Influence of different stages of rice crop on yellow stem borer, Scirpophaga incertulas (Walker) and its egg parasitoids

Abstract

A preliminary data was generated to ascertain the damage by stem borer at different age of rice crop and efficiency of its natural egg parasitoids at different stage of crop. The study was carried during August 2016 to May 2017 in the variety CO 51 at different age viz., 30, 45, 60, 75 and 90 DAP. The results revealed maximum dead heart damage (10.47%) at 60 DAP and minimum (3.98%) at 45 DAP. Four different egg parasitoids were recorded viz., Telenomus sp., Tetrastichus schoenobii, Trichogramma japonicum, Trichomalopsis sp. The influence of crop age on individual egg parasitization revealed highest parasitization of T. schoenobii (40.64%) followed by Telenomus sp. (19.69%) at 30 DAP while that of T. japonicum (1.65%) and Trichomalopsis sp. (0.87%) during 45 DAP. Total eggmass parasitisation was also highest at 30 DAP (34.48%). The stem borer damage was minimum in the crops while the egg parasitoids were higher.