Abstract

The well-being of a colony and replenishment of the workers depends on a healthy queen. Diseases in queens are seldom reported, and our knowledge on viral infection in queens is limited. In this study, 86 honey bee queens were collected from beekeepers in Denmark. All queens were tested separately by two real-time PCRs: one for the presence of deformed wing virus (DWV), and one that would detect sequences of acute bee-paralysis virus, Kashmir bee virus and Israeli acute paralysis virus (AKI complex). Worker bees accompanying the queen were also analysed. The queens could be divided into three groups based on the level of infection in their head, thorax, ovary, intestines and spermatheca. Four queens exhibited egg-laying deficiency, but visually all queens appeared healthy. Viral infection was generally at a low level in terms of AKI copy numbers, with 134/430 tissues (31 %) showing the presence of viral infection ranging from 101 to 105 copies. For DWV, 361/340 tissues (84 %) showed presence of viral infection (DWV copies ranging from 102 to 1012), with 50 tissues showing viral titres >107 copies. For both AKI and DWV, the thorax was the most frequently infected tissue and the ovaries were the least frequently infected. Relative to total mass, the spermatheca showed significantly higher DWV titres than the other tissues. The ovaries had the lowest titre of DWV. No significant differences were found among tissues for AKI. A subsample of 14 queens yielded positive results for the presence of negative-sense RNA strands, thus demonstrating active virus replication in all tissues.

Highlights

  • Honey bees (Apis mellifera L.) harbour a variety of pathogens such as bacteria, fungus, protozoa, viruses and pests such as mites and insects

  • Most virus studies focus on honey bee workers, as all nonreproductive functions are carried out by worker bees and heavy loss of worker bees can lead to the collapse of colonies (Vanengelsdorp et al, 2009)

  • The viruses analysed in this study were those of the acute bee-paralysis virus (ABPV)–Kashmir bee virus (KBV)–Israeli acute paralysis virus (IAPV) complex (AKI) and deformed wing virus (DWV)

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Summary

INTRODUCTION

Honey bees (Apis mellifera L.) harbour a variety of pathogens such as bacteria, fungus, protozoa, viruses and pests such as mites and insects. The viruses analysed in this study were those of the ABPV–KBV–Israeli acute paralysis virus (IAPV) complex (AKI) (de Miranda et al, 2010) and DWV (de Miranda & Genersch, 2010) These viruses were chosen because of their pathogenic importance, implications in global pandemics such as colony collapse disorder, association with. DWV has been reported in drone tissues (Fievet et al, 2006), including semen (Yue et al, 2006), suggesting that queens may be infected during mating Both positive- and negativestrand DWV RNA has been found in the head, thorax and abdomen of crippled workers, but was found only in the thorax and abdomen of asymptomatic bees (Yue & Genersch, 2005). We investigated the qualitative and quantitative aspects of the AKI complex and DWV infection in five tissues of 86 honey bee queens

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