Studies On Pathogens Of Microspordiosis In Hunan Silkworm

This paper studies on the pathogens of silkworm pebrine disease in Hunan Province. It isTrying to check out the mainly source of pathogenic of microsporidian which endanger Hunanprovincial sericiculture industry. Silkworm pebrine disease is caused by microsporidian Nosemabombyci. But some other microsporidian that infects Pieris rapae and Hemerophila atrilinetacan also infect silkworm. It is critical that identify the pathogens of pebrine that enable ascientific method to prevent the spread of the disease. The microsporidian from silkworm areisolated and its biological characters, nosogenesis mechanism and their difference with N.b arestudied. The results are listed as follows:1. Silkworm pebrine desease in Hunan province comes from the open mulberry field insect,the mainly source of the pathogen is Pieris rapae microsporidian(CFD) and Hemerophilaatrilineta microsporidian(SCH).In a three years continuously observation of the mulberry field insects and disinfection themulberry leaf, the microsporidians are isolate and pinpoint observed under microscope from boththe silkworm and other field insects. It is confirmed that the silkworm microsporidian do have across infection with the other insects microsporidian, this work will do an important effect tocontrol the silkworm pebrine disease by build up an early-warning mechanism.2. Using phylogenetic analysis to study this two mainly sources of microsporidians thatcome from the field insects CFD and SCH. The result confirmed that this two microsporidianhave a strong infection to silkworm and have a weak germinal infection to the eggs. It courses ofillnesses is all long when this two microsporidians of original generation or the after generationinfecting the silkworm but symptom of the disease is weak. The disease proceeding come onslowly and have little effect on breeding and eggs laying. It is observably difference with N.b sojudge it as an unusual mcrisporidian.3. Silkworms which infected by CFD microsporidians or SCH microsporidians are observedby dissection. Its organizations like medium bowel, silk gland, malpighian tube, the fat tissue allcan test out the microsporidians. It is elucidated that the two kinds of insect microsporidian canparasitize in silkworm fitfully. It just similar to the infection of N.b and belong to the whole bodyautoeciousness pathogeny. 4. The CFD spores of P,F1,F2 generation is observed under the scanning-electron-microscope. That the CFD spores diameter proportion and size have a variational trend aftergeneration. The difference between the individual spores shape and size were reducing. Thecolony tends to be orderliness and the diameter proportion reduced. The spores present to beplump. The difference with N.b is reducing after several generation propagation. But the SCH ismore stable after generation infection. But its diameter proportion and volume is tend to bediminished and near to N.b too.5. Microsporidian ultrastructure is very alike under the transmission scanning-electron-microscope. All the endospores have three layers and the polaroplast include two parts with apolar filament five-layer structure and binucleate. The karyotheca is a two-layer structure that therough endoplasmic reticulum contain a great deal of ribosome. The posterior vacuole is at theend of the spore with vacuole around. Those ultrastructure is typical with Nosema genus. Thusthe CFD and SCH microsporidian should belong to the Nosema genus too.6. SSU-rDNA are amplified and cloned by PCR with designed Primers. The gene aresequenced and analysised. Result shows that the sequence have a higher diversity with N.b butshares homologous in CFD and SCH. It elucidate that the two microsporidians were in the samecongener but not in the same homogeneity.