Prevalence of Nosema species infections in Apis cerana japonica and Apis mellifera honeybees in the Tohoku region of Japan

We investigated here, the prevalence of Nosema microsporidia infections in the honeybees, Apis cerana japonica and Apis mellifera, in the Tohoku region of Japan. We detected Nosema ceranae DNA in 14 (2.8%) of 509 A. cerana japonica and in 34 (21.9%) of 155 A. mellifera honeybees from Aomori, Iwate, Akita, Yamagata, and Fukushima prefectures. Nosema apis DNA was undetectable in A. cerana japonica and A. mellifera. The unidentifiable Nosema species that genetically differed from N. apis, N. ceranae, and N. neumanni in terms of small subunit (SSU) rDNA, large subunit rDNA, and internal transcribed spacer sequences was identified in 105 (20.6%) of 509 A. cerana japonica and in 1 (0.6%) of 155 A. mellifera honeybees, and from Iwate prefecture. A phylogenetic tree based on SSU rDNA sequences showed that the Nosema sp. belonged to the same clade as N. thomsoni detected in moth and solitary bees in North America and N. pieriae found in cabbage butterfly in Turkey, which have not hitherto been detected in honeybees. The morphological characteristics of the spores should be analyzed to enable species identification of the Nosema sp.