Genome sequence heterogeneity of Lake Sinai Virus found in honey bees and Orf1/RdRP-based polymorphisms in a single host.

Honey bees (Apis mellifera) are susceptible to a wide range of pathogens, including a broad set of viruses. Recently, next-generation sequencing has expanded the list of viruses with, for instance, two strains of Lake Sinai Virus. Soon after its discovery in the USA, LSV was also discovered in other countries and in other hosts. In the present study, we assemble four almost complete LSV genomes, and show that there is remarkable sequence heterogeneity based on the Orf1, RNA-dependent RNA polymerase and capsid protein sequences in comparison to the previously identified LSV 1 and 2 strains. Phylogenetic analyses of LSV sequences obtained from single honey bee specimens further revealed that up to three distinctive clades could be present in a single bee. Such superinfections have not previously been identified for other honey bee viruses. In a search for the putative routes of LSV transmission, we were able to demonstrate the presence of LSV in pollen pellets and in Varroa destructor mites. However, negative-strand analyses demonstrated that the virus only actively replicates in honey bees and mason bees (Osmia cornuta) and not in Varroa mites.

Holistic screening of collapsing honey bee colonies in Spain: a case study.

BACKGROUND: Here we present a holistic screening of collapsing colonies from three professional apiaries in Spain. Colonies with typical honey bee depopulation symptoms were selected for multiple possible factors to reveal the causes of collapse. RESULTS: Omnipresent were Nosema ceranae and Lake Sinai Virus. Moderate prevalences were found for Black Queen Cell Virus and trypanosomatids, whereas Deformed Wing Virus, Aphid Lethal Paralysis Virus strain Brookings and neogregarines were rarely detected. Other viruses, Nosema apis, Acarapis woodi and Varroa destructor were not detected. Palinologic study of pollen demonstrated that all colonies were foraging on wild vegetation. Consequently, the pesticide residue analysis was negative for neonicotinoids. The genetic analysis of trypanosomatids GAPDH gene, showed that there is a large genetic distance between Crithidia mellificae ATCC30254, an authenticated cell strain since 1974, and the rest of the presumed C. mellificae sequences obtained in our study or published. This means that the latter group corresponds to a highly differentiated taxon that should be renamed accordingly. CONCLUSION: The results of this study demonstrate that the drivers of colony collapse may differ between geographic regions with different environmental conditions, or with different beekeeping and agricultural practices. The role of other pathogens in colony collapse has to bee studied in future, especially trypanosomatids and neogregarines. Beside their pathological effect on honey bees, classification and taxonomy of these protozoan parasites should also be clarified.

Gamma irradiation of pollen and eradication of Israeli acute paralysis virus.

Honeybees and bumblebees are the most important pollinators of agricultural crops. For this purpose honeybees and bumblebees are reared and transported. A pathogen-free status of bees in general, is crucial. Indeed anthropogenic transports of hosts carrying parasites could alter the natural host/pathogen association, inducing an extra pathogenic stress. Therefore the creation of a pathogen-free rearing environment is needed. For bumblebees this is possible, as these species are reared in a closed environment. Although, a link remains between reared bumblebees and the outside bee community, as honeybee-collected pollen is essential food for bumblebee mass rearing. Here we evaluated if gamma irradiation can minimize the risk of this potential route of exposure and can inactivate viral particles present in honeybee-collected pollen. We show that 16.9kGy gamma irradiation induced a 100-1000 fold reduction on the ability of IAPV to cause mortality after injections. This result opens avenues toward rearing pathogen-free bumblebees and towards eliminating the risks of pathogen spillover to native wild bee species.