author(s)
Javed Khan, Rabia Ali, Ammara Blouch, Habib Iqbal Javed, Ehsan Ul Haq, Tariq Mehmood and Awais Rasool

abstract
The present study was conducted on biological parameters of parasitoid Cotesia flavipes reared on Chilo partellus larvae under laboratory condition of 25±1 °C and 60±5% relative humidity at Insect pest Management program, National Agricultural Research Centre, Islamabad. The parasitoid could not survive on first and second instar larvae of C. partellus, while it successfully completed its life cycle on 3^rd, 4^th and 5^th instar larvae. No significant difference was observed in the mean developmental duration 16.26 ± 0.37, 16.86 ± 0.36, 16.78 ± 0.27 from parasitism to adult parasitoid emergence on 3^rd, 4^th and 5^th instar larvae of C. partellus, respectively. The duration of pupae reared on 3^rd instar larvae was the longest (6.46 ± 0.13 days) and significantly different from mean pupal duration on 4^th (5.06 ± 0.21) and 5^th (5.12 ± 0.31) larval instar larvae. Mean Adult duration was 48.46 ± 0.27, 42.53 ± 0.23 and 42.34 ± 0.21 hours when reread on 3^rd, 4^th and 5^th instar larvae, respectively. Similarly, the rate of parasitism was 66.46± 0.48, 80.4± 0.51 and 71.7± 0.41% and the mean number of pupae (cocoons) was 32.66± 0.23, 44.60.32 and 39.6± 0.37, respectively thus showing significant difference, when reared on three larval instar. The most preferable stage by C. flavipes was 4^th instar larvae of C. partellus.