The influence of Bacillus thuringiensis bioinsecticides on potato tubers’ quality

The research tested the effect of experimental batches of insecticides based on the entomopathogenic Bacillus thuringiensis (BT) 994, 0371 and 787 strains on the Javor potato crop, on the starch content and the size of the starch granules, on the soluble sugar content and the protein content in potato tubers. The BT effect on the analyzed parameters was studied comparatively with the chemical insecticide Calypso. Biopreparations and chemical insecticides were used as a tool protecting potato plants against the Colorado potato beetle. An experimental batch of preparations was elaborated on the basis of bacterial strains from entomopatho-gens’ bacterial collection belonging to the state institution of the Republic Crimea “Research Institute for Agriculture of Crimea”. The strains of BT 994 and BT 0371 produce the й-endotoxin protein and the thermostable ß-exotoxin. But the strain BT 787 produces only 5-endotoxin protein. The active ingredient of Calypso is a neonicotinoid thiacloprid. The treatment of potato plants with water was used as a method of control. It is well established that bioinsecticides BT 0371, BT 994 and BT 787, introduced in Javor potato agrobiocenosis, promoted the growth of tubers by 92,9; 96,3 and 104,3 %, respectively, while chemical insecticides Calypso - only by 60,0 %. Obtainment of the environmentally safe products with a minimum negative impact on the content of starch (reduction were not more than 2,2 %), sugar (increasing were not more than 1,46 % on a dry substance), and protein (an average increasing on a 42,9 %), as well as on the size of the starch grains in the tubers was a result of the bioinsecticides application in the plants. Thus, the use of bioinsecticides based on the entomopathogenic bacteria B. thuringiensis 994, 0371 and 787 strains in potato biocenosis, unlike the use of chemical insecticide Calypso, produces environmentally safe potato with a minimum negative impact on the content of starch, protein and sugar in tubers.