...a dung beetle! Australia's Onthophagus taurus, to be precise, according to a months-long series of tests designed to determine which insect could pull the most weight. What's the dung beetle's secret? Diet.
Doctor Rob Knell from Queen Mary, University of London and Professor Leigh Simmons of the University of Western Australia set out to determine why different animals are able to pull such wildly different weights relative to their size. This dung beetle proved the strongest insect, although the experimenters did find one mite that was ever so slightly stronger. Unfortunately, it got disqualified on the grounds that it was actually an arachnid. How exactly was this not a reality show?
Onthophagus taurus can pull weights an astonishing 1,141 times its own mass. To put that in perspective, if a 150-pound person could pull 1,141 times his or her own weight, that would be more than enough to drag a Boeing 747 across a runway, with enough slack left over to add on an elephant or two.
As the coauthors explain in their article for Proceedings of the Royal Society B, a good diet is just as important to these dung beetles as it is for humans. When the beetles were forced to subsist on a poor quality diet for even just a few days, they quickly became mere shadows of their previous selves, barely able to pull any weight at all.
Knell explains why these beetles are so strong:
It's all on account of their curious sex lives. Female beetles of this species dig tunnels under a dung pat, where males mate with them. If a male enters a tunnel that is already occupied by a rival, they fight by locking horns and try to push each other out.
There was, however, one rather fascinating, testicle-related corollary to the dung beetle's physical prowess. Knell explains:
Interestingly, some male dung beetles don't fight over females. They are smaller, weaker and don't have horns like the larger males. Even when we fed them up they didn't grow stronger, so we know it's not because they have a poorer diet. They did, however, develop substantially bigger testicles for their body size. This suggests they sneak behind the back of the other male, waiting until he's looking the other way for a chance to mate with the female. Instead of growing super strength to fight for a female, they grow lots more sperm to increase their chances of fertilising her eggs and fathering the next generation.
This represents another spin on recent research that tied larger mandibles to smaller testicles, which we reported on here. One thing's for certain - whether it's of the heavy-pulling or massive-testicled variety, Onthophagus taurus is one dung beetle you don't want to mess with.