Un article passionnant sur la survie des abeilles dans les oasis du désert du Sahara extrait de la BBC: en savoir plus
Deep in the Sahara desert are honeybees that have remained isolated from all other bees for at least 5,000 years.
The bees arrived at Kufra in Libya when the Sahara was still a green savannah, and have survived ever since around an oasis in the desert, over 1,000km from their nearest neighbouring bees.
The Kufra honeybees are so isolated they remain free of a parasitic mite that threatens bees around the world.
Details of the discovery are published in the journal Conservation Genetics.
Around 10,000 years ago, the Sahara was a green savannah, a habitat well suited to honeybees (Apis mellifera).
Today, the Sahara is inhospitable to honeybees, which can’t survive in the large sand deserts that lack any vegetation.
However, honeybees do survive in many oases that litter the desert.
Most are maintained by local beekeepers that keep the insects for honey production and to pollinate oasis plants.
But some wild populations of bees survive.
One such group lives at the desert oasis at Kufra in southeast Libya, while another lives at an oasis at Brak to the west of the country.
Dr Taher Shaibi of the Al-Fatah University in Tripoli, Libya and Professor Robin Moritz of Martin Luther University at Halle-Wittenberg, Germany analysed DNA from 16 colonies of bees at Kufra, Brak and from three sites along Libya’s northern coast.
They examined 15 genetic markers which indicate the mating frequency, colony density and gene diversity of the bees in each colony and the extent to which their populations have changed over time.
As expected, the results showed that the coastal bees have high levels of genetic diversity, due to the intensive apiculture industry there, which allows large numbers of bees to intermingle.
The colony at Brak was also relatively diverse.
That is because Brak has a honey season, which encourages coastal bee keepers to visit, bringing their own bees to the oasis.
Though honeybees living at Kufra have colonies of a similar density to bees elsewhere, certain genetic traits appeared in the Kufra bees at much high frequencies, with some being unique.
That shows that the Kufra bees have remained isolated from all others for at least 5,000 years and perhaps up to 10,000 years, since the moment they were cut off by the creation of the Sahara desert.
Bees living at Kufra are also free from the Varroa destructor parasitic mite, which is decimating colonies around the world and has been implicated in a global decline of honeybee populations.
« The oasis can only be free of the Varroa mite if perfect isolation is ensured, even in times of modern transport, » the researchers write.
Perhaps surprisingly, the researchers’ analysis also showed that the Kufra bees are not suffering any ill effects, caused by inbreeding, from their isolation.
That indicates that the oasis supports a healthy population size.
The Kufra bees could also be a source of new genetic traits that could be useful to beekeepers elsewhere, the researchers suggest.
But to maintain these valuable traits, it is crucial that the Kufra bees are preserved, with foreign bees being kept away from the oasis.
Essaims et paquets d’abeilles à vendre sur eurobeestock.com
With a world awakening to the environmental, educational and economic advantages of roof-top beekeeping, it is surprising that it is illegal in New York City. Section 161.01 of the Health Code has to have been written by one of those people, familiar to beekeepers, who see a benign swarm and call for rescue from a near-death experience. The code classifies bees with animals “inclined to do harm” – bears, cougars, and alligators, not to mention binturongs, sea kraits, and zorilles. That would be amusing if a quick call to 311, the complaint line, did not put a beekeeper in jeopardy of a $2000 fine. At last, the rest of the major cities in the country can feel more sophisticated than New York. Still, the city promotes its “greening,” even if bees that do its pollination live on clandestine rooftops. Beekeeper David Graves, who has been called “the Johnny Appleseed of New York beedom,” has mentored many an urban beekeeper since 1997, when he knew of only one rooftop hive in New York. The advantage for Graves is that Manhattan is a “bear-free environment” in contrast to his apiaries in Massachusetts. He confirms that rooftop bees “work harder…(and) They’re up much earlier and work longer hours” pollinating gardens and parks – where they forage on wild bergamot, aster, sunflower, mint, goldenrod, linden trees, and even on the fresh-cut flower bouquets for sale in stalls. Graves collected 140 pounds from a rooftop hive in the Upper East Side. A film on YouTube, “NYC Bee Man,” shows him shimmying along a window ledge with a package of bees, mentoring a taxi driver, and extolling the rooftop environment for beekeeping. New York investment banker Peter Solomon harvests contentment from his rooftop bees, saying that after he works them, “Everything else in life is calm” – a nice perk in his line of work these days. John Howe first put his bees on his roof for a little peace, too, since his wife was afraid of them. Howe thinks there are at least 50 rooftop hives now in New York. Together with commercial beekeeper Andrew Coté, he has started a beekeeping “Meet-up” – a way for interested people communicating on-line to get together. i Kevan, Peter, Bees, Biology and Management, Enviroquest, Ltd, 2007, 123. Brooklyn honey. Photo by Melissa Lohman, still from her film “Rooftop Bees” At Amy Ruth’s Restaurant in Harlem, honey from chef Carl Redding’s two rooftop hives can be tasted in his spicy honey-dipped chicken. You can buy Graves’ honey, labeled by neighborhood, at farmers’ markets. How do bees navigate in a city? They do not have a way of communicating “up,” according to Peter Kevan of the University of Guelph.i He describes an experiment in which bees were trained to forage across a canyon three-quarters of a mile wide. At first the foragers flew down the canyon on one side and up the other to the feeding station, returning the same way. Eventually they learned to fly directly across the canyon and back. Kevan reports that the dance language adjusted to the shorter, more direct route. Further, he reports, bees forage at a feeding station that is behind a large building, the dance communication reflects the direction and reflects the added distance to fly around the barrier. All rooftop beekeepers have in common a dead certainty that their honey is very special indeed. Their bees may be, as well. André Lemaire, the beekeeping instructor at the Jardin du Luxembourg in Paris says that the use of chemicals and management practices in agribusiness may have such an adverse effect on bees that farmers may one day have to import bees from the rooftops in the cities.
A garden on the roof of the Chicago City Hall has hosted two hives for the last five years. Since Chicago’s 1995 heatwave caused some 600 heat related deaths, about four million square feet of such gardens have been planted on public and private rooftops – including the Cultural Center, the Apple store and McDonald’s. Mayor Richard Daley was inspired by such sites in Germany, built to absorb storm runoff, purify the air, provide insulation, and help modify heat. Thermal images of the city hall rooftop on a cloudy summer day showed it to be the same temperature as the air, 74 degrees, while a neighboring black tar roof was 152 degrees. The municipal Chicago bees forage the half acre garden rooftop and five blocks beyond to the prairie wildflowers and ornamentals in Millennium Park along Lake Michigan. Beekeepers Stephanie Averill and Michael Thompson harvest 100 to 200 pounds of honey from each hive. Clover produces a light yellow-green honey in the spring, with white aster and goldenrod the main nectar sources in the amber colored fall crop. They process it in a program at the culinary center of Gallery 37, a city center for youth. “Rooftop Honey: It’s a Buzz around City Hall” is auctioned or sold in two ounce jars at $2 each ($32 per pound) and limited to two jars per customer. Proceeds from the project benefit programs at the Chicago Cultural Center.
The pièce de résistance of rooftop bee gardens is Renzo Piano’s new Academy of Science in San Francisco. The building is the largest in the world with the highest rating for sustainability. The 2.5 acre living roof, which provides insulation, undulates in seven green hillocks – homage to the city’s topography. The live tapestry that covers it is a dense concentration of 1.7 million native plants of 40 species. Native California pollinator plants were chosen to survive with little water and tolerate ocean salt spray and wind. Among the roof’s many bee plants are: self-heal (Prunella vulgaris), miniature lupine (Lupinus nanus), and California poppy (Eschscholzia californica). An open terrace overlooking the roof allows the visitor to watch the bees forage – along with other pollinators, some of them rare.