Study On Vertical Transmission And Detection Technique Of Bmnpv In The Silkworm, Bombyx Mori L.

Bombyx mori nucleopolyhedrovirus (BmNPV) has a single double-stranded circular DNA, belong to the family Baculoviridae, which are pathogenic for invertebrates, particularly insects of the order Lepidoptera. Its main host is Bombyx mori. BmNPV is one of the four virus diseases of silkworm, cause serious economic loss every year for sericulture. In order to clear venereal transmission of BmNPV in silkworm and the effection to next generation Histopathological and Polymerase chain reaction (PCR) technology were used to in this study..1. Determine the susceptibility of the gonads cells to the BmMNPV by histopathologicalThe results showed that:NPV were detected in the nucleus of spermatocytes and the nurse cells of primary oocytes respectively in the larvae inoculated with BmNPV.2. Statistical analysis of BmNPV from infected parents to the F1 offspringThere are highly significant differences in the egg laying rate of infected females (IF) mate with infected males (IM) and the rate of hatching of eggs of F1 due to transovarial transmission of BmNPV, as well as all of the F1 generation larvae were died at first instar stage. Mating tests of healthy females (HF) with infected males (IM), infected females (IF) with healthy males (HM) were clearly reduction in fecundity and hatching of eggs (P< 0.05), also confirmed venereal transmission and the F1 offspring larvae were died at first and second instar stages.3. Polymerase chain reaction (PCR) assay with BmNPV from the Fi offspring eggsDetection of BmNPV from the F1 eggs employed Polymerase chain reaction(PCR) technology found that the F1 generation eggs of the tree mating tests (HF×IM,IF×HM,IF×IM) all contains BmNPV. It is confirmed that the viral infection is vertically transmitted to the progeny by two modes, transovarian transmission, adults mating transmission.4. Detection of BmNPV from the silkworm eggsDetection of BmNPV from the silkworm eggs, which were used for farming production showed that the percent of eggs carrying virus can reach 80%, even after surface of the egg sterilized the percent still has 10%. These results suggest that in the actual production outbreak of BmNPV disease frequently, in addition to the effect of feeding environment, vertical transmissions of BmNPV are also the important reason.