Closing in on the bee killer
Scientists in Spain believe they have found the killer parasite that is responsible for wiping out bee colonies from California to Cannes. The assassin, they believe, is Nosema ceranae, an Asian parasite which has worked its way into hives across Europe and America, wreaking terrible damage on the bees’ internal organs. This also explains the mistery of why bees seemed to simply disappear. Weakened by their inability to eat, they die far away from the beehives.
The parasite is a close cousin of Nosema apis, which has lived in relative harmony with bees in Europe and elsewhere for centuries. However, the new variety of Nosema is hardier than the old one, and so continues to thrive under harsh weather conditions. “It does not care whether it rains or whether it is more or less hot,” said researcher Mariano Higes. It also spreads easily and rapidly.
The scientists at the Regional Apiculture Center in Marchamalo, near the central Spanish city of Guadalajara, said the discovery opened the way to discovering ways of controlling and eradicating the pest.
Mr Higes said that a wave of what is known as colony collapse disorder, which has wiped out hives across two continents, may also be due to other factors, but that Nosema was a key cause. “We think that Nosema ceranae could do it alone,” he said.
The results of the Spanish research, carried out on samples from Germany, Spain, Switzerland and France, are due to be published in the next edition of the journal Invertebrate Microbiology.
The team has also been studying samples sent from the US, where colony collapse disorder has hit 35 states and affected up to 875,000 out of 2.4 million hives. The disorder, which has also wiped out bees in Canada, Brazil, India and Europe, kills up to 90% of bees in each hive. A significant collapse in the worldwide bee population could threaten food supplies as bees pollinate 90 crops around the world. Spain has an acute interest in solving this problem, as it is home to a quarter of the European Union’s bees, with 2.3 million hives.
Treatment for nosema ceranae is effective and cheap — 1 euro (US$1.4) a hive twice a year — but beekeepers first have to be convinced the parasite is the problem.
In Britain, the Department for Environment, Food and Rural Affairs has insisted that recent bee losses are not a sign of colony collapse disorder but the work of the varroa mite, which eats bees and their larvae. The Spaniards ruled out the varroa mite in their study, because it is easy to see and it was not spotted in most of the affected hives. Other theories point fingers at mobile phone aerials, but Higes notes bees use the angle of the sun to navigate and not electromagnetic frequencies. A third line of investigation was published recently by an American team in Science and blames a pathogen called Israeli acute paralysis virus.