Bioprotection of oil palm against the Rhinoceros beetle with the Oryctes rhinoceros virus

The successful introduction of Oryctes rhinoceros virus (OrV) to control outbreak of rhinoceros beetle (RB), Oryctes rhinoceros (Coleoptera: Scarabaeidae) in South Pacific Islands has led MPOB to evaluate the potential use of the virus in oil palm plantations in Malaysia. Two DNA-based technologies, the PCR and RFLP, have been developed and intensively used in the project. The PCR is sensitive, accurate and simple technique allowing us to estimate the infection status of OrV on adults and larvae. The adults are commonly infected (30 -65%) as compared to larvae (0 -35%). Pre-pupae and pupae are free from the virus infection. Analysis of OrV genome by an endonuclease enzyme HindIII, identified 4 types of OrV called as types A, B, C and D. Bioassays showed that the type B OrV is more pathogenic against neonates and L3 larvae. The release OrV system was then established. The virus solution was produced by in-vivomethod using the larvae and adults of the beetles Introducing the type B OrV in the young oil palm area (below I-year old palm) with the existing virus type A has successfully reduced the adult population and as well as palm damage. The released virus established as early as 3 month after release (MAR) and persisted up to 15 MAR. The virus was then introduced in the 3-yearsold palm area. Virus infection was gradually increased and maintained at higher level between 60 -90%. The adult population reduced and maintained at low level for a certain period before slowly increasing again to reach the second peak. Virus infection has a weak negative correlation with adult population. Slow reduction on proportion of males was possibly because of slow virus transmission as they has already adapted to virus infection. The DNA analysis showed that the type B virus was detected only at 4 MAR. Factors to ensure the success of the released virus transmission in the population were elaborated. Further research work to fully utilize the OrV to ensure maximum control of the rhinoceros beetle was also discussed.