Deformed Wing Virus Infection Research Articles

Deformed wing virus genotypes A and B do not elicit immunologically different responses in naïve honey bee hosts.

Iflavirus aladeformis (Picornavirales: Iflaviridae), commonly known as deformed wing virus(DWV), in association with Varroa destructor Anderson and Trueman (Mesostigmata: Varroidae), is a leading factor associated with honey bee (Apis mellifera L. [Hymenoptera: Apidae]) deaths. The virus and mite have a near global distribution, making it difficult to separate the effect of one from the other. The prevalence of two main DWV genotypes (DWV-A and DWV-B) has changed over time, leading to the possibility that the two strains elicit a different immune response by the host. Here, we use a honey bee population naïve to both the mite and the virus to investigate if honey bees show a different immunological response to DWV genotypes. We examined the expression of 19 immune genes by reverse transcription quantitative PCR (RT-qPCR) and analysed small RNA after experimental injection with DWV-A and DWV-B. We found no evidence that DWV-A and DWV-B elicit different immune responses in honey bees. RNA interference genes were up-regulated during DWV infection, and small interfering RNA (siRNA) responses were proportional to viral loads yet did not inhibit DWV accumulation. The siRNA response towards DWV was weaker than the response to another honey bee pathogen, Triatovirus nigereginacellulae (Picornavirales: Dicistroviridae; black queen cell virus), suggesting that DWV is comparatively better at evading host antiviral defences. There was no evidence for the production of virus-derived Piwi-interacting RNAs (piRNAs) in response to DWV. In contrast to previous studies, and in the absence of V. destructor, we found no evidence that DWV has an immunosuppressive effect. Overall, our results advance our understanding of the immunological effect that DWV in isolation elicits in honey bees.

Deformed wings in the bumblebee Bombus terrestris (Linnaeus, 1758) in Luxembourg

Deformed wing virus (DWV), a persistent pathogen in European honeybees contributing to colony losses, also affects wild bees, including bumblebees, and a wide range of other insects. Bumblebees play a crucial role in crop production in temperate and cold ecosystems. A case of wild buff-tailed bumblebee workers Bombus terrestris (Linnaeus, 1758) showing visible clinical symptoms associated with overt, acute DWV infection is documented in Luxembourg, the first report for this bumblebee species widely distributed in the country. Further investigation is needed in Luxembourg to understand the impact of infectious diseases on wild pollinators and the role of managed pollinators in pathogen spillover.

Varroa destructor parasitism and Deformed wing virus infection in honey bees are linked to peroxisome-induced pathways.

The ectoparasitic mite Varroa destructor transmits and triggers viral infections that have deleterious effects on honey bee colonies worldwide. We performed a manipulative experiment in which worker bees collected at emergence were exposed to Varroa for 72h, and their proteomes were compared with those of untreated control bees. Label-free quantitative proteomics identified 77 differentially expressed A. mellifera proteins (DEPs). In addition, viral proteins were identified by orthogonal analysis, and most importantly, Deformed wing virus (DWV) was found at high levels/intensity in Varroa-exposed bees. Pathway enrichment analysis suggested that the main pathways affected included peroxisomal metabolism, cyto-/exoskeleton reorganization, and cuticular proteins. Detailed examination of individual DEPs revealed that additional changes in DEPs were associated with peroxisomal function. In addition, the proteome data support the importance of TGF-β signaling in Varroa-DWV interaction and the involvement of the mTORC1 and Hippo pathways. These results suggest that the effect of DWV on bees associated with Varroa feeding results in aberrant autophagy. In particular, autophagy is selectively modulated by peroxisomes, to which the observed proteome changes strongly corresponded. This study complements previous research with different study designs and suggests the importance of the peroxisome, which plays a key role in viral infections.

Effects of honey bee queen exposure to deformed wing virus-A on queen and juvenile infection and colony strength metrics

Varroa destructor and the pathogens they vector have contributed significantly to high annual honey bee colony losses. Deformed wing virus (DWV) is the most prevalent honey bee virus and has been associated with overwintering colony loss. DWV is capable of infecting honey bees at all life stages and castes via horizontal and vertical transmission. Few studies have been conducted to determine the effect that pathogens have on honey bee queen health and performance. Our results suggest that queens may have mechanisms that reduce the establishment of DWV infection following a single exposure event. A queen’s exposure to DWV-A prior to colony establishment did not significantly negatively impact colony strength metrics for two of three queen genotypes tested. Additionally, brood showed little subsequent infection. These findings suggest that when queens experience a single oral or venereal inoculation of DWV-A, vertical transmission may not result in significant brood infection and that overall colony strength may be largely unaffected. Increased colony loss experienced by colonies derived from one queen source indicates that differences in susceptibility exist due to factors that need to be investigated more fully. These findings contribute to a greater understanding of host-pathogen interactions in honey bees and suggest a context-dependent variability on the influence of queen exposure to viruses on colony health.

Alcohol extract of the gypsy mushroom (Cortinarius caperatus) inhibits the development of Deformed wing virus infection in western honey bee (Apis mellifera)

Deformed wing virus (DWV) transmitted by the parasitic mite Varroa destructor is one of the most significant factors contributing to massive losses of managed colonies of western honey bee (Apis mellifera) subspecies of European origin reported worldwide in recent decades. Despite this fact, no antiviral treatment against honey bee viruses is currently available for practical applications and the level of viral infection can only be controlled indirectly by reducing the number of Varroa mites in honey bee colonies. In this study, we investigated the antiviral potential of the gypsy mushroom (Cortinarius caperatus) to reduce DWV infection in honey bees. Our results indicate that the alcohol extract of C. caperatus prevented the development of DWV infection in cage experiments as well as after direct application to honey bee colonies in a field experiment. The applied doses did not shorten the lifespan of honey bees. The reduced levels of DWV in C. caperatus-treated honey bees in cage experiments were accompanied by significant changes in the gene expression of Tep7, Bap1, and Vago. The C. caperatus treatment was not effective against the trypanosomatid Lotmaria passim. No residues of C.caperatus were found in honey harvested in the spring from colonies supplemented with the mushroom extract for their winter feeding. These findings suggest that C. caperatus alcohol extract could be a potential natural remedy to treat DWV infection in honey bees.

Impact of deformed wing virus master variants (DWV-A, DWV-B, and DWV-C) in managed honey bee colonies of Türkiye

Aim: This study aimed to determine the deformed wing virus (DWV) master variants in managed honey bee hives in Central Anatolia and the Mediterranean Regions of Türkiye. Also, the relationship of DWV genotypes circulating in the apiaries with clinical signs observed in honey bee hives was investigated. Materials and Methods: For this study, adult honey bees were collected from the same 25 hives in the spring-summer and autumn seasons of 2019 from the provinces of Aksaray, Isparta, Karaman, Konya and Nigde. DWV-specific nucleic acid and DWV genotypes were detected by DWV real-time RT-PCR assay and ABC assay, respectively. Results: Deformed wing virus infection was detected in each sampling season. While many colonies were without any clinical signs, in some of the apiaries where samples were collected, wing deformity, trembling, paralysis, swelling in the abdomen, loss of productivity, and dead bees were observed. The prevalences of DWV-A, DWV-B, and DWV-C in adult honey bees were 62%, 82%, and 24%, respectively. The dominant genotype detected in bee hives was the DWV-B master variant (98%). Also, the virus load of the DWV-A master variant was high in all of the honey bee hives with wintering losses. Conclusion: In this present study, data on the current status of DWV master variants circulating in Turkey and their impacts on honey bee colonies are reported for the first time. Thus, it is thought that DWV, which causes yield losses at varying rates in every season of the year in Turkish bee hives, should be carefully monitored.

Replicative DWV type A in Bombus terrestris in Pantelleria island (Sicily, Italy)

The deformed wing virus (DWV) is one of the most common bee pathogens, deemed responsible for both honey bee colony losses and general pollinator decline. That virus may infect both managed and wild bumblebees. In this study, the DWV infection was investigated in 52 free-flying Bombus terrestris (L., 1758) individuals from Pantelleria. This is a volcanic island in the Sicilian Channel. Of the collected individuals, 59.62% scored positive for DWV, with a mean abundance of 2.97 × 105 ± 1.46 × 106 copies per bee. Active replication of the virus could be demonstrated in all positive samples. All the sequences belonged to DWV type A. However both phylogenetic and pairwise distance analysis indicated a low similarity to Italian and Tunisian strains. Further studies are needed to elucidate the epidemiology of DWV in B. terrestris and the drivers of possible genetic modifications of the virus on Pantelleria island.

Deformed wing virus of honey bees is inactivated by cold plasma ionized hydrogen peroxide.

Deformed wing virus (DWV) is a widespread pathogen of Apis mellifera honey bees, and is considered a major causative factor for the collapse of infected honey bee colonies. DWV can be horizontally transmitted among bees through various oral routes, including via food sharing and by interactions of bees with viral-contaminated solid hive substrates. Cold plasma ionized hydrogen peroxide (iHP) is used extensively by the food production, processing and medical industries to clean surfaces of microbial contaminants. In this study, we investigated the use of iHP to inactivate DWV particles in situ on a solid substrate. iHP-treated DWV sources were ~105-fold less infectious when injected into naïve honey bee pupae compared to DWV receiving no iHP treatment, matching injected controls containing no DWV. iHP treatment also greatly reduced the incidence of overt DWV infections (i.e., pupae having >109 copies of DWV). The level of DWV inactivation achieved with iHP treatment was higher than other means of viral inactivation such as gamma irradiation, and iHP treatment is likely simpler and safer. Treatment of DWV contaminated hive substrates with iHP, even with honey bees present, may be an effective way to decrease the impacts of DWV infection on honey bees.

Prevalence and Molecular Characterization of Deformed Wing, Acute Bee Paralysis and Black Queen Cell Viruses Infecting Honey Bees and Varroa Mites

Abstract Surveys were conducted in Malatya and Elazığ provinces of Eastern Türkiye between 2018–2019 to detect the presence and distribution of Deformed wing virus (DWV), Acute bee paralysis virus (ABPV) and Black queen cell virus (BQCV) infecting honey bees and Varroa mites. Thirty Varroa mites feeding on honey bees and 147 honey bees were collected from twenty-five apiaries of Malatya and fifteen apiaries of Elazığ. The collected samples were subjected to reverse transcriptase-polymerase chain reaction. All tested viruses were found to be present in the samples singly or as mixed infections. The prevalence of the viruses were 23.81%, 12.93%, and 10.20% for DWV, ABPV and BQCV, respectively. Five out of thirty Varroa mites tested for the viruses were found to be infected only with DWV. Randomly chosen sequences of each detected virus’s partial polyprotein gene region were registered in GenBank under the accession numbers OP805878, OP805879, OP805880, OP805887, OP805888, OP805889, OP805890, OP805891 (DWV), OP805881, OP805882, OP805883, OP805884 (ABPV) and OP805885, OP805886 (BQCV). The phylogenetic tree of the viral isolates were compared with the world isolates. DWV isolates were found to be closely related to the UK, Lebanon, Türkiye, France, Germany and Israel isolates, whereas ABPV isolates were related to Türkiye, South Africa, Slovenia, Serbia, France, Hungary, Syria and USA isolates and BQCV isolates were related to China, South Korea, Czech Republic, France, Hungary, Poland, South Africa, Australia and Sweden isolates. The presence of DWV, ABPV and BQCV infections in Malatya and Elazığ provinces of Türkiye is revealed for the first time in this study.

Host-driven temperature dependence of Deformed wing virus infection in honey bee pupae

The temperature dependence of infection reflects changes in performance of parasites and hosts. High temperatures often mitigate infection by favoring heat-tolerant hosts over heat-sensitive parasites. Honey bees exhibit endothermic thermoregulation—rare among insects—that can favor resistance to parasites. However, viruses are heavily host-dependent, suggesting that viral infection could be supported—not threatened—by optimum host function. To understand how temperature-driven changes in performance of viruses and hosts shape infection, we compared the temperature dependence of isolated viral enzyme activity, three honey bee traits, and infection of honey bee pupae. Viral enzyme activity varied <2-fold over a > 30 °C interval spanning temperatures typical of ectothermic insects and honey bees. In contrast, honey bee performance peaked at high (≥ 35 °C) temperatures and was highly temperature-sensitive. Although these results suggested that increasing temperature would favor hosts over viruses, the temperature dependence of pupal infection matched that of pupal development, falling only near pupae’s upper thermal limits. Our results reflect the host-dependent nature of viruses, suggesting that infection is accelerated—not curtailed—by optimum host function, contradicting predictions based on relative performance of parasites and hosts, and suggesting tradeoffs between infection resistance and host survival that limit the viability of bee ‘fever’.

Deformed wings in introduced solitary bees, Megachile spp., independent of virus infections

Insect wing deformities can be caused by various factors, including the Deformed wing virus (DWV). Symptomatic and asymptomatic specimens of the introduced solitary wild bees Megachile sculpturalis and Megachile disjunctiformis collected at eleven Central European locations were screened for DWV infections. Even though virus spillover is common, and DWV was detected in other bee species collected in the same habitat as Megachile spp., neither DWV-A nor DWV-B were found in any of the samples (N = 54) including two symptomatic males with deformed wings. This indicates that other stressors were responsible for the observed clinical symptoms, thereby highlighting the necessity of differential diagnostics.

Virus Prevalence in Egg Samples Collected from Naturally Selected and Traditionally Managed Honey Bee Colonies across Europe.

Monitoring virus infections can be an important selection tool in honey bee breeding. A recent study pointed towards an association between the virus-free status of eggs and an increased virus resistance to deformed wing virus (DWV) at the colony level. In this study, eggs from both naturally surviving and traditionally managed colonies from across Europe were screened for the prevalence of different viruses. Screenings were performed using the phenotyping protocol of the 'suppressed in ovo virus infection' trait but with qPCR instead of end-point PCR and a primer set that covers all DWV genotypes. Of the 213 screened samples, 109 were infected with DWV, 54 were infected with black queen cell virus (BQCV), 3 were infected with the sacbrood virus, and 2 were infected with the acute bee paralyses virus. It was demonstrated that incidences of the vertical transmission of DWV were more frequent in naturally surviving than in traditionally managed colonies, although the virus loads in the eggs remained the same. When comparing virus infections with queen age, older queens showed significantly lower infection loads of DWV in both traditionally managed and naturally surviving colonies, as well as reduced DWV infection frequencies in traditionally managed colonies. We determined that the detection frequencies of DWV and BQCV in honey bee eggs were lower in samples obtained in the spring than in those collected in the summer, indicating that vertical transmission may be lower in spring. Together, these patterns in vertical transmission show that honey bee queens have the potential to reduce the degree of vertical transmission over time.

The vectoring competence of the mite Varroa destructor for deformed wing virus of honey bees is dynamic and affects survival of the mite.

The ectoparasitic mite, Varroa destructor and the viruses it vectors, including types A and B of Deformed wing virus (DWV), pose a major threat to honey bees, Apis mellifera. Analysis of 256 mites collected from the same set of field colonies on five occasions from May to October 2021 showed that less than a half of them, 39.8% (95% confidence interval (CI): 34.0 - 46.0%), were able to induce a high (overt) level DWV infection with more than 109 viral genomes per bee in the pupa after 6 days of feeding, with both DWV-A and DWV-B being vectored at similar rates. To investigate the effect of the phoretic (or dispersal) stage on adult bees on the mites' ability to vector DWV, the mites from two collection events were divided into two groups, one of which was tested immediately for their infectiveness, and the other was kept with adult worker bees in cages for 12 days prior to testing their infectiveness. We found that while 39.2% (95% CI: 30.0 - 49.1%) of the immediately tested mites induced overt-level infections, 12-day passage on adult bees significantly increased the infectiousness to 89.8% (95% CI: 79.2 - 95.6%). It is likely that Varroa mites that survive brood interruptions in field colonies are increasingly infectious. The mite lifespan was affected by the DWV type it transmitted to pupae. The mites, which induced high DWV-B but not DWV-A infection had an average lifespan of 15.5 days (95% CI: 11.8 - 19.2 days), which was significantly shorter than those of the mites which induced high DWV-A but not DWV-B infection, with an average lifespan of 24.3 days (95% CI: 20.2 - 28.5), or the mites which did not induce high levels of DWV-A or DWV-B, with an average survival of 21.2 days (95% CI: 19.0 - 23.5 days). The mites which transmitted high levels of both DWV-A and DWV-B had an intermediate average survival of 20.5 days (95% CI: 15.1 - 25.9 days). The negative impact of DWV-B on mite survival could be a consequence of the ability of DWV-B, but not DWV-A to replicate in Varroa.

Transmission of deformed wing virus between Varroa destructor foundresses, mite offspring and infested honey bees

BackgroundVarroa destructor is the major ectoparasite of the western honey bee (Apis mellifera). Through both its parasitic life-cycle and its role as a vector of viral pathogens, it can cause major damage to honey bee colonies. The deformed wing virus (DWV) is the most common virus transmitted by this ectoparasite, and the mite is correlated to increased viral prevalence and viral loads in infested colonies. DWV variants A and B (DWV-A and DWV-B, respectively) are the two major DWV variants, and they differ both in their virulence and transmission dynamics.MethodsWe studied the transmission of DWV between bees, parasitic mites and their offspring by quantifying DWV loads in bees and mites collected in in vitro and in situ environments. In vitro, we artificially transmitted DWV-A to mites and quantified both DWV-A and DWV-B in mites and bees. In situ, we measured the natural presence of DWV-B in bees, mites and mites’ offspring.ResultsBee and mite viral loads were correlated, and mites carrying both variants were associated with higher mortality of the infected host. Mite infestation increased the DWV-B loads and decreased the DWV-A loads in our laboratory conditions. In situ, viral quantification in the mite offspring showed that, after an initially non-infected egg stage, the DWV-B loads were more closely correlated with the foundress (mother) mites than with the bee hosts.ConclusionsThe association between mites and DWV-B was highlighted in this study. The parasitic history of a mite directly impacts its DWV infection potential during the rest of its life-cycle (in terms of variant and viral loads). Regarding the mite’s progeny, we hypothesize that the route of contamination is likely through the feeding site rather than by vertical transmission, although further studies are needed to confirm this hypothesis.Graphical

Investigation of deformed wing virus, black queen cell virus, and acute bee paralysis virus infections in honey bees using reverse transcriptase-polymerase chain reaction (RT-PCR) method

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.

DWV 3C Protease Uncovers the Diverse Catalytic Triad in Insect RNA Viruses.

ABSTRACTDeformed wing virus (DWV) is the most prevalent Iflavirus that is infecting honey bees worldwide. However, the mechanisms of its infection and replication in host cells are poorly understood. In this study, we analyzed the structure and function of DWV 3C protease (3Cpro), which is necessary for the cleavage of the polyprotein to synthesize mature viral proteins. Thus, it is one of the nonstructural viral proteins essential for the replication. We found that the 3Cpros of DWV and picornaviruses share common enzymatic properties, including sensitivity to the same inhibitors, such as rupintrivir. The predicted structure of DWV 3Cpro by AlphaFold2, the predicted rupintrivir binding domain, and the protease activities of mutant proteins revealed that it has a Cys-His-Asn catalytic triad. Moreover, 3Cpros of other Iflaviruses and Dicistrovirus appear to contain Asn, Ser, Asp, or Glu as the third residue of the catalytic triad, suggesting diversity in insect RNA viruses. Both precursor 3Cpro with RNA-dependent RNA polymerase and mature 3Cpro are present in DWV-infected cells, suggesting that they may have different enzymatic properties and functions. DWV 3Cpro is the first 3Cpro characterized among insect RNA viruses, and our study uncovered both the common and unique characteristics among 3Cpros of Picornavirales. Furthermore, it would be possible to use the specific inhibitors of DWV 3Cpro to control DWV infection in honey bees in future.IMPORTANCE The number of managed honey bee (Apis mellifera) colonies has considerably declined in many developed countries in the recent years. Deformed wing virus (DWV) vectored by the mites is the major threat to honey bee colonies and health. To give insight into the mechanism of DWV replication in the host cells, we studied the structure–function relationship of 3C protease (3Cpro), which is necessary to cleave a viral polyprotein at the specific sites to produce the mature proteins. We found that the overall structure, some inhibitors, and processing of 3Cpro are shared between Picornavirales; however, there is diversity in the catalytic triad. DWV 3Cpro is the first viral protease characterized among insect RNA viruses and reveals the evolutionary history of 3Cpro among Picornavirales. Furthermore, DWV 3Cpro inhibitors identified in our study could also be applied to control DWV in honey bees in future.

Effect of Chronic Exposure to Sublethal Doses of Imidacloprid and Nosema ceranae on Immunity, Gut Microbiota, and Survival of Africanized Honey Bees.

Large-scale honey bee colony losses reported around the world have been associated with intoxication with pesticides, as with the presence of pests and pathogens. Among pesticides, neonicotinoid insecticides are the biggest threat. Due to their extensive use, they can be found in all agricultural environments, including soil, water, and air, are persistent in the environment, and are highly toxic for honey bees. In addition, infection by different pests and pathogens can act synergistically, weakening bees. In this study, we investigated the effects of chronic exposure to sublethal doses of imidacloprid alone or combined with the microsporidia Nosema ceranae on the immune response, deformed wing virus infection (DWV), gut microbiota, and survival of Africanized honey bees. We found that imidacloprid affected the expression of some genes associated with immunity generating an altered physiological state, although it did not favor DWV or N. ceranae infection. The pesticide alone did not affect honey bee gut microbiota, as previously suggested, but when administered to N. ceranae infected bees, it generated significant changes. Finally, both stress factors caused high mortality rates. Those results illustrate the negative impact of imidacloprid alone or combined with N. ceranae on Africanized honey bees and are useful to understand colony losses in Latin America.

Host Genotype and Tissue Type Determine DWV Infection Intensity.

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.

Deformed wing virus infection affects the neurological function of Apis mellifera by altering extracellular adenosine signaling

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.

Real-time monitoring of deformed wing virus-infected bee foraging behavior following histone deacetylase inhibitor treatment

SummaryImpairment 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.