Nav: Home

Dung beetles navigate better under a full moon

February 04, 2019

Of all nocturnal animals, only dung beetles can hold their course using polarized moonlight. Researchers at Lund University in Sweden have now shown that the beetles can use polarized light when its signal strength is weak,which may allow them to find their bearings when artificial light from cities swamp natural moonlight.

"Our investigation reveals that these beetles would be sufficiently sensitive to orient themselves underneath a light-polluted city sky during full moon. But they would be lost during a quarter or crescent moon", explains James Foster, researcher at the Department of Biology at Lund University.

Moonlight becomes polarized when it strikes particles in the upper atmosphere on its journey to Earth. In the study, the researchers show that the strength of this polarized light-signal changes depending on the moon's phase. Polarized light from a quarter moon is only one-third as strong as at full moon, the, and just one-fifth as strong for a crescent moon.

"This is the very first evidence that the polarization of skylight changes over the lunar cycle", says James Foster.

Together with colleagues in Lund, Germany, South Africa and the USA he tested just how dung beetles cope with this weak signal at night when using polarization as their compass to roll a dung ball in a straight line across the African savannah. On clear nights they perceive this polarized light in a blue sky in a like to the one we see on a sunny day--but thousands of times darker.

In experiments the researchers showed that the beetles are extremely sensitive to polarized light. The dung beetles can cope with the weakest signals detected by diurnal insects, even when the polarized light is just one-thousandth as bright.

"They navigate just as well at night as bees do by day; bees also use polarized light", says Marie Dacke, professor at the Department of Biology at Lund University.

The different phases of the moon--full moon, quarter moon or crescent moon--thus affect how strongly-polarized the sky appears. Light pollution is also a factor. Artificial light such as street lighting in and around cities reduces the polarization of the moonlit sky. Even so, the beetles would be sensitive enough to hold their course using this weaker polarization during full moon.

Besides polarized light, dung beetles use colour and brightness patterns in the night sky to get their bearings. The research team previously gained attention in connection with their discovery that dung beetles use the Milky Way as a compass reference, helping them to roll dung balls in a straight line in the dark. However, more recent experiments have shown that on moonlit nights polarization is their most important compass reference.
-end-


Lund University

Related Beetles Articles:

Jewel beetles' sparkle helps them hide in plain sight
Bright colors are often considered an evolutionary tradeoff in the animal kingdom.
Bark beetles control pathogenic fungi
Pathogens can drive the evolution of social behaviour in insects.
Sexual competition helps horned beetles survive deforestation
A study of how dung beetles survive deforestation in Borneo suggests that species with more competition among males for matings are less likely to go extinct, according to research led by scientists from Queen Mary University of London and Nanyang Technological University, Singapore.
Dung beetles get wind
Researchers have shown for the first time that these insects use different directional sensors to achieve the highest possible navigational precision in different conditions.
Dung beetles use wind compass when the sun is high
Researchers have shown for the first time that an animal uses different directional sensors to achieve the highest possible navigational precision in different conditions.
Threatened beetles benefit from forest thinning
Wood-living beetles that use oak trees are a species-rich and threatened animal group in modern forestry and agriculture in southern Sweden.
These beetles have successfully freeloaded for 100 million years
An ancient and rare beetle fossil is the oldest example of a social relationship between two animal species.
A mating war in diving beetles has stopped the evolution of species
In nature, males eager attempts to mate with females can be so extreme that they will harm females.
Mighty mites give scrawny beetles the edge over bigger rivals
Smaller beetles who consistently lose fights over resources can gain a competitive advantage over their larger rivals by teaming up with another species.
Dung beetles navigate better under a full moon
Of all nocturnal animals, only dung beetles can hold their course using polarized moonlight.
More Beetles News and Beetles Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Uncharted
There's so much we've yet to explore–from outer space to the deep ocean to our own brains. This hour, Manoush goes on a journey through those uncharted places, led by TED Science Curator David Biello.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Dispatch 2: Every Day is Ignaz Semmelweis Day
It began with a tweet: "EVERY DAY IS IGNAZ SEMMELWEIS DAY." Carl Zimmer – tweet author, acclaimed science writer and friend of the show – tells the story of a mysterious, deadly illness that struck 19th century Vienna, and the ill-fated hero who uncovered its cure ... and gave us our best weapon (so far) against the current global pandemic. This episode was reported and produced with help from Bethel Habte and Latif Nasser. Support Radiolab today at Radiolab.org/donate.