Studies on Nosema Disease of Honey Bees 1. Isolation of Nosema apis and a Survey of Nosema Disease in Honey Bees

꿀벌의 Nosema 병(病)에 관한 연구(硏究) 1. 원인체분리(原因體分離) 및 감염실태조사(感染實態調査)

The experiments were conducted to isolate the etiogical agent and to survey the distribution of Nosema disease in honey bees. The results obtained were as follows: 1. The etiological agent of the so-called "crawling disease" in honey bees characterized by the symptoms of crawling, diarrhea, and enteritis etc. was first isolated and identified with Nosema apis (Zander 1909) in Korea. 2. 455 colonies were randomely sampled and surveyed in 4,766 bee colonies out of 56 apiaries and 51 colonies (11.2%) out of 455 bee colonies were infected with N, apis. 3. Infection rates according to the period of honeyflow as follows: Brassica napus (Apr.): 25/130 colonies (18.4%) Rohinia pseudoacacia (May) : 8/55 colonies (14.%) Trifolium repels(Jun.): 15/99 colonies (13.6%) Castanea crenate (Jul.): 3/46 colonies (6.5%) Lespedeza bicolor(Aug.): 0/60 colonies (-) Fagopyrumesculentum(Sept.) & Perilla frutescens(Oct.) 0/65 colonies (-) 4. The typical clinical signs of Nosema disease were appeared on loth day after N. apis was orally administered with the level of $16{\times}10^4$ spores/ml to the healthy adult bees. Spores could be harvested with the level of $121{\sim}236{\times}10^4$ spores/ml on 10th day and $392{\sim}429{\times}10^4$ spores/ml on 15 days after infection. 5. In adult honey bees infected with N. apis artificially the 50% lethal day of life-span was 9 to 10 days and 100% lethal day was 16 to 19 days. However, in the control 50% lethal day was 19 to 23 days and 100% lethal day was 31 to 33 days.