A Nosema ceranae isolate from the honeybee Apis mellifera

Microsporidiosis (nosema disease) of the honeybee, Apis mellifera, has spread worldwide and caused heavy economic losses in apiculture. We obtained a spore isolate from worker ventriculi of A. mellifera colonies kept on the campus of National Taiwan University and sequenced the ribosomal genes. The entire length of the ribosomal DNA is about 3828 bp and the organization is similar to that of Nosema apis. However, the SSUrRNA, ITS, and LSUrRNA sequences have comparatively low identities with those of N. apis (92, 52, and 89%, respectively) and the SSUrRNA has a 99% identity with Nosema ceranae. These results indicate that this isolate is not N. apis, but N. ceranae. Moreover, the morphological characteristics are identical to those of N. ceranae. These results show that nosema disease of the honeybee, A. mellifera, may not be caused solely by the infection of N. apis.