Butterfly antennas key to navigating in migration
By RANDOLPH E. SCHMID, AP Science Writer Randolph E. Schmid, Ap Science Writer
Thu Sep 24, 2:17 pm ET
WASHINGTON – Millions of Monarch butterflies migrate to Mexico for the winter and scientists have long speculated on how the insects find their way. Turns out, their antennas are the key.
How do we know? Well, researchers painted butterfly antennas black, and the insects got lost.
Managing to fly south may not sound like a big deal to people armed with maps and GPS receivers, but all butterflies have for navigation is the sun in the sky.
And the sun keeps moving, so the little creatures have to constantly adjust to stay on course throughout the day.
Like most animals, Monarchs have a so-called circadian clock in their brain that helps them know what time it is. Knowing the time and the position of the sun allows them to orient to the south.
But Monarch butterflies have a second clock based in their antennas, which also sense light, according to the new study led by Dr. Steven M. Reppert, chairman of neurobiology at the University of Massachusetts Medical School.
"Whatever we learn about the insect ... is going to tell us a little bit more about how our brain works," said Reppert, who studies the internal clocks in the brains of animals, including people.
Plus, he added in a telephone interview, "it's fascinating biology that's begging to be understood."
Researchers had thought the navigation took place in the brain of the butterfly, but this experiment shows that the brain and antenna each has a circadian clock and they work together, he said.
The researchers, whose study appears in Friday's edition of the journal Science, did the test by holding the butterfly wings gently and dipping their antennas in enamel paint.
The ones with black paint were unable to orient to the south, they found, while butterflies whose antennas were coated with clear paint had no trouble navigating.
That not only showed the antennas were sensing light for navigating, it also showed that the sense of smell isn't involved in finding the way, since both paints blocked that ability.
And, since the animals with black paint got lost even though their eyes were able to see light, the researchers concluded the antennas were vital to finding the way.
Butterflies whose antennas were surgically removed also became disoriented.
Charalambos P. Kyriacou of the University of Leicester, England, said the experiment indicates that the antennas serve as a sort of stand-alone global positioning system for the insects.
"The antenna clock appears to override any input from the brain clock for navigation," Kyriacou, who was not part of Reppert's research team, said in a commentary on the report.
Reppert's research was funded by the National Institutes of Health.
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On the Net:
Science: http://www.sciencemag.org
Monarch Navigation Article
Wow that is very interesting! Thanks for sharing Melanie.
You're welcome! I thought it was so neat. And then I thought, "How do I get that job?" Although, I couldn't be the one to remove their antenna - that's just too mean, even if it is in the name of science.
Very interesting.
Thanks for posting this news!
I know what you mean Melanie, I thought it was a tad mean too. I wouldn't want to be the one to do it.
I just heard that today at a presentation of a lady that is an entomologist at Botanic Gardens here.
Also something else I may have heard along the way but never stuck with me ...
The last generation of Monarchs that migrate are non-productive and unable to mate and lay eggs. Their metabolism is geared to allow them to store fat and it gives them the energy they need to endure the journey. After the hibernation (6 mths or more) period in Mexico ends and the sun warms the area and flowers bloom it develops the productive system and will begin to mate and lay eggs on the return trip. I always wondered why I didn't find eggs in late Sept and early Oct.