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Selection and characterization of Bacillus thuringiensis strains toxic against pyralid stored‐product pests
Author(s) -
Azzouz H.,
KebailiGhribi J.,
Daoud F.,
Abdelmalak N.,
Ennouri K.,
BelguithBen Hassan N.,
Tounsi S.,
Rouis S.
Publication year - 2015
Publication title -
journal of applied entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.795
H-Index - 60
eISSN - 1439-0418
pISSN - 0931-2048
DOI - 10.1111/jen.12205
Subject(s) - bacillus thuringiensis , biology , pyralidae , strain (injury) , larva , plodia interpunctella , bioassay , midgut , lepidoptera genitalia , microbiology and biotechnology , botany , bacteria , genetics , anatomy
Abstract In this study, we present the selection and the characterization of Bacillus thuringiensis strains toxic against pyralid pests of stored products. Among 201 new B. thuringiensis strains isolated from different countries, two strains ( BLB 249 and BLB 384) showed greater toxicity than the commercialized strain B. thuringiensis kurstaki HD 1 against Ephestia kuehniella larvae. Morphological, molecular and biochemical investigations revealed that these strains were similar to HD 1 but presented different cry gene content. Additional bioassays revealed that only strain BLB 249 displayed higher toxicity than HD 1 against Plodia interpunctella larvae. The study of Cry protoxin activation by midgut proteases of E. kuehniella and P. interpunctella larvae supported that higher toxicity of BLB 249 and BLB 384 strains compared to HD 1 was not due to differential protoxin activation. Moreover, the toxic strains produced δ ‐endotoxins and spores in similar amounts to HD 1. Interestingly, the δ ‐endotoxin production and the yield of BUPM 26 strain were 32.87% and 35.12% greater than that of HD 1. The potent insecticidal activities of BLB 249 and BLB 384 strains and the high level of δ ‐endotoxin production by BUPM 26 strain make them excellent candidates for use against E. kuehniella and P. interpunctella larvae.