatric populations across two different continents. In two separate bioassays, in which male T. extensa spiders were presented with either web silk or extracts from the silk of conspecific and heterospecific females, males consistently chose the silk or silk extract of conspecific females over those of heterospecifics. We examined the chemistry affecting this response using gas chromatography/mass spectrometry to analyze silk and whole-body extracts of the spiders. The major compounds in the extracts were identified as long chain aliphatic methyl ethers. The chemical profiles of the two species differed: the T. extensa profile consisted of 12,20-dimethylnonacosyl methyl ether (A), 8,14,20-trimethylnonacosyl methyl ether (B), and 6,14,20-trimethylnonacosyl methyl ether (C), while the profile of T. versicolor consisted of B and 14,20-dimethylnonacosyl methyl ether (D). Within each species, chemical profiles of females and males did not differ. Our results suggest that these methyl ethers are involved in species recognition of Tetragnatha spiders. This is the first study to propose compounds involved in species recognition in spiders.

Free-standing spider silk webs of the thomisid Saccodomus formivorus are made of composites comprising micro- and submicron fibers

Our understanding of the extraordinary mechanical and physico-chemical properties of spider silk is largely confined to the fibers produced by orb-weaving spiders, despite the diversity of foraging webs that occur across numerous spider families. Crab spiders (Thomisidae) are described as ambush predators that do not build webs, but nevertheless use silk for draglines, egg cases and assembling leaf-nests. A little-known exception is the Australian thomisid Saccodomus formivorus, which constructs a basket-like silk web of extraordinary dimensional stability and structural integrity that facilitates the capture of its ant prey. We examined the physical and chemical properties of this unusual web and revealed that the web threads comprise microfibers that are embedded within a biopolymeric matrix containing additionally longitudinally-oriented submicron fibers. We showed that the micro- and submicron fibers differ in their chemical composition and that the web threads show a remarkable lateral resilience compared with that of the major ampullate silk of a well-investigated orb weaver. Our novel analyses of these unusual web and silk characteristics highlight how investigations of non-model species can broaden our understanding of silks and the evolution of foraging webs.

Mesomechanics of a three-dimensional spider web

Spiders, silks and webs are abundant and can be found in most ecosystems: in the corner of houses, on top of bushes, or even spanning rivers. They are the proof of an evolutionary success as they were able to survive and prosper for millions of years despite being subjected to environmental and human threats, such as the displacement of spider web silk attachments or impact of prey, predators, and debris. Their success is in part due to the excellent mechanical properties of silk and webs that originate from their hierarchical structure of silk, ranging from silk protein, to fibers, to spider webs. Here, we investigate the mechanical behavior of highly complex Cyrtophora Citricola 3D spider web, the architecture of which has been digitally modeled with micron-scale details from images of full-scale laboratory experiments, under stretching and projectile impact, using coarse-grain bead-spring simulations. We show that the interplay between the nonlinear behavior of spider silk and the redundancy of complex 3D spider web structures is crucial for the robustness and resilience of spider webs. The tangle region of the spider web allows prey to fly through and be caught in the dense tent web region, providing food to the spider. It also filters out predators at low impact velocity, and consequently protects the spider located in the tent region. Understanding the role of the interplay between silk mechanics and 3D web structure in webs’ evolutionary fitness could lead to high-performance and lightweight fiber network composite for structural, material and biomedical engineering.

A golden age for ectoparasitoids of Embiodea: Cretaceous Sclerogibbidae (Hymenoptera, Chrysidoidea) from Kachin (Myanmar), Charentes (France) and Choshi (Japan) ambers

Sclerogibbid wasps are obligate parasitoids of webspinners (Embiodea). Both groups have a particularly scarce geological record and are known since the Cretaceous: there are only four species of webspinners known from Burmese amber, and only two sclerogibbids were described from Barremian Lebanese and Cenomanian Burmese ambers. Here we report transferred genus from Aptian Choshi (Japan) amber and new sclerogibbids from Cenomanian Burmese and Charentese (France) ambers. The taxa described from Burmese amber are: Burmasclerogibba aptera gen. et sp. nov., Cretosclerogibba gen. nov. (with C. antennalis sp. nov., C. contractocollis sp. nov., C. neli sp. nov. and C. rasnitsyni sp. nov.) and Edrossia vetusta gen. et sp. nov. The first European fossil sclerogibbid Gallosclerogibba alnensis gen. et sp. nov. is described from Charentese amber. The holotype of Chosia yamadai Fujiyama, from Choshi amber, is re-described; it appears to be the oldest Laurasian sclerogibbid. The significant abundance and variety of Burmese sclerogibbid wasps (60% of fossil species known worldwide), as proxy of their hosts, were probably caused by the protection granted to them by the silk webs and possibly by the limited predation from ornithuromorph birds or crown-group ants. While all three extant sclerogibbid genera have apterous females, genera with winged females (Cretosclerogibba and Edrossia) dominated in Burmese amber. Small silk galleries from hosts may have favored the preservation of wings in females of Cretaceous sclerogibbids. Most new species described in the present paper, in addition to C. yamadai, are characterized by a very slender neck and a very long frontal process concealing the antennal toruli. These characters disappeared in extant species. We suggest that this loss was caused by a change in the fauna of predators, penalizing species with long neck and rostrum.

Revealing the Venomous Secrets of the Spider's Web.

Orb-weaving spiders use a highly strong, sticky and elastic web to catch their prey. These web properties alone would be enough for the entrapment of prey; however, these spiders may be hiding venomous secrets in the web, which current research is revealing. Here, we provide strong proteotranscriptomic evidence for the presence of toxin/neurotoxin-like proteins, defensins, and proteolytic enzymes on the web silk from Nephila clavipes spider. The results from quantitative-based transcriptomic and proteomic approaches showed that silk-producing glands produce an extensive repertoire of toxin/neurotoxin-like proteins, similar to those already reported in spider venoms. Meanwhile, the insect toxicity results demonstrated that these toxic components can be lethal and/or paralytic chemical weapons used for prey capture on the web, and the presence of fatty acids in the web may be a responsible mechanism opening the way to the web toxins for accessing the interior of prey's body, as shown here. Comparative phylogenomic-level evolutionary analyses revealed orthologous genes among two spider groups, Araneomorphae and Mygalomorphae, and the findings showed protein sequences similar to toxins found in the taxa Scorpiones and Hymenoptera in addition to Araneae. Overall, these data represent a valuable resource to further investigate other spider web toxin systems and also suggest that N. clavipes web is not a passive mechanical trap for prey capture, but it exerts an active role in prey paralysis/killing using a series of neurotoxins.

Genome of the webworm Hyphantria cunea unveils genetic adaptations supporting its rapid invasion and spread

BackgroundThe fall webworm Hyphantria cunea is an invasive and polyphagous defoliator pest that feeds on nearly any type of deciduous tree worldwide. The silk web of H. cunea aids its aggregating behavior, provides thermal regulation and is regarded as one of causes for its rapid spread. In addition, both chemosensory and detoxification genes are vital for host adaptation in insects.ResultsHere, a high-quality genome of H. cunea was obtained. Silk-web-related genes were identified from the genome, and successful silencing of the silk protein gene HcunFib-H resulted in a significant decrease in silk web shelter production. The CAFE analysis showed that some chemosensory and detoxification gene families, such as CSPs, CCEs, GSTs and UGTs, were expanded. A transcriptome analysis using the newly sequenced H. cunea genome showed that most chemosensory genes were specifically expressed in the antennae, while most detoxification genes were highly expressed during the feeding peak. Moreover, we found that many nutrient-related genes and one detoxification gene, HcunP450 (CYP306A1), were under significant positive selection, suggesting a crucial role of these genes in host adaptation in H. cunea. At the metagenomic level, several microbial communities in H. cunea gut and their metabolic pathways might be beneficial to H. cunea for nutrient metabolism and detoxification, and might also contribute to its host adaptation.ConclusionsThese findings explain the host and environmental adaptations of H. cunea at the genetic level and provide partial evidence for the cause of its rapid invasion and potential gene targets for innovative pest management strategies.