![]() DWV is the most prevalent virus in apiaries worldwide and is implicated in colony losses due to its deleterious symptoms. At least three of these viruses with known symptoms, namely the acute bee paralysis virus, the deformed wing virus (DWV) and the slow bee paralysis virus, are closely associated with the presence of V. Īmong the 70 viruses that have been identified in honey bees, only a few have been associated to symptoms. mellifera and is well-known to act as a vector of several viruses. Varroa destructor is an ectoparasite of both its original host Apis cerana and the sister species A. One mite species in particular, Varroa destructor (Anderson and Trueman), has drawn the attention of scientists owing to its tremendous effects on a key pollinator: the western honey bee ( Apis mellifera). Among those vectors, Acari taxa are well represented, with more than 800 species of parasitic ticks and several entire mite genera embracing the parasitic lifestyle. Many parasitic arthropods, such as mosquitoes, flies, fleas and ticks, are well-known vectors of viral, bacterial and unicellular pathogens. ![]() This direct injection could allow the pathogen to bypass host defense barriers and facilitate access to replication sites, resulting in higher loads and/or in the emergence of detrimental symptoms. Regarding vector-borne diseases, the increase in virulence may be due to the direct injection of the pathogen by the vector, causing systemic infection of the host. Vector-borne or, more broadly speaking, horizontally transmitted pathogens are generally thought to be more harmful to their host than their vertically transmitted counterparts because they do not depend directly on host fitness to reproduce and infect new individuals. In any host–pathogen or host–parasite relationship, the mode of transmission determines the dynamics and virulence of the pathogen. 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. 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). The association between mites and DWV-B was highlighted in this study. 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. ![]() Mite infestation increased the DWV-B loads and decreased the DWV-A loads in our laboratory conditions. Resultsīee and mite viral loads were correlated, and mites carrying both variants were associated with higher mortality of the infected host. In situ, we measured the natural presence of DWV-B in bees, mites and mites’ offspring. In vitro, we artificially transmitted DWV-A to mites and quantified both DWV-A and DWV-B in mites and bees. We 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. 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. 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. Through both its parasitic life-cycle and its role as a vector of viral pathogens, it can cause major damage to honey bee colonies. Varroa destructor is the major ectoparasite of the western honey bee ( Apis mellifera).
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