Effect of Different Host Plants on the Efficacy of Bacillus thuringiensis subsp. kurstaki Against the Cotton Leaf Worm, Spodoptera littoralis

Abstract

A laboratory experiment was conducted to determine whether Bacillus thuringiensis var. kurstaki (Btk), an entomopathogenic bacteria, was compatible with four hosts from various plant families, including cucumber, Cucumis sativus L., pepper, Capsicum annuum L., cabbage, Brassica oleracea L. and tomato, Solanum lycopersicum L. against the cotton leaf worm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae). The highest mortality rate was 85.78 and 75.00% for cucumber treated with Bt at the concentrations of 0.7, 0.3 and 0.5 g/l, respectively, three days after treatment, followed by 71.7, 48.00 and 27.6% for cabbage treated with Bt at the concentrations of 0.3 g/l, 3, 5 and 7 days after treatment, respectively. When pepper was treated with Bt at the concentration of 0.7 g/l, the mortality rate reached 51, 41 and 30%, 3, 5 and 7 days after treatment, respectively. Whereas tomato treated with Bt at the concentration of 0.7 g/l, the mortality rate reached 42.5, 33.5 and 8.0 %, 3, 5 and 7 days after treatment, respectively. The high effect of Bt was obtained on the third day after treatment followed by the fifth day and then the seventh day after treatment.

Keywords:

Bacillus thuringiensis, Spodoptera littoralis, host plant, Cucumis sativus, Capsicum annuum, Brassica oleracea, Solanum lycopersicum.