A novel property of spider silk: chemical defence against ants

Spider webs are made of silk, the properties of which ensure remarkable efficiency at capturing prey. However, remaining on, or near, the web exposes the resident spiders to many potential predators, such as ants. Surprisingly, ants are rarely reported foraging on the webs of orb-weaving spiders, despite the formidable capacity of ants to subdue prey and repel enemies, the diversity and abundance of orb-web spiders, and the nutritional value of the web and resident spider. We explain this paradox by reporting a novel property of the silk produced by the orb-web spider Nephila antipodiana (Walckenaer). These spiders deposit on the silk a pyrrolidine alkaloid (2-pyrrolidinone) that provides protection from ant invasion. Furthermore, the ontogenetic change in the production of 2-pyrrolidinone suggests that this compound represents an adaptive response to the threat of natural enemies, rather than a simple by-product of silk synthesis: while 2-pyrrolidinone occurs on the silk threads produced by adult and large juvenile spiders, it is absent on threads produced by small juvenile spiders, whose threads are sufficiently thin to be inaccessible to ants.

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A natural history of web decorations in the St Andrew's Cross spider (Argiope keyserlingi)

Australian Journal of Zoology ◽

10.1071/zo06010 ◽

2007 ◽

Vol 55 (1) ◽

pp. 9 ◽

Cited By ~ 7

Author(s):

Dinesh Rao ◽

Ken Cheng ◽

Marie E. Herberstein

Keyword(s):

Natural History ◽

Sustained Attention ◽

Spider Webs ◽

History Data ◽

Web Spider ◽

Exact Function ◽

History Of ◽

Argiope Keyserlingi ◽

Orb Web ◽

The Web

A long-running debate in the spider literature concerns the function of the extra silk decorations in some spider webs. These decorations are appended to the web and constitute a highly visible signal, which is inconsistent with the trend towards web invisibility. Despite the sustained attention of researchers, the exact function of these decorations is yet to be understood. While most studies have focussed on testing particular hypotheses, there has been a dearth of natural history data regarding web decorations in field conditions. In this study we present baseline data regarding the influence of seasonality, microhabitat characteristics and ecology on the presence of web decorations in an Australian orb web spider, Argiope keyserlingi. In particular, we show that there is preference among spiders to build their webs between bushes and to face the south-east, but this preference does not influence decoration building.

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Drinking behaviour of the orb web spider Argiope bruennichi (Araneae; Araneidae)

Behaviour ◽

10.1163/000579511x603292 ◽

2011 ◽

Vol 148 (11-13) ◽

pp. 1295-1309 ◽

Cited By ~ 2

Author(s):

André Walter ◽

Constanze Westphal ◽

Peter Bliss ◽

Robin F.A. Moritz

Keyword(s):

Water Budget ◽

Water Deprivation ◽

Water Saturation ◽

Drinking Behaviour ◽

Water Droplets ◽

Web Spider ◽

Orb Web ◽

Orb Web Spiders ◽

Water Gain ◽

The Web

Abstract Water is essential for survival in terrestrial animals. Balancing the water budget can be achieved by avoiding water loss and gaining water. In arthropods drinking as a process of water gain is well investigated in insects. In spiders drinking has only been shown to be present in cursorial spiders but not revealed for web builders. However, some orb web spiders were observed to occasionally ingest water droplets in the web. We here tested whether this reflects drinking. We subjected individual Argiope bruennichi spiders to two different treatments — 'water deprivation' vs. 'water saturation'. We conducted drinking tests by recording the spider's behavioural response to spraying the web with defined amounts of water. After spraying A. bruennichi searched the silk-overstitched web hub for water droplets and ingested them. Individuals that experienced the water deprivation treatment showed significantly more water ingesting behaviours, revealing that this response represents a true drinking mode. All individuals exclusively searched the covered web hubs. We further demonstrated that this structure can retain water for up to 40 min providing an effective substrate for the spiders to drink from. Hence, without the need of leaving the web the silk-covered hubs may help A. bruennichi spiders to balance their water budget.

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The effect of predator-prey distance and prey profitability on the attack behaviour of the orb-web spider Argiope keyserlingi (Araneidae)

Australian Journal of Zoology ◽

10.1071/zo00074 ◽

2001 ◽

Vol 49 (3) ◽

pp. 213 ◽

Cited By ~ 7

Author(s):

F. E. Champion de Crespigny ◽

M. E. Herberstein ◽

M. A. Elgar

Keyword(s):

Foraging Behaviour ◽

Physiological Condition ◽

Web Design ◽

Central Place ◽

Predator Prey ◽

Web Spider ◽

Argiope Keyserlingi ◽

Orb Web ◽

Orb Web Spiders ◽

The Web

The foraging behaviour of central-place foragers is thought to be strongly influenced by the distance between the forager and the food source (predator–prey distance). Orb-web spiders are uniquely suited for investigating this idea because they make active foraging decisions towards prey entangled in the web, and they define the dimensions of their foraging arena when they construct the web. Here we manipulate the physiological condition of Argiope keyserlingi and present the spiders with prey of varying quality, in terms of size and accessibility (location within the web and distance from the spider). We found that these spiders adjust their foraging behaviour primarily in response to their physiological condition but, in contrast to other central-place foragers, are indiscriminant of predator–prey distance or the likelihood of escape of the prey. We suggest that these factors are incorporated into the design of the web, and thus increase foraging success through efficient web design.

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THE STABILIMENTUM OF THE ORB WEB SPIDER, ARGIOPE ARGENTATA: AN IMPROBABLE DEFENCE AGAINST PREDATORS

The Canadian Entomologist ◽

10.4039/ent102641-6 ◽

1970 ◽

Vol 102 (6) ◽

pp. 641-655 ◽

Cited By ~ 37

Author(s):

Michael H. Robinson ◽

Barbara Robinson

Keyword(s):

Wild Birds ◽

Mechanical Function ◽

Mechanical State ◽

Web Spider ◽

Prey Location ◽

Orb Web ◽

Final Adjustment ◽

Orb Web Spiders ◽

The Web

AbstractThe stabilimentum of orb web spiders is a structure for which several functions, both mechanical and defensive, have been suggested. Argiope argentata (Fabricius) builds a stabilimentum in the form of a white diagonal cross. Analysis of over 2500 webs of this species shows that the perfect cross is seldom built and nearly two thirds of the webs contain no stabilimentum at all. Experiments with wild birds as predators show that they can use stabilimentum-like models in prey location. From these data, and a review of the defensive adaptations of orb web spiders, it is argued that the A. argentata stabilimentum is not an anti-predator device. The evidence for a mechanical function is reviewed and discussed. It is suggested that the stabilimentum provides the spider with a means of making a final adjustment to the mechanical state of the web when this is necessary.

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Does decoration building influence antipredator responses in an orb-web spider (Argiope keyserlingi) in its natural habitat?

Australian Journal of Zoology ◽

10.1071/zo06098 ◽

2007 ◽

Vol 55 (1) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

Sean J. Blamires ◽

Dieter F. Hochuli ◽

Michael B. Thompson

Keyword(s):

Wind Speed ◽

Body Condition ◽

Natural Habitat ◽

Antipredator Behaviour ◽

Web Spider ◽

Antipredator Responses ◽

Argiope Keyserlingi ◽

Orb Web ◽

Orb Web Spiders ◽

The Web

Antipredator strategies adopted by animals need to compensate for temporal changes. Many orb-web spiders add silk decorations to their webs, which principally attract prey but may attract some predators. To identify their influence on antipredator behaviour in adult female St Andrew’s cross spiders (Argiope keyserlingi) we measured: spider body condition, web characteristics (area, spiral length and decoration building), environmental variables (air temperature, humidity, wind speed, relative prey abundance) and antipredator responses (remaining at the hub, dropping, shifting to the web periphery, or pumping the web) at three distinct periods (July–August, September–October and January–February) in the field. We developed path models from multiple regression analyses to distinguish between factors having direct and indirect effects. We found that even though both antipredator responses and decoration building change over time, antipredator responses and decoration investment are independent. Body condition and wind speed are directly positively associated with pumping frequency, and decoration building is negatively associated with the frequency of remaining at the hub because the likelihood that an object approaching the web is a predator increases if decorations are added. Wind speed is positively associated with antipredator behaviour and decoration building, due to an increased rate of feeding affecting body condition.

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The silk tuft web decorations of the orb-weaver Gasteracantha cancriformis : testing the prey attraction and the web advertisement hypotheses

Behaviour ◽

10.1163/156853908783402911 ◽

2008 ◽

Vol 145 (3) ◽

pp. 277-295 ◽

Cited By ~ 8

Author(s):

Felipe Gawryszewski ◽

Paulo Motta

Keyword(s):

Drosophila Melanogaster ◽

Foraging Success ◽

Uv Reflectance ◽

Web Advertisement ◽

Orb Web ◽

Orb Web Spiders ◽

Large Animals ◽

And Control ◽

The Web ◽

Prey Attraction

AbstractSeveral orb-web spiders build conspicuous decorations in their webs. The prey attraction hypothesis proposes that decorations increase spider foraging success by attracting prey, and that attraction is linked to UV reflectance. Alternatively, the web advertisement hypothesis proposes that decorations are a signal that advertises the presence of the web to large animals. We tested both hypotheses for the web silk tufts of Gasteracantha cancriformis. Even though tufts are UV reflective, we did not find support for the prey attraction hypothesis. In the field, when webs with tufts painted black and control webs were compared, there were no differences in the number of prey captured, number of damaged areas in webs and type of prey captured. In the laboratory, Drosophila melanogaster did not demonstrate preference for tufted silk lines versus non-tufted silk lines. Our data also did not give support for the web advertisement hypothesis. The proportion of web destruction was similar between web with tufts painted black and control webs during four days of experimentation. Therefore, two of the most favoured hypotheses that attempt to explain decorations do not apply for web silk tufts in our study system. Instead we propose that silk tufts might be an aposematic signal.

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High-performance spider webs: integrating biomechanics, ecology and behaviour

Journal of The Royal Society Interface ◽

10.1098/rsif.2010.0454 ◽

2010 ◽

Vol 8 (57) ◽

pp. 457-471 ◽

Cited By ~ 49

Author(s):

Aaron M. T. Harmer ◽

Todd A. Blackledge ◽

Joshua S. Madin ◽

Marie E. Herberstein

Keyword(s):

High Performance ◽

Three Dimensional ◽

Spider Webs ◽

Spider Dragline Silk ◽

Spider Web ◽

Web Spider ◽

Species Invasions ◽

Synthetic Materials ◽

Orb Web ◽

Spider Silks

Spider silks exhibit remarkable properties, surpassing most natural and synthetic materials in both strength and toughness. Orb-web spider dragline silk is the focus of intense research by material scientists attempting to mimic these naturally produced fibres. However, biomechanical research on spider silks is often removed from the context of web ecology and spider foraging behaviour. Similarly, evolutionary and ecological research on spiders rarely considers the significance of silk properties. Here, we highlight the critical need to integrate biomechanical and ecological perspectives on spider silks to generate a better understanding of (i) how silk biomechanics and web architectures interacted to influence spider web evolution along different structural pathways, and (ii) how silks function in an ecological context, which may identify novel silk applications. An integrative, mechanistic approach to understanding silk and web function, as well as the selective pressures driving their evolution, will help uncover the potential impacts of environmental change and species invasions (of both spiders and prey) on spider success. Integrating these fields will also allow us to take advantage of the remarkable properties of spider silks, expanding the range of possible silk applications from single threads to two- and three-dimensional thread networks.

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SILK MEDIATED DEFENSE BY AN ORB WEB SPIDER AGAINST PREDATORY MUD-DAUBER WASPS

Behaviour ◽

10.1163/15685390151074357 ◽

2001 ◽

Vol 138 (2) ◽

pp. 155-171 ◽

Cited By ~ 47

Author(s):

Todd Blackledge ◽

John Wenzel

Keyword(s):

Web Sites ◽

Predation Pressure ◽

Spider Webs ◽

Web Spider ◽

Orb Web ◽

Argiope Trifasciata

AbstractStabilimenta are zigzag and spiral designs of seemingly conspicuous silk included at the centers of many spider webs. We examined the association of stabilimenta with the ability of spiders to defend themselves against predatory mud-dauber wasps. We found that Argiope trifasciata (Araneae, Araneidae) were significantly more likely to survive attacks by Chalybion caeruleum and Sceliphron caementarium (Hymenoptera, Sphecidae) when spiders included stabilimenta in webs. This association could not be explained by factors such as differences in sizes or conditions of spiders nor locations of webs. We suggest that stabilimenta may function to delay pursuit of spiders as they drop from webs by physically blocking wasps, camouflaging spiders or distracting attacking wasps. Stabilimenta may function in a role very similar to the retreats built by many other genera of spiders and appear to be an adaptation to reduce the predation pressure faced by spiders that have evolved foraging habits at highly exposed diurnal web sites.

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Foraging behaviour in orb-web spiders (Araneidae): do web decorations increase prey capture success in Argiope keyserlingi Karsch, 1878?

Australian Journal of Zoology ◽

10.1071/zo00007 ◽

2000 ◽

Vol 48 (2) ◽

pp. 217 ◽

Cited By ~ 39

Author(s):

M. E. Herberstein

Keyword(s):

Foraging Behaviour ◽

Prey Capture ◽

Paired Comparison ◽

Mortality Rates ◽

Argiope Keyserlingi ◽

Orb Web ◽

Orb Web Spiders ◽

The Web ◽

Web Size ◽

Prey Attraction

Orb web spiders in the genus Argiope attach highly visible silk bands called decorations or stabilimenta to their webs. Two different hypotheses regarding the function of these structures were investigated in the field using Argiope keyserlingi: prey attraction and anti-predatory device. The first hypothesis suggests that web decorations attract prey to the web, and webs carrying decorations will capture more prey than those without. A field census of prey capture showed that webs adorned with more decorative bands indeed captured more but similarly sized prey per hour compared with webs carrying fewer decorations. Web height or web size, however, were not related to the rate of prey capture. This pattern was confirmed by a paired comparison of prey-capture rates within individuals that increased or decreased the number of decorative bands on consecutive days. Individuals that used more decorations also captured more prey compared with days when they spun fewer decorations. The second hypothesis suggests that these structures function as anti-predatory devices and, consequently, spiders on decorated webs benefit from a lower rate of mortality than spiders on undecorated webs. A census of the mortality rates of spiders over 19 days revealed that spiders did not disappear from undecorated webs more frequently than from decorated webs. Consequently, the idea that web decorations act as anti-predatory devices in A. keyserlingi was not supported.

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Spatial learning affects thread tension control in orb-web spiders

Biology Letters ◽

10.1098/rsbl.2013.0052 ◽

2013 ◽

Vol 9 (4) ◽

pp. 20130052 ◽

Cited By ~ 6

Author(s):

Kensuke Nakata

Keyword(s):

Spatial Learning ◽

Tension Control ◽

Web Spider ◽

The Future ◽

Thread Tension ◽

Orb Web ◽

Orb Web Spiders ◽

The Way

Although it is well known that spatial learning can be important in the biology of predators that actively move around in search for food, comparatively little is known about ways in which spatial learning might function in the strategies of sit-and-wait predators. In this study, Cyclosa octotuberculata , an orb-web spider that uses its legs to contract radial threads of its web to increase thread tension, was trained to capture prey in limited web sectors. After training, spiders that had captured prey in horizontal web sectors applied more tension on radial threads connected to horizontal sectors than spiders that had captured prey in vertical sectors. This result suggests that the effect of experience on C. octotuberculata 's behaviour is not expressed in the way the trained spider responds to prey-derived stimuli and is instead expressed in behaviour by which the spider anticipates the likely direction from which prey will arrive in the future. This illustrates that learning can be important even when the predator remains in one location during foraging bouts.

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