Spider web research shows promise for noninvasive genetic sampling

Date: January 12, 2016

Source:University of Notre Dame

Using web samples from black widow spiders fed with crickets, researchers at the University of Notre Dame have successfully used DNA samples to identify both the spider and the species of its prey. Such noninvasive sampling to obtain genetic information could have practical implications in several fields including conservation research and pest management.

As an environmental science student at Notre Dame, Charles Cong Yang Xu said he had the idea of uncovering the DNA of spiders while he was studying environmental DNA of fish in the lab of David Lodge, the Ludmilla F., Stephen J., and Robert T. Galla Professor of Biological Sciences. Xu found a novel and promising noninvasive source of spider and insect DNA through extracting the DNA from spider webs. Using web samples from spiders placed at Potawatomi Zoo in South Bend, Indiana, he then amplified and sequenced mitochondrial DNA from spider web samples, which identified both the spider and the species of the prey.

Spider and prey DNA remained detectable at least 88 days after living organisms were no longer present on the web. "Sticky spider webs may serve as a natural DNA sampling device for DNA from the spider and from what it's been eating," Xu said.

Noninvasive genetic sampling such as this enables biomonitoring without the need to directly observe or disturb target organisms. The results from this study can lead to practical applications in conservation research, pest management, biogeography studies and biodiversity assessments.

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Cobwebs Hold Genetic Secrets About Spiders and Their Prey

by Elizabeth Palermo, Associate Editor | November 25, 2015 02:09pm ET

You may want to think twice before vacuuming up any pesky cobwebs you find around your home — these messy spider lairs may contain valuable information (valuable to scientists, that is).

A spider's sticky web contains traces of the critter's DNA, as well as the DNA of whatever prey that was unlucky enough to get stuck in the web, according to a new study, which found that these tiny samples of DNA can be amplified and sequenced in a lab. In other words, an empty spider web isn't a mystery; it's a clue that can tell scientists what kind of spider built the web and what prey it snagged in its trap.

Knowing exactly which species of spider built a web in a certain area, as well as knowing what that spider feasted on, is important information for researchers in a variety of fields — from conservation ecology to pest management, said study lead author Charles C.Y. Xu, a graduate student in the Erasmus Mundus Master Programme (MEME) in evolutionary biology, a joint program hosted by four European universities and Harvard University in the United States.

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Untangling spider's webs: Largest-ever study of spider genetics shows orb weaver spiders do not share common origins

Date:
July 17, 2014

Source:
Harvard University

Summary:
The largest-ever phylogenetic study of spiders shows that, contrary to long-held popular opinion, the two groups of spiders that weave orb-shaped webs do not share a single origin.


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How Electricity Helps Spider Webs Snatch Prey and Pollutants

Jan. 14, 2014 — Spider webs actively spring towards prey thanks to electrically-conductive glue spread across their surface, Oxford University scientists have discovered.

The researchers found that the electrostatic properties of the glue that coats spider webs causes them to reach out to grab all charged particles, from pollen and pollutants to flying insects. They also showed that the glue spirals can distort Earth's electric field within a few millimetres of the web, which may enable insects to spot the webs with their antennae 'e-sensors'.

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Wolf creek: spiders spinning out of control as waters rise

PEOPLE are not the only ones trying to escape rising flood waters, spiders have also had to evacuate their homes.

In an attempt to reach safety, millions of ground-dwelling wolf spiders have covered the fields surrounding flood-stricken areas of NSW with their webs.

Web horror ... a property covered by cobwebs in Wagga. Photo: Reuters

The arachnid collection manager at the Queensland Museum, Owen Seeman, said as waters rise the eight-legged creatures climb blades of grass and let out metres of silk in the hope a gust of wind will catch the web and blow them to safety.

But the success of this ingenious escape method relies on a moderate breeze.

''What you are seeing is the result of all their failed attempts to get away,'' Dr Seeman said.

''They keep trying and trying and suddenly this entire area is coated with web.''

One spider could produce hundreds of metres of silky web in a few hours, he said.

Amber Beavis, an evolutionary geneticist and spider expert, said it was unusual to see adult spiders displaying this trait, known as ballooning.

Juvenile spiders use this technique to disperse from their birthplace, said Dr Beavis, a Churchill Fellow at the Australian National University.

Wolf spiders were typically a solitary species and did not socialise with others, she said.

''But under these extreme circumstances they obviously don't mind being around each other.''

Dr Seeman said the floods would devastate the local wolf spider population.

''A lot of these spiders aren't going to make it. It's a catastrophe for them,'' he said.

''They've been washed away, moved to other parts of the countryside or drowned.''

Farmers may experience a rise in insects that the spiders would normally eat, he said.

Read more and see fantastic photos at: http://www.smh.com.au/environment/animals/wolf-creek-spiders-spinning-out-of-control-as-waters-rise-20120307-1ukmo.html#ixzz1oWmPyB1u

Fancy Footwork and Non-Stick Leg Coating Helps Spiders Not Stick to Their Own Webs

ScienceDaily (Mar. 1, 2012) — Researchers at the Smithsonian Tropical Research Institute and University of Costa Rica studying why spiders do not stick to their own sticky webs have discovered that a spider's legs are protected by a covering of branching hairs and by a non-stick chemical coating.

They also observed that spiders carefully move their legs in ways that minimize adhesive forces as they push against their sticky silk lines hundreds to thousands of times during the construction of each orb.

The web-weaving behavior of two tropical species, Nephila clavipesand Gasteracantha cancriformis, was recorded with a video camera equipped with close-up lenses. Another video camera coupled with a dissecting microscope helped to determine that individual droplets of sticky glue slide along the leg's bristly hair, and to estimate the forces of adhesion to the web. By washing spider legs with hexane and water, they showed that spiders' legs adhered more tenaciously when the non-stick coating was removed.

Their results are published online in the journal,Naturwissenschaften.

http://www.sciencedaily.com/releases/2012/03/120301103802.htm