Transformation and attachment of Beauveria bassiana conidia on the cuticle of Tribolium confusum and Sitophilus oryzae in conjunction with diatomaceous earth

Abstract

Agrobacterium tumefaciens-mediated transformation (AMT) was used in order to create fluorescent conidia of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales). From the fungal transformants, one Enhanced Green Fluorescent Protein B. bassiana strain indicated stability (maintained the GFP characteristics) in fluorescent signal, while its pathogenicity did not differ significantly from the wild B. bassiana type. After exposure on wheat treated with the transformed conidia, fluorescence was evident on all body parts but especially on metasternon of adults of Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) and on elytra in of Sitophilus oryzae (L.) (Coleoptera: Curculionidae). No significant differences were noted in fluorescence levels in the case of T. confusum between the transformed and the wild strain. However, the addition of diatomaceous earth (DE) increased attachment, especially at increased intervals after exposure. For S. oryzae, fluorescence of the transformed strain was decreased with the increased post-exposure time, but the simultaneous presence of DE increased fluorescence. The results of this study demonstrate that fluorescent conidia of B. bassiana can be utilized as a tool for the evaluation of parameters that affect the attachment of entomopathogenic fungi in insects' cuticle.