Species composition, occurrence pattern and seasonal incidence of rice leaf folder (Cnaphalocrocis spp.) on kharif rice under Terai agro-ecological conditions of Northern Parts of West Bengal

Three different species of rice leaf folder, Cnaphalocrocis spp. were recorded among the field collected samples. The species were identified as Cnaphalcrocis medinalis (Guenee), Cnaphalocrocis patnalis (Bradley) and Cnaphalocrocis poyealis (Boisduval) with relative abundance of 71.21, 23.76 and 4.86% respectively. C. medinalis was the early colonizer and C. patnalis was found to colonize late in the season. Population of adult moths was found to increase along with the advancement of the crop growth stage and it was also noticed that the number of adult moths caught by sweeping net were consistently high during the last few weeks i.e. 43^rd, 44^th and 45^th standard meteorological weeks (SMW) when crop was near to maturity. Correlation study between number of weekly captured moths and plant phenological parameters like average tiller/hill, average leaf/tiller as well as growing degree days (GDD) revealed that the adult population was strongly and positively correlated with GDD.