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Nosema Disease

Condensed from an article by Clarence Collison and Audry Sheridan in Jan 2010 Bee Culture.

Nosema disease is one of the most prevalent adult honeybee diseases and is caused by two species of microsporida. Nosema apis and Nosema ceranae.
Nosema is spread when adult bees ingest Nosema spores when they are eating contaminated food and when they are cleaning up fecal material from infected bees. The spores germinate within the midgut and release polar tubes that transfer their sporoplasm into the midgut cells where they generate more spores. A few weeks after initial infection the spores excreted with feces become new sources of infection in the colonies.
Although infected bees do not exhibit obvious disease symptoms, infection of Nosema causes digestive disorders, shortens the life span of honeybees, decreases population size of honeybee colonies and reduces honey production and crop pollination.
Nosema ceranae is associated with reduction in honey production and increased winter mortality.
Nosema free bees inoculated with 125,000 n. ceranae spores had a 100 % mortality rate in 8 days.
A study showed that bees infected with N. ceranae had a higher hunger level that leads to reduced survival and concluded that energetic stress is the probable cause of the shortened life span. It also indicated that infected bees have a reduction in the capacity to feed larvae royal jelly therefore the brood suffers.
Queens infected with active Nosema eventually ceased oviposition and became sluggish and the last batch of eggs laid often dried up in their cells.

Ski’s note:
I was taught that you treat bees when you have a problem, and with Nosema Apis you will see bee poop in the hive or on the outside of the hive but with Nosema ceranae you will notice the problem when the bees are dead. Treating with Fumagilin-B in the spring and fall per the directions has reportedly taken care of both types of Nosema.
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