Molecular characterization and the effectiveness of native entomopathogenic Beauveria bassiana strains against adults of Mediterranean fruit fly (Ceratitis capitata)

Abstract

Molecular characterization of locally isolated Beauveria bassiana (Cordycipitaceae, Hypocreales) strains and their pathogenicity against Ceratitis capitata (Diptera: Tephritidae) adults are herein reported for the first time. Molecular identification based on the phylogenetic analyses of ITS-rDNA and combined data of TEF1 and Bloc, revealed that all fungal strains were conclusively assigned to B. bassiana clade. Interestingly, Maximum parsimony based-phylogeny analysis of the combined TEF1 and Bloc sequences detected additional genotypes among the sub-clades than ITS-rDNA analysis. Genetic diversity among strains was performed using random amplified polymorphic DNA (RAPD) markers. RAPD genotyping segregated all the strains into three clusters and characterized the 15 strains with different genotypes. RAPD-PCR clustering analysis showed that B. bassiana strains were relatively separated according to geographical origin. Molecular analyses using nuclear genes (TEF1 and Bloc) and RAPD markers suggest that B. bassiana is an aggregate of species, rather than a single species. Under laboratory conditions, B. bassiana strains were highly pathogenic to C. capitata adults with mortality rate in the range of 71.67-91.67%. Based on the Average of Survival Time (AST) and median lethal times (LT50) values, fungal strains were able to reduce significantly lifespan of flies compared to controls. Further experiments under field conditions are required to evaluate the real contribution of these fungal strains as promising biological control agents against C. capitata adults in Morocco.