Nosema warning to beekeepers 10 Jun 2015

Beekeepers are being urged to monitor their hives closely after mating flights following research showing that the so-called ‘silent killer’ Nosema Apis can be sexually transmitted from infected drones to queens.

Nosema is a highly infectious gut fungus spread mainly through infected faeces, and is found throughout Australia. It gives bees dysentery, reduces their lifespan, and can cause queens to stop laying eggs – which can ultimately lead to the collapse of the colony.

The research has been carried out by the Centre for Integrative Bee Research (CIBER) at the University of Western Australia (UWA) as part of the Honey Bee and Pollination RD&E Program, which is funded by the Rural Industries Research and Development Corporation (RIRDC) and Horticulture Innovation Australia Limited (HIA).

Lead researcher Professor Boris Baer said five years of research has gone into the findings.

“While bees have some tolerance to nosema at low levels, it’s like the flu and different strains develop. If those different strains are introduced to the hive, especially if the hive is under stress, it can have a dramatic impact on the health of the colony,” Professor Baer said.

“Knowing nosema can be found in seminal fluid will cause several changes to hive and breeding management.

“For beekeepers, it’s about checking hive entrances for signs of diarrhoea, especially now after mating flights. If the area looks dirty, it’s a sign that nosema is getting a stronger hold, and it’s time to rest the hive to allow it to recover strength.”

Professor Baer said import and export protocols for bee semen are also likely to be developed as a result of the research. 

“Bees are not born with nosema, and it appears the fungus is restricted to the gut when they’re first infected, so ideally mating should occur with younger drones.

“As the bees age, nosema spreads through more of their bodies and eventually infects the sexual organs – which is when it becomes an issue for mating.

“As beekeepers search worldwide for better genetics and Varroa resistant stocks, I can see tests developing to ensure semen is disease free – and not just with regard to nosema now we know it’s possible for disease to affect seminal fluid and be passed on to the queens.”

For more information about nosema and its management, go to

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