Microencapsulation ofBacillus thuringiensisand insecticidal activity evaluation on larvae of lepidoptera

Bacillus thuringiensis(Bt) is one of the bacterial entomopathogens most frequently studied as a toxin producer. Its insecticidal activity was attributed to the parasporal crystals formed during the stationary phase of its growth cycle, and released during sporulation. The efficacy of Bt is highly sensitive to the environmental conditions; when exposed to UV light, the insecticidal proteins undergoes to rapid degradation. Considerable research has attempted to improve Bt field persistence using ultraviolet absorbers, encapsulation and addition of clay granules to spray formulations. The aim of this study was to investigate different encapsulation processes in order to obtain the Bt-based formulations consisting of matrix-type microcapsules.