Galloping beetles could be counting steps

Oct 21, 2013

(Phys.org) —A species of dung beetle in the Western Cape has given up its ability to fly and instead gallops across the sand in a behaviour which researchers suspect evolved as a way to navigate back and forth from home.

"This species of Pachysoma grabs bits of poo and gallops forward with it. That is really odd. Most insects walk with a tripod gait. They plant three in a triangle, while swinging the other three legs forward. It's an incredibly stable way of walking because you've always got three legs on the ground. For an insect to abandon the tripod gait and use its legs together in pairs like a galloping horse is really radical. The big question is: why are they doing it?" says Professor Marcus Byrne of Wits University.

Pachysoma is also different to most dung beetles in that it collects dry dung and hoards it in a nest which it provisions with repeated foraging trips, instead of rolling one, wet, dung ball in a straight line away from competitors at the dung pile, never to return.

A team of scientists including Byrne and colleagues from Lund University in Sweden think the species might have changed the way it walks because it needs to be able to find its way back and forth from its nest.

"For most dung beetles, it's always a one way trip – grab the poo, run away and never go back. The very marked pacing of Pachysoma's gallop might be giving it a better signal in terms of estimating the return distance from the food to its nest. When it gallops, it slips less in the soft ," says Byrne.

This video is not supported by your browser at this time.
Pachysoma Endrodyi Butterfly Gait.

Ants have been shown to count their steps as a way to navigate back and forth from home, and bees have been proven to use the optical flow of scenery across their retinas to measure how far they've travelled to forage from the hive. The team thinks the Pachysoma dung beetles are doing both.

"Bees use optic flow as a measure of how fast and how far they've flown. Dung beetles have two eyes on each side of their head, one on top and one on the bottom, looking at the sand and we think Pachysoma might be registering with its bottom eye over the sand," says Byrne.

But Pachysoma has not only changed the way it moves across land, it has also lost its ability to fly.

"There are 800 species of in South Africa and most of them fly. To fly makes sense because poo is a very ephemeral resource. It's only useful for a few days and it's very patchy – you don't know where you're going to find the next dropping. That's why Pachysoma is so weird. Why would anyone give up flying?" says Byrne.

The team suspects that Pachysoma has sealed its wing cases to conserve moisture in the arid West Coast environment. "Breathing causes massive water loss. We think they've closed the elytra case to create a breathing chamber which keeps moisture inside," says Byrne.

The unique behaviour of this galloping, flightless species has allowed it to dominate a niche market among dung collectors of the Western Cape.

Explore further: Male monkey filmed caring for dying mate (w/ Video)

Related Stories

Dung beetle dance provides crucial navigation cues

Jan 18, 2012

(PhysOrg.com) -- The dung beetle dance, performed as the dung beetle moves away from the dung pile with his precious dung ball, is a mechanism to maintain the desired straight-line departure from the pile, ...

Beetles use dung balls to stay cool

Oct 22, 2012

Dung beetles roll their feasts of dung away to avoid the hoards of other hungry competitors at the dung pile. But now a team of researchers from South Africa and Sweden have discovered that they also use ...

Dung beetles use stars for orientation

Jan 24, 2013

You might expect dung beetles to keep their "noses to the ground," but they are actually incredibly attuned to the sky. A report published online on January 24 in Current Biology shows that even on the da ...

Flapping protective wings increase lift

May 29, 2012

New research from Lund University in Sweden reveals the value of carrying two layers of wings around. The researchers studied dung beetles and the way their protective forewings actually function. These wings do not only ...

Exotic manure is sure to lure the dung connoisseur

Apr 11, 2012

Although the preference of dung beetles for specific types and conditions of dung has been given substantial attention, little has been done to investigate their preference for dung from exotic mammals found on game farms ...

Recommended for you

Male monkey filmed caring for dying mate (w/ Video)

10 hours ago

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Orchid named after UC Riverside researcher

Apr 17, 2014

One day about eight years ago, Katia Silvera, a postdoctoral scholar at the University of California, Riverside, and her father were on a field trip in a mountainous area in central Panama when they stumbled ...

In sex-reversed cave insects, females have the penises

Apr 17, 2014

Researchers reporting in the Cell Press journal Current Biology on April 17 have discovered little-known cave insects with rather novel sex lives. The Brazilian insects, which represent four distinct but re ...

Fear of the cuckoo mafia

Apr 17, 2014

If a restaurant owner fails to pay the protection money demanded of him, he can expect his premises to be trashed. Warnings like these are seldom required, however, as fear of the consequences is enough to ...

User comments : 0

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Researchers develop new model of cellular movement

(Phys.org) —Cell movement plays an important role in a host of biological functions from embryonic development to repairing wounded tissue. It also enables cancer cells to break free from their sites of ...

Male monkey filmed caring for dying mate (w/ Video)

(Phys.org) —The incident was captured by Dr Bruna Bezerra and colleagues in the Atlantic Forest in the Northeast of Brazil.  Dr Bezerra is a Research Associate at the University of Bristol and a Professor ...

Scientists tether lionfish to Cayman reefs

Research done by U.S. scientists in the Cayman Islands suggests that native predators can be trained to gobble up invasive lionfish that colonize regional reefs and voraciously prey on juvenile marine creatures.