Scientists Find 27 New Viruses in Bees

A bee in the Agapostemon group of Western Hemisphere sweat bees, most of which are known as metallic green sweat bees for their color. Lakewood, California, April 13, 2018 (Photo by tdlucas5000) Creative Commons license via Flickr

By Sunny Lewis                                                                                                                           

UNIVERSITY PARK, Pennsylvania, July 12, 2018 ( News) – An international team of researchers, led by scientists at Pennsylvania State University, has discovered evidence of 27 previously unknown viruses in bees. The finding could help scientists design strategies to prevent the spread of viral pathogens among these crucial pollinators.

“Although our study nearly doubles the number of described bee-associated viruses, there are undoubtedly many more viruses yet to be uncovered, both in well-studied regions and in understudied countries,” said co-author Zachary Fuller, a postdoctoral fellow at Columbia University and a recent Penn State graduate.

To investigate viruses in bees, the team collected samples of DNA and RNA, which is responsible for the synthesis of proteins, from 12 bee species in nine countries across four continents and Oceania.

Next, they developed a novel high-throughput sequencing technique that efficiently detected both previously identified and 27 never-seen-before viruses belonging to at least six new families in a single experiment.

The results appear in the June 11, 2018 issue of the journal “Scientific Reports” under the title “Investigating the viral ecology of global bee communities with high-throughput metagenomics.

“Populations of bees around the world are declining, and viruses are known to contribute to these declines,” said co-author David Galbraith, a research scientist at Bristol Myers Squibb and a recent Penn State graduate.

Honey bees (Apis mellifera) Mwatate Sisal Plantation Dam, Kenya, June 13, 2013 (Photo by Peter Steward)

Since the late 1990s, beekeepers around the world have observed the sudden disappearance of bees, and report unusually high rates of decline in honey bee colonies.

Bees are key to food production because they pollinate crops. Vegetables, fruits, nuts, spices and edible oils – a third of the food we eat depends on pollinating insects.

But now, due to the work of this team of scientists, there is a cheaper and easier way to identify bee viruses. Because the cost of high-throughput sequencing continues to decrease, Fuller says the team’s approach provides an inexpensive and efficient technique for other researchers to identify additional unknown viruses in bee populations around the world.

“Typically, researchers would have to develop labor-intensive molecular assays to test for the presence of specific viruses,” said Fuller. “With our method, they can sequence all the viruses present in a sample without having any prior knowledge about what might be there.”

In their article, the authors wrote, “…despite the importance of bees as pollinators of flowering plants in agricultural and natural landscapes and the importance of viruses to bee health, our understanding of bee viruses is surprisingly limited: despite the diversity of bee species and their worldwide distribution, the vast majority of the studies examining bee pathogens have focused on western honey bees (Apis mellifera) populations in North America and Europe.”

Among the new viruses the team identified was one that is similar to a virus that infects plants.

“It is possible that bees may acquire viruses from plants, and could then spread these viruses to other plants, posing a risk to agricultural crops,” said co-author Christina Grozinger, professor of entomology and director of the Center for Pollinator Research at Penn State.

“We need to do more experiments to see if the viruses are actively infecting the bees – because the viruses could be on the pollen they eat, but not directly infecting the bees – and then determine if they are having negative effects on the bees and crops,” explained Grozinger.

“Some viruses may not cause symptoms or only cause symptoms if the bees are stressed in other ways,” she said.

Beyond identifying the new viruses, the team also found that some of the viruses exist in multiple bee species – such as in honey bees and in bumble bees – suggesting that these viruses may freely circulate within different bee populations.

“This finding highlights the importance of monitoring bee populations brought into the United States due to the potential for these species to transmit viruses to local pollinator populations,” said Galbraith. “We have identified several novel viruses that can now be used in screening processes to monitor bee health across the world.”

According to Galbraith, the study represents the largest effort to identify novel pathogens in global bee samples and greatly expands our understanding of the diversity of viruses found in bee communities throughout the world.

“Our protocol has provided a foundation for future studies to continue to identify novel pathogens that infect global bee populations using an inexpensive method for the detection of novel viruses,” he said.

This new method comes not a moment too soon, as bee viruses can spread quickly.

“Due to increased globalization,” the authors state in their paper, “it is likely only a matter of time before these viruses and other pathogens and parasites are spread to new regions. For example, recently a colony of an exotic stingless bee species (Plebeia frontalis) was found to be established in California, potentially harboring pathogens that could be spread to other bee species within the region.”

The National Geographic Society and the USDA Animal and Plant Health Inspection Service supported this research.

Authors on the paper include: David Galbraith, Allyson Ray, Maryann Frazier, J. Francisco Iturralde Martinez, Harland Patch, Cristina Rosa, Joyce Sakamoto, Scott Stanley, Anthony Vaudo, and Christina Grozinger, Pennsylvania  State University; Zachary Fuller, Columbia University; Axel Brockmann, National Centre for Biological Sciences, India; Mary Gikungu, National Museums of Kenya; Karen Kapheim, Utah State University and Smithsonian Tropical Research Institute, Panama; Jeffrey Kerby, Dartmouth College; Sarah Kocher, Princeton University; Oleksiy Losyev, National University of Life and Environmental Sciences of Ukraine; and Elliud Muli, International Center of Insect Physiology and Ecology, Kenya.

Featured Image: Honey bee (Apis mellifera) on a flower in northeast England, UK, July 23, 2016 (Photo by Joe Devereux)

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