LAUSR

Abstract Yellow stem borer (YSB), Scirpophaga incertulas (Walker) is considered as major pest of rice. An egg parasitoid, Trichogramma, is used for management of Lepidoptera pests of rice across the world. In order to optimize the time and number of releases of Trichogramma japonicum three different schedules of releases of T. japonicum were evaluated to manage YSB during rainy season 2017 and 2018 (June to October) under lowland rice. Each schedule consisted of multiple releases of wasps for four times at weekly interval (50,000 wasps/ha/release × four releases or 500 wasps/100 m2/release × four releases). The statistical analyses of two seasons data revealed that four releases of T. japonicum at weekly interval on the 32nd, 39th, 46th and 53rd day after transplanting of rice had reduced the damage symptoms caused by YSB by 52.8% dead heart (2.51%) and 66.1% white ear (0.62%) when compared to control plots (5.32% dead heart; 1.83% white ear). The results suggest that the time-specific multiple releases of T. japonicum @ 50,000 wasps/ha/release × four releases can be the useful to attain biocontrol of YSB.