Lowly dung beetles look to Milky Way for navigation

January 24, 2013

Lowly dung beetles look to Milky Way for navigation

Dung beetles rely on the Milky Way.

It’s not GPS, but it seems to work just as well.

According to a new study published by Lund University of Sweden, the lowly dung beetle uses the Milky Way for navigating, a first for the insect world.

While humans and birds have been known to use the night sky as a map for centuries, it was previously unclear whether insects relied on the Milky Way in a similar fashion. The study — led by scientists from Lund University in Sweden, the University of Pretoria, and the University of the Witwatersrand in South Africa — say they long suspected the beetles relied on the Milky Way when navigating between different regions, although researchers had never studied the correlation. The team’s suspicions were  reportedly peaked by the fact the dung beetles roll balls of collected animal dung in straight lines, often directly correlated to astronomical patterns in the night sky.

“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,” Lund University researcher Marie Dacke said in a statement Thursday.

In order to test their navigation skills, the research group confined dung beetles to a controlled environment within a planetarium. They set up three situations: a starry night, a sky with only the Milky Way, and an overcast sky. The scientists found that the dung beetles kept their balls of dung in a straight line during the first two types of sky. When the sky was overcast and they could not identify the Milky Way, they were not able to roll their balls in a straight line. According to the study, beetles prevented from seeing the sky took a much longer route to accomplish their dung rolling task. Some of the differences amounted to upwards of 300 percent, said researchers.

Eric Warrant, a co-author of the study from Lund University, said researchers were stunned by the discovery. Warrant said the discovery is stunning for a number of reasons, most notably its demonstration that even some of the simplest creatures hold the ability to execute complex actions.

“It’s just another example of how wonderful the animal kingdom is, how the most amazing things have evolved,” he said.

According to Dacke, observing the activities of the dung beetle at night was the key to uncovering their hidden map. Dacke noted that the ability of beetles to roll dung on moonless nights left them with few options when considering how the small insects navigated.

“Even on clear, moonless nights, many dung beetles still manage to orientate along straight paths,” she said.

These straight lines the dung beetles move in are crucial to make sure they don’t lose their food. Dung beetles find piles of dung to roll into balls and carry off to eat. Once they acquire a ball of dung, they must roll it in a straight line so no other beetles can steal their meal.

While dung beetles are often ridiculed for their reliance on dung, the act of rolling dung is quite remarkable within the insect kingdom. According to Warrant, rolling the dung balls in a straight line demonstrates the insect’s environmental awareness on several levels.

” They always roll straight. If they don’t roll straight, something is wrong,” he said. “They have to get away from the dung pile as fast as possible, or the balls they roll will be stolen by other beetles.”

It is important to note that the beetles do not rely exclusively on the Milky Way for navigating, according to researchers. The beetles apparently use the Milky Way as a guide, relying on it along with a number of other factors.

“The dung beetles are not necessarily rolling with the Milky Way or 90 degrees to it; they can go at any angle to this band of light in the sky. They use it as a reference,” Dacke said in an interview with BBC News.

Of course the latest study begs the questions why dung beetles rely on the Milky Way and not the stars, like most animals. According to a paper published in Current Biology, most of the stars in the night sky are probably too dim for insects to be able to see.

 


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