Attempts at forecasting rice planthopper populations in Malaysia

The two rice planthoppers that have caused devastating damage to rice crops in Peninsular Malaysia areNilaparvata lugens andSogatella furcifera. A surveillance system has been set up to monitor these pests. A case study in the off-season crop of 1980 in the Tanjung Karang Irrigation Scheme showed that hopperburn could be predicted a month before it happened. In the following main season, both surveillance records and ecological factors suggested that the pest would be under natural control and the forecast was accurate. The main factors considered in forecasting rice planthoppers were: migration, brachyptery, pest population, predatory: prey ratio, history of outbreaks and prevailing field conditions.