Nosema ceranae
Encyclopedia
Nosema ceranae is a microsporidia
n, a small, unicellular parasite that mainly affects Apis cerana
, the Asiatic honey bee
. It may cause nosemosis, also called nosema (see Nosema apis
, the most widespread of the adult honey bee
diseases). The dormant stage of nosema is a long-lived spore which is resistant to temperature extremes and dehydration.
Nosema ceranae was first described in 1996 and was identified as a disease of Apis mellifera in 2004 in Spain.
Researchers in Spain
have analysed samples of Apis mellifera, the European honey bee, mostly sent from colonies suffering unexpected decreases in bee population per hive or lower honey production, as reported by the beekeepers during the last two/three years. In 2004, 90% of some 3,000 samples had positive results for N. ceranae. In 2005, of 800 samples, 97% had positive results. During 2006, both France and Germany have detected the disease and recognized the genetic sequence of Nosema ceranae in their respective territories. In the United States, N. ceranae has been detected in honey bees from Nebraska, Wisconsin, Arkansas, New York and South Dakota using PCR of the 16S
gene. In New York, N. ceranae was detected in 49 counties, and of the 1200 honey bee samples collected, 528 (44%) were positive for Nosema, from which, PCR analysis of 371 spore positive samples revealed that 96% were N. ceranae, 3% had both N. ceranae and N. apis, and 1% had N. apis only.
This pathogen has been tentatively linked to Colony collapse disorder
, a phenomenon reported primarily from the United States, since fall of 2006. Highly preliminary evidence of N. ceranae was reported in a few hives in the Merced Valley area of California (USA). "Tests of genetic material taken from a "collapsed colony" in Merced County point to a once-rare microbe that previously affected only Asian bees but might have evolved into a strain lethal to those in Europe and the United States." The researcher did not, however, believe this was conclusive evidence of a link to CCD; "We don't want to give anybody the impression that this thing has been solved." A USDA bee scientist has similarly stated, "while the parasite nosema ceranae may be a factor, it cannot be the sole cause. The fungus has been seen before, sometimes in colonies that were healthy." Likewise, a Washington State beekeeper familiar with N. ceranae in his own hives discounts it as being the cause of CCD. In early 2009 Higes et al. reported an association between CCD and N. ceranae was established free of confounding factors, and that weakened colonies treated with fumagillin recovered.
News articles published in October 2010 quoted researchers who had discovered that Nosema fungus had joined with a previously-unsuspected virus, Invertebrate Iridescent Virus, or IIV6, dealing test bee colonies a lethal blow. Neither the fungus nor the virus alone kill all the test group, but the two combined do. Both the fungus and the virus are found together with high frequency in hives that have suffered CCD. Final testing is in progress with field tests on colonies.
N. ceranae and N. apis have similar life cycles, but they differ in spore morphology. Spores of N. ceranae seem to be slightly smaller under the light microscope and the number of polar filament coils is between 20 and 23, rather than the more than 30 often seen in N. apis.
The disease afflicts adult bees and depopulation occurs with consequent losses in honey production. One does not detect symptoms of diarrhea like in Nosema apis.
The most significant difference between the two types is how quickly N. ceranae can cause a colony to die. Bees can die within 8 days after exposure to N. ceranae, which is faster than bees exposed to N. apis. The foraging force seems to be affected the most. They leave the colony and are too weak to return, thus dying in the field. This leaves behind a small cluster and a weak colony, very similar to the symptoms of CCD. There is little advice on treatment but it has been suggested that the most effective control of Nosema ceranae is the antibiotic fumagillin
as recommended for Nosema apis.
The genome
of Nosema ceranae was sequenced by scientists in 2009. This should help scientists trace its migration patterns, establish how it became dominant, and help measure the spread of infection by enabling diagnostic tests and treatments to be developed.
Microsporidia
The microsporidia constitute a phylum of spore-forming unicellular parasites. They were once thought to be protists but are now known to be fungi. Loosely 1500 of the probably more than one million species are named now. Microsporidia are restricted to animal hosts, and all major groups of animals...
n, a small, unicellular parasite that mainly affects Apis cerana
Apis cerana
Apis cerana, or the Asiatic honey bee , is a species of honey bee found in southern and southeastern Asia, such as China, India, Japan, Malaysia, Nepal, Bangladesh and Papua New Guinea. This species is the sister species of Apis koschevnikovi, and both are in the same subgenus as the Western honey...
, the Asiatic honey bee
Honey bee
Honey bees are a subset of bees in the genus Apis, primarily distinguished by the production and storage of honey and the construction of perennial, colonial nests out of wax. Honey bees are the only extant members of the tribe Apini, all in the genus Apis...
. It may cause nosemosis, also called nosema (see Nosema apis
Nosema apis
Nosema apis is a microsporidian, a small, unicellular parasite that mainly affects honey bees. It causes nosemosis, also called nosema, which is the most widespread of adult honey bee diseases. The dormant stage of Nosema apis is a long lived spore which is resistant to temperature extremes and...
, the most widespread of the adult honey bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
diseases). The dormant stage of nosema is a long-lived spore which is resistant to temperature extremes and dehydration.
Nosema ceranae was first described in 1996 and was identified as a disease of Apis mellifera in 2004 in Spain.
Researchers in Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
have analysed samples of Apis mellifera, the European honey bee, mostly sent from colonies suffering unexpected decreases in bee population per hive or lower honey production, as reported by the beekeepers during the last two/three years. In 2004, 90% of some 3,000 samples had positive results for N. ceranae. In 2005, of 800 samples, 97% had positive results. During 2006, both France and Germany have detected the disease and recognized the genetic sequence of Nosema ceranae in their respective territories. In the United States, N. ceranae has been detected in honey bees from Nebraska, Wisconsin, Arkansas, New York and South Dakota using PCR of the 16S
16S ribosomal RNA
16S ribosomal RNA is a component of the 30S subunit of prokaryotic ribosomes. It is approximately 1.5kb in length...
gene. In New York, N. ceranae was detected in 49 counties, and of the 1200 honey bee samples collected, 528 (44%) were positive for Nosema, from which, PCR analysis of 371 spore positive samples revealed that 96% were N. ceranae, 3% had both N. ceranae and N. apis, and 1% had N. apis only.
This pathogen has been tentatively linked to Colony collapse disorder
Colony Collapse Disorder
Colony collapse disorder is a phenomenon in which worker bees from a beehive or European honey bee colony abruptly disappear. While such disappearances have occurred throughout the history of apiculture, the term colony collapse disorder was first applied to a drastic rise in the number of...
, a phenomenon reported primarily from the United States, since fall of 2006. Highly preliminary evidence of N. ceranae was reported in a few hives in the Merced Valley area of California (USA). "Tests of genetic material taken from a "collapsed colony" in Merced County point to a once-rare microbe that previously affected only Asian bees but might have evolved into a strain lethal to those in Europe and the United States." The researcher did not, however, believe this was conclusive evidence of a link to CCD; "We don't want to give anybody the impression that this thing has been solved." A USDA bee scientist has similarly stated, "while the parasite nosema ceranae may be a factor, it cannot be the sole cause. The fungus has been seen before, sometimes in colonies that were healthy." Likewise, a Washington State beekeeper familiar with N. ceranae in his own hives discounts it as being the cause of CCD. In early 2009 Higes et al. reported an association between CCD and N. ceranae was established free of confounding factors, and that weakened colonies treated with fumagillin recovered.
News articles published in October 2010 quoted researchers who had discovered that Nosema fungus had joined with a previously-unsuspected virus, Invertebrate Iridescent Virus, or IIV6, dealing test bee colonies a lethal blow. Neither the fungus nor the virus alone kill all the test group, but the two combined do. Both the fungus and the virus are found together with high frequency in hives that have suffered CCD. Final testing is in progress with field tests on colonies.
N. ceranae and N. apis have similar life cycles, but they differ in spore morphology. Spores of N. ceranae seem to be slightly smaller under the light microscope and the number of polar filament coils is between 20 and 23, rather than the more than 30 often seen in N. apis.
The disease afflicts adult bees and depopulation occurs with consequent losses in honey production. One does not detect symptoms of diarrhea like in Nosema apis.
The most significant difference between the two types is how quickly N. ceranae can cause a colony to die. Bees can die within 8 days after exposure to N. ceranae, which is faster than bees exposed to N. apis. The foraging force seems to be affected the most. They leave the colony and are too weak to return, thus dying in the field. This leaves behind a small cluster and a weak colony, very similar to the symptoms of CCD. There is little advice on treatment but it has been suggested that the most effective control of Nosema ceranae is the antibiotic fumagillin
Fumagillin
Fumagillin is a complex biomolecule and used as an antimicrobial agent. It was isolated in 1949 from the microbial organism Aspergillus fumigatus.-In animals:...
as recommended for Nosema apis.
The genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of Nosema ceranae was sequenced by scientists in 2009. This should help scientists trace its migration patterns, establish how it became dominant, and help measure the spread of infection by enabling diagnostic tests and treatments to be developed.