The first report of the prevalence of Nosema ceranae in Bulgaria

Nosema apis and Nosema ceranae are the two main microsporidian parasites causing nosematosis in honey bee Apis mellifera. The object of the present study is to investigate the presence of Nosema apis and Nosema ceranae in the Bulgarian honey bee. The 16S (SSU) rDNA gene region was chosen for analysis. A duplex PCR assay was performed on 108 honey bee samples from three different parts of the country (South, North and West Bulgaria). The results showed that the samples from the northern part of the country were with the highest rate of invasion (77.2%) for Nosema ceranae while those from the mountainous parts (the Rodopa Mountains, South Bulgaria) were with the lowest rate (13.9%). Infection with Nosema apis alone and co-infection N. apis/N. ceranae were not detected in any samples. These findings suggest that Nosema ceranae is the dominant species in the Bulgarian honey bee. It is not known when the introduction of Nosema ceranae in Bulgaria has occurred, but like in the rest of the world, this species has become the dominant one in Bulgarian Apis mellifera. In conclusion, this is the first report for molecular detection of Nosema infection in Bulgarian honey bee that confirms the worldwide dissemination and prevalence of Nosema ceranae.