Detection of bee viruses from Apis mellifera (Hymenoptera: Apidae) and Varroa destructor (Acari: Varroidae) in Japan.

Varroa mite, Varroa destructor Anderson and Trueman (Acari: Varroidae), causes severe damage to honeybee colonies and facilitates the transmission of several bee viruses, such as deformed wing virus (DWV), which causes wing deformity in newly molted bees. In Japan, western honeybees Apis mellifera Linnaeus (Hymenoptera: Apidae) are reared for both honey production and pollination and are infested with Varroa mites. Detailed surveillance of bee viruses in both A. melliferra and V. destructor has not been conducted in Japan. We surveyed eight major bee viruses in A. mellifera and Varroa mites from Japanese apiaries. DWV is the predominant virus in both A. mellifera and V. destructor in Japan. Two strains of the virus, DWV-A and DWV-B, are considered virulent in honeybees, but only DWV-A was detected in this study. The DWV levels in honeybees were strongly correlated with the Varroa infestation rate. We also detected other viruses in both the bees and mites, such as black queen cell and Lake Sinai viruses, but at much lower infection rates than DWV. Infection rates of these viruses were higher in colonies that did not contain Varroa mites than in Varroa-infested bee colonies. Therefore, Varroa mites in Japanese apiaries could be associated with DWV transmission, but they may rarely be associated with the transmission of other viruses. [ABSTRACT FROM AUTHOR]