COMPARATIVE-ANALYSIS OF MOLECULAR AND BIOLOGICAL CHARACTERISTICS OF STRAINS OF BEAUVERIA-BRONGNIARTII ISOLATED FROM INSECTS

Variations within the ribosomal DNA gene of the entomopathogenic filam entous genus Beauveria were examined in 28 strains of B. brongniartii and 2 strains of B. bassiana. These strains were isolated from diverse geographical and biological origins, more especially from the white g rub Hoplochelus marginalis. Internal transcribed spacer regions (ITS1 and ITS2) were analysed by polymerase chain-reaction amplification and restriction fragment-length polymorphism. The analysis revealed a hig h degree of polymorphism within B. brongniartii species and allows sep aration of the strains into seven distinct groups. One of these groups contains specifically all strains isolated from H. marginalis. The ge netic separation of these strains is supported by their biological ori gin, since they are the only strains virulent against H. marginalis. S equence data from the ITSs confirm the conclusions of PCR-RFLP analysi s and allow estimation of the genetic distances between the different groups. Intraspecific variability due to point mutation is 0.70-14.67% in ITS1 and 1.80-16.67% in ITS2. This surprisingly high level of poly morphism is discussed.