Impact of Parasitoids on Immature Stages (larva and Pupa) of Plutella Xylostella

The studies concerning the population density of Plutella xylostella and percent parasitism by various larval and pupal parasitoids in cabbage crop. The meteorological data of Taxila site was obtained from metrological center of Arid Agriculture Rawalpindi in 2012. The result related to larval and pupal population density initiated with (1.70) larvae/plant and (0.5) pupae/plant was recorded with average minimum temperature and maximum temperature (18.92°C and 34.10°C) at 40th of calendar week of October progressively. Highest larval and pupal density 11.40 ± 1.7/plant and 4.8/plant were recorded with minimum temperature and maximum temperature 11°C and 27.43°C respectively. The first parasitism 8%, 8% and 4% were recorded on Diadegma insulare, Oomyzus sokolowskii and Dinoptera collaris where the minimum temperature and maximum temperature were 18.14 °C and 32.64°C at 41st week of calendar. Highest parasitism level 16% and 12% were recorded by O. sokolowskii and D. collaris at 43rd calendar week and on D. insulare the 48% parasitism level was recorded. The effect of early and late stage of cabbage crop on larvae and pupae of P. xylostella 5.43 larvae/plant and 6.55 larvae/plant and 2.24 pupae/plant and 2.76 pupae/plant were observed during 2012. The parasitism level by parasitoids, the parasitism level 20%, 8% and 6.4% was recorded on early stage of cabbage crop by D. insulare, O. sokolowskii while, parasitism 16%, 2% and 4% on late stage were recorded, respectively.