By Rudy Ruitenberg
A virus that typically infects plants was found in honeybees and could help explain their decline, researchers in the U.S. and China wrote in a study in the American Society of Microbiology’s online journal mBio.
Routine screening of bees for frequent and rare viruses turned up the tobacco ringspot virus, or TRSV, prompting the researchers to investigate whether the plant pathogen could infect bees, the society said in an online statement.
‘‘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,’’ said the study’s lead author, Jilian Li of the Chinese Academy of Agricultural Science in Beijing.
About 5 percent of known plant viruses are pollen-transmitted and therefore potential sources of host-jumping viruses, according to the report. ‘‘Toxic viral cocktails’’ appear to have a strong link with honeybee colony collapse disorder, the society wrote.
The finding of TRSV in bees was ‘‘a serendipitous detection,’’ said Yan Ping Chen at the Agricultural Research Service of the U.S. Department of Agriculture’s lab in Beltsville, Md.
The researchers studied bee colonies classified as either strong or weak, and found viruses, including tobacco ringspot, were more common in the weak groups. Colonies with high levels of multiple viral infections started failing in late autumn and perished before February, while hives with fewer infections survived the entire cold winter months, according to the report.
TRSV was also found in varroa mites, a parasite that transmits viruses between bees while feeding on their blood.
‘‘The increasing prevalence of TRSV in conjunction with other bee viruses is associated with a gradual decline of host population and supports the view that viral infections have a significant negative impact on colony survival,’’ the researchers wrote.