In the world of the dung beetle, eating and rolling in poop is fun. Dung beetles are classified according to how they interact with manure: rollers mold dung into balls for eating or brooding purposes, tunnelers bury their poop and dwellers make a home out of excrement. According to recent research on these insects, dung beetles are attracted to the smelliest poop they can find, which happens to be dung from omnivores like us.
Dung beetles are born with an attraction toward poop: beetle larvae love snacking on solid dung, while adult beetles suck up the nutritious moisture in fecal matter. To get their share of dung, the beetles employ a variety of strategies. Some species of beetle use their sensitive noses to hone in on fresh dung, while others hitch a ride on the backs of animals and wait until they defecate.
Before you wrinkle your nose in disgust, know that dung beetles are doing a great service for the environment. Without them, the world would be a much smellier place, considering that the beetles help bury waste that would otherwise attract pests. Moreover, dung beetles help new trees grow by rolling poop that contains undigested seeds.
While dung beetles usually have very specific tastes, study researcher Wyatt Hoback, a professor at the University of Nebraska at Kearney, recently discovered that the insects are also open to certain types of exotic droppings. These picky eaters caused a catastrophe in Australia in 1778, when they rejected droppings from imported cows and other large herbivores. Stunned by the rejection of the feces lovers, the bovine poop consigned to becoming a home for flies and other nasty parasites.
The researchers were ready to get their hands dirty. To better study the beetles, they planted large buckets around a large cattle ranch in Nebraska. These gut-wrenching pitfall traps either contained feces from one of many species of animals or a popular side dish, carrion, which the beetles often consume for nourishment. Once the beetles entered the bucket to inspect their dinner, they were trapped by the high walls of the bucket. This technique was very successful; together, the researchers attracted over 9,000 dung beetles.
The dung fans were lured in with a wide selection of droppings from both native and exotic animals. Native animals included bison and cougar, and exotic animals included waterbuck, lion, and chimpanzee. In addition, carnivores, herbivores and omnivores were all represented in the dung samples. The research took two summers, but the team successfully captured and studied 15 different species of dung beetle.
Of the dung samples, human and chimpanzee feces were the biggest hits. Dead rats were the next most popular dish, followed by pig droppings, then guano from the carnivorous species, such as lions and tigers. Finally, the remainder consisted of excrement from herbivores, such as bison. The researchers believe that these preferences can be attributed to the fact that omnivore dung is a whole lot smellier than herbivore dung.
In addition, poop preferences varied between different species of dung beetle. Some species gravitated towards the omnivore dung, while others decided that dead, rotting animals were more delicious. According to Sam Whipple, a postdoctoral researcher at the University of Nebraska-Lincoln, this specificity in dietary preferences isn’t related to the quality of the dung, the animal’s diet or its origin. Whipple says that the results suggest that even closely related species of generalist dung beetles differ in their responses to novel types of dung.
Possibly the most interesting finding is that dung beetles show little interest in the feces of animals that evolved along with them, such as the bison. Many of them were adventurous in their tastes, preferring to land in the buckets of poop belonging to the more exotic zebras, donkeys and moose.
This would explain why dung beetles are now lugging their dung balls to new environments – who would not be ready for a new diet, after eating the same stuff for millions of years? Unfortunately, there are few places left for these omnipresent beetles go. The dung lovers currently reside on every continent except for Antarctica.
