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Viruses are one of the most potential risk factors that negatively affect the different life stages of honey bees. This study was conducted to determine the presence of infections caused by the deformed wing virus (DWV), black queen cell virus (BQCV), and acute bee paralysis virus (ABPV) in honey bees in the beekeeping regions of Burdur, along with obtaining information about their prevalence in this particular region. In our study, the adult bees were taken from 31 different beehives and comb samples that had different honey bee breeds and were sampled randomly from 15 beekeeping areas within the region. The collected samples were analyzed using the reverse transcriptase-polymerase chain reaction (RT-PCR), and the prevalence of DWV, BQCV, and ABPV infections were determined to be 74.19% (23/31), 25.81%, (8/31) and 74.19% (23/31), respectively. In this study, the distribution of positive samples and the rates of multiple infections were determined in the colonies. Of the positive honey bee samples, 12 (%38.71) were detected only for one virus, 9 (%29.03) were positive for two viruses (DWV-ABPV) and 8 (%25.81) were positive for all three viruses. In the present study, the presence of the three bee viruses that caused significant damage to the colonies by multiple infections in the Burdur region was determined with RT-PCR. To our knowledge, this is the first report of three mentioned bee infections in honey bees in the Burdur region. The revealed epidemiological conditions lead to the conclusion that serious measures are needed to control these infections in this region.

There is increasing evidence that honeybees (Apis mellifera L.) can adapt naturally to survive Varroa destructor, the primary cause of colony mortality world-wide. Most of the adaptive traits of naturally varroa-surviving honeybees concern varroa reproduction. Here we investigate whether factors in the honeybee metagenome also contribute to this survival. The quantitative and qualitative composition of the bacterial and viral metagenome fluctuated greatly during the active season, but with little overall difference between varroa-surviving and varroa-susceptible colonies. The main exceptions were Bartonella apis and sacbrood virus, particularly during early spring and autumn. Bombella apis was also strongly associated with early and late season, though equally for all colonies. All three affect colony protein management and metabolism. Lake Sinai virus was more abundant in varroa-surviving colonies during the summer. Lake Sinai virus and deformed wing virus also showed a tendency towards seasonal genetic change, but without any distinction between varroa-surviving and varroa-susceptible colonies. Whether the changes in these taxa contribute to survival or reflect demographic differences between the colonies (or both) remains unclear.

Deformed wing virus (DWV) is considered among the most common pathogens in bee colonies worldwide. This virus is anticipated to contribute in causing the mass collapse of bee colonies and winter colony losses. The sequences and amino acids of proteins for some strains are currently available. So, tools of bioinformatics can be applied to investigate these sequences. The objective of this study was to investigate the genetic relationships between 21 strains of this virus isolated from honey bees in Europe, Asia, USA, New Zealand and Chile based on amino acids and protein sequences. Phylogenetic relationships were studied in combination with genetic network to understand mutations in the common ancestors. The results showed low number of mutations between strains of Asia and those of the USA, New Zealand, Chile and some European countries while high number of mutations was detected between those of Asia and Western European countries. The results showed the occurrence of mutations rapidly in the sequences of this virus with suggestion to its ability to adapt with different environments. Also, sequence and statistical analyses were used to shade more lights on the variations between strains. Additionally, some specific primers were deigned based on the protein sequences of these strains. These primers were tested against the full sequences of all strains and their ability to identify DWV strains was discussed. The current investigation extends the knowledge about this dangerous virus especially the obtained results were based on protein sequences of DWV strains.

Annual losses of honey bee colonies are high in the United States, with losses often attributed to the effects of the ectoparasitic mite, Varroa destructor, and its associated viruses (e.g., Deform...

Pollinators are in decline thanks to the combined stresses of disease, pesticides, habitat loss, and climate. Honey bees face numerous pests and pathogens but arguably none are as devastating as Deformed wing virus (DWV). Understanding host-pathogen interactions and virulence of DWV in honey bees is slowed by the lack of cost-effective high-throughput screening methods for viral infection. Currently, analysis of virus infection in bees and their colonies is tedious, requiring a well-equipped molecular biology laboratory and the use of hazardous chemicals. Here we describe virus clones tagged with green fluorescent protein (GFP) or nanoluciferase (nLuc) that provide high-throughput detection and quantification of virus infections. GFP fluorescence is measured noninvasively in living bees via commonly available long-wave UV light sources and a smartphone camera, or a standard ultraviolet transilluminator gel imaging system. Nonlethal monitoring with GFP allows continuous screening of virus growth and serves as a direct breeding tool for identifying honey bee parents with increased antiviral resistance. Expression using the nLuc reporter strongly correlates with virus infection levels and is especially sensitive. Using multiple reporters, it is also possible to visualize competition, differential virulence, and host tissue targeting by co-occuring pathogens. Finally, it is possible to directly assess the risk of cross-species "spillover" from honey bees to other pollinators and vice versa.

Research Highlight: Norton, A. M., Remnant, E. J., Tom, J., Buchmann, G., Blacquiere, T., & Beekman, M. (2021). Adaptation to vector-based transmission in a honeybee virus. Journal of Animal Ecology, 90, https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2656.13493. In their paper on the adaptation to vector-based transmission via the mite Varroa destructor in a honeybee virus, Norton et al. study how high versus low levels of a viral vector affect viral load and potential competition between two strains of Deformed Wing Virus, an important highly virulent bee virus with the potential to spill-over into other pollinators and bee-associated insect species. This paper addresses two very timely issues, on the one hand on viral evolutionary ecology in response to vector-borne transmission, and on the other hand providing much needed information on an important honey bee pathogen. Using a complex natural system, this study shows that vector-borne transmission, and the control of the vector, can select for complex host-pathogen-vector interactions and that adaptations to changing transmission landscapes in fast evolving pathogens can create conditions for emerging pathogens to transition to endemic diseases.

The contents of this repository consist of the code and data required to reproduce the analysis, figures, and model results of the 2021 Journal of Applied Ecology Paper entitled "Flowers as dirty doorknobs: Demonstration of a virus transmission mechanism between Apis mellifera and Bombus impatiens." by Burnham et al. Abstract: In light of bee declines, the importance of pollination services from managed and native bees to our agriculture and economy is of great political, scientific and public interest. Bee declines are recognized as a multi-faceted problem. Viruses, first observed in honeybees, have been documented in bumblebees as well, and the prevalence and load of some RNA viruses have been associated with the presence of managed honeybees. Shared flowers may be the bridge across which viruses pass between bees, but no study has yet demonstrated that bumblebees can pick up viruses while foraging on contaminated flowers. Here, we show that Deformed Wing Virus can be transmitted from infected honeybees to bumblebees through the use of shared red clover. We developed a set of differential equations motivated by our experiments to explore several control strategies. A key insight from the model is that managing Varroa-mediated transmission in honeybee colonies can potentially have a far greater reduction in bumblebee infection than simply reducing the number of honeybees. This study suggests that treating honeybees for the Varroa mite, a known vector of RNA viruses, and increasing floral abundance, may mitigate the spread of this virus through flowers., This project was funded, in part, by a Honeybee Health Grant from NAPPC.

Funding: Biotechnology and Biological Sciences Research Council (BBSRC), BB/M00337X/2. Deformed wing virus (DWV) is the most important globally distributed pathogen of honey bees and, when vectored by the ectoparasite Varroa destructor, is associated with high levels of colony losses. Divergent DWV types may differ in their pathogenicity and are reported to exhibit superinfection exclusion upon sequential infections, an inevitability in a Varroa-infested colony. We used a reverse genetic approach to investigate competition and interactions between genetically distinct or related virus strains, analysing viral load over time, tissue distribution with reporter gene-expressing viruses and recombination between virus variants. Transient competition occurred irrespective of the order of virus acquisition, indicating no directionality or dominance. Over longer periods, the ability to compete with a pre-existing infection correlated with the genetic divergence of the inoculae. Genetic recombination was observed throughout the DWV genome with recombinants accounting for ~2% of the population as determined by deep sequencing. We propose that superinfection exclusion, if it occurs at all, is a consequence of a cross-reactive RNAi response to the viruses involved, explaining the lack of dominance of one virus type over another. A better understanding of the consequences of dual- and superinfection will inform development of cross-protective honey bee vaccines and landscape-scale DWV transmission and evolution. Publisher PDF

Deformed wing virus (DWV) is one of the most widespread viral infections of European honey bee Apis mellifera L. worldwide. So far, this is the first study which tested the effect of different ratios of synthetic protein to fat (P : F) diets on the health of broodless nurseaged honey bees in the laboratory. The aim of the current study was to determine the load of DWV in the whole body of A. mellifera that were fed different ratios of P : F diets (25 : 1, 10 : 1, 5 : 1, 1 : 1, 1 : 5, 1 : 10, 1 : 12.5 and 1 : 0 as a control). The methods involved feeding bees the tested diets for 10 days and then measuring the virus titre using qPCR technique. The results showed that DWV concentration decreased as the fat content of diets consumed increased. The copy number of viral genomes declined from 7.5 × 105 in the zero-fat diet (1 : 0) to 1.6 × 102 virus genomes in 1 : 12.5 (P : F). We can conclude that there is a positive relationship between fat diets and bee immunity and overall results suggest a connection between fat diet and bee health, indicating that colony losses can be reduced by providing a certain protein and fat supplemental feeding.

Various viruses can infect honey bees, but deformed wing virus (DWV) is considered the most dangerous virus to them and has role in the sudden decline of bee colonies. This virus has different strains; however, there are no available studies to compare the characteristics of these strains utilizing bioinformatics. In this study, 27 strains of deformed wing virus were analyzed based on their sequences and their genetic relationships. Also, some primers were designed and tested to identify their ability to separate DWV strains. The percentages range from 28.99% to 29.63%, 22.28% to 22.78%, 15.73% to 16.28%, and 31.71% to 32.86% for nucleotides A, G, C, and T, respectively in all strains. The numbers of polymorphic sites as well as nucleotide diversity were highly similar in all strains. Statistical analyses generally showed the absence of high variations between sequences. Also, the phylogenetic tree classified strains into three groups. The network between strains of each group was established and discussed based on their geographical locations. Two groups contained strains from USA and Europe while one group contained strains from Asia. Rapid variations and mutations in the sequences of DWV were suggested. Notably, genetic studies on DWV are lacking in some geographical regions. The variations between strains detected in honey bees and other organisms were discussed. Four primers were designed and tested beside two reference primers. One of the designed primers showed the best results in binding with all DWV strains except one.

Tam Metin / Full Text SCI-Expanded Q4 WOS:000621715600006 Honey bee viruses may be of severe adverse effect on bee colonies. Till now, more than twenty honey bee viruses have been identified. The aim of this study was to investigate the prevalence of seven honey bee viruses, namely Israeli acute paralysis virus (IAPV), deformed wing virus (DWV), sacbrood virus (SBV), acute bee paralysis virus (ABPV), black queen cell virus (BQCV), Kashmir bee virus (KBV), and chronic bee paralysis virus (CBPV) using a multiplex reverse transcription polymerase chain reaction (mRT-PCR). A total of 111 apiaries were randomly selected and adult bees and larvae samples were obtained from seemingly healthy colonies located at Aegean region of west Turkey. The presence of black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), acute bee paralysis virus (ABPV), and sacbrood virus (SBV) was detected, while Israeli acute paralysis virus (IAPV) or Kashmir bee virus (KBV) couldn’t be detected in studied colonies. The results showed the virus with the highest prevalence was DWV followed by BQCV, ABPV, SBV, and CBPV. PCR products for DWV, BQCV, ABPV, SBV, CBPV were sequenced and compared to the Genbank database. The Turkish strains demonstrated heterogeneous populations of DWV, BQCV, and relatively homogenous populations of ABPV, CBPV, and SBV. Based on these results, SBV and CBPV had formed different branch and genotypes when compared to previous studies. In conclusion, this study provides information about the distinctive honey bee viruses for future researches in Turkey, which holds the largest number of managed colonies in Europe. Key words: Apis mellifera, deformed wing virus, black quenn cell virus, sacbrood virus, chronic bee paralysis virus, acute bee paralysis virus

The invasion of non-native bees to new ecological territories could spread novel pathogens causing emerging infectious diseases (EIDs) in native species. We provide novel information on the prevalence, load, and co-infection network of honey bee viruses, trypanosoma, microsporidia and neogregarinorida pathogens in native Bombus dahlbomii and non-native Bombus terrestris and Bombus ruderatus. Apicystis bombi and Crithidia bombi were highly prevalent (> 78%) in three bumble bee species, with high loads of these pathogens. Nosema bombi was detected only in B. terrestris (37%) and B. ruderatus (15%). Lotmaria passim was detected in low prevalence (

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.

Global pollinator declines as a result of emerging infectious diseases are of major concern. Managed honey bees (Apis mellifera) are susceptible to numerous parasites and pathogens, many of which appear to be transmissible to sympatric non-Apis taxa. The ectoparasitic mite Varroa destructor is considered to be the most significant threat to honey bees due to its role in vectoring RNA viruses, particularly Deformed wing virus (DWV). Vector transmission of DWV has resulted in the accumulation of high viral loads in honey bees and is often associated with colony death. DWV has two main genotypes, A and B. DWV-A was more prevalent during the initial phase of V. destructor establishment. In recent years, the global prevalence of DWV-B has increased, suggesting that DWV-B is better adapted to vector transmission than DWV-A. We aimed to determine the role vector transmission plays in DWV genotype prevalence at a colony level. We experimentally increased or decreased the number of V. destructor mites in honey bee colonies, and tracked DWV-A and DWV-B loads over a period of ten months. Our results show that the two DWV genotypes differ in their response to mite numbers. DWV-A accumulation in honey bees was positively correlated with mite numbers yet DWV-A was largely undetected in the absence of the mite. In contrast, colonies had high loads of DWV-B even when mite numbers were low. DWV-B loads persisted in miticide treated colonies, indicating that this genotype has a competitive advantage over DWV-A irrespective of mite numbers. Our findings suggest that the global increase in DWV-B prevalence is not driven by selective pressure by the vector. Rather, DWV-B is able to persist in colonies at higher viral loads relative to DWV-A in the presence and absence of V. destructor. The interplay between V. destructor and DWV genotypes within honey bee colonies may have broad consequences upon viral diversity in sympatric taxa as a result of spill-over.

Viral infection damages honeybee colony health. Viruses can be carried by queen bees and apicultural production materials when imported from foreign countries. We investigated seven honeybee viruses in worker bees (Apis mellifera) from 26 healthy apiaries in Gifu, Japan between 2018 and 2019. Black queen cell virus (BQCV) was detected in 23 (88.5%) of the apiaries, followed by Israeli acute paralysis virus (42.3%), deformed wing virus (DWV) (38.5%), and sacbrood virus (3.8%). In phylogenetic analysis, BQCV and DWV in Gifu were related to those in China and South Korea. Additionally, a high prevalence of BQCV was observed among worker bees in BQCV-positive colonies. Therefore, BQCV horizontal transmission among worker bees may contribute to the high prevalence of BQCV in Gifu.

The western honeybee is the primary pollinator of numerous food crops. Furthermore, honeybees are essential for ecosystem stability by sustaining the diversity and abundance of wild flowering plants. However, the worldwide population of honeybees is under pressure from environmental stress and pathogens. Viruses from the families Iflaviridae and Dicistroviridae, together with their vector, the parasitic mite Varroa destructor, are the major threat to the world's honeybees. Dicistroviruses and iflaviruses have capsids with icosahedral symmetries. Acidic pH triggers the genome release of both dicistroviruses and iflaviruses. The capsids of iflaviruses expand, whereas those of dicistroviruses remain compact until the genome release. Furthermore, dicistroviruses use inner capsid proteins, whereas iflaviruses employ protruding domains or minor capsid proteins from the virion surface to penetrate membranes and deliver their genomes into the cell cytoplasm. The structural characterization of the infection process opens up possibilities for the development of antiviral compounds.

Many studies have reported sudden and large-scale losses in honey bee colonies. There is no precise explanation for this happening, but it may be caused by the interaction of pathogenic viruses and ectoparasite Varroa destructor. Deformed-wing virus (DWV) is common in Apis mellifera L. and has been implicated in worldwide Varroa-associated colony losses. Hygienic behavior may be one of the ways that limit V. destructor infestation level and DWV load. The purpose of this research was to determine whether the selection of higher hygienic behavior is effective against V. destructor and DWV. Workers and pupae of A. m. anatoliaca were collected from colonies showing four generations of hygienic behaviodr, and non-hygienics were used as a control. Loads of DWV were investigated by one-step RT-qPCR, and the bottom-board method was used to allow mites count. The prevalence of DWV in pupae were higher in hygienic colonies (69.0%, average viral load 234.38) than control colonies (60.8% average viral load 937.70). However, the prevalence of worker bees infected with DWV was lower in hygienic colonies (41.3%, average viral load 181627.69) than in control's (66.0%, average viral load 241982.35). Although the averages of the Varroa counts were significantly different for both hygienic (28.92) and control colonies (108.90), we could not find any correlation between DWV loads of both workers and pupae in this study. When all these results are evaluated, the selection performed in terms of hygienic behavior can said to have been said successful against DWV.

Deformed wing virus (DWV) is an emerging honeybee pathogen that has appeared across the globe in the past 40 years. When transmitted by the parasitic varroa mite, it has been associated with the collapse of millions of colonies throughout the Northern Hemisphere. However, despite the presence of the mite in the Southern Hemisphere, infested colonies survive. This study investigated the prevalence of DWV genotypes A, B and C along with their viral loads in South Africa and compared the findings with recent data from Brazil, the UK and the USA. We found that DWV-B was the most prevalent genotype throughout South Africa, although the total DWV viral load was significantly lower (2.8E+07) than found in the Northern Hemisphere (2.8E+07 vs. 2.7E+10, p > 0.00001) and not significantly different to that found in Brazil (5E+06, p = 0.13). The differences in viral load can be explained by the mite resistance in Brazil and South Africa, since mite-infested cells containing high viral loads are removed by the bees, thus lowering the colony's viral burden. This behaviour is much less developed in the vast majority of honeybees in the Northern Hemisphere.

The neonicotinoid Clothianidin has a negative impact on NF-κB signaling and on immune responses controlled by this transcription factor, which can boost the proliferation of honey bee parasites and pathogens. This effect has been well documented for the replication of deformed wing virus (DWV) induced by Clothianidin in honey bees bearing an asymptomatic infection. Here, we conduct infestation experiments of treated bees to show that the immune-suppression exerted by Clothianidin is associated with an enhanced fertility of the parasitic mite Varroa destructor, as a possible consequence of a higher feeding efficiency. A conceptual model is proposed to describe the synergistic interactions among different stress agents acting on honey bees., Pesticides could increase bees’ susceptibility to parasites, but the nature of this interaction has been unclear. Here the authors show that the pesticide Clothianidin reduces the wound healing immune response in bees, allowing the ectoparasitic Varroa mites to consume more bee hemolymph and amplify reproduction.

Varroa destructor is an ectoparasitic mite of immature and adult honey bees that can transmit several single-stranded RNA viruses to its host. Varroa reproduce in brood cells, and mite populations increase as colonies produce brood in spring and summer. Mite numbers also can sharply rise, particularly in the fall, by the migration of varroa into hives on foragers. Colonies with high levels of varroa and viruses often die over the winter. Feeding colonies pollen might keep virus levels low and improve survival because of the positive effects of pollen on immunity and colony growth. We compared varroa and virus levels and overwinter survival in colonies with (fed) and without (unfed) supplemental pollen. We also measured the frequency of capturing foragers with mites (FWM) at colony entrances to determine its relationship to varroa and virus levels. Colonies fed supplemental pollen were larger than unfed colonies and survived longer. Varroa populations and levels of Deformed wing virus (DWV) rose throughout the season, and were similar between fed and unfed colonies. The growth of varroa populations was correlated with FWM in fed and unfed colonies, and significantly affected DWV levels. Increasing frequencies of FWM and the effects on varroa populations might reduce the positive influence of supplemental pollen on immune function. However, pollen feeding can stimulate colony growth and this can improve colony survival. Electronic supplementary material The online version of this article (10.1007/s10493-020-00562-7) contains supplementary material, which is available to authorized users.

Melipona colimana is a stingless bee endemic to the temperate regions of Jalisco, Mexico, where it provides pollinating services and is cultured for the production of honey and cerumen. There is little information about the sanitary status of M. colimana, but it is critical to know more about it to keep these bees healthy and productive. The proximity of M. colimana colonies to commercial honey bee (Apis mellifera) colonies could facilitate pathogens transmission between the two species. We determined the presence, replication, and levels of two variants of deformed wing virus (DWV-A and DWV-B), and black queen cell virus (BQCV) in samples of M. colimana and A. mellifera. We also compared the DWV-A variant with variants from other regions of the world. Both A. mellifera and M. colimana were positive to DWV-A and BQCV, but negative to DWV-B. Quantification analyses showed that A. mellifera had significantly higher levels of DWV-A and BQCV than did M. colimana. Additionally, evidence of DWV-A and BQCV replication in M. colimana was demonstrated by visualizing the minus-strand of DWV and BQCV RNA using tagged primers for RT-PCR. The DWV-A variant did not seem to be atypical compared to variants from other world regions. Due to the importance of M. colimana for the conservation of regional ecosystems as well as for its use for honey and cerumen production, the potential impact of multiplying honey bee viruses in M. colimana populations deserves further investigation.

Crop pollination by the western honey bee Apis mellifera is vital to agriculture but threatened by alarmingly high levels of colony mortality, especially in Europe and North America. Colony loss is due, in part, to the high viral loads of Deformed wing virus (DWV), transmitted by the ectoparasitic mite Varroa destructor, especially throughout the overwintering period of a honey bee colony. Covert DWV infection is commonplace and has been causally linked to precocious foraging, which itself has been linked to colony loss. Taking advantage of four brain transcriptome studies that unexpectedly revealed evidence of covert DWV-A infection, we set out to explore whether this effect is due to DWV-A mimicking naturally occurring changes in brain gene expression that are associated with behavioral maturation. Consistent with this hypothesis, we found that brain gene expression profiles of DWV-A infected bees resembled those of foragers, even in individuals that were much younger than typical foragers. In addition, brain transcriptional regulatory network analysis revealed a positive association between DWV-A infection and transcription factors previously associated with honey bee foraging behavior. Surprisingly, single-cell RNA-Sequencing implicated glia, not neurons, in this effect; there are relatively few glial cells in the insect brain and they are rarely associated with behavioral plasticity. Covert DWV-A infection also has been linked to impaired learning, which together with precocious foraging can lead to increased occurrence of infected bees from one colony mistakenly entering another colony, especially under crowded modern apiary conditions. These findings provide new insights into the mechanisms by which DWV-A affects honey bee health and colony survival.

Deformed wing virus (DWV) infection is believed to be closely associated with colony losses of honeybee ( Apis mellifera ) due to reduced learning and memory of infected bees. The adenosine (Ado) pathway is important for maintaining immunity and memory function in animals, and it enhances antivirus responses by regulating carbohydrate metabolism in insects. Nevertheless, its effect on the memory of invertebrates is not yet clear. This study investigated how the Ado pathway regulates energy metabolism and memory in honeybees following DWV infection. Decreased Ado receptor (Ado-R) expression in the brain of infected bees resulted in a carbohydrate imbalance as well as impairments of glutamate-glutamine (Glu-Gln) cycle and long-term memory. Dietary supplementation with Ado not only increased the brain energy metabolism but also rescued long-term memory loss by upregulating the expression of memory-related genes. The present study demonstrated the regulation of the Ado pathway upon DWV infection and provides insights into the mechanisms underlying energy regulation and the neurological function of honeybees.

Migratory beekeeping is a widely extended practice aimed at increasing the yield of products and pollination services of honey bee colonies. However, it represents a stress factor, as it facilitates the dissemination of diseases and may compromise the genetic identity of the colonies involved. To analyze the extent of these effects, pathogens infestation rate and genetic composition were monitored in a field experiment comparing stationary and migratory colonies sharing the same environmental conditions but differing in management (stationary vs. migratory) and genetic background. We studied the pathogens infestation rate (Varroa destructor, Nosema spp., and Deformed Wing Virus (DWV)) at four different times: before migratory operation, two weeks later, at the end of the migratory period, and two weeks after the return of the migratory hives. An increased incidence of V. destructor and Nosema ceranae and a lower DWV viral load were found in migratory colonies. Temporary changes in genetic diversity were detected regardless of colony type, suggesting that stressors other than management affect the genetic diversity of the colonies. Our study demonstrates that migratory practices have variable effects on the health and genetic diversity of honey bee colonies, which should be taken into account for the development of sustainable beekeeping.

Western honey bees (Apis mellifera), a cornerstone to crop pollination in the U.S., are faced with an onslaught of challenges from diseases caused by parasites, pathogens, and pests that affect this economically valuable pollinator. Natural products (NPs), produced by living organisms, including plants and microorganisms, can support health and combat disease in animals. NPs include both native extracts and individual compounds that can reduce disease impacts by supporting immunity or directly inhibiting pathogens, pests, and parasites. Herein, we describe the screening of NPs in laboratory cage studies for their effects on honey bee disease prevention and control. Depending on the expected activity of compounds, we measured varied responses, including viral levels, honey bee immune responses, and symbiotic bacteria loads. Of the NPs screened, several compounds demonstrated beneficial activities in honey bees by reducing levels of the critical honey bee virus deformed wing virus (DWV-A and-B), positively impacting the gut microbiome or stimulating honey bee immune responses. Investigations of the medicinal properties of NPs in honey bees will contribute to a better understanding of their potential to support honey bee immunity to fight off pests and pathogens and promote increased overall honey bee health. These investigations will also shed light on the ecological interactions between pollinators and specific floral food sources.

Honey bees play a vital role in providing pollination services for agricultural crops and wild flowering plants. However, the spillover risk of their pathogens to other pollinators or wild insects is becoming a cause for concern. There is some evidence that stingless bees can carry honey bee viruses, but little is known about the presence of honey bee viruses in stingless bees in China. Here, we investigate the occurrence of major honey bee pathogens including bacteria, fungi, and viruses in stingless bees (Apidae: sp.). Our results show that the stingless bees (Apidae: sp.) were mainly infected with DWV-A, but no DWV-B and DWV-C. Phylogenetic analysis on fragments of lp, RdRp, and VP3 of DWV-A indicated that genetic variation in VP3 might an important indicator for host-specific viruses, but it requires further study. Our results indicated that DWV-A is not only the major strain of virus currently circulating in managed bee colonies in China and globally, but in stingless bee species as a whole.

Varroa mite-vectored viruses such as Deformed wing virus (DWV) are of great concern for honey bee health as they can cause disease in individuals and increase colony mortality. Two genotypes of DWV (A and B) are prevalent in the United States and may have differential virulence and pathogenicity. Honey bee genetic stocks bred to resist Varroa mites also exhibit differential infection responses to the Varroa mite-vectored viruses. The goal of this project was to determine if interactions between host genotype could influence the overall infection levels and dissemination of DWV within honey bees. To do this, we injected DWV isolated from symptomatic adult bees into mite-free, newly emerged adult bees from five genetic stocks with varying levels of resistance to Varroa mites. We measured DWV-A and DWV-B dissemination among tissues chosen based on relevance to general health outcomes for 10 days. Injury from sham injections did not increase DWV-A levels but did increase DWV-B infections. DWV injection increased both DWV-A and DWV-B levels over time with significant host stock interactions. While we did not observe any differences in viral dissemination among host stocks, we found differences in virus genotype dissemination to different body parts. DWV-A exhibited the highest initial levels in heads and legs while the highest initial levels of DWV-B were found in heads and abdomens. These interactions underscore the need to evaluate viral genotype and tissue specificity in conjunction with host genotype, particularly when the host has been selected for traits relative to virus-vector and virus resistance.

Understanding how vectors alter the interactions between viruses and their hosts is a fundamental question in virology and disease ecology. In honey bees, transmission of deformed wing virus (DWV) by parasitic Varroa mites has been associated with elevated disease and host mortality, and Varroa transmission has been hypothesized to lead to increased viral titres or select for more virulent variants. Here, we mimicked Varroa transmission by serially passaging a mixed population of two DWV variants, A and B, by injection through in vitro reared honey bee pupae and tracking these viral populations through five passages. The DWV-A and DWV-B variant proportions shifted dynamically through passaging, with DWV-B outcompeting DWV-A after one passage, but levels of both variants becoming equivalent by Passage 5. Sequencing analysis revealed a dominant, recombinant DWV-B strain (DWV-A derived 5′ IRES region with the rest of the genome DWV-B), with low nucleotide diversity that decreased through passaging. DWV-A populations had higher nucleotide diversity compared to DWV-B, but this also decreased through passaging. Selection signatures were found across functional regions of the DWV-A and DWV-B genomes, including amino acid mutations in the putative capsid protein region. Simulated vector transmission differentially impacted two closely related viral variants which could influence viral interactions with the host, demonstrating surprising plasticity in vector-host-viral dynamics.

Infectious and parasitic diseases plague honey bees similarly to that of other food animal species. A complete understanding of each is necessary for a honey bee veterinarian to establish a strong veterinarian-client-patient relationship and make sound treatment recommendations. Control and management of these diseases is paramount to success of the colony and apiary operation. The following is not meant to be an end-all of information on each of the common honey bee diseases but more so a review and photo-documentation of each. A deeper understanding can be established through various other sources previously published and referenced in this document.

Summary Impairment in the learning/memory behavior of bees is responsible for the massive disappearance of bee populations and its consequent agricultural economic losses. Such impairment might be because of o both pesticide exposure and pathogen infection, with a key contributor deformed wing virus (DWV). The present study found that sodium butyrate (NaB) significantly increased survival and reversed the learning/memory impairment of DWV-infected bees. A next-generation sequencing analysis showed that NaB affected the expression of genes involved in glycolytic processes and memory formation, which were suppressed by DWV infection. In addition, we performed a large-scale movement tracking experiment by using a wireless sensor network-based automatic real-time monitoring system and confirmed that NaB could improve the homing ability of DWV-infected bees. In short, we demonstrated the mechanism of how epigenetic regulation can resume the memory function of honeybees and suggest strategies for applying NaB to reduce the incidence of colony losses., Graphical abstract, Highlights • Sodium butyrate (NaB) reversed learning ability of bees infected by deformed wing virus • RNA-Seq showed NaB restored the expression of genes involved in glycolysis and memory • NaB improved the homing ability of deformed wing virus-infected bees, Entomology; Ethology; Molecular biology; Omics

Simple Summary Honey bees, Apis melllifera, are the most commonly managed bee in the world for pollination services. However, worldwide continuous colony losses have been reported for almost a decade. One factor of these losses is associated to pathogens being the virus one of the most important problems in honey bee health. One of the known viruses that affect the honey bee population is deformed wing virus (DWV). DWV causes physical malformation and behavioral disturbances, but also, this virus can be found in the antenna affecting the anatomical integrity of infected areas, which could compromise normal antennal functioning associated to aroma perception. Thus, we evaluate olfactory sensitivity and the expression of antenna-specific odorant-binding proteins (OBP) genes in honey bees inoculated with variant A of the DWV. We performed olfactory sensitivity analysis using the essential oils Eucalyptus globulus and Mentha piperita, but also, and molecular analysis of gene expression of nine OBPs. We found that the high level of replication of DWV-A in the antennae decreased the olfactory sensitivity and led to a down-regulation of some OBPs in middle- and forager-age worker bees. Thus, DWV-A infection in adults of honey bees could compromise volatile compound recognition inside the hive and outside the hive. Abstract Insects have a highly sensitive sense of smell, allowing them to perform complex behaviors, such as foraging and peer recognition. Their sense of smell is based on the recognition of ligands and is mainly coordinated by odorant-binding proteins (OBPs). In Apis mellifera, behavior can be affected by different pathogens, including deformed wing virus (DWV) and its variants. In particular, it has been shown that variant A of DWV (DWV-A) is capable of altering the ultra-cellular structure associated with olfactory activity. In this study was evaluated olfactory sensitivity and the expression of OBP genes in honey bees inoculated with DWV-A. Electroantennographic analyses (EAG) were carried out to determine the olfactory sensitivity to the essential oils Eucalyptus globulus and Mentha piperita. The expression of nine antenna-specific OBP genes and DWV-A load in inoculated bees was also quantified by qPCR. We observed an inverse relationship between viral load and olfactory sensitivity and the expression of some OBP proteins. Thus, high viral loads reduced olfactory sensitivity to essential oils and the gene expression of the OBP2, OBP5, OBP11, and OBP12 proteins on the antennas of middle- and forager-age bees. These results suggest that DWV-A could have negative effects on the processes of aroma perception by worker bees, affecting their performance in tasks carried out in and outside the colony.

Deformed wing virus (DWV) has been linked to the global decline of honey bees. DWV exists as three master variants (DWV-A, DWV-B, and DWV-C), each with differing outcomes for the honey bee host. Research in the USA showed a shift from DWV-A to DWV-B between 2010 to 2016 in honey bee colonies. Likewise, in the UK, a small study in 2007 found only DWV-A, whereas in 2016, DWV-B was the most prevalent variant. This suggests a shift from DWV-A to DWV-B might have occurred in the UK between 2007 and 2016. To investigate this further, data from samples collected in 2009/10 (n = 46) were compared to existing data from 2016 (n = 42). These samples also allowed a comparison of DWV variants between Varroa-untreated (feral) and Varroa-treated (managed) colonies. The results revealed that, in the UK, DWV-A was far more prevalent in 2009/10 (87%) than in 2016 (43%). In contrast, DWV-B was less prevalent in 2009/10 (76%) than in 2016 (93%). Regardless if colonies had been treated for Varroa (managed) or not (feral), the same trend from DWV-A to DWV-B occurred. Overall, the results reveal a decrease in DWV-A and an increase in DWV-B in UK colonies.

Western honey bees (Apis mellifera) are ecologically, agriculturally, and economically important plant pollinators. High average annual losses of honey bee colonies in the US have been partially attributed to agrochemical exposure and virus infections. To examine the potential negative synergistic impacts of agrochemical exposure and virus infection, as well as the potential promise of phytochemicals to ameliorate the impact of pathogenic infections on honey bees, we infected bees with a panel of viruses (i.e., Flock House virus, deformed wing virus, or Sindbis virus) and exposed to one of three chemical compounds. Specifically, honey bees were fed sucrose syrup containing: (1) thyme oil, a phytochemical and putative immune stimulant, (2) fumagillin, a beekeeper applied fungicide, or (3) clothianidin, a grower-applied insecticide. We determined that virus abundance was lower in honey bees fed 0.16 ppb thyme oil augmented sucrose syrup, compared to bees fed sucrose syrup alone. Parallel analysis of honey bee gene expression revealed that honey bees fed thyme oil augmented sucrose syrup had higher expression of key RNAi genes (argonaute-2 and dicer-like), antimicrobial peptide expressing genes (abaecin and hymenoptaecin), and vitellogenin, a putative honey bee health and age indicator, compared to bees fed only sucrose syrup. Virus abundance was higher in bees fed fumagillin (25 ppm or 75 ppm) or 1 ppb clothianidin containing sucrose syrup relative to levels in bees fed only sucrose syrup. Whereas, honey bees fed 10 ppb clothianidin had lower virus levels, likely because consuming a near lethal dose of insecticide made them poor hosts for virus infection. The negative impact of fumagillin and clothianidin on honey bee health was indicated by the lower expression of argonaute-2, dicer-like, abaecin, and hymenoptaecin, and vitellogenin. Together, these results indicate that chemical stimulants and stressors impact the outcome of virus infection and immune gene expression in honey bees.

Background Varroa destructor mites, and the numerous viruses they vector to their honey bee hosts, are among the most serious threats to honey bee populations, causing mortality and morbidity to both the individual honey bee and colony, the negative effects of which convey to the pollination services provided by honey bees worldwide. Here we use a combination of targeted assays and deep RNA sequencing to determine host and microbial changes in resistant and susceptible honey bee lineages. We focus on three study sets. The first involves field sampling of sympatric western bees, some derived from resistant stock and some from stock susceptible to mites. The second experiment contrasts three colonies more deeply, two from susceptible stock from the southeastern U.S. and one from mite-resistant bee stock from Eastern Texas. Finally, to decouple the effects of mites from those of the viruses they vector, we experimentally expose honey bees to DWV in the laboratory, measuring viral growth and host responses. Results We find strong differences between resistant and susceptible bees in terms of both viral loads and bee gene expression. Interestingly, lineages of bees with naturally low levels of the mite-vectored Deformed wing virus, also carried lower levels of viruses not vectored by mites. By mapping gene expression results against current ontologies and other studies, we describe the impacts of mite parasitism, as well as viruses on bee health against two genetic backgrounds. We identify numerous genes and processes seen in other studies of stress and disease in honey bee colonies, alongside novel genes and new patterns of expression. Conclusions We provide evidence that honey bees surviving in the face of parasitic mites do so through their abilities to resist the presence of devastating viruses vectored by these mites. In all cases, the most divergence between stocks was seen when bees were exposed to live mites or viruses, suggesting that gene activation, rather than constitutive expression, is key for these interactions. By revealing responses to viral infection and mite parasitism in different lineages, our data identify candidate proteins for the evolution of mite tolerance and virus resistance.

The most important ectoparasite of the honeybee is the remarkably adaptive mite Varroa destructor. The Varroa mite is a competent vector of Deformed Wing Virus (DWV), the Varroa-virus complex is one of the main factors associated with elevated annual honey bee colony mortality. Micro-RNAs (miRNAs) are small, non-coding RNAs of ~22-24 nucleotides, produced by all plants, animals, and viruses that influence biological processes through post-transcriptional regulation of gene expression. Knowledge of miRNAs and their functional role in mite biology remains limited. This study developed small RNA libraries from male and female V. destructor by utilizing Illumina's small RNA-Seq platform. A total of 101,913,208 and 91,904,732 small RNA reads (>18 nucleotides) from male and female mites were analyzed using the mirDeep2 algorithm. A conservative approach predicted a total of 306 miRNAs, of which 18 were upregulated and 13 were downregulated in female V. destructor compared to males. A qPCR assay validated the expression of selected differentially expressed female Varroa miRNAs. This dataset provides a list of potential miRNA targets involved in regulating vital Varroa biological processes and for deciphering new targets against Varroa and honey bee viruses they carry.

The near-globally distributed ecto-parasitic mite of theApis melliferahoneybee,Varroa destructor,has formed a lethal association with Deformed wing virus, a once rare and benign RNA virus. In concert, the two have killed millions of wild and managed colonies, particularly across the Northern Hemisphere, forcing the need for regular acaricide application to ensure colony survival. However, despite the short association (in evolutionary terms), a small but increasing number ofA. melliferapopulations across the globe have been surviving many years without any mite control methods. This long-term survival, orVarroaresistance, is consistently associated with the same suite of traits (recapping, brood removal and reduced mite reproduction) irrespective of location. Here we conduct an analysis of data extracted from 60 papers to illustrate how these traits connect together to explain decades of mite resistance data. We have potentially a unified understanding of naturalVarroaresistance that will help the global industry achieve widespread miticide-free beekeeping and indicate how different honeybee populations across four continents have resolved a recent threat using the same suite of behaviours.

The honey bee is of fundamental significance for the ecological balance of the planet and in effect, global crop and animal production. In recent years, the Deformed wing virus (DWV) has been recog...

The parasitic mite Varroa destructor and the viruses it transmits to honey bees (Apis mellifera) are often mentioned as culprits of colony losses. Therefore, surveys are conducted in different coun...

Tropilaelaps mercedesae parasitism can cause Apis mellifera colony mortality in Asia. Here, we report for the first time that tropilaelaps mites feed on both pre- and post-capped stages of honey bees. Feeding on pre-capped brood may extend their survival outside capped brood cells, especially in areas where brood production is year-round. In this study, we examined the types of injury inflicted by tropilaelaps mites on different stages of honey bees, the survival of adult honey bees, and level of honey bee viruses in 4th instar larvae and prepupae. The injuries inflicted on different developing honey bee stages were visualised by staining with trypan blue. Among pre-capped stages, 4th instar larvae sustained the highest number of wounds (4.6 ± 0.5/larva) while 2nd-3rd larval instars had at least two wounds. Consequently, wounds were evident on uninfested capped brood (5th-6th instar larvae = 3.91 ± 0.64 wounds; prepupae = 5.25 ± 0.73 wounds). Tropilaelaps mite infestations resulted in 3.4- and 6-fold increases in the number of wounds in 5th-6th instar larvae and prepupae as compared to uninfested capped brood, respectively. When wound-inflicted prepupae metamorphosed to white-eyed pupae, all wound scars disappeared with the exuviae. This healing of wounds contributed to the reduction of the number of wounds (≤10) observed on the different pupal stages. Transmission of mite-borne virus such as Deformed Wing Virus (DWV) was also enhanced by mites feeding on early larval stages. DWV and Black Queen Cell Virus (BQCV) were detected in all 4th instar larvae and prepupae analysed. However, viral levels were more pronounced in scarred 4th instar larvae and infested prepupae. The remarkably high numbers of wounds and viral load on scarred or infested developing honey bees may have caused significant weight loss and extensive injuries observed on the abdomen, wings, legs, proboscis and antennae of adult honey bees. Together, the survival of infested honey bees was significantly compromised. This study demonstrates the ability of tropilaelaps mites to inflict profound damage on A. mellifera hosts. Effective management approaches need to be developed to mitigate tropilaelaps mite problems.

The health of the honey bee Apis mellifera is challenged by introduced parasites that interact with its inherent pathogens and cause elevated rates of colony losses. To elucidate co‐occurrence, population dynamics, and synergistic interactions of honey bee pathogens, we established an array of diagnostic assays for a high‐throughput qPCR platform. Assuming that interaction of pathogens requires co‐occurrence within the same individual, single worker bees were analyzed instead of collective samples. Eleven viruses, four parasites, and three pathogenic bacteria were quantified in more than one thousand single bees sampled from sixteen disease‐free apiaries in Southwest Germany. The most abundant viruses were black queen cell virus (84%), Lake Sinai virus 1 (42%), and deformed wing virus B (35%). Forager bees from asymptomatic colonies were infected with two different viruses in average, and simultaneous infection with four to six viruses was common (14%). Also, the intestinal parasites Nosema ceranae (96%) and Crithidia mellificae/Lotmaria passim (52%) occurred very frequently. These results indicate that low‐level infections in honey bees are more common than previously assumed. All viruses showed seasonal variation, while N. ceranae did not. The foulbrood bacteria Paenibacillus larvae and Melissococcus plutonius were regionally distributed. Spearman's correlations and multiple regression analysis indicated possible synergistic interactions between the common pathogens, particularly for black queen cell virus. Beyond its suitability for further studies on honeybees, this targeted approach may be, due to its precision, capacity, and flexibility, a viable alternative to more expensive, sequencing‐based approaches in nonmodel systems., A comprehensive set of qPCR assays was established for the Biomark system (Fluidigm), which allows parallel quantification of all relevant honey bee pathogens. The method was applied on single‐bee samples from asymptomatic colonies in Southern Germany, and prevalences, population dynamics, and co‐occurrence patterns of the pathogens were analyzed.

International audience; AbstractVarroa destructor is an external parasite of Apis mellifera and feeds on the haemolymph of pupae and adult bees, vectoring numerous viral pathogens, in particular the deformed wing virus (DWV). However, the changes in haemolymph protein composition after Varroa infestation are unknown. The objective of this study was to investigate alterations in the haemolymph proteome in relation to Varroa parasitism. Using two-dimensional difference gel electrophoresis and MALDI-TOF/TOF mass spectrometry, we identified changes in 44 haemolymph proteins in response to the parasite and one in protein originated from DWV. The following pathways were affected by Varroa infestation, including carbohydrate metabolism, detoxification and oxidative stress response, nutrient reservoir activity, oxidoreductase activity and the olfactory system. Several physiological functions of honey bees, such as energy metabolism, detoxification, metamorphosis and chemosensing, may be disrupted by Varroa.

International audience; AbstractWestern honey bees (Apis mellifera) are key players in crop pollination and in the maintenance of global biodiversity. Their viability is threatened by Varroa destructor, which acts as a vector of the deformed wing virus (DWV). Several genetic DWV variants have been reported, but it is unclear whether their virulence differs. We examined the prevalence of V. destructor and DWV as well as bee health in two colonies over 21 months and then characterizing DWV variants from each colony using phylogenetics. Colony H showed no signs of disease or mortality, and DWV sequence from this colony clustered with VDV/DWV-B sequences previously reported in healthy colonies. Colony W showed DWV symptoms, and DWV sequence clustered with DWV-A sequences previously reported in colonies with symptoms. These results suggest that nucleotide variations in the DWV genome can affect its virulence. Genotyping DWV variants in colonies may be an effective tool to assess risk and initiate preventive measures early.

The health of the honey bee Apis mellifera is challenged by the ectoparasitic mite Varroa destructor, and the numerous harmful pathogens it vectors. Existing pesticide-based Varroa controls are not sustainable. In contrast, one promising approach for improved honey bee health is the breeding of hygienic bees, capable of detecting and removing brood that is parasitized or diseased. In three experiments we find evidence to support the hypothesis that stock-specific chemical brood signals are induced by Varroa and Deformed Wing Virus, and elicit hygienic response in the honey bee. By collecting, analyzing, and running bioassays involving mite-infested and control brood extracts from three honey bee breeding stocks we: 1) found evidence that a transferrable chemical signal for hygienic behavior is present in Varroa-infested brood extracts, 2) identified ten stock-specific hydrocarbons as candidates of hygienic signaling, and 3) found that two of these hydrocarbons linked to Varroa and DWV were also elevated in brood targeted for hygienic behavior. These findings expand our understanding of honey bee chemical communication, and facilitate the development of improved hygienic selection tools to breed honey bees with greater resistance to Varroa and associated pathogens.

International audience; The paradigm for all toxicological bioassays in the risk assessment of pesticide registration reflects the principle that experimental conditions should be controlled to avoid any other factors that may affect the endpoint measures. As honeybee colonies can be frequently exposed to bio-aggressors in real conditions, often concomitantly with pesticides, co-exposure to pesticide/bio-aggressors is becoming a concern for regulatory authorities. We investigated the effects of the neonicotinoid insecticide thiamethoxam on the homing performances of foragers emerging from colonies differentiated by health status (infestation with Varroa destructor mites, microsporidian parasite Nosema spp. and Deformed Wing Virus). We designed a homing test that has been recently identified to fill a regulatory gap in the field evaluations of sublethal doses of pesticides before their registration. We also assessed the effect of temperature as an environmental factor. Our results showed that the Varroa mite exacerbates homing failure (HF) caused by the insecticide, whereas high temperatures reduce insecticide-induced HF. Through an analytical Effective Dose (ED) approach, predictive modeling results showed that, for instance, ED level of an uninfested colony, can be divided by 3.3 when the colony is infested by 5 Varroa mites per 100 bees and at a temperature of 24°C. Our results suggest that the health status of honeybee colonies and climatic context should be targeted for a thorough risk assessment.

Invasive species populations periodically collapse from high to low abundance, sometimes even to extinction. Pathogens and the burden they place on invader immune systems have been hypothesised as a mechanism for these collapses. We examined the association of the bacterial pathogen (Pseudomonas spp.) and the viral community with immune gene expression in the globally invasive Argentine ant (Linepithema humile (Mayr)). RNA-seq analysis found evidence for 17 different viruses in Argentine ants from New Zealand, including three bacteriophages with one (Pseudomonas phage PS-1) likely to be attacking the bacterial host. Pathogen loads and prevalence varied immensely. Transcriptomic data showed that immune gene expression was consistent with respect to the viral classification of negative-sense, positive-sense and double-stranded RNA viruses. Genes that were the most strongly associated with the positive-sense RNA viruses such as the Linepithema humile virus 1 (LHUV-1) and the Deformed wing virus (DWV) were peptide recognition proteins assigned to the Toll and Imd pathways. We then used principal components analysis and regression modelling to determine how RT-qPCR derived immune gene expression levels were associated with viral and bacterial loads. Argentine ants mounted a substantial immune response to both Pseudomonas and LHUV-1 infections, involving almost all immune pathways. Other viruses including DWV and the Kashmir bee virus appeared to have much less immunological influence. Different pathogens were associated with varying immunological responses, which we hypothesize to interact with and influence the invasion dynamics of this species.

Transmission of viruses by Varroa destructor(Anderson &Trueman, 2000) to bees has been identified as one of the main threats to Apis mellifera L. colonies. It has also been suggested that synergistic parasite-pathogen interaction mediated by A. mellifera immunity can drive the collapse of honey bee colonies. We analyzed the relationship between deformed wing virus (DWV) viral load and gene expression levels of Toll Wheeler, cactus, domeless, TEPA, nitric oxide synthase, hymenoptaecin, vitellogenin, defensin, abaecinin winter bee samples ofA. mellifera with and without deformed wings. Samples were collected from hives in the field with high V. destructor infestation. In bees with deformed wings we found an increase in DWV titre and upregulation of genes in the Jak-STAT signalling pathway. Fil: Quintana, Silvina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Brasesco, Maria Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina Fil: Negri, Pedro. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Marin, Maia Solange. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Pagnuco, Inti Anabela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Szawarski, Nicolás. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina Fil: Reynaldi, Francisco José. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Microbiología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina Fil: Larsen, Alejandra Edith. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Microbiología. Cátedra de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina Fil: Eguaras, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina Fil: Maggi, Matías Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Artrópodos; Argentina

Introduction: Honey bees are used intensively to boost the agricultural and economic sectors worldwide. Many viruses attack honey bees and cause severe problems to the bee colonies, and constitute a real challenge for beekeeping development. Hence, understanding the genetic characteristics of bee viruses is necessary to highlight the phylogenetic relationships between them, and to find out similarity aspects based on sequences. Materials and Methods: Some public resources and free genetic analysis programs were utilized to perform this study. The complete sequences for some viruses were downloaded and analyzed using various programs and methods. Results: Some viruses shared the same base composition pattern in regards to percentage of A, T, C, and G. The phylogenetic relationships among the investigated viruses were presented and discussed. The phylogenetic trees constructed using three bioinformatics programs based on different methods emphasized the relationship between Kashmir bee virus (KBV) and Israeli acute paralysis virus (IAPV), and between deformed wing virus (DWV) and Kakugo virus (KV). These genetic relationships were also confirmed using enzymatic digestion to the sequences, gene cluster families, and open reading frames (ORFs). Conclusions: This study has presented new trends to analyze genetic similarities between organisms utilizing sequences. Different results for the phylogenetic relationships could be obtained when performing the analysis using various methods without impacting the relationships between closely related organisms. This study encourages the performance of additional studies to figure out functional components of these viruses.

Deformed wing virus (DWV) is a single-stranded RNA virus of honey bees ( Apis mellifera L.) transmitted by the parasitic mite Varroa destructor. Although DWV represents a major threat to honey bee health worldwide, the pathological basis of DWV infection is not well documented. The objective of this study was to investigate clinicopathological and histological aspects of natural DWV infection in honey bee workers. Emergence of worker honey bees was observed in 5 colonies that were clinically affected with DWV and the newly emerged bees were collected for histopathology. DWV-affected bees were 2 times slower to emerge and had 30% higher mortality compared to clinically normal bees. Hypopharyngeal glands in bees with DWV were hypoplastic, with fewer intracytoplasmic secretory vesicles; cells affected by apoptosis were observed more frequently. Mandibular glands were hypoplastic and were lined by cuboidal epithelium in severely affected bees compared to tall columnar epithelium in nonaffected bees. The DWV load was on average 1.7 × 106 times higher ( P < .001) in the severely affected workers compared to aged-matched sister honey bee workers that were not affected by deformed wing disease based on gross examination. Thus, DWV infection is associated with prolonged emergence, increased mortality during emergence, and hypoplasia of hypopharyngeal and mandibular glands in newly emerged worker honey bees in addition to previously reported deformed wing abnormalities.