SummaryHoney bee virus research is an enormously broad area, ranging from subcellular molecular biology through physiology and behaviour, to individual and colony-level symptoms, transmission and epidemiology. The research methods used in virology are therefore equally diverse.This article covers those methods that are very particular to virological research in bees, with numerous cross-referrals to other BEEBOOK papers on more general methods, used in virology as well as other research. At the root of these methods is the realization that viruses at their most primary level inhabit a molecular, subcellular world, which they manipulate and interact with, to produce all higher order phenomena associated with virus infection and disease. Secondly, that viruses operate in an exponential world, while the host operates in a linear world and that much of the understanding and management of viruses hinges on reconciling these fundamental mathematical differences between virus and host. The article concentrates heavily on virus propagation and methods for detection, with minor excursions into surveying, sampling management and background information on the many viruses found in bees. Métodos estándar para la investigación de virus en Apis mellifera ResumenLa investigación de los virus de la abeja de la miel es un área sumamente amplia, que abarca desde la biología molecular subcelular hasta la fisiología y el comportamiento, desde síntomas al nivel de individuo hasta al nivel de la colmena, transmisión y epidemiología. Los métodos de investigación en virología son, por tanto, diversos. Este artículo incluye aquellos métodos específicos de la investigación virológica en las abejas, con numerosas referencias cruzadas con otros artículos del BEEBOOK y otros más generales, usados tanto en virología como en otras disciplinas. La base de estos métodos es la comprensión de los virus en su nivel primario de hábitat molecular, ambiente subcelular, que manipulan y con el que interactúan, para producir otros fenómenos de orden superior asociados a la infección del virus y la enfermedad. En segundo lugar, estos virus actúan en un mundo exponencial, mientras que los hospedadores actúan en un mundo lineal y gran parte del entendimiento y manejo de los virus depende de los fundamentos matemáticos de las diferencias entre el virus y el hospedador. El artículo se centra principalmente en la propagación de virus y en los métodos para su detección, con inclusiones menores en su estudio, el manejo del muestreo y la información general sobre los numerosos virus que se encuentran en las abejas.

In the past centuries, viruses have benefited from globalization to spread across the globe, infecting new host species and populations. A growing number of viruses have been documented in the western honey bee, Apis mellifera. Several of these contribute significantly to honey bee colony losses. This review synthetizes the knowledge of the diversity and distribution of honey-bee-infecting viruses, including recent data from high-throughput sequencing (HTS). After presenting the diversity of viruses and their corresponding symptoms, we surveyed the scientific literature for the prevalence of these pathogens across the globe. The geographical distribution shows that the most prevalent viruses (deformed wing virus, sacbrood virus, black queen cell virus and acute paralysis complex) are also the most widely distributed. We discuss the ecological drivers that influence the distribution of these pathogens in worldwide honey bee populations. Besides the natural transmission routes and the resulting temporal dynamics, global trade contributes to their dissemination. As recent evidence shows that these viruses are often multihost pathogens, their spread is a risk for both the beekeeping industry and the pollination services provided by managed and wild pollinators.

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A country-wide screen for viral pathogens in Israeli apiaries revealed significant incidence of deformed wing virus (DWV) and Varroa destructor-1 virus (VDV-1). To understand these viruses' possible involvement in deformed wing syndrome of honey bees, we studied their replication in symptomatically and asymptomatically infected bees qualitatively and quantitatively, using RT-PCR, quantitative real-time RT-PCR, and immunodetection of the major viral capsid protein VP1. We found, for the first time, replication of VDV-1 and/or a VDV-1-DWV recombinant virus in the heads of recently emerged symptomatic bees. These viruses replicated to high copy numbers, yielding the major viral capsid VP1 processed for subsequent assembly of viral particles. Our results clearly distinguished between symptomatic and asymptomatic bees infected with VDV-1 and VDV-1-DWV and suggest the hypothesis that VDV-1, in addition to DWV, may be involved in inducing the deformed wing pathology. Thus VDV-1-DWV recombination may yield virulent strains able to cause overt infections in Varroa-infested bee colonies.

Nosema ceranae is a hot topic in honey bee health as reflected by numerous papers published every year. This review presents an update of the knowledge generated in the last 12 years in the field of N. ceranae research, addressing the routes of transmission, population structure and genetic diversity. This includes description of how the infection modifies the honey bee's metabolism, the immune response and other vital functions. The effects on individual honey bees will have a direct impact on the colony by leading to losses in the adult's population. The absence of clear clinical signs could keep the infection unnoticed by the beekeeper for long periods. The influence of the environmental conditions, beekeeping practices, bee genetics and the interaction with pesticides and other pathogens will have a direct influence on the prognosis of the disease. This review is approached from the point of view of the Mediterranean countries where the professional beekeeping has a high representation and where this pathogen is reported as an important threat.

Numerous studies have recently reported on the discovery of bee viruses in different arthropod species and their possible transmission routes, vastly increasing our understanding of these viruses and their distribution. Here, we review the current literature on the recent advances in understanding the transmission of viruses, both on the presence of bee viruses in Apis and non-Apis bee species and on the discovery of previously unknown bee viruses. The natural transmission of bee viruses will be discussed among different bee species and other insects. Finally, the research potential of in vivo (host organisms) and in vitro (cell lines) serial passages of bee viruses is discussed, from the perspective of the host-virus landscape changes and potential transmission routes for emerging bee virus infections.

SummaryPollination by honey bees plays a key role in the functioning of ecosystems and optimisation of agricultural yields. Severe honey bee colony losses worldwide have raised concerns about the sustainability of these pollination services. In many cases, bee mortality appears to be the product of many interacting factors, but there is a growing consensus that the ectoparasitic mite Varroa destructor plays the role of the major predisposing liability. We argue that the fight against this mite should be a priority for future honey bee health research. We highlight the lack of efficient control methods currently available against the parasite and discuss the need for new approaches. Gaps in our knowledge of the biology and epidemiology of the mite are identified and a research road map towards sustainable control is drawn. Innovative and challenging approaches are suggested in order to stimulate research efforts and ensure that honey bees will be able to sustainably fulfil their role in the ecosystem. Varroa destructor: alternativas para su control sostenible ResumenLa polinización por las abejas melíferas tiene una importante relevancia en el funcionamiento de los ecosistemas y en la optimización de los rendimientos agrícolas. Se ha expresado la preocupación acerca de la sostenibilidad de estos servicios de polinización, debido a las graves pérdidas de colonias de abejas melíferas a nivel mundial. En varios de estos casos, la pérdida de estas abejas parece ser el resultado de la interacción de muchos factores, existiendo un creciente consenso en que el ácaro ectoparásito Varroa destructor desempeña alguna

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