Pustaka Ilmiah Universitas Padjadjaran

Abstrak

In Vivo Production Of Helicoverpa Armigera Nuclear Polyhedrosis Virus (Hanpv) In Spodoptera Litura : The Effect Of Viral Serial Passages In S. Litura On Production And Pathogenicity Of The Virus To H. Armigera

Previous studies on our Indonesian isolate of Helicoverpa armigera Nuclear Polyhedrosis Virus (HaNPV) isolated from cadaver of Helicoverpa armigera, indicates that the virus exhibits a great potential to be used as bioinsecticide to control population of Helicoverpa armigera. The use of insect virus as biological control agent is still limited, partly due to problems related to the difficulties in virus production. For HaNPV in particular, invitro production is hinderd by the high production cost, while invivo production techniques is difficult to perform, since Helicoverpa armigera larvae used for production host exhibits canibal behaviour, thus have to be reared individually. Previous studies shows that Spodoptera litura is also pathogenic HaNPV, that it can be used as a host for HaNPV invivo production. This research study the effect of HaNPV serial passages in S. litura on production and pathogenicity of the virus to H. armigera to determine the effect of HaNPV serial passage in Spodotera litura on the production of HaNPV and pathogenicity of the resulting HaNPV to Helicoverpa armigera. The result indicates that HaNPV subcultured in Spodoptera litura exhibited a similar patogenicity to Spodoptera litura compared to that subcultured in Helicoverpa armigera. Third instar of Spodoptera litura infected with HaNPV0, HaNPV1, HaNPV10 and HaNPV20 exhibit an average larval death of 12,6 days, 9.33 days, 8.66 days and 10.83 days respectively. Furthermore, the level of viral production was not influenced by the level of HaNPV subcultures in Spodoptera litura. Third instar of Spodoptera litura infected with HaNPV0, HaNPV1, HaNPV10 and HaNPV20 exhibit HaNPV production of 0.126 X 1010 PIB/ind, 2.65 X 1010 PIB/ind, 2.02 X 1010 PIB/ind, and 2,97 X 1010 PIB/ind. The result indicates that HaNPV repeated subcultures in Spodoptera litura do not change the pathogenicity of the virus to Spodotera litura and level of viral replication capacity of the virus. However further observation on the morphology of the polyhedra indicates that there are chages, possibly mutation, on HaNPV subcultured in Spodoptera litura. The polyhedra tend to deformed as the level of subculture increased. Further investigation showed that the polyhedral deformation does not alter the pathogenicity of HaNPV to Helicoverpa armigera. Mortality data shows that infection HaNPV0, HaNPV1, HaNPV10 and HaNPV20 to third instar of Helicoverpa armigera larvae led to a similar mortality rate ie : 100%, 93.33%, 100% and 93.33% respectively.