* Asian hornets spread through France
* Hornets wipe out hive of bees in 48 hours
* Threat to crop pollination set to worsen
PARIS, Aug 18 (Reuters) - France is facing an invasion of bee-eating Chinese hornets which could hasten the mysterious decline in the honey-bee population and threaten bee-keepers' livelihoods, researchers said on Tuesday.
Colonies of Asian hornets, or Vespa velutina, have spread rapidly in southwestern France, a region popular with tourists, and are likely to reach other European countries soon.
"More and more of them are coming and they're colonising France," Quentin Rome, a researcher at the National History Museum in Paris, told Reuters.
The three centimetre-long insects, recognisable by their orange heads and yellow feet, probably arrived in France on a boat carrying ceramic goods from China, researchers believe.
The first hornets were observed in France in 2004, and the most recent study recorded 1,100 nests across the country. The hornet is now firmly established near Bordeaux and has advanced as far north as parts of Brittany in northwestern France.
"They multiply quite quickly, and they settle in a new department every year," Rome said.
The hornet is not yet present in other European countries, but will probably spread across the continent, he added.
Last week six people were hospitalised after being stung near a nest in the Lot-et-Garonne department in southwest France, prompting local authorities to warn allergy sufferers to be on their guard.
Although the hornets are not more aggressive or dangerous for humans than their European cousins, the size of the colonies, inhabiting nests measuring up to one metre in height, means the risk of attacks is higher, Rome said.
Bee-keeper Francoise Romanzin said there had been a marked rise in attacks by Asian hornets on beehives in August.
"It's going to get worse until mid-September," she said: "In three or fours years they'll be everywhere in France -- it's an invasion."
Three or four hornets can wipe out an entire beehive in 48 hours, but bee-keeping associations do not yet know how serious a threat the hornets pose for their industry, which is already facing a mysterious decline in bee numbers worldwide.
"When bee-keepers find nests nearby, their hives are destined for destruction," General Secretary of the National union of Bee-keepers Yves Vedrenne said. "We don't have the means to get rid of them".
"We don't know what kind of problems they could cause," Vedrenne said. "The problem of the Asian hornets is not the worst problem for bee populations but it adds to the difficulties bee populations are already facing," Romanzin said.
Scientists have already expressed alarm at the mysterious and rapid decline in the number of bees, which could seriously harm agriculture because of the reduction in pollination of numerous crops. (Reporting by Joseph Tandy, editing by Tim Pearce)
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