BIOACTIVITY OF DIPEL 2X, A COMMERCIAL PREPARA-TION OF BACILLUS THURINGIENSES BERLINER AGAINST THE COTTON LEAFWORM SPODOPTERA LITTORAL'S (BOISD.)

Document Type : Original Article

Author

Plant Protection Research Institute, Agricultural Research Centre, Dokki, Giza, Egypt

Abstract

The insecticidal activity as well as the latent effect of Dipel 2x , a commercial preparation of Bacillus thuringienses var. Kurstaki (Berliner) were evaluated in the laboratory . The 2nd instar larvae of the cotton leafworm Spodoptera littoralis (Boisd.) were fed on a diet surface treat­ed with various doses of Dipel 2x, i.e. 64, 192, 320, 5120 and 6400 IU/ ml at 27+2°C and 55 - 60% R.H. Data of initial and latent mortality re­vealed that Dipel 2x had slight insecticidal activity against the cotton leafworm. The ability of larvae to recover decreased with the increase in concentration or / and feeding time . Both larval and pupal duration were remarkabley prolonged with dose increase, while pupation percentage was reduced . Remarkable latent adverse effects were detected on adult emergence, fecundity and egg viability, particularly with doses above 320 IU/ml.