The Two Prevalent Genotypes of an Emerging Infectious Disease, Deformed Wing Virus, Cause Equally Low Pupal Mortality and Equally High Wing Deformities in Host Honey Bees.

Anja Tehel,Robert Paxton,Andreas Gogol-Döring,Vincent Doublet,Panagiotis Theodorou,Quynh Vu,Diane Bigot,Christina Jenkins,Peter Koch

doi:10.3390/v11020114

Abstract

Deformed wing virus (DWV) is an emerging infectious disease of the honey bee (Apis mellifera) that is considered a major cause of elevated losses of honey bee colonies. DWV comprises two widespread genotypes: the originally described genotype A, and genotype B. In adult honey bees, DWV-B has been shown to be more virulent than DWV-A. However, their comparative effects on earlier host developmental stages are unknown. Here, we experimentally inoculated honey bee pupae and tested for the relative impact of DWV-A versus DWV-B on mortality and wing deformities in eclosing adults. DWV-A and DWV-B caused similar, and only slightly elevated, pupal mortality (mean 18% greater mortality than control). Both genotypes caused similarly high wing deformities in eclosing adults (mean 60% greater wing deformities than control). Viral titer was high in all of the experimentally inoculated eclosing adults, and was independent of wing deformities, suggesting that the phenotype ‘deformed wings’ is not directly related to viral titer or viral genotype. These viral traits favor the emergence of both genotypes of DWV by not limiting the reproduction of its vector, the ectoparasitic Varroa destructor mite, in infected pupae, and thereby facilitating the spread of DWV in honey bees infested by the mite.

Highlights

Honey bees (Apis mellifera) are globally the most important commercial pollinator of crops [1], as well as playing an important role in the pollination of wild plants [2]
We have formerly shown though experimental inoculation that Deformed wing virus (DWV)-B has elevated virulence in adult honey bees compared to DWV-A [17], shortening adult lifespan [39,40] and leading to overwinter colony decline during the season when, in temperate regions, colonies are devoid of brood [18]
Both were inspected visually for V. destructor mites and by quantitative real-time PCR for eight common viral targets: DWV-A, DWV-B, Acute bee paralysis virus (ABPV), Black queen cell virus (BQCV), Chronic bee paralysis virus (CBPV), Israeli acute paralysis virus (IAPV), Sacbrood virus (SBV), and Slow bee paralysis virus (SBPV), using the primers given in McMahon et al [56]

Summary

Introduction

Honey bees (Apis mellifera) are globally the most important commercial pollinator of crops [1], as well as playing an important role in the pollination of wild plants [2]. Surveys of pests and pathogens of honey bees in the temperate Northern Hemisphere have highlighted the exotic and invasive ectoparasitic mite, Varroa destructor, which is a native ectoparasite of the S. and E. Asiatic honey bee Apis cerana, and the emerging infectious disease agent, Deformed wing virus (DWV), together being a major cause of elevated colony loss [10,11,12,13,14,15,16,17,18]. The invasion of honey bee populations by V. destructor leads to a greatly increased prevalence (proportion of infected individuals or colonies) and intensity of infection (viral titer per individual) of DWV [19,20]. DWV is a positive single-stranded RNA virus of the family Iflaviridae

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Results

Conclusion