Risk Grading for Damage of the Defoliator Orthosia songi( Lepidoptera: Noctuidae)

This study was to establish an early warning technology for forecasting outbreaks of defoliator insects Orthosia songi Chen et Zhang based on a recommended standard "Grading Methods of Natural Disaster Risk" issued by Civil Affairs of China. The main aim was to provide relevant information for risk grading and establish a warning technology of outbreak for forest and agriculture defoliator insects. This study used O. songi-host treeEucommia ulmoides system as a model located at Linbao City, Henan Province, China. Leaf area loss rate (%) and fruit dropped rate( %) were measured under different larval densities( larvae per hundred leaves). Leaf area loss rate and fruit dropped rate differed statistically significant among different larval densities. The results fitted well the prediction, indicating that the risk grading method is feasible. The risk grading method in this study was well suited for short-term predictions, i.e. prediction of risk caused by one generation.