How spiders use an electrical charge to trap insects

One of nature's greatest marvels has been found to have another advantage: a negative electrical charge, which can snap up positively charged insects.

|
Dominic Ebenbichler/Reuters/File
A honeybee gathers pollen from a flower at a farm in the western Austrian village of Seefeld in May.

The spider web - already one of nature’s greatest marvels for its strategic architectural design and the adhesive strands - has now been found to have another advantage: a negative electrical charge, which can snap up positively charged insects in a quite literally fatal attraction.

In an experiment conducted in a lab environment isolated from electrical fields, UC Berkeley post-doctoral fellow Victor Manuel Ortega-Jimenez, who usually works with hummingbirds and moths, and his colleague Robert Dudley gave a variety of newly-dead insects, including bumblebees and fruit flies, a positive-electrical charge in imitation of the charge that those insects would accumulate in life. Insects normally build up an electrical charge when they fly, much as do socked feet shuffling across a carpet, while the spider web has either a positive or neutral charge.

Dropping the insects down into spider webs collected from the European garden spider Araneus diadematus, the scientists found that individual web filaments flexed as much as 2 millimeters toward the charged insects, moving quickly and fatally at an average speed of about 2 meters per second to grab the meat into the web as it fell. The web did not flex at all toward un-charged insects dropped into the web.

“The spider web is really interesting because it's so thin and flexible," said Ortega-Jimenez, who had planned the experiment after noticing that spider webs bent toward his then four-year-old daughter's magic wand toy, which can be used to levitate oppositely charged objects. "The web is attracted to the insect, so that can increase the spider's capture rate."

Cruelly, the charge that draws insects into a spider’s web is also the property on which their survival hinges. Honeybees require an electrical charge to locate flower fields, identify which flowers have already played host to another bee, and ferry nectar on their bodies from the flower to the hive.

The scientists plan to corroborate the results, published in Science, in the wild, observing how the webs respond to live insects, said Ortega-Jimenez.

You've read  of  free articles. Subscribe to continue.
Real news can be honest, hopeful, credible, constructive.
What is the Monitor difference? Tackling the tough headlines – with humanity. Listening to sources – with respect. Seeing the story that others are missing by reporting what so often gets overlooked: the values that connect us. That’s Monitor reporting – news that changes how you see the world.

Dear Reader,

About a year ago, I happened upon this statement about the Monitor in the Harvard Business Review – under the charming heading of “do things that don’t interest you”:

“Many things that end up” being meaningful, writes social scientist Joseph Grenny, “have come from conference workshops, articles, or online videos that began as a chore and ended with an insight. My work in Kenya, for example, was heavily influenced by a Christian Science Monitor article I had forced myself to read 10 years earlier. Sometimes, we call things ‘boring’ simply because they lie outside the box we are currently in.”

If you were to come up with a punchline to a joke about the Monitor, that would probably be it. We’re seen as being global, fair, insightful, and perhaps a bit too earnest. We’re the bran muffin of journalism.

But you know what? We change lives. And I’m going to argue that we change lives precisely because we force open that too-small box that most human beings think they live in.

The Monitor is a peculiar little publication that’s hard for the world to figure out. We’re run by a church, but we’re not only for church members and we’re not about converting people. We’re known as being fair even as the world becomes as polarized as at any time since the newspaper’s founding in 1908.

We have a mission beyond circulation, we want to bridge divides. We’re about kicking down the door of thought everywhere and saying, “You are bigger and more capable than you realize. And we can prove it.”

If you’re looking for bran muffin journalism, you can subscribe to the Monitor for $15. You’ll get the Monitor Weekly magazine, the Monitor Daily email, and unlimited access to CSMonitor.com.

QR Code to How spiders use an electrical charge to trap insects
Read this article in
https://www.csmonitor.com/Science/2013/0708/How-spiders-use-an-electrical-charge-to-trap-insects
QR Code to Subscription page
Start your subscription today
https://www.csmonitor.com/subscribe