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SITTI NURAENI. Epidemiological study on pebrine diseases and grasserie on several strains and seed sources of the silkworm using molecular detection methods (supervised by Djamal Sanusi, Tutik Kuswinanti and Andi Nasruddin). This study aims to determine: 1) the morphological characteristics of Nosema bombycis and Bombyx mori Nuclear Polyhedrosis Virus (BmNPV); 2) the infectivity of N. bombycis and BmNPV; 3) the resistance level of the silkworm strains against the N. bombycis and BmNPV; 4) to investigate the relationships between the production, pebrin disease with climatic factors; 5) to detect pathogen of N. bombycis and BmNPV by using Polymerase Chain Reaction (PCR) methods on the silkworm. The results showed that there were two isolates of Nosema bombycis, PC-614 and PL-614. The isolate PC-614 was originated from imported seeds while PL-614 was derived from local seeds. Both isolates had identical physical characters with the average of spore length 3,91 ??m and the width of 2,01 ??m. the shapes for both isolates were oval while for polyhedra BmNPV was rounded to hexagonal with the average diameter of 3,59 ??m. The infectivity of PC-614 and PL-614 isolates were relativity similar. However, the highest cumulative mortality on instar inoculation 4th instar was found to be 77% for PL-614 isolate. The highest infectivity of BmNPV occurred at the latest stage of fifth instar and the highest cumulative mortality on 4th instar inoculation was 76 %. Larvae development duration was extended to 10 days for those infected by N. bombycis while those infected by BmNPV had 11.5 extra days. S03, S01 and S02 strains were relatively resistant and BS09 was highly susceptible to N. bombycis and BmNPV. The influence of Pebrine disease towards rawsilk threads had significant negative correlation of 56.31 % (p |
