Bacteria inhabiting spider webs enhance host silk extensibility.

Spider silk is a promising material with great potential in biomedical applications due to its incredible mechanical properties and resistance to degradation of commercially available bacterial strains. However, little is known about the bacterial communities that may inhabit spider webs and how these microorganisms interact with spider silk. In this study, we exposed two exopolysaccharide-secreting bacteria, isolated from webs of an orb spider, to major ampullate (MA) silk from host spiders.

Alkaline water as a potential agent for biting midge control: Managing effectiveness and non-target organism impact evaluation.

Biting midge Forcipomyia taiwana is one of the common pests in East Asia. Their nuisance and blood-sucking behavior causes problems not only for human health but also for some industries. This study aims to evaluate the effectiveness of spraying alkaline water on controlling biting midge population and potential side effects of such approach on non-target organisms.

Nanoscale Material Heterogeneity of Glowworm Capture Threads Revealed by AFM.

Adhesive materials used by many arthropods for biological functions incorporate sticky substances and a supporting material that operate synergistically by exploiting substrate attachment and energy dissipation. While there has been much focus on the composition and properties of the sticky glues of these bio-composites, less attention has been given to the materials that support them. In particular, as these materials are primarily responsible for dissipation during adhesive pull-off, little is known of the structures that give rise to functionality, especially at the nano-scale.

Size-related increase in inducible mechanical variability of major ampullate silk in a huntsman spider (Araneae: Sparassidae).

Most spiders use major ampullate silk (MAS) to perform many functions across their lifetimes, including prey capture, vibratory signal detection, and safety/dragline. To accommodate their various needs, adult spiders can use inducible variability to tailor MAS with specific mechanical properties. However, it is currently unknown whether this inducible mechanical variability develops gradually or remains consistent across spider size.

Adhesion of spider cribellate silk enhanced in high humidity by mechanical plasticization of the underlying fiber.

The disruptive nature of water presents a significant challenge when designing synthetic adhesives that maintain functionality in wet conditions. However, many animal adhesives can withstand high humidity or underwater conditions, and some are even enhanced by them. An understudied mechanism in such systems is the influence of material plasticization by water to induce adhesive work through deformation.

Mechanical and structural properties of major ampullate silk from spiders fed carbon nanomaterials.

The dragline silk of spiders is of particular interest to science due to its unique properties that make it an exceptional biomaterial that has both high tensile strength and elasticity. To improve these natural fibers, researchers have begun to try infusing metals and carbon nanomaterials to improve mechanical properties of spider silk. The objective of this study was to incorporate carbon nanomaterials into the silk of an orb-weaving spider, Nephila pilipes, by feeding them solutions containing graphene and carbon nanotubes.

Hydrothermal Effect on Mechanical Properties of Spidroin.

The superlative mechanical properties of spider silk and its conspicuous variations have instigated significant interest over the past few years. However, current attempts to synthetically spin spider silk fibers often yield an inferior physical performance, owing to the improper molecular interactions of silk proteins. Considering this, herein, a post-treatment process to reorganize molecular structures and improve the physical strength of spider silk is reported.

Uncoiling springs promote mechanical functionality of spider cribellate silk.

Composites, both natural and synthetic, achieve novel functionality by combining two or more constituent materials. For example, the earliest adhesive silk in spider webs - cribellate silk - is composed of stiff axial fibers and coiled fibers surrounded by hundreds of sticky cribellate nanofibrils. Yet, little is known of how fiber types interact to enable capture of insect prey with cribellate silk.

Nitrogen inaccessibility protects spider silk from bacterial growth.

Spider silks are protein-based fibers that are incorporated into webs with the unique combination of high mechanical toughness and resistance to microbial degradation. While spiders are undoubtedly exposed to saprophytic microorganisms in their native habitats, such as the forest understory and bush, their silks have rarely been observed to decompose in either field or laboratory studies. We performed cross-streaking assays using silk from three spider species and four bacterial strains and found no inhibition zones, indicating the absence of antibacterial properties.

Multiscale mechanisms of nutritionally induced property variation in spider silks.

Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales.

Nutrient intake determines post-maturity molting in the golden orb-web spider (Araneae: Araneidae).

While molting occurs in the development of many animals, especially arthropods, post-maturity molting (PMM, organisms continue to molt after sexual maturity) has received little attention. The mechanism of molting has been studied intensively; however, the mechanism of PMM remains unknown although it is suggested to be crucial for the development of body size. In this study, we investigated factors that potentially induce PMM in the golden orb-web spider , which has the greatest degree of sexual dimorphism among terrestrial animals.

Physicochemical Property Variation in Spider Silk: Ecology, Evolution, and Synthetic Production.

The unique combination of great stiffness, strength, and extensibility makes spider major ampullate (MA) silk desirable for various biomimetic and synthetic applications. Intensive research on the genetics, biochemistry, and biomechanics of this material has facilitated a thorough understanding of its properties at various levels. Nevertheless, methods such as cloning, recombination, and electrospinning have not successfully produced materials with properties as impressive as those of spider silk.

Evidence of Decoupling Protein Structure from Spidroin Expression in Spider Dragline Silks.

The exceptional strength and extensibility of spider dragline silk have been thought to be facilitated by two spidroins, major ampullate spidroin 1 (MaSp1) and major ampullate spidroin 2 (MaSp2), under the assumption that protein secondary structures are coupled with the expressed spidroins. We tested this assumption for the dragline silk of three co-existing Australian spiders, Argiope keyserlingi, Latrodectus hasselti and Nephila plumipes. We found that silk amino acid compositions did not differ among spiders collected in May.

Spider web and silk performance landscapes across nutrient space.

Predators have been shown to alter their foraging as a regulatory response to recent feeding history, but it remains unknown whether trap building predators modulate their traps similarly as a regulatory strategy. Here we fed the orb web spider Nephila pilipes either live crickets, dead crickets with webs stimulated by flies, or dead crickets without web stimulation, over 21 days to enforce spiders to differentially extract nutrients from a single prey source. In addition to the nutrients extracted we measured web architectures, silk tensile properties, silk amino acid compositions, and web tension after each feeding round.

Crypsis via leg clustering: twig masquerading in a spider.

The role of background matching in camouflage has been extensively studied. However, contour modification has received far less attention, especially in twig-mimicking species. Here, we studied this deceptive strategy by revealing a special masquerade tactic, in which the animals protract and cluster their legs linearly in the same axis with their bodies when resting, using the spider Ariamnes cylindrogaster as a model.

Can differential nutrient extraction explain property variations in a predatory trap?

Predators exhibit flexible foraging to facilitate taking prey that offer important nutrients. Because trap-building predators have limited control over the prey they encounter, differential nutrient extraction and trap architectural flexibility may be used as a means of prey selection. Here, we tested whether differential nutrient extraction induces flexibility in architecture and stickiness of a spider's web by feeding Nephila pilipes live crickets (CC), live flies (FF), dead crickets with the web stimulated by flies (CD) or dead flies with the web stimulated by crickets (FD).

Top down and bottom up selection drives variations in frequency and form of a visual signal.

The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey.

Mechanical performance of spider silk is robust to nutrient-mediated changes in protein composition.

Spider major ampullate (MA) silk is sought after as a biomimetic because of its high strength and extensibility. While the secondary structures of MA silk proteins (spidroins) influences silk mechanics, structural variations induced by spinning processes have additional effects. Silk properties may be induced by spiders feeding on diets that vary in certain nutrients, thus providing researchers an opportunity to assess the interplay between spidroin chemistry and spinning processes on the performance of MA silk.

Evidence of bird dropping masquerading by a spider to avoid predators.

Masquerading comes at various costs and benefits. The principal benefit being the avoidance of predators. The orb-web spider Cyclosa ginnaga has a silver body and adds a white discoid-shaped silk decoration to its web.

Nutrient deprivation induces property variations in spider gluey silk.

Understanding the mechanisms facilitating property variability in biological adhesives may promote biomimetic innovations. Spider gluey silks such as the spiral threads in orb webs and the gumfoot threads in cobwebs, both of which comprise of an axial thread coated by glue, are biological adhesives that have variable physical and chemical properties. Studies show that the physical and chemical properties of orb web gluey threads change when spiders are deprived of food.

Uncovering spider silk nanocrystalline variations that facilitate wind-induced mechanical property changes.

Spider major ampullate (MA) silk varies in mechanical properties when spun in different environments. Amino acid compositional changes induced by variations in MaSp1 and MaSp2 expression, and various biochemical and physiological glandular processes induce silk property variability. Quantifying the contributions of these mechanisms on silk variability may facilitate the development of silk biomimetics.

Wind induces variations in spider web geometry and sticky spiral droplet volume.

Trap building by animals is rare because it comes at a substantial cost. Using materials with properties that vary across environments maintains trap functionality. The sticky spiral silks of spider orb webs are used to catch flying prey.

Nutrient-mediated architectural plasticity of a predatory trap.

Background: Nutrients such as protein may be actively sought by foraging animals. Many predators exhibit foraging plasticity, but how their foraging strategies are affected when faced with nutrient deprivation is largely unknown. In spiders, the assimilation of protein into silk may be in conflict with somatic processes so we predicted web building to be affected under protein depletion.

A color-mediated mutualism between two arthropod predators.

The nature of interactions between animals varies depending on local selection pressure, trophic status of the participants, and evolutionary circumstances. Body coloration and other visual signals may also affect animal interactions. Game theory posits that if one species provides a "service" in exchange for a "goods," a mutualism may ensue.

Post-secretion processing influences spider silk performance.

Phenotypic variation facilitates adaptations to novel environments. Silk is an example of a highly variable biomaterial. The two-spidroin (MaSp) model suggests that spider major ampullate (MA) silk is composed of two proteins-MaSp1 predominately contains alanine and glycine and forms strength enhancing β-sheet crystals, while MaSp2 contains proline and forms elastic spirals.