Posts Tagged: Monarch butterflies
Surprise: it's in the antennae!
Neurobiologists at the University of Massachusetts Medical School have long wondered how monarch butterflies (Danaus plexippus) can migrate from across eastern North America to a specific grove of fir trees in Mexico.
That's 2000 miles, as a crow flies--or as a monarch flies.
The scientists figured that the key mechanism that steers the monarchs is in the brain.
Nope. It's in the antennae. The antennae aren't just "noses" or "odor detectors."
"We've known that the insect antenna is a remarkable organ, responsible for sensing not only olfactory cues but wind directions and even sound vibration." said Steven Reppert, professor and chair of neurobiology and senior author of the study, published today (Sept. 25) in the journal Science.
"But its role in precise orientation over the course of butterfly migration is an intriguing new discovery, one that may spark a new line of investigation into neural connections between the antennae and the sun compass, and navigation mechanisms in other insects," he said in press release.
For those of us who are navigationally challenged and have long admired how insects migrate from Point A to Point B, this is amazing. There are circadian clocks in the antennae.This study makes us look at monarch butterflies in an entirely different light.
Like the monarchs we spotted nectaring last weekend on the grounds of the Luther Burbank Home and Gardens, Santa Rosa.
Their antennal circadian clocks coordinate sun-compass orientation.
Or, in other words, those antennae are necessary for sun-related orientation.
It's in the Antennae
Folk singer Pete Seeger asked "Where have all the flowers gone?"
UC Davis butterfly expert Art Shapiro wants to know "Where are all the Monarchs?"
In the current edition of the Bohart Museum Society newsletter, Shapiro notes that California populations of the Monarch butterfly (Danaus plexippus) "are notoriously unstable, fluctuating wildly in numbers."
"Because the Monarch is just about everyone's favorite butterfly, certainly the best known, the public is interested in how it is doing," he wrote. "This year it is doing very poorly indeed, at least in the Sacramento Valley."
See, Shapiro tracks Monarchs (and other butteflies) throughout much of Northern California. He's been doing that since 1972, using "a combination of fixed study sites visited every two weeks and more casual 'at large' observations."
His permanent sites include the Suisun Marsh and Gates Canyon (near Vacaville), both in Solano County; West Sacramento, Yolo County; and North Sacramento and Rancho Cordova, Sacramento County. "Monarchs have been present at all of these sites every year, and bred at most of them nearly every year, until 2008," Shapiro wrote.
"As of Sept. 10, no Monarchs in any life stage have been seen at West Sacramento, North Sacramento, Rancho Cordova, or anywhere else in the Davis-Sacramento area. This has never happened before. I've spent just over 60 days at these three field sites this year, and my eyes have been open every day. So this is significant."
Personally, I don't see Monarchs, either. The last Monarch I spotted was along the Mendocino Coast, near Timber Cove, and that was on Oct. 19, 2007.
It looked drenched from the rain.
I photographed it. The next morning, I looked for it and it was gone.
(Note: For more information on butterflies, see Shapiro's book, "Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions.")
Close-up of Rain on Butterfly Wings