Pholcus Phalangioides Research Articles

From fibres to adhesives: evolution of spider capture threads from web anchors by radical changes in silk gland function.

Spider webs that serve as snares are one of the most fascinating and abundant type of animal architectures. In many cases they include an adhesive coating of silk lines-so-called viscid silk-for prey capture. The evolutionary switch from silk secretions forming solid fibres to soft aqueous adhesives remains an open question in the understanding of spider silk evolution. Here we functionally and chemically characterized the secretions of two types of silk glands and their behavioural use in the cellar spider, Pholcus phalangioides. Both being derived from the same ancestral gland type that produces fibres with a solidifying glue coat, the two types produce respectively a quickly solidifying glue applied in thread anchorages and prey wraps, or a permanently tacky glue deployed in snares. We found that the latter is characterized by a high concentration of organic salts and reduced spidroin content, showing up a possible pathway for the evolution of viscid properties by hygroscopic-salt-mediated hydration of solidifying adhesives. Understanding the underlying molecular basis for such radical switches in material properties not only helps to better understand the evolutionary origins and versatility of ecologically impactful spider web architectures, but also informs the bioengineering of spider silk-based products with tailored properties.

Biocomposite Materials Derived from Andropogon halepensis: Eco-Design and Biophysical Evaluation.

This research work presents a "green" strategy of weed valorization for developing silver nanoparticles (AgNPs) with promising interesting applications. Two types of AgNPs were phyto-synthesized using an aqueous leaf extract of the weed Andropogon halepensis L. Phyto-manufacturing of AgNPs was achieved by two bio-reactions, in which the volume ratio of (phyto-extract)/(silver salt solution) was varied. The size and physical stability of Andropogon-AgNPs were evaluated by means of DLS and zeta potential measurements, respectively. The phyto-developed nanoparticles presented good free radicals-scavenging properties (investigated via a chemiluminescence technique) and also urease inhibitory activity (evaluated using the conductometric method). Andropogon-AgNPs could be promising candidates for various bio-applications, such as acting as an antioxidant coating for the development of multifunctional materials. Thus, the Andropogon-derived samples were used to treat spider silk from the spider Pholcus phalangioides, and then, the obtained "green" materials were characterized by spectral (UV-Vis absorption, FTIR ATR, and EDX) and morphological (SEM) analyses. These results could be exploited to design novel bioactive materials with applications in the biomedical field.

Assemblage of spider diversity in Okkarai region of Pachamalai hills, Eastern Ghats, Tiruchirappalli district, Tamil Nadu, India

The Okkarai area of Pachamalai hills, Eastern Ghats, Tiruchirappalli district, Tamil Nadu, India, was studied for spider diversity in the current study. In total, 178 spiders were recorded, belonging to 12 distinct families (Araneidae, Desidae, Linyphiidae, Nephilidae, Oxyopidae, Pholcidae, Pisauridae, Salticidae, Sparassidae, Tetragnathidae, Theridiidae and Thomisidae), and 17 and 20 different genera and species, respectively. Araneidae family dominated the spider population, and the family dominance curve was in the ascending order of Araneidae (25.28%) > Oxyopidae (14.04%) > Pholcidae (14.04%) > Thomisidae (10.11%) > Tetragnathidae (7.86%) > Linyphiidae (6.74%) > Nephilidae (6.17%) > Sparassidae (5.05%) > Theridiidae (4.49%) > Pisauridae (3.37) > Salticidae (2.24%) > Desidae (0.56%). Araneidae (17.64%) had the most genera per family, and Araneidae and Oxyopidae (20.00%) had the most species per family; and about species composition, Pholcus phalangioides dominated with 14.04%. Spider guilds were represented by web patterns as well as hunting patterns. Web pattern comprised orb web (60.86%), cobweb (34.78%) and sheet web (4.34%). Orb web was represented by families Araneidae, Nephilidae and Tetragnathidae; cobweb by Desidae, Pholcidae, Pisauridae and Theridiidae; while Linyphiidae for sheet web. Ambushers (53.22%) and stalkers (46.77%) represented the hunting pattern whereas Pisauridae, Sparassidae and Thomisidae represented ambushers, and Oxyopidae and Salticidae represented stalkers. Araneidae and Oxyopidae had high species richness indicated by Hill’s (4), Margalef’s (1.33), and Menhinick’s (0.299) indices. Salticidae had high species evenness denoted by Alatalo’s (0.578), Pielou’s (0.488), Shannon’s (1.471) and Sheldon’s (1.413) indices; while Linyphiidae represented Heip’s index (1.347). Araneidae scored high on other indices, viz., Berger-Parker dominance (25.28%), community dominance (1.24), and relative dominance (20.00%); while Salticidae had a high Hill’s number abundance (1.413%), and Pholcidae had a high relative frequency (0.55). This study will contribute to the data on spider biodiversity, taxonomy, it's abundance, distribution, and community organization.

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.

Pests and predators interference on the stingless bee population inhabited at different habitats amidst south-eastern Karnataka, India

Stingless bees (Hymenoptera: Apidae: Meliponini) are called ‘Dammar bees’ live under cryptic conditions at diversified ecosystems. Stingless bees are one of the most important species, playing pivotal role as ‘Keystone Pollinators’ for various flowering plant species. Besides, they are cultured in the name of ‘Meliponi culture’ at various man-made agro-ecosystems. Reports on biological constraints of stingless bees is limited at south-eastern Karnataka, hence in the present study commonly occurring constraints and their per cent interference on stingless bee population under natural conditions from 2017 to 2019 in Bangalore Rural, Chikkaballapura and Kolar districts, Karnataka was made. The Megachile bee, Megachile (Callomegachile) disjuncta, beetle, Bitoma siccana, spider, Menemerus bivittatus, Crossopriza lyoni and Pholcus phalangioides, greater wax moth, Galleria mellonella, wall lizard, Hemidactylus species, garden lizard, Calotis versicolar and Psammophilus dorsalis acted as important constraints of stingless bee population and impacted more for their decline. Further, burning, hunting, closing their colony entrance by cow dung and cement, road construction and destruction of buildings and other man-made activities have created huge impact on stingless bee population. Stingless bee’s conservation is required to restore for conservation of local vegetation, to produce medicinally important honey and hence their natural colonies need special attention cum protection at their preferred abode.

Worldwide Web: High Venom Potency and Ability to Optimize Venom Usage Make the Globally Invasive Noble False Widow Spider Steatoda nobilis (Thorell, 1875) (Theridiidae) Highly Competitive against Native European Spiders Sharing the Same Habitats.

Venom compositions include complex mixtures of toxic proteins that evolved to immobilize/dissuade organisms by disrupting biological functions. Venom production is metabolically expensive, and parsimonious use is expected, as suggested by the venom optimisation hypothesis. The decision-making capacity to regulate venom usage has never been demonstrated for the globally invasive Noble false widow Steatoda nobilis (Thorell, 1875) (Theridiidae). Here, we investigated variations of venom quantities available in a wild population of S. nobilis and prey choice depending on venom availability. To partially determine their competitiveness, we compared their attack rate success, median effective dose (ED50) and lethal dose (LD50), with four sympatric synanthropic species: the lace webbed spider Amaurobius similis, the giant house spider Eratigena atrica, the missing sector orb-weaver Zygiella x-notata, and the cellar spider Pholcus phalangioides. We show that S. nobilis regulates its venom usage based on availability, and its venom is up to 230-fold (0.56 mg/kg) more potent than native spiders. The high potency of S. nobilis venom and its ability to optimize its usage make this species highly competitive against native European spiders sharing the same habitats.

It takes Two: Discovery of Spider Pax2 Duplicates Indicates Prominent Role in Chelicerate Central Nervous System, Eye, as Well as External Sense Organ Precursor Formation and Diversification After Neo- and Subfunctionalization

Paired box genes are conserved across animals and encode transcription factors playing key roles in development, especially neurogenesis.Pax6is a chief example for functional conservation required for eye development in most bilaterian lineages except chelicerates.Pax6is ancestrally linked and was shown to have interchangeable functions withPax2.Drosophila melanogaster Pax2plays an important role in the development of sensory hairs across the whole body. In addition, it is required for the differentiation of compound eyes, making it a prime candidate to study the genetic basis of arthropod sense organ development and diversification, as well as the role of Pax genes in eye development. Interestingly, in previous studies identification of cheliceratePax2was either neglected or failed. Here we report the expression of twoPax2orthologs in the common house spiderParasteatoda tepidariorum, a model organism for chelicerate development. The twoPax2orthologs most likely arose as a consequence of a whole genome duplication in the last common ancestor of spiders and scorpions.Pax2.1is expressed in the peripheral nervous system, including developing lateral eyes and external sensilla, as well as the ventral neuroectoderm ofP. tepidariorumembryos. This not only hints at a conserved dual role ofPax2/5/8orthologs in arthropod sense organ development but suggests that in chelicerates,Pax2could have acquired the role usually played byPax6. For the other paralog,Pt-Pax2.2, expression was detected in the brain, but not in the lateral eyes and the expression pattern associated with sensory hairs differs in timing, pattern, and strength. To achieve a broader phylogenetic sampling, we also studied the expression of bothPax2genes in the haplogyne cellar spiderPholcus phalangioides. We found that the expression difference between paralogs is even more extreme in this species, sincePp-Pax2.2shows an interesting expression pattern in the ventral neuroectoderm while the expression in the prosomal appendages is strictly mesodermal. This expression divergence indicates both sub- and neofunctionalization afterPax2duplication in spiders and thus presents an opportunity to study the evolution of functional divergence after gene duplication and its impact on sense organ diversification.

Comparison of the effectiveness of fumigant storin to control insect pests warehouse Lassioderma serricorne and Pholcus phalangioides

Insects warehouse pests contained in commodities, especially tobacco, can cause a decrease in the quantity and quality of commodity. The main pest insects found in tobacco storage warehouses are Lassioderma serricorne and Pholcus phalangioides. This study aims to analyze and compare the effectiveness of the use of fumigant storin to control insect pests L. serricorne and P. phalangioides. Methods used in this study include preparation of test insects, fumigation application, identification, calculation of mortality, and data analysis. The data were analyzed statistically using the One Way ANOVA test. The results showed that there was a significant difference in morphility between groups of test insects. Mortality is highest in the L. serricorne test insect group, which indicates that fumigant storin is very effective in controlling barn pest insects, especially L. serricorne. To control insect pests warehouses in the future, it is recommended to use biopesticides to be safer for food.

Comparison of the effectiveness of phostoxin fumigants for controlling insect pests warehouse Lassioderma serricorne and Pholcus phalangioides

Insects warehouse pests contained in commodities, especially tobacco, can cause a decrease in the quantity and quality of commodities. The main pest insects found in tobacco storage warehouses are Lassioderma serricorne and Pholcus phalangioides. This study aims to analyze and compare the effectiveness of phostoxin fumigants to control insect pests L. serricorne and P. phalangioides. Methods used in this study include preparation of test insects, fumigation application, identification, calculation of mortality, and data analysis. The data were analyzed using one way ANOVA test. The results showed that there was a significant difference in morphility between groups of test insects. The highest mortality was in the group of test insects L. serricorne, which indicated that phostoxin fumigants effectively controlling barn insect pests, especially L. serricorne. To control insect pests warehouses in the future, it is recommended to use biopesticides to be safer for food.

Assassin bugs can reduce the aggression of their spider prey before an attack

AbstractPredators that hunt dangerous prey require specialized predatory tactics to avoid counter-attack. Usually, these predatory tactics reduce the probability of detection. The assassin bugs Stenolemus bituberus and S. giraffa rely on stealth or mimicry to prey on dangerous web-building spiders. Paradoxically, however, these assassin bugs tap the spiders with their antennae prior to attacking, leaving the bugs vulnerable to detection and counter-attack. Here, we tested the function of prey tapping. We used a controlled, repeated-measures experiment to assess the responses of spiders (Pholcus phalangioides) to simulated prey and compared their responses after being tapped on the leg (mimicking tapping by Stenolemus) or sham-tapped. We show that tapping can reduce the likelihood that spiders will behave aggressively, in turn lowering the risks of injury for assassin bug predators. Tapping may be an adaptation to reduce intraspecific aggression in prey that is being exploited by their predators.

Herbivore-induced plant volatiles do not affect settling decisions by synanthropic spiders

An underlying assumption of optimal foraging models is that animals are behaviorally, morphologically, and physiologically adapted to maximize their net energy intake. Here we explored whether this concept applies to web-building spiders in a multi-trophic context. If a spider were to build her web next to herbivore-fed-on plants that signal the herbivores’ enemies for help by emitting herbivore-induced plant volatiles (HIPVs), that spider may maximize web captures in the short term. However, she would also risk predation by generalist predators that “listen” to signaling plants to find both herbivore and spider prey, likely resulting in lower overall reproductive fitness for the spider. We tested the hypothesis that HIPVs trigger avoidance responses by web-building spiders. We selected seven common HIPVs and one HIPV elicitor, and in two-choice olfactometer bioassays tested their effect on four synanthropic spider species (false black widow, Steatoda grossa; common cellar spider, Pholcus phalangioides; hobo spider, Eratigena agrestis; western black widow, Latrodectus hesperus). The 8-component HIPV/HIPV elicitor blend had a weak deterrent effect on S. grossa, but the effect did not extend to P. phalangioides, E. agrestis, and L. hesperus. Our findings imply that there was insufficient selection pressure for these spiders to recognize HIPVs in a multi-trophic context, where spiders themselves could become prey if generalist predators or spider-hunting parasitoid wasps were to respond to signaling plants.

Detection of web builder size via chemical cues present on silk by web-invading cellar spiders (Araneae: Pholcidae)

Animals often compete for resources and territory. Differences in size and body condition often play a crucial role in determining the outcome of these competitions. Web spiders not only create very costly semipermanent territories in the forms of their webs but have been shown able to gather myriad information from chemical cues present on silk. Furthermore, some web spiders are known to invade the webs of conspecifics in lieu of creating their own. We examined whether two pholcid spiders, Pholcus manueli and Pholcus phalangioides , use chemical information about the size and body condition of the web owner to inform their decisions when invading a foreign web. Specifically, we examined whether spiders could gather information about the size and hunger level of a conspecific and whether this information influenced their web-invading behaviour. We also examined whether washing webs with ethanol could remove these effects. We introduced spiders to webs built by conspecifics and recorded their latency to invade the webs. Pholcus manueli invaded webs built by larger conspecifics more slowly while P. phalangioides did not alter invasion latency to larger spiders' webs. Washing webs with ethanol removed this effect. Neither species’ behaviour was affected by the hunger level of the web builder. Our results show that P. manueli can determine the size of a conspecific from chemical cues attached to silk and adjust their web invasion behaviour accordingly, but that P. phalangioides does not adjust its behaviour in response to such cues. Importantly, our web-washing results support that chemical cues and not web structure influenced invasion behaviour of P. manueli , giving us a powerful tool for future research. The species level differences suggest separate behavioural strategies between the two similar species and that these strategies may influence the outcome of competitions between the two. • We tested whether pholcids use chemical cues to assess web builder size/condition. • Pholcids assessed the size of conspecifics from chemical cues on empty webs. • The smaller species, P. manueli , invaded webs of smaller conspecifics faster. • Pholcus phalangioides did not adjust behaviour based on web builder size. • Washing webs with ethanol removed chemical cues.

Contests between web spiders: patience as a strategy for successful invasion

When a species moves into a new area, direct contests with functionally similar residents may determine whether they can establish themselves. In recent years, the web-building cellar spider, Pholcus manueli, has largely displaced its larger well-established congener, Pholcus phalangioides, in SW Ohio. The relationship between these two species is interesting both because they are congeners and because both are invasive; the resident, P. phalangioides, had robust populations in the area for more than 100 years. We hypothesized that this example of over-invasion was related to interactions over web sites or webs. We first staged interspecific contests between adult females over empty web sites and existing webs in the laboratory. The smaller P. manueli never won but many encounters ended as ties with little active engagement between the spiders. We then staged contests with juvenile spiders that were close in size. We introduced well-fed or food-limited P. manueli into webs of P. phalangioides. In these matches, the relative size difference, a proxy for resource holding potential, determined the outcome. However, fights involving well-fed P. manueli were shorter and more aggressive than contests with hungry individuals. Additionally, well-fed invaders were more likely to take over webs whilst hungry P. manueli were less likely to engage in contests, thus allowing coexistence. We posited that newly introduced individuals, immersed in a population of P. phalangioides, persisted on the sidelines of the resident’s webs, and engaged in interspecific aggression only when the dynamics of the interaction were in their favor.

Kin Recognition in two Species of Cellar Spiders, (Pholcidae), and its Effects on Inter- and Intra-Specific Predation of Spiderlings

Intraguild predation and cannibalism are important behaviors that provide resources and influence interactions between different predators. Cannibalistic species should have a mechanism to identify offspring and suppress predation. We tested this hypothesis using two nonnative species of pholcid spiders in Ohio, Pholcus phalangioides and Pholcus manueli. In the laboratory we allowed females of both species to produce clutches. Once hatched the spiderlings were separated from their mother for 1 h and then reintroduced to the mother, a conspecific, or were introduced to an heterospecific adult female. The proportion of prey items consumed was recorded. Pholcus phalangioides predation patterns were consistent across species, but P. manueli feed on P. phalangioides young at twice the rate of young conspecifics, treating heterospecific young similar to control crickets. Further, mothers did not prey on their own young. These results highlight an important biological difference between the two species and indicate that intraguild predation may play an important role in interactions between the two species.

Ultrastructure of spider thread anchorages.

Spiders attach silken threads to substrates by means of glue-coated nanofibers (piriform silk), spun into disc-like structures. The organization and ultrastructure of this nano-composite silk are largely unknown, despite their implications for the biomechanical function and material properties of thread anchorages. In this work, the ultrastructure of silken attachment discs was studied in representatives of four spider families with Transmission Electron Microscopy to facilitate a mechanistic understanding of piriform silk function across spiders. Based on previous findings from comparative studies of piriform silk gland morphology, we hypothesized that the fibre-glue proportion of piriform silk differs in different spiders, while the composition of fibre and glue fractions is consistent. Results confirmed large differences in the relative proportion of glue with low amounts in the orb weaver Nephila senegalensis (Araneidae) and the hunting spider Cupiennius salei (Ctenidae), larger amounts in the cobweb spider Parasteatoda tepidariorum (Theridiidae) and a complete reduction of the fibrous component in the haplogyne spider Pholcus phalangioides (Pholcidae). We rejected our hypothesis that glue ultrastructure is consistent. The glue is a colloid with polymeric and fluid fractions that strongly differ in proportions and assembly. We further confirmed that in all species studied both dragline and piriform silk fibres do not make contact with the environmental substrate. Instead, adhesion is established by a thin dense skin layer of the piriform glue. These results advance our understanding of piriform silk function and the interspecific variation of its properties, which is significant for spider biology, web function and the bioengineering of silk.

Comparative reproductive output of two cellar spiders (Pholcidae) that coexist in southwest Ohio

Species differ in their reproductive abilities, which may affect their success. In southwest Ohio, populations of Pholcus phalangioides (Fuesslin, 1775) (Araneae: Pholcidae) have largely been replaced by Pholcus manueli Gertsch, 1937 (Araneae: Pholcidae). We suspected that differences in reproductive output underpinned the success of P. manueli. We documented the reproductive success of both species in the laboratory. Female P. phalangioides mated more readily and were more likely to produce eggsacs than P. manueli, but the timing of eggsac production and spiderling emergence were similar. The eggsacs of P. phalangioides contained smaller numbers of larger eggs but similar numbers of spiderlings emerged from the sacs of both species. We uncovered a negative relationship between egg size and number for P. phalangioides, but not for P. manueli. Our results do not explain the relative success of P. manueli, however, we have uncovered differences in the reproductive strategies utilized by these ecologically-similar congeners.

Ontogenetic approach reveals how cognitive capability and motivation shape prey-searching behavior inPholcus phalangioidescellar spiders

An important part of understanding the evolution of behavior is understanding how and why behavior develops and changes throughout ontogeny. Patterns of behavior are shaped by an animal's capabilities as well as its motivations, both of which are subject to selection. We ran an experiment to see how spiders' efforts to recover lost prey change with age and to determine the relative contributions of shifts in capability and motivation. We found that as spiders mature, they spend less time searching to recover lost prey, and they discriminate less between prey of different sizes. We also found that even the youngest, least experienced spiders are cognitively equipped to search for lost prey. Thus, predatory behavior in spiders fluctuated primarily with each age group's motivations to capture and consume prey, and did not seem to be hindered by behavioral or cognitive limitations at young ages.

Spider silk as a template for obtaining magnesium oxide and magnesium hydroxide fibers

Spider silk fibers, collected from Pholcus Phalangioides spider were used as a template for obtaining magnesium oxide (MgO, periclase) as well as magnesium hydroxide (Mg(OH)2, brucite) fibers. Magnesium oxide fibers were obtained in a simple manner by heat induced decomposition of magnesium salt (MgCl2) in the presence of the spider silk fibers, while magnesium hydroxide fibers were synthesized by hydration of MgO fibers at 50, 70 and 90 ?C, for 48 and 96 h. According to Scanning electron microscopy (SEM), dimensions of spider silk fibers determined the dimension of synthesized MgO fibers, while for Mg(OH)2 fibers, the average diameter was increased with prolonging the hydration period. The surface of Mg(OH)2 fibers was noticed to be covered with brucite in a form of plates. X-Ray diffraction (XRD) analysis showed that MgO fibers were single-phased (the pure magnesium oxide fibers were obtained), while Mg(OH)2 fibers were two- or single-phased brucite depending on incubation period, and/or incubation temperature.

Magnetic susceptibility of spider webs as a proxy of airborne metal pollution

The purpose of this pilot study was to test spider webs as a fast tool for magnetic biomonitoring of air pollution. The study involved the investigation of webs made by four types of spiders: Pholcus phalangioides (Pholcidae), Eratigena atrica and Agelena labirynthica (Agelenidae) and Linyphia triangularis (Linyphiidae). These webs were obtained from outdoor and indoor study sites. Compared to the clean reference webs, an increase was observed in the values of magnetic susceptibility in the webs sampled from both indoor and outdoor sites, which indicates contamination by anthropogenically produced pollution particles that contain ferrimagnetic iron minerals. This pilot study has demonstrated that spider webs are able to capture particulate matter in a manner that is equivalent to flora-based bioindicators applied to date (such as mosses, lichens, leaves). They also have additional advantages; for example, they can be generated in isolated clean habitats, and exposure can be monitored in indoor and outdoor locations, at any height and for any period of time. Moreover, webs are ubiquitous in an anthropogenic, heavily polluted environment, and they can be exposed throughout the year. As spider webs accumulate pollutants to which humans are exposed, they become a reliable source of information about the quality of the environment. Therefore, spider webs are recommended for magnetic biomonitoring of airborne pollution and for the assessment of the environment because they are non-destructive, low-cost, sensitive and efficient.

Expression and function of the zinc finger transcription factor Sp6-9 in the spider Parasteatoda tepidariorum.

Zinc finger transcription factors of the Sp6-9 group are evolutionarily conserved in all metazoans and have important functions in, e.g., limb formation and heart development. The function of Sp6-9-related genes has been studied in a number of vertebrates and invertebrates, but data from chelicerates (spiders and allies) was lacking so far. We have isolated the ortholog of Sp6-9 from the common house spider Parasteatoda tepidariorum and the cellar spider Pholcus phalangioides. We show that the Sp6-9 gene in these spider species is expressed in the developing appendages thus suggesting a conserved role in limb formation. Indeed, RNAi with Sp6-9 in P. tepidariorum leads not only to strong limb defects, but also to the loss of body segments and head defects in more strongly affected animals. Together with a new expression domain in the early embryo, these data suggest that Sp6-9 has a dual role P. tepidariorum. The early role in head and body segment formation is not known from other arthropods, but the role in limb formation is evolutionarily highly conserved.