Honeybee colony losses in Uruguay during 2013–2014

ABSTRACT Honeybee colonies are vulnerable to parasites and pathogens ranging from viruses to vertebrates. An increasingly prevalent disease of managed honeybees is caused by the microsporidian Nosema ceranae. Microsporidia are basal fungi and obligate parasites with much-reduced genomic and cellular components. A recent genome-sequencing effort for N. ceranae indicated the presence of machinery for RNA silencing in this species, suggesting that RNA interference (RNAi) might be exploited to regulate Nosema gene expression within bee hosts. Here we used controlled laboratory experiments to show that double-stranded RNA homologous to specific N. ceranae ADP/ATP transporter genes can specifically and differentially silence transcripts encoding these proteins. This inhibition also affects Nosema levels and host physiology. Gene silencing could be mediated solely by Nosema or in concert with known systemic RNAi mechanisms in their bee hosts. These results are novel for the microsporidia and provide a possible avenue for controlling a disease agent implicated in severe honeybee colony losses. Moreover, since microsporidia are pathogenic in several known veterinary and human diseases, this advance may have broader applications in the future for disease control.

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Direct Economic Impact Assessment of Winter Honeybee Colony Losses in Three European Countries

Agriculture ◽

10.3390/agriculture11050398 ◽

2021 ◽

Vol 11 (5) ◽

pp. 398

Author(s):

Despina Popovska Stojanov ◽

Lazo Dimitrov ◽

Jiří Danihlík ◽

Aleksandar Uzunov ◽

Miroljub Golubovski ◽

...

Keyword(s):

Economic Impact ◽

Management Practices ◽

Agricultural Sector ◽

Stress Factors ◽

Economic Losses ◽

Colony Losses ◽

Economic Impact Assessment ◽

Parasitic Mite ◽

Honeybee Colony ◽

Pioneer Effort

Honeybees are of great importance because of their role in pollination as well as for hive products. The population of managed colonies fluctuates over time, and recent monitoring reports show different levels of colony losses in many regions and countries. The cause of this kind of loss is a combination of various factors, such as the parasitic mite Varroa destructor, viruses, pesticides, management practices, climate change, and other stress factors. Having in mind that the economic aspect of honeybee colony losses has not been estimated, a pioneer effort was made for developing a methodology that estimates the economic impact of honeybee colony losses. Winter loss data was based on 2993 answers of the COLOSS standard questionnaire survey of honeybee winter colony losses for 2016/2017. In addition, market and financial data were used for each country. In a comparative analysis, an assessment on the economic impact of colony losses in Austria, Czechia, and Macedonia was made. The estimation considered the value of the colonies and the potential production losses of the lost colonies and of surviving but weak colonies. The direct economic impact of winter honeybee colony losses in 2016/2017 in Austria was estimated to be about 32 Mio €; in Czechia, 21 Mio €; and in Macedonia, 3 Mio €. Economic impact reflects the different value levels in the three countries, national colony populations, and the magnitude of colony losses. This study also suggests that economic losses are much higher than the subsidies, which underlines the economic importance of honeybees for the agricultural sector.

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Haemolymph removal by Varroa mite destabilizes the dynamical interaction between immune effectors and virus in bees, as predicted by Volterra's model

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2019.0331 ◽

2019 ◽

Vol 286 (1901) ◽

pp. 20190331 ◽

Cited By ~ 14

Author(s):

Desiderato Annoscia ◽

Sam P. Brown ◽

Gennaro Di Prisco ◽

Emanuele De Paoli ◽

Simone Del Fabbro ◽

...

Keyword(s):

Viral Evolution ◽

Colony Losses ◽

Viral Pathogen ◽

Dynamical Interaction ◽

Deformed Wing Virus ◽

Pathogen Virulence ◽

Mite Feeding ◽

Parasitic Mite ◽

Honeybee Colony ◽

Honeybee Health

The association between the deformed wing virus and the parasitic mite Varroa destructor has been identified as a major cause of worldwide honeybee colony losses. The mite acts as a vector of the viral pathogen and can trigger its replication in infected bees. However, the mechanistic details underlying this tripartite interaction are still poorly defined, and, particularly, the causes of viral proliferation in mite-infested bees. Here, we develop and test a novel hypothesis that mite feeding destabilizes viral immune control through the removal of both virus and immune effectors, triggering uncontrolled viral replication. Our hypothesis is grounded on the predator–prey theory developed by Volterra, which predicts prey proliferation when both predators and preys are constantly removed from the system. Consistent with this hypothesis, we show that the experimental removal of increasing volumes of haemolymph from individual bees results in increasing viral densities. By contrast, we do not find consistent support for alternative proposed mechanisms of viral expansion via mite immune suppression or within-host viral evolution. Our results suggest that haemolymph removal plays an important role in the enhanced pathogen virulence observed in the presence of feeding Varroa mites. Overall, these results provide a new model for the mechanisms driving pathogen–parasite interactions in bees, which ultimately underpin honeybee health decline and colony losses.

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Dead or Alive: Deformed Wing Virus and Varroa destructor Reduce the Life Span of Winter Honeybees

Applied and Environmental Microbiology ◽

10.1128/aem.06537-11 ◽

2011 ◽

Vol 78 (4) ◽

pp. 981-987 ◽

Cited By ~ 170

Author(s):

Benjamin Dainat ◽

Jay D. Evans ◽

Yan Ping Chen ◽

Laurent Gauthier ◽

Peter Neumann

Keyword(s):

Life Expectancy ◽

Life Span ◽

Varroa Destructor ◽

Colony Losses ◽

Deformed Wing Virus ◽

Content Type ◽

Parasitic Mite ◽

Honeybee Colony ◽

Underlying Mechanisms ◽

Acute Bee Paralysis Virus

ABSTRACTElevated winter losses of managed honeybee colonies are a major concern, but the underlying mechanisms remain controversial. Among the suspects are the parasitic miteVarroa destructor, the microsporidianNosema ceranae, and associated viruses. Here we hypothesize that pathogens reduce the life expectancy of winter bees, thereby constituting a proximate mechanism for colony losses. A monitoring of colonies was performed over 6 months in Switzerland from summer 2007 to winter 2007/2008. Individual dead workers were collected daily and quantitatively analyzed for deformed wing virus (DWV), acute bee paralysis virus (ABPV),N. ceranae, and expression levels of thevitellogeningene as a biomarker for honeybee longevity. Workers from colonies that failed to survive winter had a reduced life span beginning in late fall, were more likely to be infected with DWV, and had higher DWV loads. Colony levels of infection with the parasitic miteVarroa destructorand individual infections with DWV were also associated with reduced honeybee life expectancy. In sharp contrast, the level ofN. ceranaeinfection was not correlated with longevity. In addition,vitellogeningene expression was significantly positively correlated with ABPV andN. ceranaeloads. The findings strongly suggest thatV. destructorand DWV (but neitherN. ceranaenor ABPV) reduce the life span of winter bees, thereby constituting a parsimonious possible mechanism for honeybee colony losses.

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Honeybee colony losses and threats in Scotland. (2012-2017)

10.20933/10000106 ◽

2017 ◽

Author(s):

Christopher Connolly ◽

John Durkacz

Keyword(s):

Colony Losses ◽

Honeybee Colony

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Effect of Oral Administration of 1,3-1,6 β-Glucans in DWV Naturally Infected Newly Emerged Bees (Apis mellifera L.)

Veterinary Sciences ◽

10.3390/vetsci7020052 ◽

2020 ◽

Vol 7 (2) ◽

pp. 52

Author(s):

Antonio Felicioli ◽

Mario Forzan ◽

Simona Sagona ◽

Paola D’Agostino ◽

Diego Baido ◽

...

Keyword(s):

Viral Load ◽

Control Group ◽

Rt Pcr ◽

Colony Losses ◽

Deformed Wing Virus ◽

Faecal Samples ◽

Honeybee Colony ◽

Experimental Protocols ◽

One Step ◽

Dose Dependent

Honeybee pathogens have an important role in honeybee colony mortality and colony losses; most of them are widely spread and necessitate worldwide solutions to contrast honeybee’s decline. Possible accepted solutions to cope with the spread of honeybee’s pathogens are focused on the study of experimental protocols to enhance the insect’s immune defenses. Honeybee’s artificial diet capable to stimulate the immune system is a promising field of investigation as ascertained by the introduction of 1,3-1,6 β-glucans as a dietary supplement. In this work, by collecting faecal samples of honeybees exposed to different dietary conditions of 1,3-1,6 β-glucans (0.5% and 2% w/w), it has been possible to investigate the Deformed wing virus (DWV) viral load kinetic without harming the insects. Virological data obtained by a one-step TaqMan RT-PCR highlighted the ability of 1,3-1,6 β-glucans to reduce the viral load at the 24th day of rearing. The results indicated that the diet supplemented with 1,3-1,6 β-glucans was associated with a dose-dependent activation of phenoloxidase. The control group showed a higher survival rate than the experimental groups. This research confirmed 1,3-1,6 β-glucans as molecules able to modulate honeybees’ defense pathways, and this is the first report in which the kinetic of DWV infection in honeybee faeces has been monitored by a RT-qPCR.

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Effect of oral administration of 1,3-1,6 β-glucans in DWV naturally infected newly emerged bees (Apis mellifera L.)

10.1101/2019.12.23.887091 ◽

2019 ◽

Author(s):

Felicioli Antonio ◽

Forzan Mario ◽

Sagona Simona ◽

D’agostino Paola ◽

Diego Baido ◽

...

Keyword(s):

Viral Load ◽

Control Group ◽

Daily Consumption ◽

Colony Losses ◽

Faecal Samples ◽

Honeybee Colony ◽

Experimental Protocols ◽

One Step ◽

Immune Defences ◽

Dose Dependent

AbstractHoneybee pathogens have an important role in honeybee colony mortality and colony losses, most of them are widely spread and necessitate worldwide solutions to contrast honeybee’s decline. Possible accepted solutions to cope with the spread of honeybee’s pathogen are focused on the study of experimental protocols to enhance the insect’s immune defences. Honeybee’s artificial diet capable to stimulate the immune system is a promising field of investigation as ascertained by the introduction of 1,3-1,6 β-glucans as a dietary supplement. In this work, by collecting faecal samples of honeybees exposed to different dietary conditions of 1,3-1,6 β-glucans (0.5% and 2% w/w), it has been possible to investigate the DWV viral load kinetic without harming the insects. Virological data obtained by a one-step TaqMan RT-PCR highlights the ability of 1,3-1,6 β-glucans to reduce the viral load at 24th day of rearing. Furthermore, results indicated that the diet supplemented with 1,3-1,6 β-glucans was associated with a dose-dependent activation of phenoloxidase. Control group showed a higher survival rate than honeybees exposed to different dietary conditions of 1,3-1,6 β-glucans while no differences have been observed concerning syrup daily consumption.

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An Overview on Honeybee Colony Losses in Buenos Aires Province, Argentina

Sociobiology ◽

10.13102/sociobiology.v66i1.3366 ◽

2019 ◽

Vol 66 (1) ◽

pp. 75 ◽

Cited By ~ 2

Author(s):

Maria Laura Genchi Garcia ◽

Santiago Plischuk ◽

Claudio Marcelo Bravi ◽

Francisco Jose Reynaldi

Keyword(s):

Honey Bees ◽

Buenos Aires ◽

Buenos Aires Province ◽

Colony Collapse Disorder ◽

Colony Losses ◽

High Prevalence ◽

Different Types ◽

Colony Collapse ◽

Honeybee Colony

Honey bees (Apis mellifera) are essential for the ecosystem, so their loss threatens biodiversity and agriculture. Several factors have been proposed as possible causes of both massive losses and Colony Collapse Disorder. In August 2017 episodes of colony losses were registered in General Alvear, Buenos Aires province. The aim of the present study was to find possible causes of these events. The samples were screened for presence of several pathogens and the determination of maternal lineages was also performed. Seven out of ten colonies were positive for pathogens, but there was no high prevalence of any of them. It will be necessary to carry out a standardization of studies, and delineate boundaries that allow comparing cases in order to discriminate different types of mortality of colonies that occur worldwide.

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Exposure to Inactivated Deformed Wing Virus Leads to Trans-Generational Costs but Not Immune Priming in Honeybees (Apis mellifera)

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.626670 ◽

2021 ◽

Vol 9 ◽

Author(s):

Matti Leponiemi ◽

Gro V. Amdam ◽

Dalial Freitak

Keyword(s):

Immune System ◽

Priming Effect ◽

Immune Challenge ◽

Colony Losses ◽

Viral Pathogen ◽

Deformed Wing Virus ◽

Immune Priming ◽

Viral Loads ◽

Honeybee Colony ◽

Pupal Mortality

Pathogens are identified as one of the major drivers behind the honeybee colony losses, as well as one of the reasons for the reported declines in terrestrial insect abundances in recent decades. To fight infections, animals rely on their immune system. The immune system of many invertebrates can be primed by exposure to a pathogen, so that upon further exposure the animal is better protected. The protective priming effect can even extend to the next generation, but the species capable of priming the immune system of their offspring are still being investigated. Here we studied whether honeybees could prime their offspring against a viral pathogen, by challenging honeybee queens orally with an inactivated deformed wing virus (DWV), one of the most devastating honeybee viruses. The offspring were then infected by viral injection. The effects of immune priming were assayed by measuring viral loads and two typical symptoms of the virus, pupal mortality, and abnormal wing phenotype. We saw a low amount of wing deformities and low pupal mortality. While no clear priming effect against the virus was seen, we found that the maternal immune challenge, when combined with the stress caused by an injection during development, manifested in costs in the offspring, leading to an increased number of deformed wings.

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