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There are a number of RNA virus pathogens that represent a serious threat to the health of managed honey bees (Apis mellifera). That some of these viruses are also found in the broader pollinator community suggests the wider environmental spread of these viruses, with the potential for a broader impact on ecosystems. Studies on the ecology and evolution of these viruses in the arthropod community as a whole may therefore provide important insights into these potential impacts. We examined managed A. mellifera colonies, nearby non-Apis hymenopteran pollinators, and other associated arthropods for the presence of five commonly occurring picorna-like RNA viruses of honey bees - black queen cell virus, deformed wing virus, Israeli acute paralysis virus, Kashmir bee virus and sacbrood virus. Notably, we observed their presence in several arthropod species. Additionally, detection of negative-strand RNA using strand-specific RT-PCR assays for deformed wing virus and Israeli acute paralysis virus suggests active replication of deformed wing virus in at least six non-Apis species and active replication of Israeli acute paralysis virus in one non-Apis species. Phylogenetic analysis of deformed wing virus also revealed that this virus is freely disseminating across the species sampled in this study. In sum, our study indicates that these viruses are not specific to the pollinator community and that other arthropod species have the potential to be involved in disease transmission in pollinator populations.

Although overall pollinator populations have declined over the last couple of decades, the honey bee (Apis mellifera) malady, colony collapse disorder (CCD), has caused major concern in the agricultural community. Among honey bee pathogens, RNA viruses are emerging as a serious threat and are suspected as major contributors to CCD. Recent detection of these viral species in bumble bees suggests a possible wider environmental spread of these viruses with potential broader impact. It is therefore vital to study the ecology and epidemiology of these viruses in the hymenopteran pollinator community as a whole. We studied the viral distribution in honey bees, in their pollen loads, and in other non-Apis hymenopteran pollinators collected from flowering plants in Pennsylvania, New York, and Illinois in the United States. Viruses in the samples were detected using reverse transcriptase-PCR and confirmed by sequencing. For the first time, we report the molecular detection of picorna-like RNA viruses (deformed wing virus, sacbrood virus and black queen cell virus) in pollen pellets collected directly from forager bees. Pollen pellets from several uninfected forager bees were detected with virus, indicating that pollen itself may harbor viruses. The viruses in the pollen and honey stored in the hive were demonstrated to be infective, with the queen becoming infected and laying infected eggs after these virus-contaminated foods were given to virus-free colonies. These viruses were detected in eleven other non-Apis hymenopteran species, ranging from many solitary bees to bumble bees and wasps. This finding further expands the viral host range and implies a possible deeper impact on the health of our ecosystem. Phylogenetic analyses support that these viruses are disseminating freely among the pollinators via the flower pollen itself. Notably, in cases where honey bee apiaries affected by CCD harbored honey bees with Israeli Acute Paralysis virus (IAPV), nearby non-Apis hymenopteran pollinators also had IAPV, while those near apiaries without IAPV did not. In containment greenhouse experiments, IAPV moved from infected honey bees to bumble bees and from infected bumble bees to honey bees within a week, demonstrating that the viruses could be transmitted from one species to another. This study adds to our present understanding of virus epidemiology and may help explain bee disease patterns and pollinator population decline in general.

Few areas of the world have western honey bee (Apis mellifera) colonies that are free of invasive parasites Nosema ceranae (fungi) and Varroa destructor (mites). Particularly detrimental is V. destructor; in addition to feeding on host haemolymph, these mites are important vectors of several viruses that are further implicated as contributors to honey bee mortality around the world. Thus, the biogeography and attendant consequences of viral communities in the absence of V. destructor are of significant interest. The island of Newfoundland, Province of Newfoundland and Labrador, Canada, is free of V. destructor; the absence of N. ceranae has not been confirmed. Of 55 Newfoundland colonies inspected visually for their strength and six signs of disease, only K-wing had prevalence above 5% (40/55 colonies = 72.7%). Similar to an earlier study, screenings again confirmed the absence of V. destructor, small hive beetles Aethina tumida (Murray), tracheal mites Acarapis woodi (Rennie), and Tropilaelaps spp. ectoparasitic mites. Of a subset of 23 colonies screened molecularly for viruses, none had Israeli acute paralysis virus, Kashmir bee virus, or sacbrood virus. Sixteen of 23 colonies (70.0%) were positive for black queen cell virus, and 21 (91.3%) had some evidence for deformed wing virus. No N. ceranae was detected in molecular screens of 55 colonies, although it is possible extremely low intensity infections exist; the more familiar N. apis was found in 53 colonies (96.4%). Under these conditions, K-wing was associated (positively) with colony strength; however, viruses and N. apis were not. Furthermore, black queen cell virus was positively and negatively associated with K-wing and deformed wing virus, respectively. Newfoundland honey bee colonies are thus free of several invasive parasites that plague operations in other parts of the world, and they provide a unique research arena to study independent pathology of the parasites that are present.