Deformed wing virus: replication and viral load in mites (Varroa destructor)

Area of Science:

• Apiculture
• Virology
• Entomology

Background:

• Deformed wing virus (DWV) typically causes asymptomatic infections in honeybees.
• The ectoparasitic mite Varroa destructor is a known vector for DWV.
• DWV transmission by V. destructor can lead to significant bee mortality and morphological deformities.

Purpose of the Study:

• To investigate the role of Varroa destructor mite infestation in the development of DWV-induced crippled wings in bees.
• To determine the correlation between DWV replication within mites and the severity of wing deformities in bees.

Main Methods:

• Analysis of individual Varroa destructor mites for the presence and replication of Deformed wing virus.
• Quantification of viral genome equivalents within mites to assess DWV load.

Main Results:

• A strong correlation was observed between DWV replication within mites and the incidence of morphologically deformed bees.
• Mites inducing overt DWV infections harbored significantly higher viral loads (10^10–10^12 genome equivalents/mite) compared to those not inducing deformities (≤10^8 genome equivalents/mite).

Conclusions:

• Crippled wing development in bees is dependent on DWV transmission by Varroa destructor.
• Viral replication within the mite vector and the mite's initial DWV titre are critical factors in the pathogenesis of DWV.
• Understanding these factors is crucial for managing DWV and protecting honeybee populations.