Seasonal incidence of rice caseworm, Nymphula depunctalis Guenee in different rice ecosystem

Abstract

Field experiment was conducted at research farm of Indira Gandhi Krishi Vishwavidyalaya, Raipur during kharif season 2013-14 under different rice ecosystems. The results of field experiments revealed that the maximum population was found in August-September month. Among the ecosystem highest caseworm, N. depunctalis adult population was recorded in LLC (0.44 adults/25 sweeps), followed by LLO (0.31 adults/25 sweeps), MNT (0.25 adults/25 sweeps), MSR (0.15 adults/25 sweeps) and UTP (0.11 adults/25 sweeps). The incidence of caseworm, N. depunctalis revealed that the per cent leaf infestation was noticed from 31 to 32 SMW of July to August with 0.08 to 0.20 and disappears after 37 to 38 SMW of September in among the rice ecosystem. There was an increase in population in subsequent weeks and the maximum per cent of leaf infestation was recorded during 34 to 37 SMW of August-September with (0.00%), (0.19%), (0.46%), (0.31%), (0.69%), and (0.46%) leaf infestation/hill in upland direct seeded rice ecosystem (UDS), upland transplanted rice ecosystem (UTP), midland normal transplanted rice ecosystem, midland SRI rice ecosystem (MSR), lowland organic rice ecosystem (LLO), lowland conventional rice ecosystem (LLO), respectively. On the basis of seasonal mean it is crystal clear that the maximum per cent of leaf damage/hill was recorded in LLC (0.20 % leaf damage/hill), followed by LLO with (0.13 % leaf damage/hill), MNT (0.10 % leaf damage/hill), MSR (0.0.07 % leaf damage /hill), UPT (0.0.05 % leaf damage/hill) and UDS (0.00% leaf damage/hill)