Viral impacts on honey bee populations: A review

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

From infection to cancer: how DNA tumour viruses alter host cell central carbon and lipid metabolism

Infections cause 13% of all cancers globally, and DNA tumour viruses account for almost 60% of these cancers. All viruses are obligate intracellular parasites and hijack host cell functions to replicate and complete their life cycles to produce progeny virions. While many aspects of viral manipulation of host cells have been studied, how DNA tumour viruses manipulate host cell metabolism and whether metabolic alterations in the virus life cycle contribute to carcinogenesis are not well understood. In this review, we compare the differences in central carbon and fatty acid metabolism in host cells following infection, oncogenic transformation, and virus-driven cancer of DNA tumour viruses including: Epstein–Barr virus, hepatitis B virus, human papillomavirus, Kaposi''s sarcoma-associated herpesvirus and Merkel cell polyomavirus.     

Increased survival of the honey bee Apis mellifera infected with the microsporidian Nosema ceranae by effective gene silencing

This study examined the control of nosemosis caused by Nosema ceranae, one of the hard-to-control diseases of honey bees, using RNA interference (RNAi) technology. Double-stranded RNA (dsRNA) for RNAi application targeted the mitosome-related genes of N. ceranae. Among the various mitosome-related genes, NCER_100882, NCER_101456, NCER_100157, and NCER_100686 exhibited relatively low homologies with the orthologs of Apis mellifera. Four gene-specific dsRNAs were prepared against the target genes and applied to the infected A. mellifera to analyze Nosema proliferation and honey bee survival. Two dsRNAs specifics to NCER_101456 and NCER_100157 showed high inhibitory effects on spore production by exhibiting only 62% and 67%, respectively, compared with the control. In addition, these dsRNA treatments significantly rescued the honey bees from the fatal nosemosis. It was confirmed that the inhibition of Nosema spore proliferation and the increase in the survival rate of honey bees were resulted from a decrease in the expression level of each target gene by dsRNA treatment. However, dsRNA mixture treatment was no more effective than single treatments in the rescue from the nosemosis. It is expected that the four newly identified mitosome-related target genes in this study can be effectively used for nosemosis control using RNAi technology.     

Time-restricted foraging under natural light/dark condition shifts the molecular clock in the honey bee,Apis mellifera

ABSTRACT

Honey bees have a remarkable sense of time and individual honey bee foragers are capable of adjusting their foraging activity with respect to the time of food availability. Although, there is compelling experimental evidence that foraging behavior is guided by the circadian clock, nothing is known about the underlying molecular mechanisms. Here we present for the first time a study that explores whether time-restricted foraging under natural light-dark (LD) condition affects the molecular clock in honey bees. Food was presented in an enclosed flight chamber (12 m × 4 m × 4 m) either for 2 hours in the morning or 2 hours in the afternoon for several consecutive days and daily cycling of the two major clock genes, cryptochrome2 (cry2) and period (per), were analyzed for three different parts of the nervous system involved in feeding-related behaviors: brain, subesophageal ganglion (SEG), and the antennae with olfactory sensory neurons. We found that morning and afternoon trained foragers showed significant phase differences in the cycling of both clock genes in all three tissues. In addition, the phase differences were more pronounced when the feeder was scented with the common plant odor, linalool. Together our findings suggest that foraging time may function as a Zeitgeber that might have the capability to modulate the light entrained molecular clock.     

Generalized food deception: colour signals and efficient pollen transfer in bee‐pollinated species of Eulophia (Orchidaceae)

Non‐rewarding plants use a variety of ruses to attract their pollinators. One of the least understood of these is generalized food deception, in which flowers exploit non‐specific food‐seeking responses in their pollinators. Available evidence suggests that colour signals, scent and phenology may all play key roles in this form of deception. Here we investigate the pollination systems of five Eulophia spp. (Orchidaceae) lacking floral rewards. These species are pollinated by bees, notably Xylocopa (Anthophorinae, Apidae) or Megachile (Megachilidae) for the large‐flowered species and anthophorid (Anthophorinae, Apidae) or halictid (Halictidae) bees for the small‐flowered species. Spectra of the lateral petals and ultraviolet‐absorbing patches on the labella are strongly contrasting in a bee visual system, which may falsely signal the presence of pollen to bees. All five species possess pollinarium‐bending mechanisms that are likely to limit pollinator‐mediated self‐pollination. Flowering times extend over 3–4 months and the onset of flowering was not associated with the emergence of pollinators, some of which fly year round. Despite sharing pollinators with other plants and lacking rewards that would encourage fidelity, the Eulophia spp. exhibited relatively high levels of pollen transfer efficiency compared with other rewarding and deceptive orchids. We conclude that the study species employ generalized food deception and exploit food‐seeking bees. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013 , 171 , 713–729.     

Geochemistry of Virus–Prokaryote Interactions in Freshwater and Acid Mine Drainage Environments,Ontario, Canada

An extensive water sample survey was conducted in southern Ontario, Canada across a variety of freshwater systems in order to further understand the role of viruses in aquatic environments. Backwards stepwise multiple regression analysis found that VLP (virus-like particle) abundance, phosphate, pH, sulfate, and magnesium are predictors of prokaryotic abundance with the model describing 90% of the variability in the data (R² = 0.90). Statistically significant (P < 0.05) predictors of VLP abundance were mineral saturation indices (SI) of goethite (R² = 0.78) although moderate Pearson component analysis correlations (r) were noted with ferrihydrite, jarosite, and pyrolusite. These relationships indicate that viral inactivation through mineral attachment may be a contributor to the moderate relationship between VLP and prokaryotic abundance (r_s = 0.45). In addition, VLP abundance is shown to have a stronger correlation with minerals SI values than prokaryotes indicating a stronger mineral influence with viruses.     

Botanical affinity of pollen harvested by Apis mellifera L. in a semi-arid area from Bahia,Brazil

We analysed the botanical composition of pollen harvested by Apis mellifera L. in the Canudos Biological Station, Bahia, Brazil, and the influence of climatic factors on pollen sample composition was assessed. Forty-six pollen types were identified belonging to species occurring in the study area. The family Leguminosae was of significant importance amongst the samples, represented by ten pollen types. Diodia radula, Rhaphiodon echinus, and Mimosa misera pollen types occurred most constantly among the samples. We observed that isolated pollen class characterises samples analysed. It was also observed that pollen type richness is directly linked to rainfall, reflecting the strong influence of this climatic parameter on flowering intensity, and thus on the ability of the bees to obtain food resources.     

Analysis of protein content in pollen loads produced in north-west Spain

An analysis was made of the protein content of pollen loads produced by the bees in a hive situated in Viana do Bolo (Ourense, north-west Spain), to establish whether or not the relative quantity of protein in the pollen of each plant species influences the preference made by the bee of the flowers that supply pollen to the hive. This analysis was performed on all types of pollen that formed more than 5% of the pollen spectrum. Pollen load samples were collected directly from the hive from March to September. Pollen loads were separated by colour, and their specific homogeneity was confirmed microscopically. The Bradford method has been used for protein extraction and spectrophotometry was used for the determination of protein content. The results show that the different pollen loads have high protein content. Pollen of the plant species that reached relatively higher percentages in the pollen spectrum are also those that have the highest protein content. These were Cytisus scoparius type, uncultivated Poaceae, Quercus robur type, Sanguisorba minor, Salix fragilis and Spergularia rubra type. The pollen of the systematic units, which had pollen loads that could be identified at the level of species, maintained a constant value of protein content independently of the date the samples were obtained. The pollen of the systematic units, which had pollen loads that could be identified at the level of pollen type, has varied in protein content in the analyses performed on samples obtained on different dates. This result is due to the fact that the different species that integrate the pollen type flower on different dates, and thus have a pollenkitt with different characteristics.     

The manifold characters of orbicules: structural diversity,systematic significance,and vectors for allergens

In the anthers of flowering plants, gymnosperms, and seed ferns, tiny (±1?μm) granules might occur on the radial and innermost tangential wall of secretory tapetum cells. These sporopollenin granules develop simultaneously with the pollen exine and are called orbicules or Ubisch bodies. The present paper focuses on two quite different topics associated with orbicules.

The morphological and ultrastructural diversity of orbicules in the order Gentianales is summarized, and it is demonstrated that orbicules are a plesiomorphic feature in the order. Furthermore, orbicule characters seemed to be correlated with evolutionary trends in pollen dispersal unit and tapetum type features.

In the second part, we report on our investigation of Corylus avellana L. (Hazel) pollen, using immunogold electron microscopy to gain an insight into the possible role that orbicules may play as a vector of pollen allergens. During the pollen season orbicules are dispersed into the atmosphere along with Hazel pollen grains. The localisation of homologues of the new birch pollen allergen Bet v 7 was studied at the subcellular level in Hazel anthers. The results of this study indicate that orbicules and pollen of Hazel might act as very effective vectors for homologues of Bet v 7 and that debris of Hazel anthers represent vectors of allergens after the pollen season.     

Exploring nucleo-cytoplasmic large DNA viruses in Tara Oceans microbial metagenomes

Nucleo-cytoplasmic large DNA viruses (NCLDVs) constitute a group of eukaryotic viruses that can have crucial ecological roles in the sea by accelerating the turnover of their unicellular hosts or by causing diseases in animals. To better characterize the diversity, abundance and biogeography of marine NCLDVs, we analyzed 17 metagenomes derived from microbial samples (0.2–1.6 μm size range) collected during the Tara Oceans Expedition. The sample set includes ecosystems under-represented in previous studies, such as the Arabian Sea oxygen minimum zone (OMZ) and Indian Ocean lagoons. By combining computationally derived relative abundance and direct prokaryote cell counts, the abundance of NCLDVs was found to be in the order of 10⁴–10⁵ genomes ml⁻¹ for the samples from the photic zone and 10²–10³ genomes ml⁻¹ for the OMZ. The Megaviridae and Phycodnaviridae dominated the NCLDV populations in the metagenomes, although most of the reads classified in these families showed large divergence from known viral genomes. Our taxon co-occurrence analysis revealed a potential association between viruses of the Megaviridae family and eukaryotes related to oomycetes. In support of this predicted association, we identified six cases of lateral gene transfer between Megaviridae and oomycetes. Our results suggest that marine NCLDVs probably outnumber eukaryotic organisms in the photic layer (per given water mass) and that metagenomic sequence analyses promise to shed new light on the biodiversity of marine viruses and their interactions with potential hosts.