Spiders hear better than expected, new research


This video says about itself:

13 October 2016

In a test of hearing airborne noises, a small dark jumping spider stops moving abruptly (red pointer appears) when researchers broadcast a tone similar to the scary droning of the wings of a predatory wasp.

Video: G. Menda, Hoy Lab at Cornell

From Science News:

Be careful what you say around jumping spiders

Arachnids hear airborne sounds over greater distances than thought

By Susan Milius

8:00am, October 15, 2016

Accidental chair squeaks in a lab have tipped off researchers to a new world of eavesdroppers.

Spiders don’t have eardrums, though their exquisitely sensitive leg hairs pick up vibrations humming through solids like web silk and leaves. Biologists thought that any airborne sounds more than a few centimeters away would be inaudible. But the first recordings of auditory nerve cells firing inside a spider brain suggest that the tiny Phidippus audax jumping spider can pick up airborne sounds from at least three meters away, says Ronald Hoy of Cornell University.

During early sessions of brain recordings, Hoy’s colleagues saw bursts of nerve cell, or neuron, activity when a chair moved. Systematic experiments then showed that from several meters away, spiders were able to detect relatively quiet tones at levels comparable to human conversation. In a hearing test based on behavior, the spiders also clearly noticed when researchers broadcast a low droning like the wing sound of an approaching predatory wasp. In an instant, the spiders hunkered down motionless, the researchers report online October 13 in Current Biology.

Jumping spiders have brains about the size of a poppy seed, and Hoy credits the success of probing even tinier spots inside these (anesthetized) brains to Cornell coauthor Gil Menda and his rock-steady hands. “I close my eyes,” Menda says. He listens his way along, one slight nudge of the probe at a time toward the auditory regions, as the probe monitor’s faint popping sounds grow louder.

When Menda first realized the spider brain reacted to a chair squeak, he and Paul Shamble, a study coauthor now at Harvard University, started clapping hands, backing away from the spider and clapping again. The claps didn’t seem earthshaking, but the spider’s brain registered clapping even when they had backed out into the hallway, laughing with surprise.

Clapping or other test sounds in theory might confound the experiment by sending vibrations not just through the air but through equipment holding the spider. So the researchers did their Cornell neuron observations on a table protected from vibrations. They even took the setup for the scary wasp trials on a trip to the lab of coauthor Ronald Miles at State University of New York at Binghamton. There, they could conduct vibration testing in a highly controlled, echo-dampened chamber. Soundwise, Hoy says, “it’s really eerie.”

Neuron tests in the hushed chamber and at Cornell revealed a relatively narrow, low-pitched range of sensitivity for these spiders, Hoy says. That lets the spiders pick up rumbly tones pitched around 70 to 200 hertz; in comparison, he says, people hear best between 500 and 1,000 Hz and can detect tones from 50 Hz to 15 kilohertz.

Spiders may hear low rumbles much as they do web vibes: with specialized leg hairs, Hoy and his colleagues propose. They found that making a hair twitch could cause a sound-responsive neuron to fire.

“There seems to be no physical reason why a hair could not listen,” says Jérôme Casas of the University of Tours in France. When monitoring nerve response from hairs on cricket legs, he’s tracked airplanes flying overhead. Hoy’s team calculates that an 80 Hz tone the spiders responded to would cause air velocities of only 0.13 millimeters a second if broadcast at 65 decibels three meters away. That’s hardly a sigh of a breeze. Yet it’s above the threshold for leg hair response, says Friedrich Barth of the University of Vienna, who studies spider senses.

An evolutionary pressure favoring such sensitivity might have been eons of attacks from wasps, such as those that carry off jumping spiders and immobilize them with venom, Hoy says. A mother wasp then tucks an inert, still-alive spider into each cell of her nest where a wasp egg will eventually hatch to feed on fresh spider flesh. Wasps are major predators of many kinds of spiders, says Ximena Nelson of the University of Canterbury in Christchurch, New Zealand. If detecting their wing drone turns out to have been important in the evolution of hearing, other spiders might do long-distance eavesdropping, too.

Spotted-wing vinegar flies, video


This 24 September 2016 video by Silvia Hellingman in the Netherlands is about spotted-wing vinegar flies.

They are originally from Asia, but were brought to North America and Europe. They are a threat both to commercially grown fruit and wild fruit.

Hornets drinking and eating, video


This 13 September 2016 video from the Netherlands shows hornets drinking sap at a ‘bleeding’ tree, and catching a honeybee.

More about hornets is here.

New insect discoveries on dead animals


This video from the USA says about itself:

Black Scavenger Fly (Sepsidae) Wing-waving

Photographed at Grand Forks, North Dakota (31 May 2010).

Translated from Dutch Vroege Vogels radio:

New insects discovered on dead animals

Sunday, September 4, 2016

Deliberately leaving dead animals in the wild in the Kuinderbos forest (Flevoland province) has resulted in three insect species new for the Netherlands. In the framework of the project “Death gives life” the Forestry Commission gathered in a special place corpses of deer, beech martens and a heron. That attracted various scavengers, including many insect species. Entomologist Elias de Bree of EIS Insects Research Netherlands therefore placed an insect trap there.

After analyzing the trapped animals he was able to identify three new species for the Netherlands: two species of ensign flies (Sepsidae) and a species of the family Piophilidae … . Small flies from 4 to 5 mm. They live as larvae in manure and carcasses of vertebrates. The Forestry Commission is pleased with the new discoveries: it says something about the biodiversity in the Kuinderbos.

Dragonflies, butterflies, great cormorant video


This 3 August 2016 video shows dragonflies, butterflies, a great cormorant and other wildlife on Voorne island in the Netherlands.

Praying mantis in the USA


This video from the USA says about itself:

30 August 2016

Making friends with a Praying Mantis hunting insects on the porch! These fascinating insects have personalities and unlike most insects seem to relate to humans and humans seem to instinctively sense their awareness and do not harm them! They of course, are extremely beneficial to have around.

Flowers and insects of Voorne island


This 28 August 2016 video is about flowers, hoverflies, dragonflies and other insects at the Beerenplaat nature reserve on Voorne island in the Netherlands.