Insecticidal activity of Bacillus thuringiensis strains isolated from soil and water.

We attempted to search novel Bacillus thuringiensis strains that produce crystals with potential utility in plant protection and with higher activity than strains already used in biopesticide production. Seven B. thuringiensis soil and water isolates were used in the research. We predicted the toxicity of their crystals by cry gene identification employing PCR method. The isolate MPU B63 with interesting, according to us, genes content was used in evaluating its crystal toxicity against Cydia pomonella caterpillars. The strain MPU B63 was cultured from water sample and had cry1Ab, cry1B, and cry15 genes. The LC₅₀ crystals of MPU B63 were compared to LC₅₀ of commercial bioinsecticide Foray determined against C. pomonella (codling moth). The activity of MPU B63 inclusions against codling moth larvae was approximately 24-fold higher than that of Foray. The results are a promising introduction for further study evaluating the potential usefulness of isolate MPU B63 crystals in plant protection.