Behavior Of Spiders Research Articles

Community Detection Based on Differential Evolution Using Social Spider Optimization

Community detection (CD) has become an important research direction for data mining in complex networks. Evolutionary algorithm-based (EA-based) approaches, among many other existing community detection methods, are widely used. However, EA-based approaches are prone to population degradation and local convergence. Developing more efficient evolutionary algorithms thus becomes necessary. In 2013, Cuevas et al. proposed a new differential evolution (DE) hybrid meta-heuristic algorithm based on the simulated cooperative behavior of spiders, known as social spider optimization (SSO). On the basis of improving the SSO algorithm, this paper proposes a community detection algorithm based on differential evolution using social spider optimization (DESSO/CD). In this algorithm, the CD detection process is done by simulating the spider cooperative operators, marriage, and operator selection. The similarity of nodes is defined as local fitness function; the community quality increment is used as a screening criterion for evolutionary operators. Populations are sorted according to their contribution and diversity, making evolution even more different. In the entire process, a random cloud crossover model strategy is used to maintain population diversity. Each generation of the mating radius of the SSO algorithm will be adjusted appropriately according to the iterative times and fitness values. This strategy not only ensures the search space of operators, but also reduces the blindness of exploration. On the other hand, the multi-level, multi-granularity strategy of DESSO/CD can be used to further compensate for resolution limitations and extreme degradation defects based on modular optimization methods. The experimental results demonstrate that the DESSO/CD method could detect the community structure with higher partition accuracy and lower computational cost when compared with existing methods. Since the application of the SSO algorithm in CD research is just beginning, the study is competitive and promising.

On maximizing reliability of grid transaction processing system considering balanced task allocation using social spider optimization

Abstract This paper deals with the problem of task allocation in the grid transaction processing system. There has been quite some research on the development of tools and techniques for grid computing systems, yet some important issues, e.g., service reliability with load balanced transaction allocation in grid computing system, have not been sufficiently studied. Load balanced transaction allocation becomes a challenging job in such a complex and dynamic environment as both the application and computational resources are heterogeneous. The problem is further complicated by the fact that these resources may fail at any point of time. The problem of finding an optimal task allocation solution is known to be an NP-hard. We propose grid transaction allocation based on social spider optimization (LBGTA_SSO) method for this problem. The LBGTA_SSO is based on the cooperative behavior of social spiders to find a collection of task allocation solutions. We also derive reliability formulae for grid transactions considering resource availability. For comparison we modify some existing algorithms to obtain the task allocation algorithms. The results show that our algorithm works better than the modified existing algorithms.

Individual differences are consistent across changes in mating status and mediated by biogenic amines

Although aspects of an individual’s state are well-known to influence the expression of behavior, it is still unclear how elements of state affect consistent among-individual differences in behavior. With binary, irreversible elements of state, such as mating status, there may be optimal behavioral phenotypes before and after mating, with individuals often prioritizing mate acquisition before and resource acquisition after. Yet, limited plasticity may prevent optimal behavior in both contexts. Additionally, it remains largely unknown if some consistencies in neural or physiological traits may limit the ability of the organism to respond to state changes. In this study, we investigated how changes in a binary state variable, mating status, affected both the mean expression and among-individual variation in behavior and web structure of the redback spider, Latrodectus hasselti. Furthermore, we explored the role of biogenic amines in potentially mediating individual differences in behavior and web structure. We found that mated females were overall more aggressive than virgin females and also built webs structured primarily for capturing prey rather than safety. We also found that individual differences in behavior and web structure were maintained across mating statuses, which indicates the stability of these traits and may drive personality-specific state-dependent fitness trade-offs. Finally, we found that aggressive spiders had higher central nervous system dopamine levels. Interestingly, web structure was often correlated with a catabolite of tyramine (N-acetyltyramine), suggesting that variation in amine catabolism, and not the concentrations of the amines themselves, may drive individual differences in some traits. Our results demonstrate that although individuals show plasticity in response to changes in state, specifically mating status, individuals also maintain among-individual differences across this state change. Thus, aggressive individuals before mating will tend to be aggressive after. This maintenance of individual differences across state may drive differential fitness benefits before and after mating for different behavioral phenotypes. Furthermore, we show that biogenic amines and their catabolites are related to individual differences, thus identifying a potential mechanism underlying consistent variation.

Silk wrapping of nuptial gifts aids cheating behaviour in male spiders

Sexual traits, such as nuptial gifts, are costly and often condition-dependent. Males should be under selection to reduce these costs without impairing their reproductive success. Spider gifts consist of silk-wrapped food, but may also consist of worthless (non-nutritive) donations that successfully lead to mating, despite yielding shorter copulations. Worthless gifts may either represent a cheaper cheating strategy or the inability to produce genuine gifts due to resource limitations (i.e. poor body condition). Unless energetic constraints limit expenditure in silk, males should apply more silk to worthless gifts to compensate for their lower reproductive value. We ask whether in Pisaura mirabilis 1) worthless gifts are condition-dependent and 2) males strategically use silk based on gift type (genuine vs worthless). We tested whether male body condition explains the gift-giving strategy and compared silk amounts covering each gift type, in gifts collected from the field and produced in the laboratory by males given different feeding regimes. Our findings show that worthless gifts are not promoted by poor body condition or limited resources. They rather result from a cheating strategy evolved to opportunistically reduce the costs of genuine gifts while ensuring nutritional advantages, with cheaters gaining body mass. Males applied more silk to worthless gifts regardless of their body condition or feeding state, suggesting they can strategically adjust silk expenditure despite its costs. By masking gift contents and prolonging female feeding, silk is crucial for the maintenance of cheating, likely resulting from an evolutionary arms race between male deception and female assessment.

Analysis of digestion of rice planthopper by Pardosa pseudoannulata based on CO-I gene

In order to systematically study the predatory behavior and digestion regularity of spiders, real-time fluorescence quantification PCR technique was used to detect the number of CO-I genes in Pardosa pseudoannulata after it preyed on rice planthoppers in different temperatures within different periods. At 28 °C, 0, 1, 2, 4, 8, 16, and 24 h after P. pseudoannulata preyed on rich planthopper, DNA was extracted from cephalothorax and abdomen of P. pseudoannulata. Routine PCR and real-time fluorescence PCR techniques were employed for CO-I gene amplification. The results show that: The prey liquid was temporarily stored in the sucking stomach of the spider head within 2 h after prey, and gradually transferred to the midgut of the abdomen with the prolongation of time. After 4 h, CO-I gene residues of rice planthopper in the cephalothorax gradually decreased. The CO-I gene of rice planthopper was basically transferred to the abdomen after 16 h. During 0–1 h, food contained in abdominal midgut and other digestive organs was very small, CO-I gene detection was not obvious. Over time, food entered into the midgut from the sucking stomach for digestion. During 2–4 h, CO-I gene amount increased, at 2–4 h, detected CO-I gene residue reached the peak; but rapidly declined after 8, 16, and 24 h, even it is still detectable. The results at different temperatures reveal that: As the temperature increased from 26 °C to 32 °C, CO-I gene residues of rich planthopper in cephalothorax and abdomen of P. pseudoannulata gradually decreased, which indicated that the digestion rate increased with the increase of temperature with some range. However, when the temperature continued to increase to 34 °C, the digestion rate decreased.

Predation of Halyomorpha halys (Hemiptera: Pentatomidae) from Web-Building Spiders Associated with Anthropogenic Dwellings

The brown marmorated stink bug, or Halyomorpha halys, is an invasive pest in North America and Europe that causes severe agricultural damage and nuisance problems for homeowners; and it is originally from China, Taiwan, and the Republic of Korea. While the natural enemy community of H. halys has been evaluated in several agroecosystems, it has not been examined where H. halys overwinters in anthropogenic structures. The aims of the current study were to evaluate 1) whether spider webs commonly found in the home and yard can successfully ensnare H. halys, 2) whether entanglement resulted in consumption by spiders inhabiting the webs, and 3) how frequently H. halys becomes entangled in webs under ambient conditions. To accomplish this, adult H. halys were introduced into webs in and near anthropogenic structures in West Virginia and Maryland, United States, and the behavior of spiders was observed for 5-min intervals at 0, 1, 2, and 24 h after introduction. In addition, a survey of webs was performed to determine the frequency with which spiders naturally capture H. halys inside buildings and in the landscape. Overall, the study found seven spider families in anthropogenic structures. Adult H. halys that were introduced into the webs of Theridiidae, Pholcidae, or Agelenidae had a greater than 50% chance of being ensnared and consumed. Adult H. halys were found naturally most often in webs of Theridiidae. Webs with a funnel or cob web architecture had the greatest probability of ensnaring H. halys, while those with orb structures resulted in the fewest caught. In the wild, 13–20% of spider webs contained dead H. halys. Our results suggest that spiders may be an important contributing factor for mortality of H. halys at overwintering sites, and spiders in or outside homes may help reduce nuisance problems caused by H. halys.

TROPICAL BIOLOGY AWARD 2016

The Tropical Biology Award is an international scientific award given for a prolonged and significant contribution to the understanding and conservation of tropical organisms.For decades, Dr. Eberhard has made an internationally recognized contribution to our knowledge of the evolutionary process —from intracellular organelles to the behavior of insects and spiders— with emphasis on the evolution of arthropod genitalia and reproductive behavior.

Dispersal behavior in agrobiont spiders (Linyphiidae) — differential response to a wind chamber

Two species of common, farmland-inhabiting money/dwarf spider, Erigone atra Blackwall, 1833 and Oedothorax fuscus (Blackwall, 1834), were exposed to light wind conditions within a wind chamber to determine their propensity to exhibit dispersal behaviors over a nine-month period. A novel design of wind chamber, incorporating two tangential fans, produced a wide outflow thereby allowing behaviors to be expressed over a relatively large test area (1 m × 0.65 m). Sticks placed at 3 cm intervals in an undulating foam surface structurally mimicked a natural field setting. Whereas the majority of E. atra expressed dispersal and related behaviors (tiptoe and drop posture and ballooning) in every month testing occurred, corresponding behaviors were rarely recorded in O. fuscus. Results are discussed in relation to knowledge of the dispersal activity of O. fuscus in the field and factors which may influence dispersal frequency and initiation.

Low-Tech, Pilot Scale Purification of a Recombinant Spider Silk Protein Analog from Tobacco Leaves.

Spider dragline is used by many members of the Araneae family not only as a proteinogenic safety thread but also for web construction. Spider dragline has been shown to possess high tensile strength in combination with elastic behavior. This high tensile strength can be attributed to the presence of antiparallel β-sheets within the thread; these antiparallel β-sheets are why the protein is classified as a silk. Due to the properties of spider silk and its technical and medical uses, including its use as a suture material and as a scaffold for tissue regeneration, spider dragline is a focus of the biotechnology industry. The production of sufficient amounts of spider silk is challenging, as it is difficult to produce large quantities of fibers because of the cannibalistic behavior of spiders and their large spatial requirements. In recent years, the heterologous expression of genes coding for spider silk analogs in various hosts, including plants such as Nicotiana tabacum, has been established. We developed a simple and scalable method for the purification of a recombinant spider silk protein elastin-like peptide fusion protein (Q-/K-MaSp1-100× ELP) after heterologous production in tobacco leaves involving heat and acetone precipitation. Further purification was performed using centrifugal Inverse Transition Cycling (cITC). Up to 400 mg of highly pure spider silk protein derivatives can be isolated from six kilograms of tobacco leaves, which is the highest amount of silk protein derivatives purified from plants thus far.

Parallel social spider clustering algorithm for high dimensional datasets

The Social-Spider Optimization (SSO) is one of the recently developed swarm intelligence. It is inspired from the social behavior of spiders living in huge colonies. In this manuscript, a parallel version of this algorithm is formulated and termed as P-SSO by making a position update process of spiders (female, dominant and non-dominant male) running simultaneously. Simulation studies on cluster analysis of benchmark high-dimensional datasets using proposed P-SSO are found to be nearly 10 times computationally faster than the original version of SSO. Comparative analysis with other standard parallel version algorithms like Adaptive Parallel Particle Swarm Optimization (PPSO), Real Coded Parallel Genetic Algorithm (RCPGA) and K-means reveals the superior clustering accuracy of the proposed method. The designed algorithm is also tested on real life application where multi-spectral image segmentation is formulated as a clustering problem. The images are taken from NASA landsat 8. It covers an area of 200km of Northwest Chennai obtained before and after flood conditions. This is done to analyze the flood severity. The overall accuracy of P-SSO is highest among all the methods. Also, in case of detection of water flooded areas the producer's accuracy is 76.89% which is two times better than K-means.

Spider behaviors include oral sexual encounters.

Several clades of spiders whose females evolved giant sizes are known for extreme sexual behaviors such as sexual cannibalism, opportunistic mating, mate-binding, genital mutilation, plugging, and emasculation. However, these behaviors have only been tested in a handful of size dimorphic spiders. Here, we bring another lineage into the picture by reporting on sexual behavior of Darwin’s bark spider, Caerostris darwini. This sexually size dimorphic Madagascan species is known for extreme web gigantism and for producing the world’s toughest biomaterial. Our field and laboratory study uncovers a rich sexual repertoire that predictably involves cannibalism, genital mutilation, male preference for teneral females, and emasculation. Surprisingly, C. darwini males engage in oral sexual encounters, rarely reported outside mammals. Irrespective of female’s age or mating status males salivate onto female genitalia pre-, during, and post-copulation. While its adaptive significance is elusive, oral sexual contact in spiders may signal male quality or reduce sperm competition.

Ontogenetic variation in the predatory behavior of the orb-weaver spider Azilia histrio: detecting changes in behavioral organization

Spiders in different ontogenetic stages vary in their predatory behavior. The more advanced the development of an individual, the more similar is its behavior to that of the adult. Studies have shown that the behavior of subadult and adult spiders are similar, but the similarity may be superficial, since the analytical approach usually adopted cannot evaluate important features, such as the organization of the foraging system. Systems are characterized by a modular organization, which needs appropriate analytical approaches to be properly evaluated. We tested whether there is a difference between the predatory sequences of adult and subadult spiders (Azilia histrio) and identified the most appropriate methodological procedure for the characterization of this difference. We used multivariate analysis, contrasting an approach that focuses on frequency of behavioral categories, taken independently, with an approach that directly evaluates the sequential organization of behavioral categories, thus allowing the analysis of the structure of the foraging system. While the independent variables approach did not show differences between ontogenetic stages, the organizational analytical approach resulted in a number of important differences between the ontogenetic stages. We describe the foraging system for the first time in the genus Azilia, while discussing hypotheses for the observed organizational change.

Courtship and the use of pheromones byPholcus manueli(Araneae: Pholcidae)

Most web spiders use chemical and vibratory cues for intersexual communication prior to mating. Little is known regarding the behavior of the web spider, Pholcus manueli Gertsch, 1937. In the laboratory, we examined the behavior of males in female webs. Some webs were washed and allowed to air dry. Both washed and unwashed webs were tested with and without females. Overall, male behaviors were similar to courtship reported for other pholcid species and their frequency was related to male size. Web washing delayed the initiation of activity, reduced abdomen flexes, and increased the likelihood of pedipalp expansion and aggression. The presence of females caused males to initiate movement sooner and to increase silk pulling behavior. These results suggest that courtship is multimodal and that the vibratory dialog between males and females works along with chemical communication in this species. Hopefully, these data will enhance future studies of sexual selection in pholcids.

The contribution of developmental experience vs. condition to life history, trait variation and individual differences.

1. Developmental experience, for example food abundance during juvenile stages, is known to affect life history and behaviour. However, the life history and behavioural consequences of developmental experience have rarely been studied in concert. As a result, it is still unclear whether developmental experience affects behaviour through changes in life history, or independently of it. 2. The effect of developmental experience on life history and behaviour may also be masked or affected by individual condition during adulthood. Thus, it is critical to tease apart the effects of developmental experience and current individual condition on life history and behaviour. 3. In this study, we manipulated food abundance during development in the western black widow spider, Latrodectus hesperus, by rearing spiders on either a restricted or ad lib diet. We separated developmental from condition-dependent effects by assaying adult foraging behaviour (tendency to attack prey and to stay on out of the refuge following an attack) and web structure multiple times under different levels of satiation following different developmental treatments. 4. Spiders reared under food restriction matured slower and at a smaller size than spiders reared in ad lib conditions. Spiders reared on a restricted diet were more aggressive towards prey and built webs structured for prey capture, while spiders reared on an ad lib diet were less aggressive and built safer webs. Developmental treatment affected which traits were plastic as adults: restricted spiders built safer webs when their adult condition increased, while ad lib spiders reduced their aggression when their adult condition increased. The amount of individual variation in behaviour and web structure varied with developmental treatment. Spiders reared on a restricted diet exhibited consistent variation in all aspects of foraging behaviour and web structure, while spiders reared on an ad lib diet exhibited consistent individual variation in aggression and web weight only. 5. Developmental experience affected the average life history, behaviour and web structure of spiders, but also shaped the amount of phenotypic variation observed among individuals. Surprisingly, developmental experience also determined the particular way in which individuals plastically adjusted their behaviour and web structure to changes in adult condition.

Cuticular bacteria appear detrimental to social spiders in mixed but not monoculture exposure.

Much of an animal’s health status, life history, and behavior are dictated by interactions with its endogenous and exogenous bacterial communities. Unfortunately, interactions between hosts and members of their resident bacterial community are often ignored in animal behavior and behavioral ecology. Here, we aim to identify the nature of host–microbe interactions in a nonmodel organism, the African social spider Stegodyphus dumicola. We collected and identified bacteria from the cuticles of spiders in situ and then exposed spiders to bacterial monocultures cultures via topical application or injection. We also topically inoculated spiders with a concomitant “cocktail” of bacteria and measured the behavior of spiders daily for 24 days after inoculation. Lastly, we collected and identified bacteria from the cuticles of prey items in the capture webs of spiders, and then fed spiders domestic crickets which had been injected with these bacteria. We also injected 1 species of prey-borne bacteria into the hemolymph of spiders. Only Bacillus thuringiensis caused increased mortality when injected into the hemolymph of spiders, whereas no bacterial monocultures caused increased mortality when applied topically, relative to control solutions. However, a bacterial cocktail of cuticular bacteria caused weight loss and mortality when applied topically, yet did not detectibly alter spider behavior. Consuming prey injected with prey-borne bacteria was associated with an elongated lifespan in spiders. Thus, indirect evidence from multiple experiments suggests that the effects of these bacteria on spider survivorship appear contingent on their mode of colonization and whether they are applied in monoculture or within a mixed cocktail. We urge that follow-up studies should test these host–microbe interactions across different social contexts to determine the role that microbes play in colony performance.

Modified Social-Spider Optimization Algorithm Applied to Electromagnetic Optimization

Social-spider optimization (SSO) is a new nature-inspired algorithm of the swarm intelligence field to global optimization applications, which is based on the simulation of cooperative behavior of social spiders. To enhance the performance of the standard SSO, a modified SSO (MSSO) approach based on beta distribution and natural gradient local search was proposed in this paper. In order to verify the performance of the MSSO, tests using Loney’s solenoid benchmark and a brushless direct current motor benchmark are realized comparing the effectiveness of the SSO and the proposed MSSO. The results of this paper demonstrated that the MSSO performance is promising in electromagnetics optimization.

Risky Courtship: Background Contrast, Ornamentation, and Display Behavior of Wolf Spiders Affect Visual Detection by Toad Predators

AbstractMales that search widely for females and perform conspicuous courtship displays run a high risk of being detected by their predators. Therefore, gains in reproductive success might be offset by increased mortality due to predation. Male brush‐legged wolf spiders (Schizocosa ocreata) with larger decorative traits (foreleg tufts) are preferred by females as mates, but are more readily detected by predators. However, predation risk may also be influenced by the interaction between components of signals and the environment in which signaling occurs. Courting male spiders were readily accepted as prey by a sympatric predator, the American toad (Anaxyrus americanus). We used video playback to tease apart the interactive effect between visual signals and the signaling environment on the ability of toads to detect courting spiders as a function of distance, background contrast, the presence or absence of male foreleg tufts, and behavioral activity. The response of toads to video sequences of male spiders was similar to their response to live male spiders. Toad response varied over distance toward spiders displayed against high contrast (sunny) vs. low contrast (shaded) backgrounds. Beyond 30 cm, more toads detected courting male spiders against light, ‘sunny’ backgrounds and detected them faster when compared to the same spider stimulus against darker, ‘shady’ backgrounds. In choice tests, toads oriented more often toward courting males with leg tufts than those without. Toad responses also varied with male spider behavior in that only videos of moving males were attacked. Latency to orient and detection by toads was significantly greater for walking males than courting males, and this effect was most evident at distances between 30 cm and 50 cm. Results supported that courting wolf spiders are at significant risk of predation by visually acute predators. Distance, background contrast, and the presence of foreleg decorations influence detection probability. Thus, the same complex visual signals that make males conspicuous and are preferred by females can make males more vulnerable as prey to toads.

Linking consistent individual differences in web structure and behavior in black widow spiders

Individuals may vary consistently in their architectural makeup of the constructions they build, which might have tremendous implications for their ecology and fitness. In particular, the relationship between individual differences in architectural constructions and behavior (i.e., animal personalities) is largely unexplored. Individual black widow spiders, Latrodectus hesperus, build a 3D cobweb made up of distinctive components serving to support foraging (gumfooted lines) or antipredator protection (structural lines). To explore the relationship between individual differences in behavior and architectural constructions, we quantified 1) the level of consistent individual variation in several elements of web structure and 2) the level of consistent individual variation in foraging behavior and its relationship with web structure. We controlled for condition-dependent or environmental effects by satiating all spiders prior to assays and maintaining them in standardized conditions. Spiders exhibited consistent differences in the number of gumfooted lines they built for capturing preys and overall web weight, but not in the number of structural lines. Individuals also varied consistently in their tendency to attack a prey cue, despite all spiders being satiated. Finally, spiders producing more gumfooted lines exhibited a higher tendency to attack the prey cue. Our results suggest that the architectural constructions may impact the expression of individual behavioral differences (or animal personalities) and suggest that individual behavior and extended phenotype may be part of alternative foraging strategies in L. hesperus.

Female preference for multi-modal courtship: multiple signals are important for male mating success in peacock spiders.

A long-standing goal for biologists has been to understand how female preferences operate in systems where males have evolved numerous sexually selected traits. Jumping spiders of the Maratus genus are exceptionally sexually dimorphic in appearance and signalling behaviour. Presumably, strong sexual selection by females has played an important role in the evolution of complex signals displayed by males of this group; however, this has not yet been demonstrated. In fact, despite apparent widespread examples of sexual selection in nature, empirical evidence is relatively sparse, especially for species employing multiple modalities for intersexual communication. In order to elucidate whether female preference can explain the evolution of multi-modal signalling traits, we ran a series of mating trials using Maratus volans. We used video recordings and laser vibrometry to characterize, quantify and examine which male courtship traits predict various metrics of mating success. We found evidence for strong sexual selection on males in this system, with success contingent upon a combination of visual and vibratory displays. Additionally, independently produced, yet correlated suites of multi-modal male signals are linked to other aspects of female peacock spider behaviour. Lastly, our data provide some support for both the redundant signal and multiple messages hypotheses for the evolution of multi-modal signalling.

Dynamical measurements on viscoelastic behaviors of spiders in electro-dynamic loudspeakers

Spiders in electro-dynamic loudspeakers are most commonly concentrically corrugated fabric disks, and their viscoelastic behaviors affect the loudspeaker reproductions. A noncontact dynamic measuring technology is presented by a subwoofer closed box to excite the tested spiders pneumatically with a Laser Doppler Vibrometer (LDV) to measure the velocity of the moving spiders. Correlation techniques were employed to get an accurate and reliable acoustical transfer function between the measured velocity and sound pressure. The Young’s moduli of the tested spider composite materials were derived from the measured vibration modes. The creep effect and the level dependent behaviors of tested spiders were investigated. The results indicate that, the Young’s moduli of the tested spiders are frequency dependent. The mechanical stiffness increases with a small slope in low frequency range while a large slope in high frequency range. The loss factor exhibits the maximum around the resonance frequency, and after that it decreases with increasing frequency. The effective stiffness has a monotonic decrease with input voltage levels and the harder the spider, the less stiffness changes with input levels.