Nosemosis

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The Nosemose (also Nosemosis , Nosema disease , Nosema , spring consumption , bowel disease ) is a parasitic intracellular-acting by the small Apicomplexa ( Microspora ) Nosema apis and Nosema ceranae caused disease in honeybees . Nosemosis is the most common disease in adult bees and is highly contagious. According to the latest findings from several current studies from the USA and France, honey bees contaminated with pesticides are more likely to develop nosemosis.

Pathogen

Until recently, Nosema apis was the only nosemose pathogen in western honey bees . Nosema apis , first described by Enoch Zander in 1909 , is a unicellular parasite from the division of microsporidia ( Microsporidia ), which are small spore animals that are usually counted among the fungi . The dormant stage of Nosema apis is a long-lived spore that can survive for up to seven years in clean, 4 ° C cold water and around two years in bee droppings, while it dies more quickly in water containing bacteria, dead bees or if it dries out. At temperatures of 33 ° C, the spores are viable for about 21 days.

In 1996, a similar microsporidium was discovered in Asia as a parasite of the eastern honey bee ( Apis cerana ), which is consequently called Nosema ceranae . Little is known about the symptoms and the course of the disease in the Asian honey bee.

Chinese researchers (Huang et al. 2005) found Nosema ceranae on the western honey bee ( Apis mellifera ) for the first time in Taiwan in spring 2005 . Shortly afterwards, Spanish bee scientists (Higes et al.) Reported that the new pathogen was also discovered in Spain in 2005 and, according to their findings, has a significantly higher virulence than the western variant. The nosemosis caused by Nosema ceranae in western honey bees in Spain is associated with a more severe clinical picture that deviates from the typical findings (unusually severe intestinal damage in the bees, no diarrhea, preferential infestation of older forager bees that die far away from their homes, and the resulting "empty flies “And collapse of the bee colonies). Furthermore, a very strong spread of nosemosis was observed within a few years and its occurrence at previously unusual times of the year (all year round), which is apparently due to the higher resistance of Nosema ceranae . It is therefore also assumed that the bee colonies have a higher rate of reinfection, as the pathogen survives longer in the external environment.

The two types of pathogen cannot be differentiated with the routine examinations that have been customary up to now, but can only be distinguished with the help of molecular genetic methods ( PCR ).

The researchers consider the fact that Nosema ceranae has apparently prevailed against Nosema apis in Spain (almost only eastern specimens were found) as worrying . They therefore link the appearance of this pathogen to the massive bee deaths observed in Spain since autumn 2004. They suspect that a similar finding could also be made in other European countries, since France (since the end of the 1990s) and Germany (2002/2003) have also reported increased and so far inconclusive colony losses.

In the first random samples of German reference laboratories in the winter of 2005/2006, the new pathogen type was also detected in eight out of ten apiaries in Germany (CVUA Freiburg), with the distribution fluctuating from state to state. The bees with the classic pathogen Nosema apis came from Thuringia and Bavaria , while Nosema ceranae was found in Baden-Württemberg , Bavaria and North Rhine-Westphalia . In the meantime, reports of Nosema ceranae finds in colonies affected by increased mortality have also been reported from Switzerland (July 2006) and several regions of Italy (September 2006) ( see also Colony Collapse Disorder ).

The German scientists (Ritter, CVUA Freiburg) asked themselves in 2006 whether the “eastern” pathogen (the origin is unclear) might not have been present in Europe for some time and so far only not from Nosema apis. was distinguished. It is possible that the current course of the disease is more extreme when a Nosema infestation increases, because the colonies are weakened overall by the Varroa mite and other factors and are therefore more susceptible. However, there are actually signs in Germany that the course of nosemosis has changed and that, in contrast to the classic form, the disease now occurs throughout the year.

The study of 131 colonies from Bavaria, most of them clinically abnormal, as part of a dissertation (Zohni, July 2006) supports the thesis that bee viruses, which are transmitted by arthropods (such as the varroa mite), are causally involved in the periodic mass losses. Since only a comparatively few of these colonies were contaminated with microsporidia (in 14.5% of the cases, evidence of microsporidia spores was found, half of these findings were due to Nosema apis or Nosema ceranae ), a correlation between microsporidia infestation and virus infection could not be found to be established. The question of whether the colony deaths are due to the “new” variety of Nosema, which (possibly) has a higher pathogenicity, or to viruses associated with the Varroa infestation, is therefore still the subject of international controversy among scientists and beekeepers .

A peer-review study by Klee et al. (2007), in which older and more recent Nosema samples from all over the world were evaluated, now showed that the newly discovered pathogen apparently did indeed change host from Apis cerana to Apis in the last decade mellifera and has spread remarkably quickly. Today it is found on the western honey bee in North and South America , in the Caribbean and across Europe and Asia. Only on the islands of Ireland and New Zealand could only Nosema apis be detected. In order to be able to make a more comprehensive statement, samples from Africa , Australia and Great Britain are still missing . However, the high degree of distribution and the occurrence even on remote islands of the Danish archipelago suggest that Nosema ceranae will very soon be represented worldwide.

transmission

The transmission to other colonies occurs through contaminated honeycombs or equipment of the beekeeper or through robbery and fly away of individual bees.

Newly hatched bees are practically free of parasites. The bees are infected by ingesting spores. The parasite enters its vegetative development phase and colonizes the epithelial cells of the midgut of the bee ( ventriculus ). This is where the cell's own RNA synthesis becomes enlarged and reproduced, resulting in severe damage to the intestine. After about a week, the affected intestinal epithelial cell is filled with spores. It flakes off and the digestive enzymes release the spores (30 to 50 million) from the cell. They are excreted in the bees' excrement, mostly on honeycombs and within the bee housing.

Symptoms

The symptoms of nosemosis are relatively unspecific, which can lead to confusion with other bee diseases . It usually occurs in spring after periods of bad weather. The workers are most affected, less so the drones . Since infested bees hardly ever take part in feeding the queen bee , the queen bee is also infected less often.

The most important symptom is dysentery ("diarrhea"), which in Nosema apis shows up in yellow stripes of feces inside (on frames and honeycombs , on the hive wall) and outside the hive. Bees infested by Nosema apis are often unable to fly and crawl around near the hive until they die. In Nosema ceranae there is hardly any decay of the prey or the honeycomb structure. Infested bees crawl out of the prey (often with their abdomen curved downwards) and sit (often in small groups), unable to fly, apathetically on the ground. In addition, there may be an increase in the size of the abdomen , a lack of lancing reflex and an early replacement of the queen. The honey production and life expectancy of the bees decrease due to the reduced utilization of pollen .

If the queen becomes ill, her ovaries degenerate and her egg production decreases due to atrophy of the egg cells . This triggers a replacement for the queen among the colony.

The clinical picture described by Higes et al. In Spain and associated with the infestation by Nosema ceranae shows some peculiarities. The changes in the digestive tract observed in infested bees were much more serious than the damage known from Nosema apis and were associated with particularly severe and extensive cell lesions. On the other hand, there were no classic symptoms such as diarrhea, crawling, noticeable death in the vicinity of the stand, etc. The reason for the continuing decrease in the number of bees in the colony is assumed to be, among other things, the infestation of flying bees, which do not return and die far away from the stand. As a result, less and less feed is brought in, which, together with the other consequences of bee decline, can lead to the collapse of the population.

Ritter (CVUA Freiburg) also reported changes in the course of the disease in nosemosis in 2006; in contrast to the classic, creeping form, crawls and losses occurred throughout the year. In winter, some people died from in a short time and the bees lay dead in the box (unlike in Spain where the hives were usually easy bees empty). At this point in time it was not yet possible to conclusively clarify whether these symptoms are related to the new form of nosematosis. In the meantime, the specific physiological and behavioral effects of an infestation with Nosema ceranae on western honey bees have been examined in more detail at the INRA Avignon bee research institute .

Neurotoxins (pesticides) intensify nosemosis

More recent studies show an indirect effect of pesticides on the growth of pathogens in bees. As American researchers reported in early 2012, they exposed bee colonies to sublethal doses of the neonicotinoid imidacloprid during three breeding cycles . The newly hatched bees were then exposed to the intestinal parasite Nosema. The pesticide doses used were below the level that had an impact on the longevity and foraging behavior of the adult bees. Nosemose infections increased significantly in the colonies exposed to pesticides.

French researchers from Orléans found similar results in 2011 after tests with the pesticides fipronil and thiacloprid . With regard to imidacloprid, tests at the bee research institute INRA Avignon in 2009 had already suggested this result.

diagnosis

The laboratory diagnosis is made on the basis of a light microscopic examination of native specimens of the intestines or the ground abdomen of bees unfit to fly or otherwise suspicious bees on spores. The two pathogen types Nosema apis and Nosema ceranae cannot be differentiated, or only with great difficulty (this requires genetic testing).

The beekeeper can diagnose Nosema relatively easily: one pulls the prickle apparatus and the attached rectum from the abdomen of a dead bee between the thumb nail and the tip of the index finger. If the contents of the rectum are whitish-glassy, ​​it is very likely that it is Nosema. A healthy bee has yellowish-light brown intestinal contents.

treatment

Treatment can be with the antibiotic fumagillin (from Aspergillus fumigatus ), which prevents the spores from developing in the intestine. However, it does not remove the spores themselves. Disinfection of the combs and utensils is recommended. The spores are sensitive to acetic acid , formalin , ultrasound and gamma radiation . Biological control through the formation of bruises is also possible. The International Federation of Beekeeping Associations Apimondia recommends preventive treatment with the herbal preparation Protofil . Prevention is possible through care measures such as after-parent care .

Nosemosis in other animals

Pathogens of the genus Nosema also attack other insects , e.g. B. Nosema vespula (European wasp species ), Nosema oulemae ( cereal leaf beetle ), Nosema trichoplusiae ( Gammaeulenart Trichoplusia ni ), Nosema furnacalis ( Zünslerart Ostrinia furnacalis ), Nosema necatrix ( Eulenfalterart Mythimna unipuncta ), Nosema bombycis ( silkworm ). The spotting caused by Nosema bombycis (Pébrine's disease) is one of the most important parasitic diseases of the silkworm.

Pathogens similar to Nosema sp. can also cause disease in mammals . In veterinary practice , encephalitozoonosis in rabbits , also known as nosematosis , is an infection of the brain with the intracellular parasitic microsporidium Encephalitozoon cuniculi . The outdated name nosematosis comes from the fact that the encephalitozoa (the other species of which also affect humans ) are phylogenetically closest to the genus Nosema and were previously included in it.

swell

  1. ^ A b Johannes Eckert, Karl Theodor Friedhoff, Horst Zahner, Peter Deplazes: Textbook of Parasitology for Veterinary Medicine. 2nd Edition. Georg Thieme, 2008, ISBN 978-3-8304-1072-0 , p. 140.
  2. ↑ Ingmar Fries et al: Nosema ceranae n. Sp. (Microspora, Nosematidae), morphological and molecular characterization of a microsporidian parasite of the Asian honey bee Apis cerana (Hymenoptera, Apidae). In: European Journal of Protistology. 32 (1996), No. 3, pp. 356-365.
  3. ↑ Wei-Fone Huang et al .: Complete rRNA Sequence of the Nosema ceranae from honeybee (Apis mellifera) . National Taiwan University, Taipei 2005.
  4. ↑ a b Higes u. a: Two articles, see bibliography
  5. ↑ a b Wolfgang Ritter (CVUA Freiburg): Nosema ceranae. Asian Nosema pathogen detected. Newly distributed or just now discovered? In: ADIZ, the bee, the beekeeper friend. (Journal of the regional associations) 3/2006, p. 7 (online on the website of the regional association of Schleswig-Holstein and Hamburg beekeepers eV).
  6. ↑ Dalia Zohni:On the epidemiology of arthropod-borne viruses in the honeybee, Apis mellifera, in Bavaria.(PDF; 22.1 MB) . Munich 2006 ( inaugural dissertation at the veterinary faculty of the Ludwig Maximilians University Munich).
  7. ↑ J. Klee, AM Besana, E. Genersch, S. Gisder, A. Nanetti, DQ Tam, TX Chinh, F. Puerta, JM Ruz, P. Kryger, D. Message, F. Hatjina, S. Korpela, I Fries, RJ Paxton: Widespread dispersal of the microsporidium Nosema ceranae, an emergent pathogen of the western honey bee, Apis mellifera ( Memento February 7, 2012 in the Internet Archive ), 2007, Journal of Invertebrate Pathology.
  8. ↑ 50-year import ban on Australian honey lifted. ( Memento of the original from September 29, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Possible reasons for New Zealand's freedom from Nosema ceranae . @1@ 2Template: Webachiv / IABot / www.nzherald.co.nz
  9. ↑ crawlers = crawling bees with spread wings and distended abdomen.
  10. ↑ Claudia Dussaubat Arriagada: Effets de Nosema ceranae (Microsporidia) sur la santé de l'abeille domestique Apis mellifera L. Changements physiologiques et comportementaux . Dissertation, University of Avignon, December 2012.
  11. ↑ Jeffery S. Pettis, Dennis van Engelsdorp, Josephine Johnson, Galen Dively: Pesticide exposure in honey bees results in increased levels of the gut pathogen Nosema . In: Natural Sciences . 99, issue 2 (February 2012), pp. 153–158.
  12. ↑ Cyril Vidau, Marie Diogon, Julie Aufauvre, Régis Fontbonne, Bernard Viguès et al: Exposure to Sublethal Doses of Fipronil and Thiacloprid Highly Increases Mortality of Honeybees Previously Infected by Nosema ceranae . In: PLoS ONE . 6, issue 6 (June 2011), p. E21550.
  13. ↑ Cédric Alaux, Jean-Luc Brunet, Claudia Dussaubat, Fanny Mondet, Sylvie Tchemitchen, Marianne Coucin, Julien Brilard, Aurélie Baldy, Luc Belzunces, Yves Le Conte: Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera) . In: Environmental Microbiology. 12, issue 3 (March 2010), pp. 774–782, doi: 10.1111 / j.1462-2920.2009.02123.x First published in French on December 27, 2009 under the title Interaction toxicopathologique entre les microsporidies Nosemose et l'imidaclopride chez Apis mellifera.

literature

  • G. Chioveanu et al: Control of Nosemosis-Treatment with 'Protofil' ( Memento from February 9, 2012 in the Internet Archive ) In: Apiacta. 39 (2004), pp. 31-38.
  • C. Dussaubat Arriagada: Effets de Nosema ceranae (Microsporidia) sur la santé de l'abeille domestique Apis mellifera L. Changements physiologiques et comportementaux. (Effects of the microsporidium Nosema ceranae on the health of the western honey bee Apis mellifera L. Physiological and behavior-related changes.) Dissertation . University of Avignon, December 2012.
  • TA Gochauer et al: The Hive and the honeybee . Chapter 21 Diseases and enemies of the honey bee. Dadant 1975.
  • Mariano Higes and others: El Síndrome de Despoblamiento de las Colmenas en España (The phenomenon of bee deaths in Spain). In: Vida Apícola. 133 (September / October 2005), pp. 15-21 (Montagud Editores, Barcelona , Spain).
  • Mariano Higes et al: Nosema ceranae, a new microsporidian parasite in honeybees in Europe. In: Journal of Invertebrate Pathology. 92 (2006), pp. 93-95 ( Elsevier ).
  • Mariano Higes et al .: Honeybee colony collapse due to Nosema ceranae in professional apiaries. In: Environmental Microbiology Reports. 1 (2009), pp. 110-113.
  • Thomas C. Webster et al: Nosema apis infection in worker and queen Apis mellifera / Nosema apis infection of workers and queens (Apis mellifera). In: Apidology. 35: 49-54 (2004) (EDP Sciences, Les Ulis, France).

Web links

Wiktionary: Nosemose  - explanations of meanings, word origins, synonyms, translations