Study: Dung beetles use Milky Way to travel across the African savanna
It seems humans, birds, and seals are not the only creatures on Earth that use the night sky to navigate. According to a team of international researchers, at least one insect also keeps its eyes on the sky: the dung beetle.
According to a report published in Current Biology, dung beetles navigate across width swaths of land via the starry sky. Using the glow of the Milky Way, these sky-tuned insects travel in straight lines during dark nights, a first for the insect world.
The study, led by researchers at Sweden’s Lund University, is the result of researchers long suspecting the dung beetle of using the night sky to roll balls of animal sung in straight lines.
“This led us to suspect that the beetles exploit the starry sky for orientation — a feat that had, to our knowledge, never before been demonstrated in an insect,” stated Marie Dacke, a biologist at Sweden’s Lund University and lead author of the study.
To study this phenomenon, researchers conducted several experiments. First, they built a ten-foot-wide circular arena in a South African game reserve. The researchers provided some beetles tiny cardboard hats, while other beetles received transparent hats to wear while rolling their balls of dung across the arena. The insects were observed in action during moonless, moon-lit, and cloudy nights to see whether they were successful in their attempts at traveling in straight lines.
To eliminate the possibility of dung beetles using landmarks to remain in a straight line, researchers then moved the arena to the Johannesburg Planetarium and conducted the same experiment. They programmed the planetarium in a variety of settings, all geared to determine the influence of the Milky Way on the dung beetles’ paths. They eventually discovered that dung beetles able to see the stars of the Milky Way took a much shorter path when rolling balls of dung. In some cases the difference in distance amounted to a 400 percent increase in distance traveled.
“The dung beetles don’t care which direction they’re going in. They just need to get away from the bun fight at the poo pile,” said Johannesburg’s Wits University professor Marcus Byrne, a co-author of the study. “But when we turned off the Milky Way, the beetles got lost.”
While the study may seem trivial, traveling in a straight line is a matter of survival for the beetle. Should a dung beetle accidentally loop back to the original dung pile, they often face dung beetles vying for their dinner.
The dung beetle is the first known insect to use celestial navigation to make its way. A number of insects are already known to use the night sky to navigate, but researchers say the last study is the first to point to the Milky Way as a specific night sky marker for an insect.