A historical review of managed honey bee populations in Europe and the United States and the factors that may affect them.

https://www2.hu-berlin.de/bienenkunde/Bilder-Downloads/Publikationen/2007/4-Nosema_2007_Klee_et_al_JIP_96_1-10.pdf

Widespread dispersal of the microsporidian Nosema ceranae, an emergent pathogen of the western honey bee, Apis mellifera

On February 22, 2007, many Americans woke up to media reports that something was awry with their honey bees. A significant proportion of American beekeepers were complaining of unusually high rates of colony loss as their bees broke from their overwintering clusters. Loss of some colonies (say 10%) in early spring is normal and occurs every year. In 2007, however, losses were particularly heavy and widespread—beekeepers in 22 states (including Hawaii) reported the problem. Some beekeepers lost nearly all of their colonies. And the problem is not just in the United States. Many European beekeepers complain of the same problem. Moreover, beekeepers and researchers do not understand the specific causes of the losses.

/pdf/what-s-killing-american-honey-bees-2gwjwpw315.pdf

What's killing American honey bees?

A multiplex PCR-based method, in which two small-subunit rRNA regions are simultaneously amplified in a single reaction, was designed for parallel detection of honeybee microsporidians (Nosema apis and Nosema ceranae). Each of two pairs of primers exclusively amplified the 16S rRNA targeted gene of a specific microsporidian. The multiplex PCR assay was useful for specific detection of the two species of microsporidians related to bee nosemosis, not only in purified spores but also in honeybee homogenates and in naturally infected bees. The multiplex PCR assay was also able to detect coinfections by the two species. Screening of bee samples from Spain, Switzerland, France, and Germany using the PCR technique revealed a greater presence of N. ceranae than of N. apis in Europe, although both species are widely distributed. From the year 2000 onward, statistically significant differences have been found in the proportions of Nosema spp. spore-positive samples collected between and within years. In the first period examined (1999 to 2002), the smallest number of samples diagnosed as Nosema positive was found during the summer months, showing clear seasonality in the diagnosis, which is characteristic of N. apis. From 2003 onward a change in the tendency resulted in an increase in Nosema-positive samples in all months until 2005, when a total absence of seasonality was detected. A significant causative association between the presence of N. ceranae and hive depopulation clearly indicates that the colonization of Apis mellifera by N. ceranae is related to bee losses.

Outcome of colonization of Apis mellifera by Nosema ceranae.

https://bienenkunde.uni-hohenheim.de/uploads/media/Fries_Nceranae_JIP2010.pdf

Nosema ceranae in European honey bees (Apis mellifera).

Microsporidiosis (nosema disease) of the honeybee, Apis mellifera, has spread worldwide and caused heavy economic losses in apiculture. We obtained a spore isolate from worker ventriculi of A. mellifera colonies kept on the campus of National Taiwan University and sequenced the ribosomal genes. The entire length of the ribosomal DNA is about 3828 bp and the organization is similar to that of Nosema apis. However, the SSUrRNA, ITS, and LSUrRNA sequences have comparatively low identities with those of N. apis (92, 52, and 89%, respectively) and the SSUrRNA has a 99% identity with Nosema ceranae. These results indicate that this isolate is not N. apis, but N. ceranae. Moreover, the morphological characteristics are identical to those of N. ceranae. These results show that nosema disease of the honeybee, A. mellifera, may not be caused solely by the infection of N. apis.

/pdf/a-nosema-ceranae-isolate-from-the-honeybee-apis-mellifera-2jpk3xomf9.pdf

A Nosema ceranae isolate from the honeybee Apis mellifera

Fumagillin is the only antibiotic approved for control of nosema disease in honey bees and has been extensively used in United States apiculture for more than 50 years for control of Nosema apis. It is toxic to mammals and must be applied seasonally and with caution to avoid residues in honey. Fumagillin degrades or is diluted in hives over the foraging season, exposing bees and the microsporidia to declining concentrations of the drug. We showed that spore production by Nosema ceranae, an emerging microsporidian pathogen in honey bees, increased in response to declining fumagillin concentrations, up to 100% higher than that of infected bees that have not been exposed to fumagillin. N. apis spore production was also higher, although not significantly so. Fumagillin inhibits the enzyme methionine aminopeptidase2 (MetAP2) in eukaryotic cells and interferes with protein modifications necessary for normal cell function. We sequenced the MetAP2 gene for apid Nosema species and determined that, although susceptibility to fumagillin differs among species, there are no apparent differences in fumagillin binding sites. Protein assays of uninfected bees showed that fumagillin altered structural and metabolic proteins in honey bee midgut tissues at concentrations that do not suppress microsporidia reproduction. The microsporidia, particularly N. ceranae, are apparently released from the suppressive effects of fumagillin at concentrations that continue to impact honey bee physiology. The current application protocol for fumagillin may exacerbate N. ceranae infection rather than suppress it.

/pdf/nosema-ceranae-escapes-fumagillin-control-in-honey-bees-3ze86o1ael.pdf

Nosema ceranae Escapes Fumagillin Control in Honey Bees

https://www.life.illinois.edu/scameron/pdfs/Cordes%20et%20al.%202012.pdf

Wei Fone Huang

Papers

A Nosema ceranae isolate from the honeybee Apis mellifera

Nosema ceranae Escapes Fumagillin Control in Honey Bees

Interspecific geographic distribution and variation of the pathogens Nosema bombi and Crithidia species in United States bumble bee populations

Comparative development and tissue tropism of Nosema apis and Nosema ceranae.

The comparison of rDNA spacer regions of Nosema ceranae isolates from different hosts and locations.