Specificity and Insecticidal Activity of Chilean Strains of Bacillus thuringiensis

Abstract

Twenty-eight samples containing Bacillus thuringiensis were obtained from 137 soil samples collected from the Maule Region of Chile. Two isolates were selected for evaluation of insecticidal activity against two agronomically important insects, according to the following criteria: colony and parasporal inclusion morphology, SDS-PAGE, Western blot, and flagellar serotypes. Results showed that strains indexed as 114 (var. kurstaki serotype H3a3b3c) and G11g (var. kenyae serotype H4a4C) synthesized entomocidal proteins of the Cry I group. The insecticidal activity of strain 114 was similar to control strain var. kurstaki HD-1 toward Scrobipalpula absoluta larvae and presented 30% of activity of control strain against Helicoverpa zea larvae. Isolate G11g was found to be approximately 20% less active than the other screened strains.