Common bee disease spread through flowers

Aug. 7 (UPI) -- A common honeybee disease can make the jump to wild bees via flowers, according to a new study.

The pathogen Nosema ceranae, a small, unicellular parasite, is the most common disease among managed honeybees, affecting both the Asiatic and European honeybee. New research suggest the disease can also affect wild bees, specifically, a stingless species native to Australia.

Honeybees infected by Nosema ceranae become less active, develop an increased appetite and perish prematurely. The pathogen is deadliest among Asiatic honeybees. European hives are mostly able to contain the infection.

"Pathogen spillover from bees kept by bee keepers to wild bee populations is increasingly considered as a possible cause of wild pollinator decline," Terence Purkiss, student researcher at James Cook University in Australia, said in a news release. "Spillover has been frequently documented, but not much is known about the pathogen's virulence in wild bees or how long pathogens can survive on a flower."

When scientists exposed "sugar bag" bees, Tetragonula hockingsi, to the pathogen, two-thirds of the wild bees became infected. Mortality rates among the wild bee test population tripled.

Experiments proved that flowers can help spread the disease from honeybees to wild bees.

"About two-thirds of the flowers exposed to infected European honey bees were found to be carrying Nosema ceranae spores," said Lori Lach, an ecologist and professor at James Cook. "In every case, at least one stingless bee that foraged on the flowers contracted the pathogen. What this means is that wild bees can be infected with the disease by sharing a flower with an infected European bee."

Over a six-month period, scientists found evidence of the invasive pathogen at five of the six stingless bee hives they regularly monitored. Researchers published the results of their experiments and monitoring efforts this week in the journal Proceedings of the Royal Society B.

As a result of climate change and habitat loss, wild bee populations are increasingly coming in to contact with humans and managed honey bees. As a result, diseases common among honeybees could begin to infect wild bee species.

"We know that new hosts will not have had the opportunity to develop defenses against new pathogens and may be particularly susceptible," Lach said. "For example, human immunodeficiency virus and severe acute respiratory syndrome jumped from chimpanzees and bats, respectively, to humans and have resulted in millions of deaths."