Apis Mellifera Filamentous Virus Research Articles

New insights into honey bee viral and bacterial seasonal infection patterns using third-generation nanopore sequencing on honey bee haemolymph

Honey bees are rapidly declining, which poses a significant threat to our environment and agriculture industry. These vital insects face a disease complex believed to be caused by a combination of parasites, viruses, pesticides, and nutritional deficiencies. However, the real aetiology is still enigmatic. Due to the conventional analysis methods, we still lack complete insights into the honey bee virome and the presence of pathogenic bacteria. To fill this knowledge gap, we employed third-generation nanopore metagenomic sequencing on honey bee haemolymph to monitor the presence of pathogens over almost a year. This study provides valuable insights into the changes in bacterial and viral loads within honey bee colonies. We identified different pathogens in the honey bee haemolymph, which are not included in honey bee screenings. These pathogens comprise the Apis mellifera filamentous virus, Apis rhabdoviruses, and various bacteria such as Frischella sp. and Arsenophonus sp. Furthermore, a sharp contrast was observed between young and old bees. Our research proposes that transgenerational immune priming may play a role in shaping infection patterns in honey bees. We observed a significant increase in pathogen loads in the spring, followed by a notable decrease in pathogen presence during the summer and autumn months. However, certain pathogens seem to be able to evade this priming effect, making them particularly intriguing as potential factors contributing to mortality. In the future, we aim to expand our research on honey bee transgenerational immune priming and investigate its potential in natural settings. This knowledge will ultimately enhance honey bee health and decrease colony mortality.

First detection and prevalence of Apis mellifera filamentous virus in Apis mellifera and Varroa destructor in the Republic of Korea

Apis mellifera filamentous virus (AmFV) is a double-stranded DNA virus that infects Apis mellifera bees. To our knowledge, this is the first comprehensive study aiming to detect and analyse the genetic diversity and prevalence of AmFV in Korean honeybee colonies. Phylogenetic analysis based on baculovirus repeat open reading frame–N gene (Bro–N) sequences revealed that AmFV isolates from the Republic of Korea (ROK) fell into two distinct lineages, with genetic origins in Switzerland and China, with nucleotide similarities of 98.3% and 98.2%, respectively. Our prevalence analysis demonstrated a noteworthy infection rate of AmFV in 545 honeybee colonies, reaching 33.09% in 2022 and increasing to 44.90% by 2023. Intriguingly, we also detected AmFV in Varroa destructor mites, highlighting their potential role as vectors and carriers of AmFV. The presence of AmFV was correlated with an increased infection rate of sacbrood virus, deformed wing virus, Lake Sinai virus 2, black queen cell virus, and Nosema ceranae in honeybee colonies. These findings provide valuable insight into the prevalence and potential transmission mechanisms of AmFV in honeybee colonies in the ROK. The results of this study may be instrumental in the effective management of viral infections in honeybee apiaries.

Varroa destructor economic injury levels and pathogens associated with colony losses in Western Canada

IntroductionThe honey bee parasitic mite, Varroa destructor, is considered the main factor associated with winter colony losses. To control this mite, beekeepers must implement Integrated Pest Management (IPM) strategies. An effective IPM strategy is based on timely monitoring of mite levels to treat the colonies when the mites reach an economic threshold and before they grow to damaging levels (economic injury level). Additionally, concerns have been raised about the possible interaction between V. destructor and other stressors; stressors acting additively or synergistically may lead to high colony mortality.MethodologyVarroa destructor levels were recorded in colonies from five regions of British Columbia, Canada: Lower Mainland, Kootenay, Okanagan, Cariboo, and Peace. Mite levels were analyzed for associations with colony strength and mortality, as well as with other pathogens that were identified using total RNA sequencing.ResultsThe Kootenay and Lower Mainland regions had the highest V. destructor levels in the fall (3.38±0.65 and 2.51±0.57, respectively) followed by the Okanagan (1.54±0.36), Cariboo (1.31±0.39), and Peace (0.66±0.25) regions. The Peace region had a significantly lower proportion of dead colonies than the other regions. Varroa destructor levels in the fall significantly predicted odds of colony mortality in the spring. Colonies with ≥ 1% mite infestation in the fall (August) had a significantly higher mortality rate (p=0.005) compared to colonies with <1% mite levels. Therefore, treatment is recommended above that threshold. Also, deformed wing virus-B levels were 8.4 times higher than those of deformed wing virus-A variant in all the regions and were highest in the Kootenay region, which also had the highest rate of colony losses. Lastly, Malpighamoeba mellificae and Nosema (Vairimorpha) apis transcripts were identified along with other pathogens that deserve further investigation, including Apis mellifera filamentous virus, Apis rhabdovirus, Lake Sinai virus, Varroa tymo-like, and Apis mellifera solinvivirus 1.DiscussionThe dynamic nature of host-pathogen interactions requires frequent pathogen surveillance to determine the prevalence and levels of parasitic mites and associated infectious diseases, and their impact on honey bee health, not only in the regions of this study, but globally. Nevertheless, more studies are needed to determine the nature of the type of interaction between the identified pathogens and V. destructor. Also, more research is needed to evaluate their potential impact on colony survival, to provide accurate mite and disease control recommendations to beekeepers.

Apis mellifera filamentous virus from a honey bee gut microbiome survey in Hungary

In Hungary, as part of a nationwide, climatically balanced survey for a next-generation sequencing-based study of the honey bee (Apis mellifera) gut microbiome, repeated sampling was carried out during the honey production season (March and May 2019). Among other findings, the presence of Apis mellifera filamentous virus (AmFV) was detected in all samples, some at very high levels. AmFV-derived reads were more abundant in the March samples than in the May samples. In March, a higher abundance of AmFV-originated reads was identified in samples collected from warmer areas compared to those collected from cooler areas. A lower proportion of AmFV-derived reads were identified in samples collected in March from the wetter areas than those collected from the drier areas. AmFV-read abundance in samples collected in May showed no significant differences between groups based on either environmental temperature or precipitation. The AmFV abundance correlated negatively with Bartonella apihabitans, Bartonella choladocola, and positively with Frischella perrara, Gilliamella apicola, Gilliamella sp. ESL0443, Lactobacillus apis, Lactobacillus kullabergensis, Lactobacillus sp. IBH004. De novo metagenome assembly of four samples resulted in almost the complete AmFV genome. According to phylogenetic analysis based on DNA polymerase, the Hungarian strains are closest to the strain CH-05 isolated in Switzerland.

Discovery and characterization of novel DNA viruses in Apis mellifera: expanding the honey bee virome through metagenomic analysis.

To date, many viruses have been discovered to infect honey bees. In this study, we used high-throughput sequencing to expand the known virome of the honey bee, Apis mellifera, by identifying several novel DNA viruses. While the majority of previously identified bee viruses are RNA, our study reveals nine new genomes from the Parvoviridae family, tentatively named Bee densoviruses 1 to 9. In addition, we characterized a large DNA virus, Apis mellifera filamentous-like virus (AmFLV), which shares limited protein identities with the known Apis mellifera filamentous virus. The complete sequence of AmFLV, obtained by a combination of laboratory techniques and bioinformatics, spans 152,678 bp. Linear dsDNA genome encodes for 112 proteins, of which 49 are annotated. Another large virus we discovered is Apis mellifera nudivirus, which belongs to a group of Alphanudivirus. The virus has a length of 129,467 bp and a circular dsDNA genome, and has 106 protein encoding genes. The virus contains most of the core genes of the family Nudiviridae. This research demonstrates the effectiveness of viral binning in identifying viruses in honey bee virology, showcasing its initial application in this field.IMPORTANCEHoney bees contribute significantly to food security by providing pollination services. Understanding the virome of honey bees is crucial for the health and conservation of bee populations and also for the stability of the ecosystems and economies for which they are indispensable. This study unveils previously unknown DNA viruses in the honey bee virome, expanding our knowledge of potential threats to bee health. The use of the viral binning approach we employed in this study offers a promising method to uncovering and understanding the vast viral diversity in these essential pollinators.

A first approach in the correlation of pathogens load affecting Bombus pauloensis to the land use in Buenos Aires Province

Bombus pauloensis is a native bumble bee species widely distributed over South America and a key pollinator for native plants and commercial crops. This species is affected by pathogens such as Nosema ceranae, Crithidia bombi and Apis mellifera Filamentous Virus (AmFV). This work aims to document the presence and intensity of exogenous pathogens on the native bumble bee B. pauloensis in different periods of the year during spring and summer. Bumble bees were sampled in four study areas with contrasting land uses to preliminary evaluate if anthropization levels can be related to the presence and intensity of pathogens. DNA was isolated from twenty individuals per sampling site and N. ceranae, C. bombi and AmFV pathogens load were quantified by quantitative PCR. The results showed a wide and ubiquitous prevalence of N. ceranae and C. bombi pathogens in all the sampled bumble bees throughout the year, with a pathogens load that did not differ significantly among the sampling sites. AmFV was undetected in any of the individuals analyzed in any sampling site. This suggests that human activities could equally impact all habitats populated by B. pauloensis. Honey bees were detected with a relevant abundance in all the sampling sites and could be one of the main anthropogenic drivers of pathogens spread and host switches in the analyzed sampling sites. This study analyzes the general occurrence of the prevalence and intensity of the pathogens in a native Argentinian bumble bee species and attempts the correlation with the land use

Data mining reveals tissue-specific expression and host lineage-associated forms of Apis mellifera filamentous virus.

Apis mellifera filamentous virus (AmFV) is a large double-stranded DNA virus of uncertain phylogenetic position that infects honey bees (Apis mellifera). Little is known about AmFV evolution or molecular aspects of infection. Accurate annotation of open-reading frames (ORFs) is challenged by weak homology to other known viruses. This study was undertaken to evaluate ORFs (including coding-frame conservation, codon bias, and purifying selection), quantify genetic variation within AmFV, identify host characteristics that covary with infection rate, and examine viral expression patterns in different tissues. Short-read data were accessed from the Sequence Read Archive (SRA) of the National Center for Biotechnology Information (NCBI). Sequence reads were downloaded from accessions meeting search criteria and scanned for kmers representative of AmFV genomic sequence. Samples with kmer counts above specified thresholds were downloaded in full for mapping to reference sequences and de novo assembly. At least three distinct evolutionary lineages of AmFV exist. Clade 1 predominates in Europe but in the Americas and Africa it is replaced by the other clades as infection level increases in hosts. Only clade 3 was found at high relative abundance in hosts with African ancestry, whereas all clades achieved high relative abundance in bees of non-African ancestry. In Europe and Africa, clade 2 was generally detected only in low-level infections but was locally dominant in some North American samples. The geographic distribution of clade 3 was consistent with an introduction to the Americas with 'Africanized' honey bees in the 1950s. Localized genomic regions of very high nucleotide divergence in individual isolates suggest recombination with additional, as-yet unidentified AmFV lineages. A set of 155 high-confidence ORFs was annotated based on evolutionary conservation in six AmFV genome sequences representative of the three clades. Pairwise protein-level identity averaged 94.6% across ORFs (range 77.1-100%), which generally exhibited low evolutionary rates and moderate to strong codon bias. However, no robust example of positive diversifying selection on coding sequence was found in these alignments. Most of the genome was detected in RNA short-read alignments. Transcriptome assembly often yielded contigs in excess of 50 kb and containing ORFs in both orientations, and the termini of long transcripts were associated with tandem repeats. Lower levels of AmFV RNA were detected in brain tissue compared to abdominal tissue, and a distinct set of ORFs had minimal to no detectable expression in brain tissue. A scan of DNA accessions from the parasitic mite Varroa destructor was inconclusive with respect to replication in that species. Collectively, these results expand our understanding of this enigmatic virus, revealing transcriptional complexity and co-evolutionary associations with host lineage.

First detection of Lake Sinai virus in the Czech Republic: a potential member of a new species.

Lake Sinai virus (LSV) is one of over 20 honey bee viruses. Variants of LSV have been classified as members of two officially recognised species, Lake Sinai virus 1 and Lake Sinai virus 2. However, there are currently a limited number of whole-genome sequences, and the genetic variability of the virus indicates that additional species may need to be established. Extracted nucleic acid of 209 honey bee samples was screened by PCR for 11 honey bee viruses. LSV was the third most abundant virus (36.9% of positive samples), after Apis mellifera filamentous virus (72.2%) and deformed wing virus (52.5%). LSV-positive samples were analyzed further by PCR with primers targeting the region encoding the viral RNA-dependent RNA polymerase. Subsequently, the PCR products were sequenced, and the resulting sequences were used for a first round of phylogenetic analysis. Based on those results, several isolates were selected for whole-genome sequencing, and the complete genome sequences were used for additional phylogenetic analysis. The results indicated the presence of at least three genetically distinct groups of LSV in the Czech Republic, the most prevalent one being related to LSV2 but too dissimilar to be considered a member of the same species. Two sequences of a major LSV strain cluster native to the Czech Republic were determined, representing the first Czech LSV strains published to date.

Genomics and proteomics of Apis mellifera filamentous virus isolated from honeybees in China.

Apis mellifera filamentous virus (AmFV) is a large DNA virus that is endemic in honeybee colonies. The genome sequence of the AmFV Swiss isolate (AmFV CH–C05) has been reported, but so far very few molecular studies have been conducted on this virus. In this study, we isolated and purified AmFV (AmFV CN) from Chinese honeybee (Apis mellifera) colonies and elucidated its genomics and proteomics. Electron microscopy showed ovoid purified virions with dimensions of 300–500 ​× ​210–285 ​nm, wrapping a 3165 ​× ​40 ​nm filamentous nucleocapsid in three figure-eight loops. Unlike AmFV CH–C05, which was reported to have a circular genome, our data suggest that AmFV CN has a linear genome of approximately 493 ​kb. A total of 197 ORFs were identified, among which 36 putative genes including 18 baculoviral homologs were annotated. The overall nucleotide similarity between the CN and CH–C05 isolates was 96.9%. Several ORFs were newly annotated in AmFV CN, including homologs of per os infectivity factor 4 (PIF4) and a putative integrase. Phylogenomic analysis placed AmFVs on a separate branch within the newly proposed virus class Naldaviricetes. Proteomic analysis revealed 47 AmFV virion-associated proteins, of which 14 had over 50% sequence coverage, suggesting that they are likely to be main structural proteins. In addition, all six of the annotated PIFs (PIF-0–5) were identified by proteomics, suggesting that they may function as entry factors in AmFV infection. This study provides fundamental information regarding the molecular biology of AmFV.

An Investigation of Honey Bee Viruses Prevalence in Managed Honey Bees (Apis mellifera and Apis cerana) Undergone Colony Decline

Objective: In the absence of known clinical symptoms, viruses were considered to be the most probable key pathogens of honey bee. Therefore, the aim of this study was to investigate the prevalence and distribution of honey bee viruses in managed Apis mellifera and Apis cerana in China. Methods: We conducted a screening of 8 honey bee viruses on A. mellifera and A. cerana samples collected from 54 apiaries from 13 provinces in China using RT-PCR. Results: We found that the types and numbers of viral species significantly differed between A. mellifera and A. cerana. Black Queen Cell Virus (BQCV), Chronic Bee Paralysis Virus (CBPV), Apis mellifera filamentous virus (AmFV), and Kakugo virus (DWV-A/KV) were the primary viruses found in A. mellifera colonies, whereas Chinese Sacbrood Bee Virus (CSBV) and Sacbrood Bee Virus (SBV) were the primary viruses found in A. cerana. The percentage infection of BQCV and CSBV were 84.6% and 61.6% in all detected samples. We first detected the occurrences of Varroa destructor virus-1 (VDV-1 or DWV-B) and DWV-A/KV in China but not ABPV in both A. mellifera and A. cerana. Conclusion: This study showed that BQCV and CSBV are the major threat to investigated A. mellifera and A. cerana colonies.

Metagenomic Approach with the NetoVIR Enrichment Protocol Reveals Virus Diversity within Ethiopian Honey Bees (Apis mellifera simensis).

Metagenomics studies have accelerated the discovery of novel or divergent viruses of the honey bee. However, most of these studies predominantly focused on RNA viruses, and many suffer from the relatively low abundance of viral nucleic acids in the samples (i.e., compared to that of the host). Here, we explored the virome of the Ethiopian honey bee, Apis mellifera simensis, using an unbiased metagenomic approach in which the next-generation sequencing step was preceded by an enrichment protocol for viral particles. Our study revealed five well-known bee viruses and 25 atypical virus species, most of which have never been found in A. mellifera before. The viruses belong to Iflaviridae, Dicistroviridae, Secoviridae, Partitiviridae, Parvoviridae, Potyviridae, and taxonomically unclassified families. Fifteen of these atypical viruses were most likely plant-specific, and the remaining ten were presumed to be insect-specific. Apis mellifera filamentous virus (AmFV) was found in one sampling site out of 10. Two samples contained high read counts of a virus similar to Diatraea saccharales densovirus (DsDNV), which is a virus that causes high mortality in the sugarcane borer. AmFV and the DsDNV-like virus were the only DNA viruses found. Three viruses that primarily infect Drosophila spp. were also discovered: La Jolla virus (LJV), Kilifi virus (KiV), and Thika virus. Our study suggests that phoretic varroa mites are involved in the transmission of LJV and KiV and that both viruses replicate in mites and adult bees. We also found an overwhelming dominance of the deformed wing virus type B variant, which fits well with the apparently harmless infestation by Varroa destructor. It was suggested that Ethiopian bees have developed tolerance against virus infections as the result of natural selection.

Molecular detection of bee pathogens in honey

Honey bees are affected by a wide variety of parasites and pathogens, some of them were previously found in bee honey. Considering that spore-forming microorganisms are expected to remain latent in raw honey, presence of microsporidia, spore-forming bacteria, and viruses protected by peptide structures might represent a threat for bees. It is widely known that parasites and pathogens are one of the main factors implied in the worldwide decline of wild pollinators and colony losses of managed bees, and their detection in honey could be used to prevent the spread of diseases among colonies. Honey from 57 apiaries of Argentina located in Buenos Aires, Córdoba, Corrientes, Entre Ríos, Formosa, La Rioja, Neuquén, Río Negro and Santa Fe provinces was collected between March and October, 2012. DNA was extracted from the pellet obtained by centrifugation of 10 g of honey and pathogen DNA was amplified by qPCR, and products were purified, sequenced and analysed using BLAST software. Honey from every apiary contained DNA of at least one pathogen, with a high occurrence ofApis mellifera filamentous virus (AmFV) andApicystis bombi, althoughNosema ceranae, Paenibacillus larvae, andAscosphaera apis were also detected. Here, we report the presence of DNA of several bee pathogens in honey from commercial apiaries, and provide a fast and efficient screening method that could be useful to indirectly estimate pathogen presence in apiaries.

Pathogens Detection in the Small Hive Beetle (Aethina tumida (Coleoptera: Nitidulidae)).

Aethina tumida Murray is currently a worldwide emergent pest of Apis mellifera L. hives. Although the damaging effect on the colony stores and brood is well known, the possible role of these beetles as a disease carrier is not clear. This is the first report of DNA presence of the trypanosome honeybee parasite Lotmaria passim and Crithidia bombi, and the Apis mellifera filamentous virus (AmFV) in A. tumida. Further studies will be needed to determine if A. tumida is indeed a mechanical or biological vector of these pathogens.

Shotgun sequencing of honey DNA can describe honey bee derived environmental signatures and the honey bee hologenome complexity

Honey bees are large-scale monitoring tools due to their extensive environmental exploration. In their activities and from the hive ecosystem complex, they get in close contact with many organisms whose traces can be transferred into the honey, which can represent an interesting reservoir of environmental DNA (eDNA) signatures and information useful to analyse the honey bee hologenome complexity. In this study, we tested a deep shotgun sequencing approach of honey DNA coupled with a specifically adapted bioinformatic pipeline. This methodology was applied to a few honey samples pointing out DNA sequences from 191 organisms spanning different kingdoms or phyla (viruses, bacteria, plants, fungi, protozoans, arthropods, mammals). Bacteria included the largest number of species. These multi-kingdom signatures listed common hive and honey bee gut microorganisms, honey bee pathogens, parasites and pests, which resembled a complex interplay that might provide a general picture of the honey bee pathosphere. Based on the Apis mellifera filamentous virus genome diversity (the most abundant detected DNA source) we obtained information that could define the origin of the honey at the apiary level. Mining Apis mellifera sequences made it possible to identify the honey bee subspecies both at the mitochondrial and nuclear genome levels.

Parasites and pathogens associated with native bumble bees (Hymenoptera: Apidae: Bombus spp.) from highlands in Bolivia and Peru

ABSTRACT Bumble bees of the genus Bombus spp. play a key role as effective pollinators in the biodiversity rich Central Andean region; however, parasites and pathogens may negatively influence their abundance and population numbers. In this study, we aimed at verifying the occurrence of these natural enemies in the Andes regions of Bolivia and Peru. Workers and males of Bombus funebris, Bombus opifex and Bombus pauloensis were collected in three localities from highlands at ~1,700 m.a.s.l. Analyses by both optical and molecular techniques revealed the presence of the Apis mellifera filamentous virus (AmFV), the microsporidium Vairimorpha ceranae, the flagellates Crithidia bombi and Lotmaria passim, and five species of mites in the genera Parasitellus Willmann, Pneumolaelaps Berlese, Proctolaelaps Berlese, Tyrophagus Oudemans, and Kuzinia Zachvatkin. Given the potential entry of the allochthonous bumble bee Bombus terrestris to the region, this information is essential to evaluate autochtonous biodiversity conservation strategies.

Phoretic mites on South American bumblebees (Bombus spp.) as parasite carriers: a historical input

Phoretic mites associated with bumblebees are considered commensals that represent little or no risk for their hosts. The aim of the present study was to assess the potential role of the phoretic mites Pneumolaelaps longanalis and Parasitellus fucorum, as carriers of parasites that are known to affect bees. Mites were extracted from bumblebees dating between 1945 and 1981 which belong to museum collections, and from a freshly collected queen. The DNA was extracted and amplified, and the final products were sequenced and analyzed. Parasite’s DNA was found in all samples. Ascosphaera spp., Crithidia bombi, Lotmaria passim, and Nosema ceranae were present in both mite species. Moreover, DNA from Apis mellifera filamentous virus (AmFV), Apicystis bombi, Ascosphaera apis, Nosema apis, and Nosema bombi was found in P. longanalis. This study represents the oldest report of parasite’s DNA in bumblebee phoretic mites, highlighting the relevance of museum samples for historical studies in parasitology.

Occurrence and Molecular Phylogeny of Honey Bee Viruses in Vespids.

Since the discovery that honey bee viruses play a role in colony decline, researchers have made major breakthroughs in understanding viral pathology and infection processes in honey bees. Work on virus transmission patterns and virus vectors, such as the mite Varroa destructor, has prompted intense efforts to manage honey bee health. However, little is known about the occurrence of honey bee viruses in bee predators, such as vespids. In this study, we characterized the occurrence of 11 honey bee viruses in five vespid species and one wasp from four provinces in China and two vespid species from four locations in France. The results showed that all the species from China carried certain honey bee viruses, notably Apis mellifera filamentous virus (AmFV), Deformed wing virus (DWV), and Israeli acute paralysis virus (IAPV); furthermore, in some vespid colonies, more than three different viruses were identified. In France, DWV was the most common virus; Sacbrood virus (SBV) and Black queen cell virus (BQCV) were observed in one and two samples, respectively. Phylogenetic analyses of IAPV and BQCV sequences indicated that most of the IAPV sequences belonged to a single group, while the BQCV sequences belonged to several groups. Additionally, our study is the first to detect Lake Sinai virus (LSV) in a hornet from China. Our findings can guide further research into the origin and transmission of honey bee viruses in Vespidae, a taxon of ecological, and potentially epidemiological, relevance.

First molecular detection of Apis mellifera filamentous virus (AmFV) in honey bees (Apis mellifera) in Argentina

Although many honey bee RNA viruses have been correlated with colony declines, little is known regarding the potential role of DNA viruses. Apis mellifera filamentous virus (AmFV) is a large double stranded DNA virus of honey bees and its prevalence and relationship with other parasites is poorly known. In the present work, we have described a high prevalence of AmFV in Argentinian apiaries, and a retrospective survey of archived honey bee samples revealed that AmFV has been present in Argentina since at least 2006. This is the first report involving AmFV in South America.

Occurrence of multiple honeybee viruses in the ectoparasitic mites Varroa spp. in Apis cerana colonies

In this study, we investigated the prevalence of honeybee viruses in Varroa destructor and Varroa underwoodi infesting Apis cerana colonies in China. Deformed wing virus (DWV) was the most prevalent virus in these two mite species, followed by Israeli acute paralysis virus (IAPV), Black queen cell virus (BQCV), Kashmir bee virus (KBV), Chronic bee paralysis virus (CBPV), Apis mellifera filamentous virus (AmFV) and Sacbrood virus (SBV) in V. destructor, while in V. underwoodi, it was followed by CBPV, AmFV, BQCV, IAPV and KBV. In addition, multiple viruses were commonly detectable in both mite species.

First molecular detection of Apis mellifera filamentous virus in honey bees (Apis mellifera) in Hungary

Western honey bees (Apis mellifera) are important pollinators in the ecosystem and also play a crucial economic role in the honey industry. During the last decades, a continuous decay was registered in honey bee populations worldwide, including Hungary. In our study, we used metagenomic approaches and conventional PCR screening on healthy and winter mortality affected colonies from multiple sites in Hungary. The major goal was to discover presumed bee pathogens with viral metagenomic experiments and gain prevalence and distribution data by targeted PCR screening. We examined 664 honey bee samples that had been collected during winter mortality from three seemingly healthy colonies and from one colony infested heavily by the parasitic mite Varroa destructor in 2016 and 2017. The subsequent PCR screening of honey bee samples revealed the abundant presence of Apis mellifera filamentous virus (AmFV) for the first time in Central Europe. Based on phylogeny reconstruction, the newly-detected virus was found to be most closely related to a Chinese AmFV strain. More sequence data from multiple countries would be needed for studying the detailed phylogeographical patterns and worldwide spreading process of AmFV. Here we report the prevalent presence of this virus in Hungarian honey bee colonies.