A Comparison of Deformed Wing Virus in Deformed and Asymptomatic Honey Bees.

Gideon Mordecai,Jessica da Silva,Stephen Martin,Marina Vicente-Rubiano,Laura Brettell,Declan Schroeder,Ian Jones

doi:10.3390/insects8010028

Abstract

Deformed wing virus (DWV) in association with Varroa destructor is currently attributed to being responsible for colony collapse in the western honey bee (Apis mellifera). The appearance of deformed individuals within an infested colony has long been associated with colony losses. However, it is unknown why only a fraction of DWV positive bees develop deformed wings. This study concerns two small studies comparing deformed and non-deformed bees. In Brazil, asymptomatic bees (no wing deformity) that had been parasitised by Varroa as pupae had higher DWV loads than non-parasitised bees. However, we found no greater bilateral asymmetry in wing morphology due to DWV titres or parasitisation. As expected, using RT-qPCR, deformed bees were found to contain the highest viral loads. In a separate study, next generation sequencing (NGS) was applied to compare the entire DWV genomes from paired symptomatic and asymptomatic bees from three colonies on two different Hawaiian islands. This revealed no consistent differences between DWV genomes from deformed or asymptomatic bees, with the greatest variation seen between locations, not phenotypes. All samples, except one, were dominated by DWV type A. This small-scale study suggests that there is no unique genetic variant associated with wing deformity; but that many DWV variants have the potential to cause deformity.

Highlights

Honey bees with deformed wings have become a universal sign for the presence of deformed wing virus (DWV) in colonies infested by Varroa destructor across the world
High resolution melt (HRM) analysis and Sanger sequencing indicated that all bees were dominated by the Deformed wing virus (DWV) type A
Using a combination of next generation sequencing (NGS), RT-qPCR and HRM, we confirmed that DWV type A dominated in all samples types B and C, as well as A/B and A/C recombinants were found to be replicating at lower levels

Summary

Introduction

Honey bees with deformed wings have become a universal sign for the presence of deformed wing virus (DWV) in colonies infested by Varroa destructor across the world. DWV is reported as the most important honey bee viral pathogen causing the death of millions of colonies across the northern hemisphere [1,2]. The proportion of honey bees with deformed wings (i.e., symptomatic bees) in a colony is normally low (

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