Studies On The Morphology And Biology Of Nosema Bombi

This paper reports a examination of N.bombi isolated from national bumblebee (B.lucorum) in China using light and electron microscopy to study its morphology and biology, compare with N. bombi(B.terrestris) and N.apis, investigating infection intensity and mortality of queens(B.lucorum, B.pyrosoma, B.ignitus) with N.bombi in China.N. bombi (B.lucorum) are oval, showing blue refraction , its surface is smooth ,no any characteristical shape was found. And no difference were found on the morphology of N.bombi obtained from B.lucorum and B.terrestris , significant differences were found on the ultra-structure of N.bombi (B.lucorum )and N.apis. N.apis Releasing polar filament were observed easily under the light microscope, it is difficult to release polar filament for spore of N. bombi (B.lucorum) and N. bombi(B.terrestris), So the results show that N. bombi (B.lucorum) was separated from N.apis.Experiment cross-infections of adult and pupa and larval workers between B.lucorum and B.terrestris with the Nosema bombi showed all stages to be susceptible. N.bombi (B.lucorum )were found to be infective for worker of B.lucorum .B.pyrosoma, B.ignitus and B.terrestris ,although less so in these foreign hosts, case mortality was significantly higher in foreign hosts than in B.lucorum .Different sources of Nosema spores differed in their success in infecting different host colonies suggesting genotype-genotype interactions between host colonies and parasite colonies.Infection intensity and mortality of queen bumble bees (B.lucorum, B.pyrosoma, B.ignitus) with N. bombi were low. In the course of rearing , Infection intensity and mortality of queen bumble bees were reduce gradually, it is connected with infection N. bombi level, no infected eggs were found.Experimental infection of adult and workers and second generation queens mated with N.bombi from B.lucorum queens in China show that no outward signs of disease were found for infected bumblebees, there is no difference between queens with severe N.bombi infections and queens without pathogens. Infected larvae and pupae delay developing. Infected workers often become sluggish, die early, infected second generation queens delay brooding for 2-4 day.