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Nosema spp[edit | edit source]

Nosema ceranae originates from Asia and was originally described as a pathogen of the Asian cavity nesting bee Apis cerana (Fries et al., 1996). It was later found to occur in colonies of Apis mellifera in Taiwan(Huang et al., 2007) and reported from Spain (Higes et al., 2006). It has been suggested that N. ceranae may be more virulent than Nosema apis when infecting A. mellifera, and it has been reported to cause severe colony losses, especially in southern Europe (Higes et al., 2007, 2008). N. ceranae has been present in the US since at least 1995 (Chen et al., 2007a, 2007b) and in Europe (Finland) since 1998 (Paxton et al., 2007). Nosema disease (nosemosis) caused by the honeybee microsporidia is one of the most important diseases in honeybees and is worldwide in distribution (Nixon, 1982). Microsporidia are possibly the smallest single-cell organisms with a true nucleus. The genus Nosema is a parasitic fungus that infects insects such as honeybees, bumble bees and silkworms. Nosema apis, which infects the Western honeybee, Apis mellifera, was first described by Zander (1909). Nosema ceranae, which attacks the Asian honeybee, Apis cerana, was reported in 1996 by Fries et al. (1996). They invade the midgut epithelial cells of the worker bees, queens and drones. Nosema has negative effects on the bee colony. It can affect the productivity and survival of honeybee colonies including adult bee longevity, queen bees, brood rearing, bee biochemistry, pollen collection and other bee behavior (Kang et al., 1976). The prevalence of Nosema has raised concerns especially with the recent declines in honeybee populations. Many of these losses have been attributed to Colony Collapse Disorder (CCD), although the specific causes of most losses are undetermined. It was reported that co-infection by virus and Nosema in honeybee might be associated with colony collapse (Bromenshenk et al., 2010).