Behavior Of Spiders Research Articles

Does reproductive behaviour reflect phylogenetic relationships? An example from Central EuropeanAlopecosawolf spiders (Araneae: Lycosidae)

Species-specific patterns of courtship behaviour are often used in wolf spider species delimitation. However, differences in courtship patterns are rarely assessed in an evolutionary context. The wolf spider genus Alopecosa comprises 150 species, for which the distribution and mating periods commonly overlap. We analysed the courtship and copulatory behaviour of 14 European Alopecosa species that are traditionally classified into four sibling species complexes (groups) and sequenced one mitochondrial (COI) and two nuclear genes (28S, H3) to reconstruct their phylogenetic relationships. The courtship behaviour of Alopecosa wolf spiders includes 17 elements, involving palpal, pedal, opisthosomal and whole-body movements. The observed courtship and copulation behaviours exhibit both conserved elements and species-specific combinations of traits. The results of the phylogenetic analyses were largely incongruent with the traditional, morphology-based grouping. Species from the ‘pulverulenta’ group formed a monophylum, although members of the ‘striatipes’ and ‘fabrilis’ groups were recovered as para- or polyphyletic. Furthermore, monophyly of Alopecosa was not recovered. We provide a checklist of species-specific traits presented during courtship and copulation that can be used to identify sibling species complexes.

Behavioural adaptations of cave orb spiders

Given the low abundance of flying insects in subterranean habitats, it is surprising that troglophile orb spiders in the genus Meta (family Tetragnathidae) are relatively abundant in subterranean habitats, especially in the twilight zone of European caves. As is the case for most subterranean invertebrates, we know very little about their behaviour. However, they have been reported to possess a number of specific behavioural adaptations to the cave environment. These include modifications of the traditional orb web such that webs do not have frame and anchor threads, but instead have the radii (the spokes in the web) attaching directly to the cave walls, and that cave spiders, unlike epigean orb spiders, allegedly engage in off-web foraging as well as on-web foraging. Here I review the evidence for these claims and compare these to the behaviour of epigean spiders in the related Metellina genus including preliminary comparative data on both morphology and web characteristics. In addition, I will discuss the potential of using the cave Meta spiders, especially M. menardi and M. bourneti, as model organisms for studying search behaviour, mate finding behaviour and sexual selection, as these spiders show an interesting life cycle with young instars leaving the cave environment to spend an instar in the epigean environment before returning. It is currently not known how spiderlings locate subterranean habitats, how males find female webs or whether the level of sexual selection is lower in the resource-limited subterranean habitat compared to the epigean habitat.

Ariadna spiders as bioindicator of heavy elements contamination in the Central Namib Desert

The present study represents the first attempt to promote Ariadna spider as bioindicator of heavy elements contamination in the central region of the Namib Desert. Various spider populations belonging to undescribed Ariadna species have been described in Central Namib gravel plains and identified as sit-and-wait predators. By spending their life in individual tunnels, Ariadna spiders resemble the behaviour of ground-dwelling spiders that are well known as bioaccumulators of heavy elements. In the present study, 60 individuals of Ariadna spiders were collected from three populations located at various distances from major mining areas of Namib Desert. Contents of fifteen heavy elements were measured in sand samples taken around spider burrows as well as in spider bodies. Several oxidative stress responses as CAT and GST, MDA levels, aside cholinergic function (Cholinesterases), were assayed. Body burden of Ag, Cd, Cu and Zn resulted significantly higher than levels measured in sand, while Co, Cr, Ni, Pb, U and V levels were one or two order of magnitude lower in spider body than in sand samples. All enzymes activities (CAT, GST, ChE) as well as MDA levels were detectable in Ariadna spiders despite lower values than other species. Though we cannot affirm that all sampled spiders belong to the same species, their enzymatic activities reflect their ability to accumulate heavy elements regardless the specific habitat features, confirming so the value of this genus as bioindicator of heavy elements in the Central Namib Desert.

Identification and analysis of odorant-binding protein genes from the wolf spider Pardosa pseudoannulata (Araneae: Lycosidae) based on its transcriptome

Pardosa pseudoannulata, one of the dominant predators in the paddy ecosystem, is a potential resource in the biological control of rice pests. Olfaction is crucial for insect behaviors such as feeding, mating and foraging, and odorant-binding proteins (OBPs) play a vital role in smell sensing, so we suppose that OBPs may be also important in spider behaviors. In this study, we identified two putative OBP genes and obtained their complete cDNA sequences. PpseOBP1 is 842 bp long and encodes a 188 amino acids protein. PpseOBP2 is 996 bp long and encodes a 213 amino acids protein. By our predictions and analysis, both of the PpseOBPs share some similar physicochemical and structural characteristics with insect classic OBP genes, but they do not strictly observe the cysteine pattern of OBPs in insects, in which there are three amino acid residues between the second and the third cysteine residues but 27 amino acid residues in P. pseudoannulata. Phylogenetic analysis showed that two PpseOBPs clustered together at the edge of the tree, indicating their distant relationship with insects. Regarding insects, PpseOBPs were most closely related to the Periplaneta americana OBP1. Both PpseOBPs are mainly expressed in appendages (pedipalps and legs). Expression of PpseOBP1 was significantly higher in female appendages than in male appendages, while PpseOBP2 showed an extreme expression level in male pedipalps. This is the first report of molecular characterization and expression patterns of OBPs in Lycosidae and will establish a foundation for better understanding of molecular mechanisms of P. pseudoannulata olfaction and facilitate its function in biological control.

Next-generation sequencing analysis of Pardosa pseudoannulata's diet composition in different habitats.

Spiders are the most common and predominant predators in terrestrial ecosystems. The predatory behavior of spiders affects the energy flow across the food web within an ecosystem. Traditiaonal methods for analyzing spider diets such as field observation, anatomy and faeces analysis are not suitable for spider experiments due to spiders’ special dietary behavior. The molecular method based on the specific primers of prey DNA seems to be inefficient either in spite of its wide application in diet analysis. As the next-generation sequencing (NGS) technology becomes prevalent in many different areas, several cases of the NGS-based analysis of mammal diets have been published. This study analyzed the diet differences of Pardosa pseudoannulata (Araneae: Lycosidae) in four habitats (a wetland, a tea plantation, an alpine meadow and a paddy field) by using the NGS technology, combined with the DNA barcode method. The results suggested that the Pardosa pseudoannulata feed on a broad range of prey, and 7 orders and 24 families of insects were detected in the four investigated habitats. Moreover, it is found that the diet diversity of Pardosa pseudoannulata is greatly influenced by their living environments and seasons. In a nutshell, this study established an NGS-based methodology for spider diets analysis, and the results provided some basic materials to inform the protection and utilization of the Pardosa pseudoannulata as a potential eco-friendly predator against pests.

Spontaneous movement behaviour in spiders (Araneae) with different hunting strategies

Spontaneous movement behaviour in spiders (Araneae) with different hunting strategies

Electric Fields Elicit Ballooning in Spiders

SummaryWhen one thinks of airborne organisms, spiders do not usually come to mind. However, these wingless arthropods have been found 4 km up in the sky [1], dispersing hundreds of kilometers [2]. To disperse, spiders “balloon,” whereby they climb to the top of a prominence, let out silk, and float away. The prevailing view is that drag forces from light wind allow spiders to become airborne [3], yet ballooning mechanisms are not fully explained by current aerodynamic models [4, 5]. The global atmospheric electric circuit and the resulting atmospheric potential gradient (APG) [6] provide an additional force that has been proposed to explain ballooning [7]. Here, we test the hypothesis that electric fields (e-fields) commensurate with the APG can be detected by spiders and are sufficient to stimulate ballooning. We find that the presence of a vertical e-field elicits ballooning behavior and takeoff in spiders. We also investigate the mechanical response of putative sensory receivers in response to both e-field and air-flow stimuli, showing that spider mechanosensory hairs are mechanically activated by weak e-fields. Altogether, the evidence gathered reveals an electric driving force that is sufficient for ballooning. These results also suggest that the APG, as additional meteorological information, can reveal the auspicious time to engage in ballooning. We propose that atmospheric electricity adds key information to our understanding and predictive capability of the ecologically important mass migration patterns of arthropod fauna [8].Video

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.

Social spider foraging-based optimal resource management approach for future cloud

With the expansion of computing infrastructure of heterogeneous and distributed environment, resource management has become a big challenge. In a cloud computing environment, problems of management of resources with the tasks are encountered. Resources are the backbone of cloud, and it is very important to handle the issue of resource management efficiently. Unfortunately, the existing resource management policies, frameworks, and mechanisms are proved ineffective to handle these applications and resources. So to provide better performance of the application, the aforementioned characteristics must be addressed effectively. This paper proposes an approach that targets the maximization of server capacity by managing the resources properly, hence improving the performance of resources. In a hierarchical multilayer cloud framework, the resource management layer determines the utilization of the task set and admitted utilization of virtual machines that guarantees performance. A new novel nature inspired algorithm based on the foraging behavior of the social spider is implemented to increase the efficiency and effectiveness.

On the development of a predictive functional trait approach for studying terrestrial arthropods.

The characterization of ecological communities with functional traits allows to consider simultaneously the ability of a species to survive and reproduce in an environment, its interactions with other species and its effects on the ecosystem. Functional traits have been studied mainly by plant ecologists, but are increasingly common in the study of other taxa including arthropods. Arthropods represent a group for which a functional trait approach could be highly profitable because of their high diversity, abundance, ubiquity and role in many important ecological processes. This review synthesizes two decades of functional trait research on terrestrial arthropods. We show that while the approach has gained popularity, particularly in the last decade, the absence of clearly postulated hypotheses is a recurrent problem limiting generalization. Furthermore, studied traits are often poorly related to studied functions. To address these problems, we propose a step-by-step protocol to postulate clear hypotheses prior to trait selection and emphasize the need for a common set of more generalizable traits in future studies. Extending the functional trait approach to arthropods opens the door to improving our understanding of interspecific interactions and potential links between response and effect traits. We present the concept of trait-matching with several examples of arthropod traits known to be effective predictors of consumer-resource interactions. The development of a successful functional trait approach for terrestrial arthropods will necessitate an understanding of relevant traits, standardized measurement protocols and open access databases to share this information. Such progress will provide ecologists with a new set of tools to answer broad questions in several fields including the study of community assembly, ecological networks and multitrophic functionality.

The effects of overwintering and habitat type on body condition and locomotion of the wolf spider Pardosa alacris

Overwintering in temperate regions is a prominent mortality risk for invertebrates and may affect their behaviour and body condition. Pardosa alacris is a common ground dwelling spider in central European native and plantation forests, and habitat type and prey availability may play important roles in their overwintering. The effect of overwintering on body condition and behaviour of spiders in semi natural and exotic habitats is relatively unknown. Here we assess the effects of winter on spiders from native poplar and exotic pine plantations. The locomotory behaviour of P. alacris (distance covered and speed) was assessed by tracking their movement in a white circular plastic arena. We assessed body condition, body size, and total fat content. Forest type and sex had significant effects on body length. Fat content was significantly higher in the spring than in autumn, and spiders covered larger distances and were faster in autumn than in spring. Fat content had a significant negative effect on average speed. Spiders in native forests were smaller but grew more during the winter than in exotic plantations, possibly due to higher prey availability in native forests. Visually-hunting predators may significantly affect spiders. Fat spiders with better body condition moved less, and were thus less detectable by predators. However the low movement rate may result in a low rate of encountering prey items, thus lowering feeding efficiency.

Social spider optimisation algorithm for dimension reduction of electroencephalogram signals in human emotion recognition

Due to some limitations of current heuristics and evolutionary algorithms, this paper proposed a new swarm based algorithm for feature selection method called Social Spider Optimization (SSO-FS). In this research, SSO-FS is used in the EEG-based emotion recognition model as searching method to find optimal feature set to maximize classification performance and mimics the cooperative behaviour and mechanism of social spiders in nature. This proposed feature selection method has been tested on DEAP EEG dataset with six subjects and compared with the most popular heuristic algorithms such as GA, PSO and ABC. The results show that the SSO-FS provides a remarkable and comparable performance compared to other existing methods. Whereby, the max accuracy obtained is 66.66% and 70.83%, the mean accuracy obtained is 55.51 7.17 and 60.97 8.38 for 3-level of valence emotions and 3-level of arousal emotions classification respectively.

A novel protocol for generating intact, whole-head spider cephalothorax tissue sections.

The diversity of spider behavior and sensory systems provides an excellent opportunity for comparative studies of the relationship between the brain and behavior. However, the morphology of spiders poses a challenge for histologists since the spider cephalothorax contains heterogeneous tissues and has both tough external and internal sclerotized regions. Unlike the heads of insects, the cephalothorax is highly pressurized, which can cause tissues to shift during processing and can reduce tissue cohesion in thick sections.This work describesa novel protocol for producing thick whole-head sections for morphological study by softening the exoskeleton and stabilizing friable tissue, without freezing or dehydration. It also presents an effective whole-head DiI staining method that uses minimal dehydration and highlights neural structures.

Automatic segmentation of gallbladder using bio-inspired algorithm based on a spider web construction model

In medical image processing, an accurate segmentation and classification are very important and this field still needs an effective computer-based algorithm for accomplishing the task. In gallbladder segmentation, only few automatic segmentation methodologies have been presented. The accuracy is very important in medical image processing for accurate diagnosis of the disease. In this paper, by exploiting the basic web building behavior of spiders, we developed a bio-inspired algorithm based on the spider web construction process for image segmentation process in medical images. The aim of this paper is to detect the shape of the gallbladder and to segment the gallstones and polyps located inside the gallbladder using a computer-based algorithm. It is necessary to apply a suitable preprocessing method in order to eliminate the irregularities presenting in the ultrasound scan images. In the preprocessing stage, histogram equalization and DooG filter are applied to enhance the contrast of the image. After that, the proposed spider web algorithm is applied in the segmentation process. The performance metrics of the proposed method are evaluated by implementing the proposed method to test the input dataset of 60 patients and it is compared with the results obtained from conventional segmentation methods. The values of DSC, OF, OV and PE for images with no lesions are 0.873167, 0.8389, 0.81705 and 0.81452.

Laboratory-reared and field-collected predators respond differently to same experimental treatments

Laboratory studies of animal behavior can use animals with different developmental histories, including those that have spent most of their lives in the field or those raised in the laboratory. Both types of animals are assumed to respond similarly to experimental treatments. The goal of this study was to test if this assumption is true, if field-collected and lab-reared animals respond similarly to experimental treatments. In the first experiments, we test how diet (high lipid or protein) affected mating behaviors of male jumping spiders, Phidippus audax. Male spiders had opposite responses to diet based on their rearing condition in both scramble competition and male-male interaction trials. Field-collected spiders fed with high-protein diets and lab-reared spiders fed with high-lipid diets found mates quicker and were more aggressive than their counter parts fed with different diets. Field-collected spiders were also more active in open arenas and courted females more actively than lab-reared spiders. In a second experiment, we tested spiders for preference of flower color, and found that both lab-reared and field-collected spiders selected flowers with color over white flowers. However, field-collected spiders prefer red flowers with UV fluorescence, while lab-reared spiders seem to prefer red without UV. These results suggest that lab-reared and field-collected animals can respond differently to the same experimental treatments. Further work is needed to test if this happens in other animals, and which types of individuals (lab-reared or field collect) best reflect the responses of animals in nature. Laboratory studies are commonly used to study animal behavior. Animals used in these studies can be either raised in the laboratory or collected from the field just prior to the study. While lab-reared and field-collected animals can differ sometimes in their behavior (e.g., more or less active in response to a treatment), they are both assumed to respond in qualitatively the same manner. However, this does not appear to be the case in our study of a common species of jumping spider, Phidippus audax. Lab-reared and field-collected animals responded in opposite directions to identical treatment conditions. These results suggest that the developmental histories of animals can fundamentally affect how they respond to experimental treatments in the laboratory and, hence, the conclusions drawn from such studies.

A Social Spider Optimization Algorithm with Chaotic Initialization for Robust Clustering

Several real-life datasets at times contain few observations whose characteristics are completely different from the rest of the patterns. Such patterns occur due to faulty readings taken or due to presence of noise are termed as outliers. In this paper a recently developed algorithm Social Spider Optimization (SSO) is employed for robust clustering. The robust clustering takes care of the outliers with the use of Robust Distance (RD) as the cost function. The SSO is a swarm intelligence algorithm inspired by the cooperative behavior of spiders on a web. In this paper the initialization of spiders are carried out by Chaotic sequence which enhances its performance compared to the original SSO which uses random sequence. The simulation studies are carried out on two synthetic and three real life datasets. Comparative analysis reveals superior performance of proposed Chaotic SSO (C-SSO) over Original SSO, Chaotic PSO, PSO, Chaotic K-means and K-means algorithms. It is observed that the Chaotic versions of the algorithms have better accuracy ( here represented by lower mis-classification index) over the regular algorithms.

The role of silk in courtship and chemical communication of the false widow spider, Steatoda grossa (Araneae: Theridiidae)

In spiders, sex pheromones are often associated with silk produced by females, and function in mate attraction, recognition, and evaluation. Silk-bound pheromones typically elicit courtship behaviour in web-building spiders. Here we (1) describe courtship interactions of Steatoda grossa males with virgin or mated females, and (2) show that silk and methanol extracts of silk produced by virgin females trigger courtship behaviour (silk production) by males, whereas silk of mated females does not. Our results indicate that (1) virgin females produce a silk-bound sex pheromone, (2) males discriminate between virgin and mated females based on silk cues, and (3) male silk likely functions in sexual communication.

Influence of aging on brain and web characteristics of an orb web spider

In animals, it is known that age affects the abilities of the brain. In spiders, we showed that aging affects web characteristics due to behavioral alterations during web building. In this study, we investigated the effects of age on the associations between morphological changes to the spider brain and changes in web characteristics. The orb web spider Zygiella x-notata (Araneae, Araneidae) was used to test these relationships. Experiments were conducted on young (19 ± 2 days after adult molt, N = 13) and old (146 ± 32 days, N = 20) virgin females. The brain volume decreased with age (by 10%). Age also had an impact on the number of anomalies in the capture area generated during web building. The statistical relationships between the volume of the brain and web characteristics showed that there was an effect of age on both. Our results showed that in spiders, aging affects the brain volume and correlates with characteristics (anomalies) of the web. As web building is the result of complex behavioral processes, we suggest that aging affects spider behavior by causing some brain alterations.

Neurons and a sensory organ in the pedipalps of male spiders reveal that it is not a numb structure

The primary function of male copulatory organs is depositing spermatozoa directly into the female reproductive tract. Typical male copulatory organs are sensorily active. This is in contrast to the copulatory organs of male spiders (i.e. palpal bulbi), which have been assumed to lack nerves and muscles until recently. Neurons have been found within the bulbus of the spider Hickmania troglodytes, a taxon basal to all Neocribellata. We provide the first evidence for neurons and an internalized multi-sensillar sensory organ in the bulbus of an entelegyne spider (Philodromus cespitum). The sensory organ likely provides mechanical or chemical feedback from the intromitting structure, the embolus. We found further neurons associated with two glands within the bulbus, one of which is likely responsible for sperm extrusion during mating. These findings provide a new framework for studies on reproductive behaviour and sexual selection in spiders.

Spider silk foam coating of fabric

Abstract Silks are well known natural fibers used for textile applications and have got for the first time available upon sericulture of silkworms (Bombyx mori) several thousand years ago in China. In contrast to silkworm silk, spider silks offer better mechanical properties such as higher tensile strength and much better toughness, but natural spider silk is less accessible due to the cannibalistic behavior of spiders prohibiting large scale farming, and therefore has not been employed in textile industry yet. In this study, a biotechnologically produced spider silk protein was introduced as a new material for textile applications in form of foam coating material. The spider silk foam coating was developed to increase the abrasion behavior of natural and polymeric furniture textiles. Modern textiles are high-tech materials and optimized concerning yarn design and fabric weave to fit a wide range of applications. Often hydrofluorocarbons based coatings are used to enhance textile performances. Upon coating with sustainable spider silk, yarn fraying was significantly reduced lowering the tendency to form knots and loops. Further, the textile abrasion resistance, analyzed by pilling tests, was improved significantly (17–200%) for all tested types of fabrics, in particular long term strain pilling was minimized.