The first full analysis of the gut microbial community present in queen bees shows a "microbiome" completely different from what's found in worker bees, U.S. researchers say.

Despite the vital role queen bees play in the successful function and health of a hive, previous analyses of honey bees microbiomes have been limited to only worker bees, the researchers say.

The internal microbiome plays an important role in protecting any organism against disease, they explain, and the health of honeybees - which pollinate a third of all food crops grown around the world - is vital for agriculture.

Research into honeybees and their health has seen an increase in urgency with the decline in bees during recent years, with losses of bee colonies reaching 40 percent during winter months.

That makes understanding the role of microbes in the productivity of queen bees and the overall health of bee colonies of extreme importance, Indiana University researcher and collaborators say in their study published in the journal Applied and Environmental Microbiology.

"This might be a case in which 'mother does not know best,'" says IU biology professor Irene L.G. Newton. "In many animals, transmission of the microbiome is maternal."

However, she says, "In the case of the honey bee, we found that the microbiome in queen bees did not reflect those of worker bees -- not even the progeny of the queen or her attendants. In fact, queen bees lack many of the bacterial groups that are considered to be core to worker microbiomes."

The development of microbiomes in infants of many species, including humans, is typically influenced by the microbiome of their mothers.

In honeybees, however, gut bacteria is acquired from the surrounding environment and through a social context, a process scientists call horizontal transmission.

In a healthy bee colony, the researchers explain, worker bees normally develop their gut bacteria through contact with microbes inside the hive.

Queen bees, in contrast, most likely acquire the microbiome through "royal jelly," the protein-rich food worker bees produce that can cause a queen bee to develop beginning in the larval stage.

Unlike worker bees, queen bees continue to consume royal jelly all the way to maturity.

That diet, and isolation from the microbes and dirt inherent in day-to-day life in the colony, is likely a factor in a queen's development of a different, unique microbiome, the researchers say.

By the time they are mature, Newton says, "queens have developed a microbial signature distinct from the rest of the colony."

The findings suggest that typical beekeeping practices, which sees beekeepers regularly removing queens from their home colonies and moving them to new hives, do not represent a risk to the health of either the old or the new colony, since the queen's microbiome does not reflect that of workers in a colony, the researchers say.

 "In many ways, these conclusions are very reassuring for the commercial-production apiculture industry," Newton says.

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