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.
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