Slow Bee Paralysis Virus Research Articles

Caught in the act: the invasion of a viral vector changes viral prevalence and titre in native honeybees and bumblebees.

Novel transmission routes change pathogen landscapes and may facilitate disease emergence. The varroa mite is a virus vector that switched to western honeybees at the beginning of the last century, leading to hive mortality, particularly in combination with RNA viruses. A recent invasion of varroa on the French island of Ushant introduced vector-mediated transmission to one of the last varroa-naive native honeybee populations and caused rapid changes in the honeybee viral community. These changes were characterized by a drastic increase in deformed wing virus type B prevalence and titre in honeybees, as well as knock-on effects in bumblebees, particularly in the year following the invasion. Slow bee paralysis virus also appeared in honeybees and bumblebees, with a 1 year delay, while black queen cell virus declined in honeybees. This study highlights the rapid and far-reaching effects of vector-borne transmission that can extend beyond the directly affected host species, and that the direction of the effect depends on the pathogen's virulence.

Nationwide Screening for Bee Viruses in Apis mellifera Colonies in Egypt

Honey bees are essential for crop and wild plant pollination. However, many countries have reported high annual colony losses caused by multiple possible stressors. Diseases, particularly those caused by viruses, are a major cause of colony losses. However, little is known about the prevalence of honey bee pathogens, particularly virus prevalence, in Egyptian honey bees. To address this shortfall, we determined the prevalence of widespread bee viruses in honey bee colonies in Egypt-whether it is affected by geography, the season, or infestation with Varroa destructor (varroa) mites. Honey bee worker samples were collected from 18 geographical regions across Egypt during two seasons: winter and summer of 2021. Three apiaries were chosen in each region, and a pooled sample of 150 worker bees was collected from five colonies in each apiary then screened by qPCR for 10 viral targets: acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV) genotypes A (DWV-A), B (DWV-B) and D (Egyptian bee virus), Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV), sacbrood virus (SBV), and slow bee paralysis virus (SBPV). Our results revealed that DWV-A was the most prevalent virus, followed by BQCV and ABPV; the DWV genotype now spreading across the world, DWV-B, was not detected. There was no difference in varroa infestation rates as well as virus prevalence between winter and summer. However, colonies infected with BQCV had a significantly higher varroa count (adjusted p < 0.05) in the winter season, indicating that there is a seasonal association between the intensity of infestation by varroa and the presence of this virus. We provide data on the current virus prevalence in Egypt, which could assist in the protection of Egypt's beekeeping industry. Moreover, our study aids in the systematic assessment of the global honey bee virome by filling a knowledge gap about the prevalence of honey bee viruses in Egypt.

Honey bees and climate explain viral prevalence in wild bee communities on a continental scale

Viruses are omnipresent, yet the knowledge on drivers of viral prevalence in wild host populations is often limited. Biotic factors, such as sympatric managed host species, as well as abiotic factors, such as climatic variables, are likely to impact viral prevalence. Managed and wild bees, which harbor several multi-host viruses with a mostly fecal–oral between-species transmission route, provide an excellent system with which to test for the impact of biotic and abiotic factors on viral prevalence in wild host populations. Here we show on a continental scale that the prevalence of three broad host viruses: the AKI-complex (Acute bee paralysis virus, Kashmir bee virus and Israeli acute paralysis virus), Deformed wing virus, and Slow bee paralysis virus in wild bee populations (bumble bees and solitary bees) is positively related to viral prevalence of sympatric honey bees as well as being impacted by climatic variables. The former highlights the need for good beekeeping practices, including Varroa destructor management to reduce honey bee viral infection and hive placement. Furthermore, we found that viral prevalence in wild bees is at its lowest at the extreme ends of both temperature and precipitation ranges. Under predicted climate change, the frequency of extremes in precipitation and temperature will continue to increase and may hence impact viral prevalence in wild bee communities.

HONEYBEE VIRUSES PRESENCE IN SERBIAN APIARIES: A REVIEW

The honey bee Apis mellifera is an important beneficial insect recognized by production of honeybee products, having an important role in agricultural production through pollination, and play an equally crucial role in conserving the biodiversity in many natural ecosystems. According to available literature data, in the last more than 20 years, dramatic honey bee winter colony losses have been reported frequently all over the world that could have a direct influence on human food resources and can affect not only apiculture or agriculture, but also has an anthropological threats. One among many reasons for global bees-decline phenomenon is the influence of many viruses on honeybees’ health. Until today, in total, 36 viruses is detected in honey bees, and for many of them still without known pathogenicity on honeybees’ health. However, it is well known that some of these viruses like Acute Bee Paralysis Virus (ABPV), Chronic Bee Paralysis Virus (CBPV), Deformed Wing Virus (DWV), Black Queen Cell Virus (BQCV), Sacbrood Virus (SBV), Kashmir Bee Virus (KBV), Israeli Acute Paralysis Virus (IAPV), Slow bee paralysis virus (SBPV), Varroa destructor virus (VDV1) and some others has direct or indirect influence on individual honeybee or on whole honeybees colony health. In this paper the review of existing literature data on the presence, prevalence and characterization of honeybee viruses detected in honeybee colonies and apiaries from different regions in Serbia from first detection of their presence in 1986 till nowadays is presented and discussed.

Honey bee viruses are highly prevalent but at low intensities in wild pollinators of cucurbit agroecosystems

Managed and wild bee populations are in decline around the globe due to several biotic and abiotic stressors. Pathogenic viruses associated with the Western honey bee (Apis mellifera) have been identified as key contributors to losses of managed honey bee colonies, and are known to be transmitted to wild bee populations through shared floral resources. However, little is known about the prevalence and intensity of these viruses in wild bee populations, or how bee visitation to flowers impacts viral transmission in agroecosystems. This study surveyed honey bee, bumble bee (Bombus impatiens) and wild squash bee (Eucera (Peponapis) pruinosa) populations in Cucurbita agroecosystems across Pennsylvania (USA) for the prevalence and intensity of five honey bee viruses: acute bee paralysis virus (ABPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV), and slow bee paralysis virus (SBPV). We investigated the potential role of bee visitation rate to flowers on DWV intensity among species in the pollinator community, with the expectation that increased bee visitation to flowers would increase the opportunity for transmission events between host species. We found that honey bee viruses are highly prevalent but in lower titers in wild E. pruinosa and B. impatiens than in A. mellifera populations throughout Pennsylvania (USA). DWV was detected in 88% of B. impatiens, 48% of E. pruinosa, and 95% of A. mellifera. IAPV was detected in 5% of B. impatiens and 4% of E. pruinosa, compared to 9% in A. mellifera. KBV was detected in 1% of B. impatiens and 5% of E. pruinosa, compared to 32% in A. mellifera. Our results indicate that DWV titers are not correlated with bee visitation in Cucurbita fields. The potential fitness impacts of these low viral titers detected in E. pruinosa remain to be investigated.

Transovarial transmission of a core virome in the Chagas disease vector Rhodnius prolixus.

Triatomine assassin bugs comprise hematophagous insect vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Although the microbiome of these species has been investigated to some extent, only one virus infecting Triatoma infestans has been identified to date. Here, we describe for the first time seven (+) single-strand RNA viruses (RpV1-7) infecting Rhodnius prolixus, a primary vector of Chagas disease in Central and South America. We show that the RpVs belong to the Iflaviridae, Permutotetraviridae and Solemoviridae and are vertically transmitted from the mothers to the progeny via transovarial transmission. Consistent with this, all the RpVs, except RpV2 that is related to the entomopathogenic Slow bee paralysis virus, established persistent infections in our R. prolixus colony. Furthermore, we show that R. prolixus ovaries express 22-nucleotide viral siRNAs (vsiRNAs), but not viral piRNAs, that originate from the processing of dsRNA intermediates during viral replication of the RpVs. Interestingly, the permutotetraviruses and sobemoviruses display shared pools of vsiRNAs that might provide the basis for a cross-immunity system. The vsiRNAs are maternally deposited in the eggs, where they likely contribute to reduce the viral load and protect the developing embryos. Our results unveil for the first time a complex core virome in R. prolixus and begin to shed light on the RNAi-based antiviral defenses in triatomines.

Virus Prevalence and Genetic Diversity Across a Wild Bumblebee Community.

Viruses are key population regulators, but we have limited knowledge of the diversity and ecology of viruses. This is even the case in wild host populations that provide ecosystem services, where small fitness effects may have major ecological impacts in aggregate. One such group of hosts are the bumblebees, which have a major role in the pollination of food crops and have suffered population declines and range contractions in recent decades. In this study, we investigate the diversity of four recently discovered bumblebee viruses (Mayfield virus 1, Mayfield virus 2, River Liunaeg virus, and Loch Morlich virus), and two previously known viruses that infect both wild bumblebees and managed honeybees (Acute bee paralysis virus and Slow bee paralysis virus) from isolates in Scotland. We investigate the ecological and environmental factors that determine viral presence and absence. We show that the recently discovered bumblebee viruses were more genetically diverse than the viruses shared with honeybees. Coinfection is potentially important in shaping prevalence: we found a strong positive association between River Liunaeg virus and Loch Morlich virus presence after controlling for host species, location and other relevant ecological variables. We tested for a relationship between environmental variables (temperature, UV radiation, wind speed, and prevalence), but as we had few sampling sites, and thus low power for site-level analyses, we could not conclude anything regarding these variables. We also describe the relationship between the bumblebee communities at our sampling sites. This study represents a first step in the description of predictors of bumblebee infection in the wild.

The Bee Hemolymph Metabolome: A Window into the Impact of Viruses on Bumble Bees.

State-of-the-art virus detection technology has advanced a lot, yet technology to evaluate the impacts of viruses on bee physiology and health is basically lacking. However, such technology is sorely needed to understand how multi-host viruses can impact the composition of the bee community. Here, we evaluated the potential of hemolymph metabolites as biomarkers to identify the viral infection status in bees. A metabolomics strategy based on ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry was implemented. First, we constructed a predictive model for standardized bumble bees, in which non-infected bees were metabolically differentiated from an overt Israeli acute paralysis virus (IAPV) infection (R2Y = 0.993; Q2 = 0.906), as well as a covert slow bee paralysis virus (SBPV) infection (R2Y = 0.999; Q2 = 0.875). Second, two sets of potential biomarkers were identified, being descriptors for the metabolomic changes in the bee’s hemolymph following viral infection. Third, the biomarker sets were evaluated in a new dataset only containing wild bees and successfully discriminated virus infection versus non-virus infection with an AUC of 0.985. We concluded that screening hemolymph metabolite markers can underpin physiological changes linked to virus infection dynamics, opening promising avenues to identify, monitor, and predict the effects of virus infection in a bee community within a specific environment.

Capsid opening enables genome release of iflaviruses.

The family Iflaviridae includes economically important viruses of the western honeybee such as deformed wing virus, slow bee paralysis virus, and sacbrood virus. Iflaviruses have nonenveloped virions and capsids organized with icosahedral symmetry. The genome release of iflaviruses can be induced in vitro by exposure to acidic pH, implying that they enter cells by endocytosis. Genome release intermediates of iflaviruses have not been structurally characterized. Here, we show that conformational changes and expansion of iflavirus RNA genomes, which are induced by acidic pH, trigger the opening of iflavirus particles. Capsids of slow bee paralysis virus and sacbrood virus crack into pieces. In contrast, capsids of deformed wing virus are more flexible and open like flowers to release their genomes. The large openings in iflavirus particles enable the fast exit of genomes from capsids, which decreases the probability of genome degradation by the RNases present in endosomes.

Viral impacts on honey bee populations: A review.

Honey bee is vital for pollination and ecological services, boosting crops productivity in terms of quality and quantity and production of colony products: wax, royal jelly, bee venom, honey, pollen and propolis. Honey bees are most important plant pollinators and almost one third of diet depends on bee’s pollination, worth billions of dollars. Hence the role that honey bees have in environment and their economic importance in food production, their health is of dominant significance. Honey bees can be infected by various pathogens like: viruses, bacteria, fungi, or infested by parasitic mites. At least more than 20 viruses have been identified to infect honey bees worldwide, generally from Dicistroviridae as well as Iflaviridae families, like ABPV (Acute Bee Paralysis Virus), BQCV (Black Queen Cell Virus), KBV (Kashmir Bee Virus), SBV (Sacbrood Virus), CBPV (Chronic bee paralysis virus), SBPV (Slow Bee Paralysis Virus) along with IAPV (Israeli acute paralysis virus), and DWV (Deformed Wing Virus) are prominent and cause infections harmful for honey bee colonies health. This issue about honey bee viruses demonstrates remarkably how diverse this field is, and considerable work has to be done to get a comprehensive interpretation of the bee virology.

Host density drives viral, but not trypanosome, transmission in a key pollinator.

Supplemental feeding of wildlife populations can locally increase the density of individuals, which may in turn impact disease dynamics. Flower strips are a widely used intervention in intensive agricultural systems to nutritionally support pollinators such as bees. Using a controlled experimental semi-field design, we asked how density impacts transmission of a virus and a trypanosome parasite in bumblebees. We manipulated bumblebee density by using different numbers of colonies within the same area of floral resource. In high-density compartments, slow bee paralysis virus was transmitted more quickly, resulting in higher prevalence and level of infection in bumblebee hosts. By contrast, there was no impact of density on the transmission of the trypanosome Crithidia bombi, which may reflect the ease with which this parasite is transmitted. These results suggest that agri-environment schemes such as flower strips, which are known to enhance the nutrition and survival of bumblebees, may also have negative impacts on pollinators through enhanced disease transmission. Future studies should assess how changing the design of these schemes could minimize disease transmission and thus maximise their health benefits to wild pollinators.

Contrasting impacts of a novel specialist vector on multihost viral pathogen epidemiology in wild and managed bees.

Typically, pathogens infect multiple host species. Such multihost pathogens can show considerable variation in their degree of infection and transmission specificity, which has important implications for potential disease emergence. Transmission of multihost pathogens can be driven by key host species and changes in such transmission networks can lead to disease emergence. We study two viruses that show contrasting patterns of prevalence and specificity in managed honeybees and wild bumblebees, black queen cell virus (BQCV) and slow bee paralysis virus (SBPV), in the context of the novel transmission route provided by the virus‐vectoring Varroa destructor. Our key result is that viral communities and RNA virus genetic variation are structured by location, not host species or V. destructor presence. Interspecific transmission is pervasive with the same viral variants circulating between pollinator hosts in each location; yet, we found virus‐specific host differences in prevalence and viral load. Importantly, V. destructor presence increases the prevalence in honeybees and, indirectly, in wild bumblebees, but in contrast to its impact on deformed wing virus (DWV), BQCV and SBPV viral loads are not increased by Varroa presence, and do not show genetic evidence of recent emergence. Effective control of Varroa in managed honeybee colonies is necessary to mitigate further disease emergence, and alleviate disease pressure on our vital wild bee populations. More generally, our results highlight the over‐riding importance of geographical location to the epidemiological outcome despite the complexity of multihost‐parasite interactions.

The Single von Willebrand factor C-domain protein (SVC) coding gene is not involved in the hymenoptaecin upregulation after Israeli acute paralysis virus (IAPV) injection in the bumblebee Bombus terrestris

Within insects, inductions of antimicrobial peptides (AMPs) have been reported after different virus challenges. It is believed that this link is not directly induced by the virus itself, but rather indirectly induced by secondary effects of virus infection. Here we explored if direct sensing of the virus could trigger AMP expression. Recently, a cytokine-like molecule vago, a member of the Single von Willebrand factor C-domain (SVC) protein family, has been shown to be induced by virus infection in a Dicer-2 dependent manner. SVCs are also reported to be responsive in relation to multiple environmental challenges including bacterial infections and the nutritional status in the model species Drosophila melanogaster. Within the bumblebee Bombus terrestris only one SVC member has been identified and is proven to be involved in both the host antiviral defense and the basal expression of AMP genes, thereby it is a possible candidate linking virus infection and AMPs induction. Here we showed that the injection of Israeli acute paralysis virus (IAPV) resulted in a higher hymenoptaecin expression at 1dpi. This expression is IAPV specific as neither injection of slow bee paralysis virus (SBPV) nor random dsRNA results in a similar induction at 1dpi. We could not prove that hymenoptaecin expression after IAPV treatment was related to BtSVC, as a silencing experiment did not lower hymenoptaecin induction. This leaves indirect activation by secondary effects of IAPV infection as a mechanism of AMP genes induction, or that IAPV infection influences the AMP expression dynamics which is initially induced by non-virus related triggers.

Isolation and characterization of a new iflavirus from Armigeres spp. mosquitoes in the Philippines.

During an entomological surveillance for arthropod-borne viruses in the Philippines, we isolated a previously unrecognized virus from female Armigeres spp. mosquitoes. Whole-genome sequencing, genetic characterization and phylogenetic analysis revealed that the isolated virus, designated Armigeres iflavirus (ArIFV), is a novel member of the iflaviruses (genus Iflavirus, family Iflaviridae) and phylogenetically related to Moku virus, Hubei odonate virus 4, slow bee paralysis virus and Graminella nigrifrons virus 1. To our knowledge, this is the first successful isolation of iflavirus from a dipteran insect. Spherical ArIFV particles of approximately 30 nm in diameter contained at least three major structural proteins. ArIFV multiplied to high titres (~109 p.f.u. ml-1) and formed clear plaques in a mosquito cell line, C6/36. Our findings provide new insights into the infection mechanism, genetic diversity and evolution of the Iflaviridae family.

Slow Bee Paralysis Virus (SBPV) 신속 검출을 위한 초고속 역전사 중합효소 연쇄반응법의 개발

Slow Bee Paralysis Virus (SBPV)는 꿀벌 그리고 뒤영벌의 병원성 바이러스로써, 벌의 앞발을 마비시킴으로 폐사를 야기한다. 본 연구는, 뒤영벌에서 빠르게 SBPV 검출하고자 SBPV 특이 초고속 PCR법을 개발한 것을 보고하는 것이다.BR SBPV 특이 초고속 PCR은 제반 조건을 최적화한 후, 1.0×108 분자의 SBPV 특이 유전자의 존재를 3분 35초 만에 인식할 수 있었으며, 최소 1.0×101 분자의 DNA까지 정량적으로 측정할 수 있었다. 한편, 국내외에서 생산된 뒤영벌을 시료로 SBPV 특이 초고속 역전사 PCR을 시행하였으며, 수입된 뒤영벌과 국내생산 뒤영벌 1종에서 SBPV가 존재함을 보일 수 있었다. 국내 처음으로 뒤영벌에서의 SBPV의 존재를 확인한 것이다.BR SBPV 특이 유전자 초고속 역전사 PCR법은 실험실 내에서 뿐만 아니라 현장에서 정량적 검출을 하기에 유용한 방법이 될 것이며 더 나아가 뒤영벌 수출입을 위한 검역 기준을 이용하여 집단적 발병 방지에 기여하기를 기대한다.

Absence of deformed wing virus and Varroa destructor in Australia provides unique perspectives on honeybee viral landscapes and colony losses

Honeybee (Apis mellifera) health is threatened globally by the complex interaction of multiple stressors, including the parasitic mite Varroa destructor and a number of pathogenic viruses. Australia provides a unique opportunity to study this pathogenic viral landscape in the absence of V. destructor. We analysed 1,240A. mellifera colonies across Australia by reverse transcription-polymerase chain reaction (RT-PCR) and next-generation sequencing (NGS). Five viruses were prevalent: black queen cell virus (BQCV), sacbrood virus (SBV), Israeli acute paralysis virus (IAPV) and the Lake Sinai viruses (LSV1 and LSV2), of which the latter three were detected for the first time in Australia. We also showed several viruses were absent in our sampling, including deformed wing virus (DWV) and slow bee paralysis virus (SBPV). Our findings highlight that viruses can be highly prevalent in A. mellifera populations independently of V. destructor. Placing these results in an international context, our results support the hypothesis that the co-pathogenic interaction of V. destructor and DWV is a key driver of increased colony losses, but additional stressors such as pesticides, poor nutrition, etc. may enable more severe and frequent colony losses to occur.

Infections of virulent and avirulent viruses differentially influenced the expression of dicer-1, ago-1, and microRNAs in Bombus terrestris

The microRNA (miRNA) pathway is well established to be involved in host-pathogen interactions. As key insect pollinators, bees are suffering from widely spreading viruses, especially honeybees and bumblebees. In order to better understand bee-virus interaction, we comparatively analyzed the involvement of the bumblebee miRNA pathway upon infection by two different viruses. In our setup, an avirulent infection is induced by slow bee paralysis virus (SBPV) and a virulent infection is induced by Israeli acute paralysis virus (IAPV). Our results showed the increased expressions of dicer-1 and ago-1 upon SBPV infection. There were 17 and 12 bumblebee miRNAs differentially expressed upon SBPV and IAPV infections, respectively. These results may indicate the involvement of the host miRNA pathway in bumblebee-virus interaction. However, silencing of dicer-1 did not influence the genome copy number of SBPV. Target prediction for these differentially expressed miRNAs showed their possible involvement in targeting viral genomic RNA and in the regulation of networks in bumblebee. Our study opens a new insight into bee-virus interaction meditated by host miRNAs.

Condition-dependent virulence of slow bee paralysis virus in Bombus terrestris: are the impacts of honeybee viruses in wild pollinators underestimated?

Slow bee paralysis virus (SBPV)—previously considered an obligate honeybee disease—is now known to be prevalent in bumblebee species. SBPV is highly virulent in honeybees in association with Varroa mites, but has been considered relatively benign otherwise. However, condition-dependent pathogens can appear asymptomatic under good, resource abundant conditions, and negative impacts on host fitness may only become apparent when under stressful or resource-limited conditions. We tested whether SBPV expresses condition-dependent virulence in its bumblebee host, Bombus terrestris, by orally inoculating bees with SBPV and recording longevity under satiated and starvation conditions. SBPV infection resulted in significant virulence under starvation conditions, with infected bees 1.6 times more likely to die at any given time point (a median of 2.3 h earlier than uninfected bees), whereas there was no effect under satiated conditions. This demonstrates clear condition-dependent virulence for SBPV in B. terrestris. Infections that appear asymptomatic in non-stressful laboratory assays may nevertheless have significant impacts under natural conditions in the wild. For multi-host pathogens such as SBPV, the use of sentinel host species in laboratory assays may further lead to the underestimation of pathogen impacts on other species in nature. In this case the impact of ‘honeybee viruses’ on wild pollinators may be underestimated, with detrimental effects on conservation and food security. Our results highlight the importance of multiple assays and multiple host species when testing for virulence, in order for laboratory studies to accurately inform conservation policy and mitigate disease impacts in wild pollinators.

Cryo-EM study of slow bee paralysis virus at low pH reveals iflavirus genome release mechanism

Viruses from the family Iflaviridae are insect pathogens. Many of them, including slow bee paralysis virus (SBPV), cause lethal diseases in honeybees and bumblebees, resulting in agricultural losses. Iflaviruses have nonenveloped icosahedral virions containing single-stranded RNA genomes. However, their genome release mechanism is unknown. Here, we show that low pH promotes SBPV genome release, indicating that the virus may use endosomes to enter host cells. We used cryo-EM to study a heterogeneous population of SBPV virions at pH 5.5. We determined the structures of SBPV particles before and after genome release to resolutions of 3.3 and 3.4 Å, respectively. The capsids of SBPV virions in low pH are not expanded. Thus, SBPV does not appear to form "altered" particles with pores in their capsids before genome release, as is the case in many related picornaviruses. The egress of the genome from SBPV virions is associated with a loss of interpentamer contacts mediated by N-terminal arms of VP2 capsid proteins, which result in the expansion of the capsid. Pores that are 7 Å in diameter form around icosahedral threefold symmetry axes. We speculate that they serve as channels for the genome release. Our findings provide an atomic-level characterization of the genome release mechanism of iflaviruses.

Prevalence of honeybee viruses in different regions of China and Argentina.

Honeybees are threatened by various pathogens and parasites. More than 18 viruses have been described in honeybees and many of them have been detected in China and Argentina. In China, both Apis cerana and Apis mellifera are raised. In Argentina, beekeepers raise different ecotypes of A. mellifera: European honeybees (in both temperate and subtropical regions) and Africanised honeybees (in subtropical areas only). A thorough study was carried out in both China and Argentina to analyse the current virus presence and distribution in different climatic zones and gather information on different bee species/subspecies. Adult honeybees were collected from apiaries in temperate and subtropical regions of China (including areas with exclusive populations of A. mellifera, areas where A. mellifera and A. cerana co-exist, and areas with exclusive populations of A. cerana) and Argentina. Six viruses, namely, deformed wing virus (DWV), black queen cell virus (BQCV), sacbrood virus (SBV), chronic bee paralysis virus (CBPV), acute bee paralysis virus (ABPV) and Israeli acute paralysis virus (IAPV) were detected in China, both in A. cerana and in A. mellifera, while four viruses (DWV, BQCV, CBPV and ABPV) were present in Argentina. Interestingly, multiple infections were commonly found in China, with up to five different viruses co-circulating in some colonies without apparent abnormalities. In this study, no Chinese samples were positive for slow bee paralysis virus. The most prevalent viruses were BQCV (China) and DWV (Argentina). Kashmir bee virus was absent from samples analysed for both countries.