Efeito do extrato hexânico de Ricinus communis L. sobre esporos de Bacillus thuringiensis

Abstract

In biological and alternative production systems, plant-based products are used, such as essential oils, plant extracts, as well as entomopathogenic microorganisms, including Bacillus thuringiensis (Bt). Such agents can be applied separately or combined to control insect-pests, one of which may interfere with the action of the other. In this sense, the objective of this work was to evaluate the effects of the hexane extract of castor bean (Ricinnus communis) EHRC on Bt spores. For such, the effect of EHRC at 2% was evaluated on Bt spores, simulating the joint application. Tests with spores were performed in vitro, from concentrations of 1x10-6 CFU/mL of each Bt-based product (Crystal®, Dipel® and Xentari®). An aliquot of 60 μL of this suspension was added to Erlenmeyer flasks, containing 10 mL of the 2% EHRC solution. Subsequently, the mixture was inoculated in three Petri dishes, at seven points on the nutrient agar culture surface, and then the CFU/mL per point was quantified. It was observed that the EHRC at 2% reduced the CFU/mL of Bt in all treatments, compared to the respective controls, ranging from 27.18% to 93.18%. Therefore 2% EHRC is not compatible with Bt spores from commercial products Crystal®, Dipel® and Xentari®.