41st Annual Meeting of the Society for Invertebrate Pathology
and 9th International Conference on Bacillus thuringiensis

The deformed wing virus (DWV) is one of the most prevalent virus in honey bee colonies. The high prevalence of DWV is likely correlated to its ability to be transmitted by the mite Varroa destructor. PCR amplification of DWV negative RNA strands in mites and the tremendous DWV loads recorded from mites argue for the replication of DWV in both varroa and bees. Besides, there is strong evidence that DWV is also transmitted either horizontally by food exchange or vertically through eggs. DWV RNA loads measured in 360 seemingly healthy bee colonies from pools of 100 bees using quantitative PCR showed that bee colonies can tolerate very high loads of viruses without external clinical signs. We further identified DWV RNA in several bee organs by in situ hybridization and showed that queen and drone fertility could be impaired by such infection. In queen, the fat body cells were particularly infected while in drone, the whole reproductive reacted positively to DWV probe. Moreover, in crippled winged individuals from where very high DWV RNA genome copies were recorded, the digestive tract was heavily infected, indicating a probable negative effect on the digestive function. Our data strongly support that DWV produces pathogenic effects in severely infected individuals from the colony but these deleterious effects might not always have an impact on the colony fitness