A common honey bee disease is spread through flowers

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A common honey bee disease is spread through flowers

Scientists at James Cook University have discovered that a common disease of honey bees can be fatal to native Australian wild bees and can be transmitted by flowers - the first time this link has been established.

JCU Associate Professor Lori Lach supervised the study on the sensitivity of Australian bees without stings or "sugar bags" to Nosema ceranae, a parasite that causes European honeybees to become less active, develop an increased appetite and die early.

"The spread of pathogens from bees beekeepers to wild bee populations is increasingly seen as a possible cause of the decline of wild pollinators. Encroachment has often been documented, but little is known about the virulence of the pathogen in wild bees or the survival time of pathogens on a flower," said Terence Purkiss, the student who conducted the study with distinction.

Scientists have found that just over two-thirds of wild bees exposed to the disease have caught it and those who have caught it have died almost three times as often as those who have not. Most European hives contain the disease to some extent.

Scientists have also discovered that flowers can transmit the disease.

"About two thirds of the flowers exposed to infected European bees were infected with Nosema ceranae spores. In all cases, at least one bee without a sting that fed on the flowers contracted the pathogen. This means that wild bees can be infected with the disease by sharing a flower with an infected European bee," says Dr. Lach.

Five of the six hives without bee stings that the researchers monitored for five months tested positive for the pathogen at least once.

According to Mr. Lach, the geographical distribution of species is changing rapidly due to habitat loss, climate change and the introduction of new species by humans.

"This leads to new combinations of interacting species that do not share any evolutionary history. Introduced species can bring their pathogens and parasites with them and give them the opportunity to spread to new species," said Dr. Lach.

Dr. Lach said more work needs to be done outside the laboratory and in different seasons to get a clearer picture of the danger the pathogen poses to wild bees.

"We know that new hosts will not have had the opportunity to develop defences against new pathogens and could be particularly sensitive. For example, the human immunodeficiency virus and severe acute respiratory syndrome have jumped from chimpanzees and bats, respectively, to humans and caused millions of deaths, she said.

Dr. Lach said it was the first study to discover an overflow of the pathogen from European bees onto non-stinged bees in Australia.

"Reducing the risk of pathogen transmission from managed bees to wild bees presents multiple challenges and must involve the beekeeping community so that any real change can occur. The development of rapid and effective diagnostic tools and reliable means of preventing and treating infection will also be an important step forward," she added.

The work was published today in the Proceedings of the Royal Society B.