Nosema, caused by the parasite Nosema apis and ceranae, leads to dysentery and other serious side effects such as reduced yield, increased winter losses, shortened life span and increased susceptibility to supersedure. Nosema is also known as 'Spring Dwindling Disease' because as the weather improves and bees are able to leave the hive to defecate so the disease level often drops and (although colonies will not do as well as those that were uninfected), they often recover for the summer.
The most easily observed symptom of Nosema is dysentery, which can be seen as yellow streaks outside [Fig 1+2] and (in cases of severe infestation) within the hive.[Fig 2]. Supersedure may be induced and physical signs such as increased abdomen girth are possible. Colony productivity is adversely affected and colony population will drop (female worker bees are particularly affected).
The best methods of prevention are good husbandry techniques such as removing stress factors and providing sufficient nutrition.
The traditional treatment for Nosema has been the antibiotic Fumagillin. However, many beekeepers have stopped using Fumagillin because they found that colonies built up too quickly and swarm control became nearly impossible. This product has also been withdrawn from a number of countries because of antibiotic residues in hive products. An alternative is VitaFeed Gold, a natural biostimulant that provides controlled brood build-up, stimulates colony development and is particularly effective when applied to colonies infected with Nosema. VitaFeed Gold contains no antibiotics and leaves no harmful residues.