Identification and bioactivity of native strains of Bacillus thuringiensis from grain-related habitats in Turkey

Abstract

A native collection of Bacillus thuringiensis (Bt) strains originated from grain-related habitats in Turkey was characterized according to serotype, cry1 gene content, and bioactivity against Ephestia kuehniella (Lepidoptera: Phycitidae) and Spodoptera littoralis (Lepidoptera: Noctuidae). Twenty-three different serotypes as well as 24 unknown serotypes were obtained from 56 positively agglutinated strains with previously characterized antisera. Most common serovars were sotto, kim, and tochigiensis with the percentages of 14, 14, and 13, respectively. Among the cry1 gene-positive 36 strains, cry1E (100%), cry1Aa (94%), cry1Ac (92%), and cry1D (83%) genes were the most abundant. Bioactivity tests with 56 Bt strains carrying cry1, cry2, and/or cry9 genes indicated that all of them resulted in growth retardation or inhibition of larvae of both E. kuehniella and S. littoralis; however, only one strain, 85PPb (serovar morrisoni), caused high mortality in both insects (84% and 100%, respectively). Different crystal morphology was observed for the strain 85PPb and the standard strain B. thuringiensis subsp. morrisoni. Finally, no correlation was found among serotype, cry gene content and biotoxicity of Bt strains in the collection.

A promising HD133-like strain of Bacillus thuringiensis with dual efficiency to the two Lepidopteran pests: Spodoptera littoralis (Noctuidae) and Ephestia kuehniella (Pyralidae)

“…For instance, HD1 is remarkably toxic against E. kuehniella but not as toxic against S. littoralis . Conversely, HD133 is exceptionally toxic to S. littoralis but not as toxic to E. kuehniella (Apaydin et al, 2008).…”

Molecular characterization of indigenous Bacillus thuringiensis strains isolated from Kashmir valley

“…In addition, the mortality range of 13 strains was lower than 10% and that of 6 strains was moderate (30-50%). However, only one strain (85PPb) showed very high toxicity (84% mortality) (Apaydin et al 2008).…”

Selection and characterisation of an HD1‐like Bacillus thuringiensis isolate with a high insecticidal activity against Spodoptera littoralis (Lepidoptera: Noctuidae)

“…Several collections of Bt strains are characterised mainly by molecular, serological and morphological methods in order to predict their insecticidal activity against Spodoptera species . Thus, the correlation between toxicity of Bt strains, cry gene content and serotype was established .…”