Efficiency of batsikol based on a new strain Bacillus thuringiensis var. darmstadiensis № 25 for biocontrol of phytophagous pests and phytopathogens

Environmentally friendly products are one of the most important tasks in agriculture. Microorganisms of different origin are used for the production of biological preparations pathogenic to pests. The preparations based on entomopathogenic bacteria Bacillus thuringiensis (Bt) are of the most interest due to their selective action, safety for humans, warm-blooded animals, beneficial insects and the environment. The departmental collection of beneficial microorganisms for agricultural purposes (RCAM collection, St. Petersburg) stores B. thuringiensis with known cultural, morphological, physiological, biochemical, technological, insecticidal and other properties. One of the priorities of collection strains is B. thuringiensis var. darmstadiensis (BtH 10) № 25, which bases the preparation Batsikol and has a specific effect on Coleoptera and antifungal activity against a number of pathogenic fungi. Strain BtH 10 № 25 deposited in the RCAM collection under registration number 01490 RCAM (patent № 2514023, 2014). To obtain qualitative preparation with a maximum accumulation of exotoxin and high titer we need to create optimal conditions for cultivation and improve the formulation of nutrient media for microorganisms-producers of biological preparations. The objective of our research was to choose nutrient medium, work out cultivation regimes (aeration, temperature, pH, dosage, form, and age of inoculum) of strain BtH 10 № 25, and to determine its technological effectiveness, insecticidal and antifungal activity as well as the extent of exotoxin formation in test objects. The best results were obtained in the pea flour medium, instead of soy flour: spores titer in liquid culture was 4½10 9/ml, activity to housefly (exotoxin content) was LC 50 3.1 mkl/g feed, the inhibitory activity was 70.0 % to Fusarium oxysporum and 75.0 % to Botrytis cinerea. It was found that barley, oat flour, and mixtures of soybean and barley flour could be used for the preparation production. The optimal development of the culture was observed at a ratio of medium volume-to-air from 1:30 to 1:15, and pH of the nutrient medium 6.65-7.20. Liquid culture media and the spore culture rinse can be used as an inoculum. Laboratory and field evaluation of preparation revealed its high efficiency against phytophagous pests (79-100 %) and plant pathogens (70-90 %). Thus, the activity of the strain B. thuringiensis var. darmstadiensis № 25 against the larvae of beetles on different crops is 1.3-1.4 times higher than the activity of strain B. thuringiensis var. darmstadiensis № 109.