Efficacy of Trichogramma japonicum Ashmead against yellow stem borer, Scirpophaga incertulas walk on rice in Nagaland.
The efficacy of Trichogramma japonicum Ashmead at different rates of release on suppression of yellow stem borer was studied under the agro-ecosystem of Nagaland. The rates of release had significant effect in reducing the dead heart at mid- and late vegetative stages of the crop. Single release treatment at its highest release rate (300,000 adults/ha) applied at 30 DAT had the maximum reduction in dead heart infestation with the least mean record of it followed by the treatment with 200,000 adults/ha applied in two equal split releases at 30 & 50 DAT. The white ear head infestation was lower under higher rates of release in split doses; the lowest record was by the treatment with 200,000 adults/ha splitted in four equal doses. Split releases had better impact on grain yield. A maximum increase of 12.62% in yield over untreated control was achieved from the treatment with 100,000 adults/ha applied in two equal split doses.