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Vicious Dung Beetle Found In Peru

January 21, 2009

The dung beetle is emerging from the bottom of the food chain led by a brand new and scary species.

A Peruvian scarab type species has been recorded fighting and devouring millipedes 10 times its size.

The species D. valgum is done with dung. In its place, the nocturnal critter prefers to chop the heads off their prey with its “teeth” and then consume their guts.
 
This is an uncommon occurrence of a scavenger evolving into a carnivore, say US scientists.  Dung beetles are normally not carnivores, normally consuming animal feces.

Once the Peruvian critter Deltochilum valgum was seen fighting millipedes larger than themselves, Dr Trond Larsen of Princeton University wanted to see if the dung beetle may be plundering other creatures.

Once in the Peruvian rainforest, his team arranged 1,000 traps to entice the beetles. The traps were set will of dung, fungus, fruit, and live, injured or dead millipedes.

They noted that D. valgum preferred the millipedes, targeting the prey that was still alive but hurt. With infrared cameras, they captured an adult beetle fighting and slaughtering an injured millipede.

“This is a remarkable transition,” wrote Larsen in the journal Biology Letters. “Despite its close relationships with dung feeding species, D. valgum has entirely abandoned its ball-rolling behavior. This is the first known case of an obligate predatory dung beetle species.”

These predatory beetles used their mouthparts to attack and slay their prey. When placed together in observation containers, the beetles grabbed the millipedes with their mid- and hind-legs. The beetles then popped their shielded teeth into the body segments, using a sawing motion with their fore-teeth.

“During one kill we observed, the force of the beetle’s prying severed the millipede’s head from the rest of its body,” Larsen told BBC News.

The team says that this find illustrates how minute alterations in the physiology of a variety of animal can lead the way to changes in their behavior.

Unlike the majority of dung beetle species, which bury their food once finished with it, the Peruvian species left the millipede remains out in the open.

“It seems like such a huge jump – from a scavenger to a hunter-predator – so the real story is, how did it get from A to Z?” Dr Adrian Forsyth, a co-author on the paper said. “We knew plenty of dung beetles which are attracted to dead insects – drawn by their potent cyanide-rich odors. And now we find a species which just couldn’t wait.”

“This is a beetle which says: ‘It doesn’t matter if it’s dead or alive, I’m going to eat it’” said Forsyth. “It’s a nice example of how you can take an apparently big step – to become a carnivore.”

The scientists contribute this change to elevated levels of rivalry for food. Dung beetles endure ferocious struggle for resources, equally between and within species. Adult beetle assertively protect their dung balls from others by fighting each other.

The same behavior was seen in beetles which had captured millipedes. The evolutionary changes might clarify the coexistence of the diversity in types of insects, researchers state.

“I find it amazing that what we thought was just another dung beetle turned out to be something rather exceptional,” Forsyth said.

Image Caption: Most dung beetle species feed on balls of feces. Image Courtesy Wikipedia

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