A number of viruses acting together may help explain cases of colony collapse.
This is the VOA Special English Agriculture Report.
Colony collapse disorder first struck honey bees in the United States in late 2006. Over the next two years, beekeepers lost more than one-third of their honey bees.
Scientists in the United States and other countries have been working to explain the mysterious disappearances of bees. Now, a new study suggests that several viruses may act together.
Scientists from the University of Illinois and the United States Department of Agriculture did the study. Their report appeared in the Proceedings of the National Academy of Sciences.
The team compared bees from affected colonies with those from healthy colonies. They were looking for differences in gene expression in the guts of the bees.
The scientists found that the affected bees had a number of viruses from a group called picorna-like viruses. The infections observed in the bees included Israeli acute paralysis virus and deformed wing virus.
Tiny insects likely play a big part in spreading the viruses. Varroa mites have been causing serious problems in bee colonies in the United States since the late 1980s. These mites carry picorna-like viruses.
The viruses appear to harm the bees' ability to use their genetic material to produce proteins needed to fight infections. Researcher Reed Johnson, now at the University of Nebraska-Lincoln, says the study suggests that the damaged proteins are unable to respond effectively when attacked.
University of Illinois Professor May Berenbaum says it appears that bees could deal with one or two viruses at the same time, but not three or four.
She says the picorna-like viruses "hijack" the ribosome in cells. Ribosomes are structures in which proteins are made. As a result the ribosome produces only viral proteins.
The professor says ribosome is central to the survival of any organism. If it is compromised, then the bees could not defend themselves against pesticides or fungal infections or bacteria or poor nutrition.
These have all been identified as possible causes of the collapse disorder. Spanish researchers, for example, recently said they suspected a parasitic fungus which has been found among affected bees in Spain.
Bees add billions of dollars in value to many crops worldwide. For now, beekeepers have been doing their best to try to protect their colonies.
And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Faith Lapidus.
colony: a group of the same kind of animals, plants, or one-celled organisms living or growing together 群体，群落
proceedings: a record of business carried on by a society or other organization 组织议项，会议记录
picorna-like virus: 类似于细小核糖核酸病毒的病毒
Varroa mite: a genus of parasitic mites associated with honey bees 瓦螨
ribosome: a small, dense, functional structure found in most known cells that assemble proteins and polypeptides used in cell division 核糖体
fungal: of or relating to fungus 真菌的
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(Source: VOA 英语点津编辑）