Friday, March 26, 2010

Worlds Strongest Insect

Here is the answer to a question that has been concerning me for years.  Just what is the strongest animal in the world?  For the insect world at least, you will be happy to know the answer is Onthophagus taurus.  Still not sure what that is?  This bug works out by pushing dung- its a dirty job, but somebody has to do it.  The findings are published in the current issue of the journal Proceedings of the Royal Society B, as reported by livescience.com.
The beetle, called Onthophagus taurus, was found to be able to pull a whopping 1,141 times its own body weight, which is the equivalent of a 150-pound (70 kilogram) person lifting six full double-decker buses. While the study researcher knows of a mite that can take on a hair more, that organism is an arachnid, not an insect.
The beetles aren't the dung-ball-carrying variety, and instead the females bury most of the fecal material (with a little help from males) from, say, cow droppings.
The females build little tunnels where they use the dung to lay their eggs in. It's in this tunnel where mating, and the pre-mating fights between waiting males, takes place. But not all males are equipped for battle, with some sporting horns and others hornless. The no-horn beetles instead wait at the tunnel's entrance, sometimes hiding out in self-built side tunnels, and sneak in to mate before getting caught by a horned male. The horned males, on the other hand, duke it out head-to-head.
"Their horns kind of meet on the shoulders, and they push each other backward and forward, and the guy being pushed will brace when pushed in the tunnel," Rob Knell from Queen Mary, University of London told LiveScience. Obviously, a story like this is crying for a Youtube video, so here it is in the PG-13 version.

So how do you test an insect's strength.  Bench pressing and push-ups are pretty much out of the question.  One method is determining the load it can pull.
In the study, Knell and Leigh Simmons from the University of Western Australia set up a similar fighting scenario. But first they fed the horned beetles a good diet, poor diet or no food at all.
To test strength, the researchers attached a cotton thread to the rear of each beetle participant, before letting the insect walk into a tiny tunnel created in the lab. Once in the tunnel, the beetle got a tug from the researchers pulling on its little leash. The pulling caused the beetle to brace its legs against the tunnel in a manner similar to that used when fighting.
The beetles with horns, also called major males, that were fed good food got much stronger when fed compared with those not fed. The hornless males on a good-food diet, however, grew much more massive testes without showing the surge in strength.
Here's the likely reason: "The little males don't fight at all, but when they get to mate with a female, they only get to mate with her once," Knell said. "She's also mating with one of the guard males [that guards the tunnel]. So the small male has to invest in testes mass so he can inseminate the female with as much sperm as possible."
The results of this study have implications for the understanding of evolution.  This and more can be found at this link.  There is good evidence that a strong population of dung beetles burying cattle dung produces richer soil than other methods without requiring a much fertilizer.  They not only bury the dung in the soil but by tunneling down, they aerate the soil.  To dig deeper in the story (sorry) read this fascinating article.
Finally, this story has implications here in Missouri, as described in the Missouri Conservationist.
Tumble bugs, or dung beetles, do appear to have declined in Missouri and elsewhere. There are several likely causes for the decline. These include the use of fly and intestinal parasite control chemicals on cattle, which pass through their system and can make their dung toxic to insects. The popularity today of cool-season grass pastures can lead to drier and more compacted soils that are less hospitable to digging insects (dung beetles bury their dung balls to provide food for their young). As we manage more native prairies using grazing cattle, dung beetles are becoming more common on those sites. They provide many benefits, such as controlling insect pests, nutrient recycling and improving soil structure. For more information, visit: http://attra.ncat.org/attra-pub/dungbeetle.html.

There are now chemical companies producing products to protect cows from flies without harming the dung beetle population.  The Beatles- "We love you, yeah, yeah, yeah!"

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