S. Karthikeyan, T. Abdul Razak, A. Manivannan and S. Sekar
Abstract
The bioefficacy of X. japonica from entomopathogenic nematode Steinernema kushidai (Mamiya) was assessed along with and without Bacillus thuringiensis using the rice leaffolder Cnaphalocrosis medinalis (Lepidoptra : Crambidae). The X. japonica at 108 cells per mL dosage showed 95-100 per cent and 20-35 per cent mortalities with and without Bt combination respectively during 60-72 h after treatment. During 12 h after treatment, in the dosage level of 108 cells per mL of the X. japonica + Bt, 10 per cent larval mortality was recorded and in all other treatments the mortality level was nil. The X. japonica at 108 cells per ml without Bt combination recorded the least value of 12.5 per cent larval mortality. Sole application of Bt at one gram and two gram per L. caused 15 and 37.5 per cent larval mortalities respectively. It is observed that X. japonica is less effective without Bt. Thus we assume that Bt has synergistic effect over X. japonica.