PROTECTION OF <i>BACILLUS THURINGIENSIS</i> FROM INACTIVATION BY SUNLIGHT

Abstract

Abstract The effectiveness of several commercially available sunlight screens in protecting Bacillus thuringiensis Berliner ( B.t. ) against inactivation by solar irradiation was assessed in the laboratory and field. Spore viability and residual insecticidal activity of B.t. were rapidly reduced by solar radiation in the range of 300 to 400 nm wavelength. The addition of ultraviolet absorbers, Uvinul DS49 and Erio Acid Red, to a Thuricide spray formulation prolonged the insecticidal residual activity on coniferous trees, resulting in greater effectiveness against the spruce budworm, Choristoneura fumiferana (Clem.), compared with a formulation lacking these protectants.