Infectivity of DWV associated to flower pollen: experimental evidence of a horizontal transmission route

PLoS One. 2014 Nov 24;9(11):e113448. doi: 10.1371/journal.pone.0113448. eCollection 2014.

Abstract

Deformed wing virus (DWV) is a honeybee pathogen whose presence is generally associated with infestation of the colony by the mite Varroa destructor, leading to the onset of infections responsible for the collapse of the bee colony. DWV contaminates bee products such as royal jelly, bee-bread and honey stored within the infected hive. Outside the hive, DWV has been found in pollen loads collected directly from infected as well as uninfected forager bees. It has been shown that the introduction of virus-contaminated pollen into a DWV-free hive results in the production of virus-contaminated food, whose role in the development of infected bees from virus-free eggs has been experimentally demonstrated. The aim of this study was twofold: (i) to ascertain the presence of DWV on pollen collected directly from flowers visited by honeybees and then quantify the viral load and (ii) determine whether the virus associated with pollen is infective. The results of our investigation provide evidence that DWV is present on pollen sampled directly from visited flowers and that, following injection in individuals belonging to the pollinator species Apis mellifera, it is able to establish an active infection, as indicated by the presence of replicating virus in the head of the injected bees. We also provide the first indication that the pollinator species Osmia cornuta is susceptible to DWV infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bees / genetics
  • Bees / physiology
  • Bees / virology*
  • Flowers / genetics
  • Flowers / parasitology
  • Flowers / virology*
  • Gene Transfer, Horizontal*
  • Host-Parasite Interactions
  • Host-Pathogen Interactions
  • Insect Viruses / genetics
  • Insect Viruses / physiology*
  • Pollen / genetics
  • Pollen / parasitology
  • Pollen / virology*
  • Pollination
  • Reverse Transcriptase Polymerase Chain Reaction
  • Viral Load / genetics
  • Virus Replication / genetics

Grants and funding

This study was financially supported in part by European Union FP/Project STEP (Grant n° 244090-STEP-FP) and by Fondi di Ateneo 2013. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.