Abstract
Entomopathogenic fungi of the genus Beauveria are considered promising agents for the sustainable biological control of insect pests. The aim of this study was to investigate the morphological and molecular characteristics of two native Beauveria bassiana strains, BCa-09 and BP2-07, isolated from members of the order Coleoptera in southern and southeastern Kazakhstan, respectively, and to evaluate their virulence against the greenhouse whitefly, Trialeurodes vaporariorum. Colony growth rates were determined on potato dextrose agar (PDA) and Sabouraud dextrose agar (SDA) at 25 °C for 14 days. We performed molecular identification by sequencing the internal transcribed spacer (ITS) region of ribosomal RNA, followed by phylogenetic analysis using the Neighbor-Joining method with 1,000 bootstrap replicates. Virulence was evaluated based on the activity of conidial suspensions against T. vaporariorum nymphs at a concentration of 1 × 10⁷ conidia/mL over 11 days. Strain BCa-09 exhibited a significantly higher colony growth rate on both media compared with BP2-07 (p < 0.01). BLAST analysis showed ≥99% nucleotide sequence similarity between both strains and reference B. bassiana sequences deposited in the GenBank database, confirming their taxonomic identity. In the phylogenetic analysis, both strains clustered with reference B. bassiana isolates with 99% bootstrap support. Both strains exhibited pathogenic activity against T. vaporariorum: by day 11, cumulative mortality reached 87.5 ± 4.7% for BCa-09 and 80.0 ± 4.1% for BP2-07. These results confirm the virulence of the investigated B. bassiana strains and indicate their potential for further evaluation as biological control agents against T. vaporariorum.