Presence of Ascosphaera apis, the causative agent of chalkbrood disease, in honeybees Apis mellifera (Hymenoptera: Apidae) in Japan

The presence of Ascosphaera apis , a fungus that is the causative agent of chalkbrood disease, was surveyed in Japan using a diagnostic polymerase chain reaction (PCR). A total of 336 individual European honeybees Apis mellifera were taken from 25 different apiaries in various regions of Japan. Of the 112 colonies surveyed, A. apis was detected in 27 colonies (24.1%). Positive results by PCR were obtained from 49 out of 336 surveyed individuals (14.6%). Based on these results, the distribution of A. apis in A. mellifera is widespread across Japan and does not exhibit significant differences between geographic areas. DNA sequences of the ITS and 5.8S rRNA region from all 17 isolates of A. apis were identical, even though they were from geographically distinct areas in Japan. It is suggested that no intra-species variation may be due to a recent bottleneck effect probably caused by humans before geographical expansion of the fungus.