Nosemosis

The Nosema disease is a parasitic disease of adult honey bees (Apis mellifera) caused by two species of microsporidia, Nosema apis and Nosema ceranae, which form spores in adverse living conditions.

Honeybees afflicted with nosemosis start to forge earlier, while pathological changes of their mid-gut epithelial cells, as well as digestive and metabolic disorders, cause malnutrition leading to premature deaths.

Spores enter the digestive tract of bees via infected food and drink or on the occasion of social food exchange with other bees. The most common sources of infection include unsanitary water supply, honeycomb marked with faeces of infected bees, and contaminated honey. After reaching the mid-gut, Nosema sp. spores germinate under the influence of diverse chemical stimuli and their vegetative form invades epithelial cells of the mid-gut where they multiply. A part of spores is expelled from destroyed epithelial cells of the gut via excrements and a part remains in the lumen where they take vegetative form and invade the previously healthy epithelial cells of the mid-gut. Consequently, bees are constantly hungry and take larger quantities of food which accumulates in their rectums as sweet faecal matter infected with spores.

New Nosema ceranae is highly pathogenic and there are usually no visible symptoms of diarrhoea or adult bee deaths and there is a total lack of seasonality in the diagnosis, and little is known about pathogenicity.

Factors favouring the spread of the disease include robbery in honeybee colonies and bad bee-keeping practices, as well as sudden temperature fluctuations, poor pasture, disturbance, and frequent movements of honeybee colonies.
Conditions which also influence spreading of the disease are the long-lasting impossibility of cleansing flights during winter and the honeydew honey which was brought by bees into the hive in autumn and the beekeeper could not extract on time.

The disease arises in early spring. Many dead honeybees are detected around the hive, but also in the hive, the colony weakens and very often the bee queen also dies. Fecal matter in the form of diarrhoea, which is the source of further infection, can be observed on frames, honeycomb, foundations and around the hive.

  • “Last spring, just before acacia blossoming I lost all the flying bees, with piles of dead bees in front of the beehives. Besides Beevital, I was successful in rebuilding them by regular treatment with Nozevit as well as with a timely feeding supplement. By September all the 35 colonies were in great shape!” — Damir Rogulja, beekeper, Zagreb, Croatia, http://www.pcelinjak.hr