A virus that typically infects plants has been found in honeybees, possibly helping to explain the insect's dramatic decline.
The discovery of tomato ringspot virus, or TRSV, was made by U.S. and Chinese researchers during routine screening of bees for viruses, according to a news release.
"The results of our study provide the first evidence that honeybees exposed to virus-contaminated pollen can also be infected and that the infection becomes widespread in their bodies,"lead author Ji Lian Li, at the Chinese Academy of Agricultural Science in Beijing, said in the news release.
Research already has shown that honeybees can transmit TRSV when they move from flower to flower, thereby spreading the disease from one plant to another.
About 5 percent of known plant viruses are pollen-transmitted and possibly potential sources of host-jumping diseases.
RNA viruses, such as TRSV, are particularly dangerous because they lack a genetic function that edit errors. As a result, these viruses can generate a flood of varying copies with differing infective properties.
This high replication rates results in populations of RNA viruses that are "quasispecies" of genetically related variants that appear to work together to determine the pathology of their hosts.
Toxic viral cocktails appear to be linked strongly to colony collapse disorder, a mysterious malady that wipes out entire honeybee hives.
It was first reported in 2006.
Other viruses known to infect bees include Israel acute paralysis virus, acute bee paralysis virus, chronic paralysis virus, Kashmir bee virus, deformed wing bee virus, black queen cell virus and Sacbrood virus.
When the researchers examined colonies classified as strong or week, TRSV and other viruses were more common among the week colonies.
Bee populations with high levels of multiple viral infections began failing in late fall and died before February.
That compares to colonies with fewer viral infections that survived the entire winter months.
TRSV also has been found inside the bodies of varroa mites, consider the most serious bee pest.
The pinhead sized parasite attaches itself to adult bees and literally sucks the life out of them.
Because of where TRSV was found in the mite, the researchers theorize the bites spread the virus within the hive but don't become infected themselves.
But the researchers did find that queen bees infected with TRSV lay infected eggs.
Their work was published Jan. 21 in mBio, the online journal of the American Society for Microbiology.