Abundance of yellow stem borer, Scirpophaga incertulas, Walker egg parasitoids in relation to cultural practices in West Bengal, India.

Field study by randomized block design on the incidence of both yellow stem borer (YSB) and its important parasitoids were carried out in the field of rice cultivar Swarna mashuri (MTU 7029) during four consecutive crop years (2005-2008) at Raiganj, Uttar Dinajpur, West Bengal, India. Observations include all the life stages of YSB (egg, larvae and pupa) and its important hymenopteran parasitoids species. T. rowani, Gahan (Scelionidae), T. schoenobii, Ferriere (Eulophidae) and T. chilonis, Ishii (Trichogrammatidae) were identified as the three important egg parasitoids in this region. High average parasitization at early vegetative stages (63.85%) decreased steadily and remained constant during mid-tillering stage (34.65%), and further declined during the ripening stage (14.67%). The overall egg mass parasitization (%) by T. chilonis, T. rowani and T. schoenobii was 18.23-71.67%, 15.56-67.34% and 10.23-52.56% respectively. Abundance of T. chilonis was maximum in 37 standard meteorological weeks (SMW) and minimum in 30 SMW. Maximum number of T. rowani was recorded in 37 SMW and lowest in 30 SMW. Number of T. schoenobii was maximum in 37 SMW and minimum in 30 SMW.