Potential Use of Entomopathogenic Virus Native to Sumatra Island as Biological Control Agent of Setora nitens L. (Lepidoptera:Limacodidae), the Main Pest of Oilpalm

Abstract

Slug caterpillars Setora nitens, have been appearing to be more serious insect pest of oil palm as it might cause frond damages up to 90%. Many effort had been made to control the caterpillars using insecticides but the insects are still existing and causing significant damages to the palm. Microbial insecticide, especially the one developed from indigenous entomopathogenic virus, is a promising method of controlling the insect since its toxicity to non target animals and humans is extremely low. A conventional way of controlling S. nitens using crude sap of infected larvae has been applied in several oil palm plantations in Sumatra Island, but various improvements are required to make the method more effective, efficient, widely acceptable and scientifically justified. A research on the potential use of entomopathogenic virus native to Sumatra Island as biological control agent of slug caterpillar was conducted to comprehend the pathogenicity and virulence of the entomopathogenic virus and to reveal the morphological identify of its particle. The results showed that the use of virus infecting caterpillars to control the insect was quite successful in term of increasing the number of infected caterpillars and reducing the rate of population development in the field. The use of homogenized infected caterpillars to orally infect healty S. nitens caterpillars resulted in the symptoms characteristics to viral infections appeared in all treated caterpillars with various extent of symptom developments. Some caterpillars could spine cocons but failed to release adult moth. Purification of the virus particles from infected caterpillars resulted in the apperarance of white band in the sucrose gradient indicated the presence of viral RNA. Electron microscopic observation showed that the white band in the sucrose gradient contained sphericle shape of virus particles justifying that the agent infecting S. nitens caterpillars is a virus which still need further analysis for its complete identification.