The newly molted 5th larval instar of B. mori were injected with E. coli (G-) (1.1 x 106 cells/ml), B. thuringiensis (G+) (Dipel) was injec-ted at concentrations of 0.5, 1.0 and 1.5 ppm and physiological saline (Sigma, UK), as control. Each larva was injected with 50 μL in the dorsal segment of larvae by BD Micro-fine™ plus syringe. Five replicates, 60 newly molted larvae were used for each treat-ment.