Seasonal Incidence of Insect Fauna Associate with Rice Ecosystem

Experiment was carried out at ICAR-National Rice Research Institute Cuttack, Odishato observe the insect fauna associated with the kharif rice ecosystem. Rice crop provide shelter to a number of insect species. The harmful species mainly belong to insect order of Lepidoptera (stem borer, leaf folder) and Hemiptera (plant hopper, gundhi bug) whereas the beneficial one includes several species of dragonflies, damselflies, predatory bug, predatory beetle and spider, a non-insect arthropod species. The incidence of harmful species was observed starting from August to November. The duration of sunshine hours plays an important and significant role in the incidence of yellow stem borer whereas maximum temperature plays a prime role in the incidence of leaf folder and plant hopper population. Minimum temperature and rainfall were negatively and significantly correlated with the population fluctuation of gundhi bug. The populations of predatory fauna such as dragonflies, damselflies, predatory bug, predatory beetle as well as spider fluctuate over a mean value throughout the cropping season. The population of dragonflies and damselflies were known to be more prevalent during the early growth period of the crop whereas the population of predatory bug and beetle were known to be more prevalent during the later period of growth. Spider populations were constant throughout the cropping season.The incidence of adult moth of yellow stem borer started at the end ofAugust which reaches its peak during the third week of October. Similarly, the incidence of leaf folder started during the first week of August with its peak during the second week of September. The incidence of the hopper population started during the second week of August. The population of brown plant hopper was maximum during the third week of September as compared to that of green leaf hopper which reaches maximum during the beginning of October. The incidence of gundhi bug started during the second week of October as the crop enters into the reproductive stage and continued up to the harvesting of the crop.