How gene silencing could help save the honey bees
A team of researchers in Israel has designed a genetic switch that may help bees overcome one of their worst enemies.
Last winter was terrible for many people in the United States, but it was even worse for the bees.
The pollinators responsible for the health of more than 70 crops in some states were hammered by a combination of record-breaking cold, disease and parasitic mites. In Ohio alone, the state Department of Agriculture estimates 50 to 80 percent of beekeepers suffered hive losses.
“It’s a pretty devastating loss,” beekeeper Barry Conrad told the Columbus Dispatch. “It’s been getting worse each year.”
While the rate of colony loss varies year to year and from country to country, there is widespread concern of how to adequately prop up bee populations and fight back the multitude of threats to hive health. That's the focus of the research at the B. Triwaks Bee Research Center at The Hebrew University of Jerusalem, where director Sharoni Shafir and his team are examining the root causes of colony collapse disorder.
“It is very reasonable to assume that losses occurring in different parts of the world are not all due to one cause, or even to the same suite of causes,” Shafir told From the Grapevine. “But the usual suspects are pesticides, malnutrition, Varroa, associated viruses and other pathogens. Basically, any additional form of stress makes it more difficult for bees to cope with any of these problems.”
One of the crucial threats to hive health that Shafir and his team are focusing on is the aptly named Varroa destructor – a mite that attacks two species of bee, including the widespread European honeybee. The mites enter the hive’s brood cells, attaching themselves to the body of the young bee and weakening it by sucking hemolymph – the “lifeblood” of a bee’s circulation system.
Left untreated, bee colonies infested by Varroa are either killed outright by late autumn or are rendered so weak that they sucumb to winter cold or other stresses. The method of control that Shafir is studying involves a clever genetic kill switch that is passed from the host to the parasite. “We are looking at reducing Varroa mite populations by feeding bees with dsRNA,” he said. “These small pieces of RNA, which are specific to important Varroa genes, are mixed in sugar water fed to the colony. The dsRNA gets into the bee hemolymph, and then taken up by the mite when it parasitises the bee larvae and adult bees. The dsRNA causes gene silencing of important Varroa genes, killing the mite.”
In a paper published in February 2012, Shafir and his team noted a 60 percent reduction in the mite population as a result of the gene silencing technique.
In addition to genetic weapons, researchers around the world are also studying the ways Varroa impacts certain species – with a hope of selecting lines of honeybees that can better cope with the parasites. “It is not an easy task, and we don't yet have a superbee. But over time we are likely to see better adapted bees,” said Shafir.
Despite the multiple challenges facing bee populations, Shafir is optimistic the world’s top pollinators will not disappear anytime soon. “I think that the great amount of attention and realisation by the public of the importance of bees is encouraging,” he said. “I see the fight for the bees as part of the continuum of the fight for a more sustainable world – reducing the use of pesticides, maintaining more natural open spaces, polycultures, ecological and organic farming practices, reducing pollution of air, soil and water, all will benefit the bees and humankind alike.”
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