Abstract

GRIJALBA B, ERIKA PAOLA; VILLAMIZAR R, LAURA  and  COTES P, ALBA MARINA. Evaluation of the stability of Paecilomyces sp. and Beauveria bassiana under ultraviolet radiation. Rev. Colomb. Entomol. [online]. 2009, vol.35, n.1, pp.1-6. ISSN 0120-0488.

Two biopesticide prototypes were developed, formulated as wettable powders by using two native isolates of Paecilomyces sp. and Beauveria bassiana previously selected for their high biocontrol activity on Bemisia tabaci. Considering that ultraviolet (UV) radiation is one of the most limiting factors when microorganisms are applied under field conditions, the aim of this study was to determine the stability of formulated and unformulated conidia of these fungi when exposed to UV light. Germination of the microorganisms was evaluated in malt extract agar before and after three, six and 24 hours of exposure to UV “C” radiation, under laboratory conditions. In addition, the effect of solar radiation under field conditions was evaluated during six hours of direct exposure to sun in the municipality of El Espinal (Tolima). The UVC radiation did not affect germination of unformulated Paecilomyces sp. conidia, while solar radiation reduced germination by 43 and 42% for unformulated and formulated conidia, respectively. UVC and solar radiation reduced germination of unformulated B. bassiana conidia by 43 and 46%, respectively. For formulated conidia, solar radiation reduced germination by 26%. The evaluated formulation protected conidia of B. bassiana against solar radiation, but not those of Paecilomyces sp., making it necessary for the latter to evaluate sunscreens that might be included in the formulation.

Keywords : Solar radiation; Biopesticide; Formulation.

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