The occurrence, biodiversity and toxicity of Bacillus thuringiensis strains isolated from the insect pest Lymantria dispar (Poland)

• Published in: Polish journal of microbiology 2009, Vol.58 (2), p.155-161
• Main Authors: Guz, Katarzyna, Bugla-Płoskońska, Gabriela, Doroszkiewicz, Włodzimierz
• Format: Article
• Language: English
• Subjects: Animals; Bacillus; Bacillus thuringiensis; Bacillus thuringiensis - genetics; Bacillus thuringiensis - metabolism; Bacterial Proteins - metabolism; Bacterial Proteins - toxicity; Bacterial Toxins - metabolism; Bacterial Toxins - toxicity; Biodiversity; Drosophila melanogaster; Electrophoresis; Lepidoptera; Lepidoptera - drug effects; Lepidoptera - microbiology; Lymantria dispar; Poland
• ISSN: 1733-1331

The aim of this investigation was to survey the occurrence, biodiversity, and toxicity of Bacillus thuringiensis strains originating from dead caterpillars of the forest pest, Lymantria dispar (Lepidoptera). Morphological, biochemical, and microscopic identification of isolates from the insects showed the presence of five different Bacillus species, including 2% of B. thuringiensis. Based on the biochemical profiles, the B. thuringiensis were determined to be B. thuringiensis finitimus-like and B. thuringiensis alesti-like bacilli. Both produced spherical inclusions composed of three or five protoxins. The molecular weights of these proteins varied from 20 to ca. 64 kDa. Mixtures of spores/inclusions of the B. thuringiensis were tested for their toxicity against larvae of Drosophila melanogaster. The mortality levels of the larvae caused by these spores and crystalline inclusions varied from 5 to 15%. The lethal doses (LD50) of these isolates against D. melanogaster were 8.8 x 10(12) spores/ml for B. thuringiensis finitimus and 1.3 10(18) spores/ml for B. thuringiensis alesti.