ORIGINAL ARTICLE Genetic diversity among Brazilian isolates of Beauveria bassiana: comparisons with non-Brazilian isolates and other Beauveria species E ´ .K.K. Fernandes 1,2 ,A ´ .M.L. Moraes 3 , R.S. Pacheco 4 , D.E.N. Rangel 1,* , M.P. Miller 1,  , V.R.E.P. Bittencourt 2 and D.W. Roberts 1 1 Department of Biology, Utah State University, Logan, UT, USA 2 Curso de Po ´ s Graduac ¸a ˜o em Cie ˆ ncias Veterina ´ rias, Universidade Federal Rural do Rio de Janeiro, Serope ´ dica, RJ, Brazil 3 Laborato ´rio de Taxonomia, Bioquı´mica e Bioprospecc ¸a ˜ o de Fungos, Instituto Oswaldo Cruz, Fundac ¸a ˜ o Oswaldo Cruz, Rio de Janeiro, RJ, Brazil 4 Laborato ´ rio de Sistema ´tica Bioquı´mica, Instituto Oswaldo Cruz, Fundac ¸a ˜ o Oswaldo Cruz, Rio de Janeiro, RJ, Brazil Introduction Beauveria (Balsamo) Vuillemin (Ascomycota: Hypocreales) is a cosmopolitan genus of primarily entomopathogenic fungi of which many isolates have been studied worldwide as biological control agents of many arthropod-pest species (Ferron et al. 1991; Alves 1998). Beauveria bassiana is the most studied species of the genus; however, the genetics of B. bassiana is not well characterized (Rehner 2005), and little is known about the factors that drive the genetic diversity within and among populations. Attempts to logically group B. bassiana isolates based on their genetic differences have included: (1) isolates originating from the same or nearby geographical locations (St. Leger et al. 1992a; Glare and Inwood 1998; Fernandes et al. 2006), (2) isolates from widely scattered locations (Wang et al. 2003; Rehner and Buckley 2005), (3) isolates originating from the same or very similar arthropod-host species (Bridge et al. 1990; Mauer et al. 1997; Neuve ´glise et al. 1997), (4) isolates from similar habitat types (Bidochka et al. 2002), and (5) ignoring host and geographical origin as a basis for group- ing (Bidochka et al. 1994; Berreta et al. 1998; Castrillo and Keywords AFLP, Beauveria bassiana, Beauveria spp., Engyodontium albus, genetic variability, isozymes electrophoresis, ITS sequencing. Correspondence Donald W. Roberts, Department of Biology, Utah State University, Logan, UT 84322-5305, USA. E-mail: dwroberts@biology.usu.edu Present addresses *Drauzio E.N. Rangel, Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraı ´ba, Sa ˜ o Jose ´ dos Campos, SP 12244-000, Brazil.  Mark P. Miller, U.S. Geological Survey Forest and Rangeland Ecosystem Science Center, 3200 SW Jefferson Way, Corvallis, OR 97331, USA. 2008 ⁄ 1317: received 28 July 2008, revised 12 November 2008 and accepted 10 January 2009 doi:10.1111/j.1365-2672.2009.04258.x Abstract Aims: The genetic diversity of Beauveria bassiana was investigated by compar- ing isolates of this species to each other (49 from different geographical regions of Brazil and 4 from USA) and to other Beauveria spp. Methods and Results: The isolates were examined by multilocus enzyme elec- trophoresis (MLEE), amplified fragment length polymorphism (AFLP), and rDNA sequencing. MLEE and AFLP revealed considerable genetic variability among B. bassiana isolates. Several isolates from South and Southeast Brazil had high similarity coefficients, providing evidence of at least one population with clonal structure. There were clear genomic differences between most Brazilian and USA B. bassiana isolates. A Mantel test using data generated by AFLP provided evidence that greater geographical distances were associated with higher genetic distances. AFLP and rDNA sequencing demonstrated nota- ble genotypic variation between B. bassiana and other Beauveria spp. Conclusion: Geographical distance between populations apparently is an important factor influencing genotypic variability among B. bassiana popula- tions in Brazil. Significance and Impact of the Study: This study characterized many B. bassi- ana isolates. The results indicate that certain Brazilian isolates are considerably different from others and possibly should be regarded as separate species from B. bassiana sensu latu. The information on genetic variation among the Brazil- ian isolates, therefore, will be important to comprehending the population structure of B. bassiana in Brazil. Journal of Applied Microbiology ISSN 1364-5072 760 Journal compilation ª 2009 The Society for Applied Microbiology, Journal of Applied Microbiology 107 (2009) 760–774 ª 2009 The Authors