LOS ANGELES – A rapidly mutating virus has leaped from plants to honeybees, where it is reproducing and contributing to the collapse of colonies vital to the multibillion-dollar agricultural industry, according to a new study.
Tobacco ringspot virus, a pollen-borne pathogen that causes blight in soy crops, was found during routine screening of commercial honeybees at a U.S. Department of Agriculture laboratory, where further study revealed the RNA virus was replicating inside its Apis mellifera hosts and spreading to mites that travel from bee to bee, according to the study published online Tuesday in the journal mBio.
The discovery is the first report of honeybees becoming infected by a pollen-born RNA virus that spread systematically through the bees and hives. Traces of the virus were detected in every part of the bee examined, except its eyes, according to the study.
Only about 5 percent of plant viruses are known to be transmitted by pollen, and fewer still have been known to jump from the plant kingdom to insects.
The tobacco ringspot virus acts as a “quasi-species,” replicating in a way that creates ample mutations that subvert the host’s immune response.
“I want to be cautious,” said Yan Ping Chen, a bee pathologist at the USDA Agricultural Research Service laboratory in Maryland and lead author of the study.
“The cause of colony collapse disorder remains unclear. But we do have evidence that TRSV along with other viruses that we screen on a regular basis are associated with lower rates of over-winter survival,” Chen said.