Population dynamics of insect pests under different planting methods of rice ecosystem

The population of leaf folder (Cnaphalocrosis medinalis Guenee), yellow stem borer (Scirpophaga incertulas Walker) and blue beetle (Leptispa pygmae Baly) were recorded on rice under different planting methods viz., transplanting, drill sowing and aerobic cultivation during Kharif, 2010. The blue beetle appeared in the vegetative phase of the crop growth. Its population was significantly high in drill sown rice, followed by transplanted and least in aerobic method. The incidence of leaf folder was low and almost static during vegetative phase of the crop. Peak activity of leaf folder was noticed during reproductive phase of the crop. Drill sown crop supported significantly higher population compared to aerobic rice. Similarly, the population of yellow stem borer crossed threshold level only in aerobic rice during reproductive phase of the crop.