Tuesday, November 22, 2005

Mexico sees bigger butterfly migration

By Anahi Rama Sun Nov 20, 2:59 PM ET

EL ROSARIO, Mexico (Reuters) - Wildlife officials say good weather should bring a surge in the number of monarch butterflies migrating to Mexico this year, after last year's cold resulted in the lowest numbers in more than a decade.

Each fall tens of millions of the bright orange and black butterflies begin arriving in central Mexico's Michoacan state to winter in the fir trees after a 3,000-mile (4,800-km) trek from Canada that fascinates biologists.

A migrating Monarch butterfly sits on the branch of a tree at the Rosario natural reserve in Michoacan state west of Mexico City in this November 29, 2001 file photo. Wildlife officials say good weather should bring a surge in the number of monarch butterflies migrating to Mexico this year, after last year's cold resulted in the lowest numbers in more than a decade. (Daniel Aguilar/Reuters)

At El Rosario reserve, one of five butterfly sanctuaries in Mexico, officials expect the insects to occupy far more forest this year than the 2.2 hectares (5.4 acres) they took up last year, which saw the smallest migration in 14 years.

"There is good news for the monarch butterfly this year," said Eduardo Rendon, of the Monarch Program that brings together government officials and environmental groups. "The omens are there will be many more, after last year's adverse weather meant there were so few."

Experts should know by December how much territory will be occupied by the monarchs this year, the best indication of their numbers. The largest migration on record was in 1996-97, when the insects took up 18 hectares (44 acres).

The migration has long been a focus of study and source of mystery for scientists and wildlife watchers. Not one butterfly makes the round-trip journey, and the descendants of those who start it head instinctively for a place they have never been.

After leaving Mexico, it takes three or four generations of monarch butterflies to reach their summer grounds in Canada and the northern United States.

The last generation, which has a longer life span, then makes the journey south to Mexico for the winter.

The fragile insects are not considered in danger of extinction, but their numbers are threatened by the use of pesticides in the United States and Canada, and by logging that erodes their wintering grounds in Mexico.

Wildlife officials are working to provide tourism jobs to poor residents around the sanctuaries, which draw some 120,000 visitors a year.

"They know the butterflies are not rivals, because about 2,000 people are benefiting from tourism jobs," Rendon said.

Still, residents say they are not provided sufficient incentives to protect the reserves rather than take advantage of lucrative timber resources.

Earlier this month an ultralight aircraft that had accompanied the butterflies from Canada landed in another Mexican reserve with the first arrivals.

Vico Gutierrez flew his 420-pound (190-kg) plane alongside the monarchs for 72 days to film their flight and highlight the need for their preservation.


Sunday, November 20, 2005

Butterfly wings work like LEDs

When scientists developed an efficient device for emitting light, they hadn't realised butterflies have been using the same method for 30 million years.

Fluorescent patches on the wings of African swallowtail butterflies work in a very similar way to high emission light emitting diodes (LEDs).
The way light is extracted from the butterfly's system is more than an analogy - it's all but identical in design to the LEDPete Vukusic, University of Exeter

These high emission LEDs are an efficient variation on the diodes used in electronic equipment and displays.

The University of Exeter, UK, research appears in the journal Science.

In 2001, Alexei Erchak and colleagues at the Massachusetts Institute of Technology (MIT) demonstrated a method for building a more efficient LED.

Most light emitted from standard LEDs cannot escape, resulting in what scientists call a low extraction efficiency of light.

Ingenious design

The LED developed at MIT used a two-dimensional (2D) photonic crystal - a triangular lattice of holes etched into the LED's upper cladding layer - to enhance the extraction of light.

The butterflies use the fluorescent patches to signal each other

And layered structures called Bragg reflectors were used to control the emission direction. These high emission devices potentially offer a huge step up in performance over standard types.

Pete Vukusic and Ian Hooper at Exeter have now shown that swallowtail butterflies evolved an identical method for signalling to each other in the wild.

Swallowtails belonging to the Princeps nireus species live in eastern and central Africa. They have dark wings with bright blue or blue-green patches.

The wing scales on these swallowtails act as 2D photonic crystals, infused with pigment and structured in such a way that they produce intense fluorescence.

Pigment on the butterflies' wings absorbs ultra-violet light which is then re-emitted, using fluorescence, as brilliant blue-green light.

Performance-enhancing bugs

Most of this light would be lost were it not for the pigment being located in a region of the wing which has evenly spaced micro-holes through it.

This slab of hollow air cylinders in the wing scales is essentially mother nature's version of a 2D photonic crystal.

Like its counterpart in a high emission LED, it prevents the fluorescent colour from being trapped inside the structure and from being emitted sideways.

Two components of the scales enhance light emission

The scales also have a type of mirror underneath them to upwardly reflect all the fluorescent light that gets emitted down towards it. Again, this is very similar to the Bragg reflectors in high emission LEDs.

"Unlike the diodes, the butterfly's system clearly doesn't have semiconductor in it and it doesn't produce its own radiative energy," Dr Vukusic told the BBC News website "That makes it doubly efficient in a way.

"But the way light is extracted from the butterfly's system is more than an analogy - it's all but identical in design to the LED."

Dr Vukusic agreed that studying natural designs such as this could help scientists improve upon manmade devices.

"When you study these things and get a feel for the photonic architecture available, you really start to appreciate the elegance with which nature put some of these things together," he said.


Friday, November 11, 2005

Gujarat Council of Science City propose to set up eco-gardens and butterfly parks.

S D Vora, Executive Director Gujarat Council of Science City, on popularising science among masses

What plans do you have for the development of the Science City?

As of now the focus is on completion of the first phase. It includes a space and communication pavilion wherein visitors will get to know how different types of communication signals are emitted, transformed, encoded and decoded. The Life Science park will show case the beauty and mysteries of nature to the public. We propose to set up eco-gardens and butterfly parks.