Parasitising Efficiency of Egg Parasitoid, Trichogramma japonicum Ashmead at Four Temperature Regimes

Parasitising efficiency of Trichogramma japonicum on Chilo partellus eggs was studied at four temperatures (25, 30, 35 and 40 ± 1°C) and at 60±5% R.H. with female parasitoid densities (1, 2, 3, 4 & 5). The mean % of parasitism obtained was uniform ranging from 25.1–33.2% at 25°C, 1.2–60.0 at 30°C and 11.4–35.4 at 35°C and it differed with parasitism obtained at 40°C at various female densities. There were no significant differences in parasitism due to different female density of T. japonicum. Low % parasitism was recorded at 40°C with all the female parasitoid densities. However, at 25° to 35° C. superparasitism ranging from 20–25% was recorded in treatments where 3–5 females were released. The duration of development from oviposition to adult emergence varied from 6.8 to 13 days. The parasitoid completed development at 25–35° C, but it failed to complete development at 40°C. At 25°C and 60± 5% RH, 2 females: 50-Chilo partellus eggs was found to be the most suitable ratio for laboratory parasitisation.