Web Construction Behaviour Research Articles

Web construction behavior of Deinopis cf. cylindracea (Deinopidae: Araneae) and its comparison to webs of other Deinopidae

Deinopid spiders use highly specialized webs composed of a triangular non-sticky scaffolding (NS scaffolding) containing three radii and a modified orbicular web with a rectangular shape to capture prey. Spiders actively manipulate their webs to capture prey. We describe the web construction behavior of Deinopis cf. cylindracea and compare it and the shape of the sticky silk spiral (SS spiral) of other deinopid species using images in the literature and on the Internet. The web-building behavior in D. cf. cylindracea follows the pattern previously described for other species of Deinopis MacLeay, 1839. Web construction takes approximately 15 min in D. cf. cylindracea and has two stages: NS scaffolding construction and SS spiral construction. The final structure of the SS spiral has four closely spaced capture cords, five placed further apart, three near the top of the web, and two cords on the handles, making a total of 12. Other species of Deinopis have different numbers of cords. Finally, a novel finding is that the youngest spiders do not make webs with sticky lines, but instead use a simplified web to lunge forward, using only their legs to contact prey. To our knowledge, such behavior has never been described in this or any other group.

Web building behavior in a wall spider (Oecobiidae) suggests a close relationship with orb-weavers

Behavior is often phylogenetically informative and detailed descriptions of behavior have been used to support taxonomic relationships in several groups, such as birds, lizards, and arthropods. Web building behavior has provided informative traits to several spider families, but observations are lacking for other families, such as wall spiders Oecobiidae. Recent phylogenetic hypotheses based on molecular traits placed oecobiids either close to cribellate orb weavers (Uloboridae) or to long-spinneret spiders (Hersiliidae). Here, we describe for first time the web construction behavior and details of the web design in the oecobiid Oecobius concinnus Simon 1893 (Oecobiidae). We compare them with uloborid and araneoid orb weavers. If Oecobiidae and Uloboridae are closely related, we expect that O. concinnus share some web construction behaviors with these orb weavers. Video recordings and analyses of web structures suggest the sequence of web construction (radii, then sticky spiral construction) and the arrangement of cribellate threads are possible homologies between Oecobiidae and orb weavers, supporting a close relationship of Oecobiidae with Uloboridae.

Differences in web structure of Tetragnatha tenuissima (Araneae: Tetragnathidae) due to environmental conditions

Spiders can modify their web construction behaviour according to environmental conditions. Here, we examined how the web structure of Tetragnatha tenuissima differentiates depending on habitat type (swamp or river edge) at La Selva Biological Station, Costa Rica. We characterized the web architecture based on length, number of radii, and the spiral spacing relative to web length. There were no significant differences on the length or number of radii between the webs present in the swamp and river habitats. In terms of the spiral spacing relative to web length, there was a significant difference between habitats, with less distance in river-side webs than in the ones on swamps. This could be explained by the potential differential resource availability on each environment. Therefore, habitat type appears as an explanatory variable for differences on the web structure of T. tenuissima. Due to the small number of identifiable individuals of other Tetragnatha species, the effect of congeneric species co-occurrence on web structure remains as a factor to be tested in future research.

Complex behavioral plasticity is not reduced in spiderlings with miniature brains.

The brains of smaller animals are smaller than those of their larger relatives, but it is not clear whether their adaptive behavioral flexibility is more limited. Previous interspecific comparisons found that aspects of web construction behavior of very small orb weaving spiders (0.005 mg) were no less precise than those of much larger related orb weavers (30 mg), but the behaviors tested were relatively simple. Here we perform a more sensitive intraspecific test involving the multiple behavioral adjustments of orb web designs made by Leucauge argyra to confinement in very small spaces. Web adjustments of spiderlings as small as ~0.1 mg were compared to previously published observations of ~80 mg conspecific adults. Spiderlings in constrained spaces made all of the complex adjustments made by adults in at least seven independent web design variables, and their adjustments were no less precise. Rough estimates based on previously published data on total brain volumes and the mean diameters of neuron cell bodies suggested that spiderlings and adult females of Leucauge may have similar numbers of neurons, due to spiderlings having smaller neurons and a greater percentage of body tissues dedicated to the brain. We speculate that this neural similarity may explain why L. argyra spiderlings showed no behavioral deficits compared with adults.

Spinosad application in an apple orchard affects both the abundance of the spider Araneus diadematus and its web construction behaviour.

The principles of organic production are based on the respect of ecological processes including the promotion of natural enemies to control pests. However, as a last resort, some natural pesticides can be applied such as the pesticide spinosad. This neurotoxic insecticide is now widely used even in non-organic production systems. As generalist predators, spiders, and especially orb web spiders, which prey on flying pests, are thought to be useful for biocontrol. To study the effects of spinosad on orb web spiders, we applied spinosad (Success4®) at the normal application rate (96 g ha-1) in an orchard covered by nets where Araneus diadematus was very abundant. Its abundance (number of webs), location when present on the web and web characteristics were determined one day before (D - 1) and 1, 3, 6, 10 and 14 days after the application (D + 1, D + 3, D + 6, D + 10 and D + 14). After spinosad application, at D + 1 and D + 14, the number of A. diadematus webs decreased by 28% and 47%, respectively, compared to D - 1 where we observed on average 0.2 webs m-2. This decrease is likely due to a combination of direct pesticide effects, reduced prey availability and mechanical effects of the air blast sprayer. The short-term toxicity of spinosad was assessed using behavioural markers: (i) the percentage of abnormally located spiders (i.e. neither in the centre of the web nor hidden under the apple leaves) for 30 and 50% of the webs at D + 1 and D + 3 respectively, (ii) the percentage of incomplete webs (made only of the non-sticky spiral) in 35 and 75% of the cases at D + 1 and D + 3 respectively and (iii) one web characteristic, the mean parallelism between spirals, that was significantly reduced at D + 1 compared to D - 1. The study of the other web characteristics indicated that spiders did not modify the capture area but rather significantly decreased their investment in silk at D + 6 and D + 10 by reducing the number of radii and spiral turns. Overall, the application of spinosad (Success4®), representing a triple disturbance (mechanical, toxicological and alimentary), has a negative impact on the orb web spider A. diadematus and should thus be used with caution if growers want to promote the contribution of these spiders to natural biocontrol in their fields.

Evidence that Polysphincta-group wasps (Hymenoptera: Ichneumonidae) use ecdysteroids to manipulate the web-construction behaviour of their spider hosts

Evidence that Polysphincta-group wasps (Hymenoptera: Ichneumonidae) use ecdysteroids to manipulate the web-construction behaviour of their spider hosts

Modular patterns in behavioural evolution: webs derived from orbs

AbstractImperfect knowledge of ancestral behaviour often hampers tracing behavioural evolution. This limitation is reduced in orb weaving spiders, because spider orb web construction behaviour and the cues used by modern orb-weavers are well-studied and highly conserved. Several species in orb-weaving families build non-orb webs that are clearly derived from orbs, allowing transitions from ancestral to modern behaviours to be described with high confidence. Three major patterns of general evolutionary significance were found in 69 phylogenetically independent transitions in 15 groups in 8 families: ancestral traits were often maintained as units; the most frequent of the eight different types of ancestral trait change was transfer of an ancestral behaviour to a new context; and ‘new’ traits that had no clear homology with ancestral traits were also common. Changes occurred in all major stages of orb construction. This may be the most extensive summary of evolutionary transitions in behaviour yet compiled.

Web building and prey wrapping behavior ofAglaoctenus castaneus(Araneae: Lycosidae: Sosippinae)

Funnel webs are common and widespread taxonomically, but little is known about how they are built or details of their structure. Aglaoctenus castaneus (Mello-Leitão, 1942) (Lycosidae) builds horizontal, densely meshed funnel webs of non-adhesive silk, with a tangle of lines above. Web construction behavior was unique in that the spider frequently laid swaths of lines rather than simple drag lines, both to float bands of fine lines on the breeze as bridges to distant objects and to fill in the sheet. Spiders utilized special spinneret movements to widen the swaths of lines that they laid on sheets. These movements have not been seen in web construction by other araneomorphs, but are were similar to and perhaps evolutionarily derived from those used during prey wrapping by many other species. Observations, made with a compound microscope, of the construction behavior of the agelenid Melpomene sp. O.P. Cambridge 1898, and of lines and attachments in sheets of these species and another funnel web spider, the zoropsid Tengella radiata (Kulczyński, 1909) demonstrated the possibly general nature of including obstacles in the web. This probably disadvantageous behavior may be related to constraints in selecting web sites imposed by the need for sheltered retreats, or to the spider's inability to remove preliminary lines. The observation also showed the importance of further improvements in the discriminations made between “sheet” and “brushed” webs in recent discussions of spider web evolution.

Cues guiding uloborid construction behavior support orb web monophyly

Abstract Behavior can provide useful traits for testing phylogenetic hypotheses, and some details of orb web construction behavior have been especially useful in characterizing higher-level groups in spiders. The cues used to guide construction behavior and behavioral responses to these cues hold similar promise, but have never been used in phylogenetic studies. Here we use several techniques to test the hypothesis that orb webs in the two major branches of orb-weaving araneomorph spiders (Araneoidea and Deinopoidea) are monophyletic, using both the cues that guide orb construction and the spiders’ responses to these cues. If orb webs evolved only once, the expectation is that these traits should be similar in members of both evolutionary lines. This prediction was supported: species in the two groups use several of the same cues, and respond to them in similar ways. These cues include two identical reference stimuli for positioning sticky spiral lines; supplies of silk available in their glands that affe...

Ontogenetic and Sexual Differences in Exploration and Web Construction in the SpiderPhysocyclus globosus(Araneae: Pholcidae)

Summary Differences in reproductive interests between the sexes can affect web construction behaviour, which can vary across ontogeny. This study tested whether exploration and web building behaviour varies with age and sex in Physocyclus globosus (Pholcidae), a spider that weaves an irregular, domed sheet web with a tangle above. Spiders were placed in cages with four interconnected chambers. Most fifth instar juveniles and adult females (but only half adult males) wove a sheet in only one chamber. Adult females built the denser sheets. Although adults attached more threads to the walls than juveniles, the latter attached more new threads there over time. Juveniles laid 91% of their threads in the sheet chamber, compared to adult females (55%) and adult males (41%). All spiders (especially adult males) attached many exploration threads throughout 18 days, suggesting repeated abandonments of the web. The reduced rate of exploration by juveniles suggests that they establish webs more quickly to increase th...

Correlations Between Leg Positions and Spaces Between Sticky Lines in the Orbs of Micrathena duodecimspinosa (Araneae: Araneidae)

Although orb web construction behaviour is relatively well studied, there are few studies of the mechanisms with which behavioural decisions are executed, in terms of where the spider grasps lines and attaches them to each other. Video analyses were used here to show that the distance from the previous sticky loop at which the araneid spider Micrathena duodecimspinosa gripped the radius with her leg oIV during sticky spiral construction varied according to the spider's position in her web with respect to both gravity and the edge of the web. This grasping site, in turn, was correlated with the site on the radius where the spider attached the sticky line. The spacing between loops of sticky spiral, a functionally important aspect of orb design, was thus determined in part, though not completely, by the site at which leg oIV grasped the radius at the moment of attachment.

Sheet-web construction by Melpomene sp. (Araneae: Agelenidae)

Abstract Sheet-webs are built by a variety of unrelated spiders. Some of these spiders are common, but information on their web construction behavior is scarce. This study describes the sheet-web construction behavior of Melpomene sp. (Agelenidae) and the sites where webs are built. I recorded the beginning of sheet-web construction by several spiders and analyzed photographs of webs in the field and the laboratory. Web construction consisted basically of two alternating behaviors: laying support threads and the filling in the sheet. These behaviors were repeated during several construction sessions until the available area was filled, or until the web reached approximately 80 cm2. Apparently the spider uses both ampullate and aciniform lines for web construction, contrary to a recent description.

Are smaller animals behaviourally limited? Lack of clear constraints in miniature spiders

Because of scaling trends in physiology and morphology, very small animals are expected to suffer especially strong selection to reduce the cost of the central nervous system, which may make them more likely to sacrifice behavioural capacities to economize on nervous tissue. This ‘size-limitation’ hypothesis predicts reduced behavioural capabilities in smaller animals. I tested this hypothesis by comparing web construction behaviour of young nymphs and adults of a very small orb-weaving spider, Anapisona simoni (young nymphs ∼0.005 mg, adults ∼0.8 mg), with those of relatives up to 10 4 times larger. In these comparisons I took advantage of the special opportunities offered by orb webs to study fine behavioural details during web construction, because the webs represent precise records of large numbers of behavioural decisions. Combining these results with those of a previous study, the size-limitation hypothesis was not supported: very small spiders failed to show three predicted trends, and they showed four other trends that were in directions opposite to those predicted by the hypothesis. Two additional intraweb comparisons (at least one of which was probably biased against equal performance by the smallest species) gave a mix of support and lack of support for the predictions, while only one interspecific difference supported the predictions. Other studies have shown that small spiders have relatively large central nervous systems for their body sizes, suggesting that they may maintain behavioural capabilities comparable to those of larger orb weavers by paying the material and metabolic costs of building and maintaining large volumes of nervous tissue. These considerations may have general consequences for the probability of evolving small body sizes and egg sizes in spiders and other animals.

Modification of Nephila clavipes (Araneae Nephilidae) webs induced by the parasitoids Hymenoepimecis bicolor and H. robertsae (Hymenoptera Ichneumonidae)

Some polysphinctine ichneumonid wasps induce alterations in the web construction behaviour of their host spiders, and then suspend their pupal cocoons from the resulting “cocoon webs”. Cocoon webs that have been described previously appear to be designed to increase the web's mechanical stability, and thus to protect the wasp's cocoon. This study describes the cocoon webs of Nephila clavipes that are induced by two wasp species, Hymenoepimecis bicolor and H. robertsae, and shows that the alterations induced by H. bicolor make the webs more resistant to destruction. The cocoon webs of both species include a hub-like platform from which the cocoon is suspended, and are usually protected by a nearby tangle of barrier lines of variable density. The web alterations induced by H. bicolor are apparently not a consequence of parasitised spiders being in a poorer nutritional state, because orbs spun by parasitised spiders preceding the final “cocoon webs” were not significantly smaller than those of unparasitised spiders. Cocoon webs themselves were all highly reduced, and some of those induced by H. bicolor resemble the “skeleton” webs that are occasionally made by unparasitised N. clavipes. We document a possible spider defence (molting) against polysphinctine parasitisation.

New Types of Behavioral Manipulation of Host Spiders by a Parasitoid Wasp

The larva of the parasitic waspZatypotasp. nr.solanoiinduces its host spidersAnelosimusspp. to modify its web in ways not seen in normal webs of this species or in any other species, providing apparent protection and support for the wasp's cocoon by covering the entire web with a protective sheet and adding a central platform and opening a space below in the enclosed tangle, where the larva suspends its cocoon. These modifications differ qualitatively from those induced by a congeneric wasp. Parasitized spiders appeared to adjust modified web construction behavior to local conditions, implying that larval manipulations may occur at higher rather than lower levels of behavioral control (e.g., eliciting overall design decisions, rather than particular motor patterns).

WEB CONSTRUCTION AND MODIFICATION BY ACHAEARANEA TESSELATA (ARANEAE, THERIDIIDAE)

Abstract The web construction behavior of Achaearanea tesselata (Keyserling 1884) was observed in the field and in captivity using suspended wire frames that allowed detailed observations. Construction included three stages: preliminary exploration during which lines were broken, reeled up, and replaced; construction of anchor lines and the upper tangle; and construction and then filling in of the sheet below the tangle. Repeated visits to the mouth of the retreat during tangle construction resulted in the apparent reinforcement of the few lines radiating from this area, a possible adaptation to sense the location of prey in the web, and to facilitate orientation of the spider to prey in the web. Filling in the sheet, which alternated with additions to the tangle, included two previously undescribed behavioral patterns: irregular wandering on the sheet and apparent attachments of the dragline using only the two legs IV to hold previous lines against the spinnerets. The spider needed 1–2 nights, working se...

Web-Construction Behavior of Linyphiid Spiders (Araneae, Linyphiidae): Competition and Co-Existence Within a Generalist Predator Guild

The web-construction behavior of three species of linyphiid spider (Erigone autumnalis, Meioneta unimaculata and Bathyphantes pallida) was studied in the laboratory to examine competition and co-existence within predator guilds. Competitive interactions between spiders potentially reduce their role in biological control. We tested the hypothesis that at high densities, intraguild competition for web-sites would occur but spatial separation of microhabitat would reduce interguild competition, thus allowing co-existence. High mortality and reduced web-size were observed at high B. pallida densities but Linyphiinae co-existed with Erigoninae which constructed webs at different strata. Competitive exclusion by larger individuals occurred between species whose microhabitat niche overlapped. The biocontrol potential of spider or arthropod predator guilds could ultimately be enhanced by maximizing the diversity of species whose niche axes vary.

Difference in Web Construction Behavior at Newly Occupied Web Sites Between Two Cyclosa Species

AbstractAnimals make decisions based on subjective assessments of their environment. To determine their future foraging activities, animals probably assess food availability from past foraging experiences. Thus, foraging also functions as a way for animals to collect information, with the uncertainty of an assessment decreasing as foraging activity increases. This suggests that different needs for a correct assessment may affect the investment made in foraging activities. Orb‐web spiders sometimes relocate their webs and relocation rate differs among species. After web relocation, several spider species have been reported to construct the first webs at newly occupied web sites using less silk than usual, possibly to avoid the risk of an overinvestment at sites where food availability has not been determined. Nevertheless, they may pay a cost, because of inadequate decision‐making, if webs constructed with less silk convey less information and increase the uncertainty of an assessment. We expect that stronger site tenacity necessitates a greater requirement for correct assessment of web site and the degree to which spiders reduce the amount of web silk in the first web after web relocation is smaller in species that use the same site longer. To test this hypothesis, we examined web construction in two orb‐web spiders, Cyclosa octotuberculata and C. argenteoalba. At the same time we found that these two species exhibit different web‐site tenacity, as C. octotuberculata does not relocate its webs as frequently as does C. argenteoalba. After artificially induced web relocation, C. argenteoalba constructed webs that were initially smaller and contained only about 2/3 of the silk in control webs that were constructed at the original site. In contrast, C. octotuberculata did not exhibit such decreases in web size or in the amount of web silk used. This result is consistent with our hypothesis.

Webs of theridiid spiders: construction, structure and evolution

Understanding the web construction behaviour of theridiid (comb-footed) spiders is fundamental to formulating specific evolutionary hypotheses and predictions regarding the reduction of orb-webs. We describe for the first time in detail the web construction behaviour of Achaearanea tepidariorum, Latrodectus geometricus, Theridion sisyphium and T varians as well as webs of a range of other theridiids. In our survey we distinguish four major web types. Among webs with gumfooted lines, we distinguish between webs with a central retreat (Achaearanea-type) and those with a peripheral retreat (Latrodectus-type). Among webs without gumfooted lines, we distinguish between those which contain viscid silk (Theridion-type) and those with a sheet-like structure, which do not (Coleosoma-type). Theridiid gumfoot-webs consist of frame lines that anchor them to surroundings and support threads which possess viscid silk. Building of gumfooted lines constitutes a unique stereotyped behaviour and is most probably homologous for Nesticidae and Theridiidae. Webs remained in place for extended periods and were expanded and repaired, but no regular pattern of replacement was observed. We suggest that the cost of producing and maintaining viscid silk might have led to web reduction, at least in theridiids. (C) 2003 The Linnean Society of London.

UNDER THE INFLUENCE: WEBS AND BUILDING BEHAVIOR OF PLESIOMETA ARGYRA (ARANEAE, TETRAGNATHIDAE) WHEN PARASITIZED BY HYMENOEPIMECIS ARGYRAPHAGA (HYMENOPTERA, ICHNEUMONIDAE)

On the evening that it will kill its host, the orb-weaving spider Plesiometa argyra, the larva of the ichneumonid wasp Hymenoepimecis argyraphagainduces the spider to perform highly ste- reotyped construction behavior and build an otherwise unique ''cocoon web'' that is particularly well- designed to support the wasp larva's cocoon. Cocoon web construction behavior is nearly identical with the early steps in one subroutine of normal orb construction, and is repeated over and over. Usually all other normal orb construction behavior patterns are completely or nearly completely repressed. Experi- mental removal of the larva one or a few hours before cocoon construction would normally occur is sometimes followed by nearly normal cocoon web construction, and sometimes by construction of other highly altered web designs. The mechanism by which the larva induces these changes in the spider's behavior is thus apparently a fast-acting chemical, with effects that are manifested gradually. Partial recovery of orb designs sometimes occurred several days later.