Allelopathic influence of apple trees leaves on entomopathogenic strains Bacillus thuringiensis

Abstract

Article investigates the effect of water and alcohol soluble extracts – and volatile discharge of leaves of apple trees on entomopathogenic strains of spore bacteria Bacillus thuringiensis (Bt) 0371, 0376, 0408, 787, which are promising to build on their basis preparation for biocontrol of harmful leaf-eating insects in apple orchard. For longer storage B. thuringiensis on the leaves of apple and accordingly to improve its protective effect against harmful insects we need to use entomopathogenic bacteria strain less sensitive to allelopathic influence of apple. Among the studiedones the strain of Bt 0408 meets this requirement best. During the research it showed the highest tolerance to discharge apple, even after prolonged contact with leaves most of its cells retained their viability and growth inhibition culture was minimal among the strains. According to following features the most sensitive strain to action selections are apple strain Bt 787. However, Bt strain 0371 resists the damaging effect of volatile secretions apple leaves longer than other strains, because it is largely manifested only after 10 days of their contact, and insect larvae may take longer contaminated pathogen leaves, increasing the effectiveness of biocontrol. It has been established that Bt strains 0371 and 0408 have the most tolerant allelopathic action on apple trees leaves and therefore have a longer and more numerous storage on the leaf surface after processing the garden.