Study And Control On Several Population Of Pathogenic Microsporidian In The Silkworm, Bombyx Mori (Bombycidae, Lepidoptera)

Microsporidia are lacking mitochondriate unicellular eukaryotes and all obligate intracellular parasites and infecting a wide range of vertebrate and invertebrate hosts such as insects and fishes and mammals. Microsporidum which was first discovered is Nosema bombycis Naegeli 1857 from the silkworm and it was established for quarantine objective because of transovarial transmission and pathogenetic to filial generation. My study first established its epidemic curve, control model and area distriating of pathogeny kinds. Before Nosema bombycis was considered only microsporidia pathogen of the silkworm but in my study new several kinds of microsporidia was found and isolated two species microsporidia from the silkworm in Sichuan China, the big spore SCM6(Nosema sp) and small spore SCM7(Endoreticulatus bombycis sp nov).SCM6(Nosema sp) fresh spores were oval in shape and 3.91±0.25 X 2.56±0.28μm in size. The mean polar filament length was 126 ± 8.23 μ m . Ultrastructural studies showed that the spore binucleate and the polar filament normally arranged in 14 or 15 coils and occasionally in 16 coils. The cycle of life include merogony and sporogony stages and the sporont a fusiform diplokayotic cell and change to spore and there shows Nosema Genus characteristic. The microsporidum can parasitic to many tissues of the silkworm and highly invaded into silk-glands, but merogony and sporogony were low in mid-gut and occasionally invaded into reproduction gonad. SCM6(Nosema sp) transovarial transmission rate only were 1.44±0.75% and lower 10 times than Nosema bombycis, No pathogenicity to the silkworms progeny. It is a new pathogenetic microsporidum in the silkworm and belongs to Genus Nosema in taxonomy and is recorded as Nosema sp.SCM7(Endoreticulatus bombycis sp nov) spores were ovoidal, 2.26 ± 0.21X1.19± 0.81 μm . The polar filament length was 39.90-60.18μm .The electroscope studies revealed that the spore uninucleate and the polar filament in single coil with 7~9 turns. All development stage is enveloped by parasitophorous vacuole from a double membrane of host endoplasmic reticulum and producing many spores and the developmental features were similar to Genus Endoreticulatus. The isolate only infects the midgut epithelial cell of the silkworm but no invade to reproduction gonad and no transovarial transmission to pathogenetic to progeny. The isolate was new species of microsporidum by taxonomy searching and is recorded Endoreticulatus bombycis sp nov. SCM7(Endoreticulatus bombycis sp nov) small subunit(16S) ribosomal RNA gene partial sequence has 1230pb and it have over 98% similarity to Endoreticulatus.schuerg.Because SCM6(Nosema sp) transovarial transmission rate only were 1.44±0.75% and SCM7 no transovarial transmission, the study lay down the inspection technique distinguishing from Nosema bombycis and counting method of the moth infecting rate andqualified rules of the silkworm eggs to the SCM6 and SCM7 , and the technique is applied to disease area . According to application report of the inspection organization, it retrieved how much loss of the silkworm eggs and tremendous economic result. The study took theoretical and practical breakthrough and is innovation production in home and international, and solved a great problem of the silkworm eggs production in China.Another, a previously undescribed microsporidum is isolated from the Cerace stipatana (Walker) in October 2000, in Langzhong, Sichuan province, China. We describe this microsporidium as a new species of Vairimorpha, and name it as Vairimorpha ceraces sp.nov. According to taxonomy system (Sprague 1992), it belongs to Phylum Microspora, Class Dihalophasea, Order meiodihalophasea, and Family Burenellidae. Type Host: Cerace stipatana Walker (Lepidoptera,Tortricoidea).Site of Infection: Infection to midgut epithelial and muscle cells, fat body, derma cell.Type Locality: LangZhong, Sichuan province(32 °N,105 °E),China. Prevalence of infection: Seventy-five of three hundred larvae, Cerace stipatana examined were infected (25%). Diagnosis: spore is ova...