Test of Pathogenicity of Bacillus thuringensis (Berliner) in Biological Control for the Cotton Leaf Worm, Spodoptera littoralis (Boisd.)

The study was carried out to evaluate the pathogenicity of the bacteria, Bacillus thuringensis of the cotton leafworm, Spodoptera littoralis (Boisd) at the rate of 1x106 spores/ml Laboratory results revealed that egg hatching percentage, at the age of 1-2 days were 0.0, 0.0 and 8.2 % 2 and 4 days after application respectively. While the hatching percentage of the 3-4 days old eggs was 6.8% at the age of 2-4 days after 2 days' treatment. The mortality rate of larval stages (2, 4, 6 instars) was 100% 14 days after application. When pupae were treated with the bacteria adult emergence percentage was 51.3 % 15 days after treatment compared to 100% emergence for the control treatment. The results in greenhouse show that the entomopathogenic bacteria also achieved mortality rate for 2, 4, 6 larval instars of the pest were 94.4, 91.8, 100, 88.4, 85.6 and 81.3 % for the soil and plant treatments respectively, 14 days after application.