[Isolation and identification of a newbacterial pathogen infecting larvae of honeybee (Apismellifera ) Perish]

A bacteroidal disease of honeybee (Apis mellifera ) larvae was found in some regions of Zhejiang Province, China , in early spring 2005. The diseased larvae lost its shine, became yellow and rotted when serious. This symptom was different to any bacteroidal disease of honeybee larval been reported. So, it is considered to be a new bacteroidal disease of honeybee larval. Five pure cultures of bacteria were separated from ten collections of diseased honeybee larvae, named as L1, L2, L3, IA and L5. Among these five pure cultures, only L2 could make the healthy honeybee larvae become diseased in both field and lab test. The symptom caused by L2 was similar to the natural-infection. From the diseased larvae caused by L2 could isolate bacteria the same as L2. Thus 12 was determined as the causing agent of this bacteroidal disease of honeybee larval. L2 was identified according to the characteristics of morphology, physiological biochemical characteristics and 16S rRNA gene sequence. As a result, the morphology and physiological biochemical characteristics of L2 were similar to E. faecium. And its 16S rRNA sequences highly matched to E. faecium, the similarities between them were higher than 99%. The overall similarity values between L2 and the published 16S rRNA sequences of 41 typical species of Enterococcus were 93.9% - 99.5% , the top value was between 12 and E. faecium. In the phylogenetic tree, L2 and E. faecium were assembled in the same ramification. So 12 was identified as E. faecium. Although Enterococcus faecium was known as pathogen to many post, account for 12% of all nosocomial infections, only second to E. coli, but there is no report about this bacteria infects honeybee up to now. So it is a new pathogen to honeybee. The isolation and identification of pathogen of this new bacteroidal larvae disease, afford a good feasibility for available prevention and cure to this new disease.