Characterization of Beauveria bassiana isolates from Kyrgyzstan

Abstract

We report on the enzootic foci of the insect pathogenic fungus, Beauveria bassiana, found in high meadows in the middle mountain steppes of Kyrgyzstan, at elevations from 1000 m to 2200 m. The growth characteristics of various B. bassiana isolates on different media and as a function of temperature were studied. In addition, the ability of the fungal isolates to produce enzymes with amylase, protease and lipase activities was investigated. Dense biomass production on inexpensive solid media (oatmeal and bean oil meal) produced conidia used for insect bioassays targeting white grub larvae (Phyllophaga fullo, Coleoptera, Scarabaeidae) and nymphal and adult populations of whiteflies (Trialeurodes vaporariorum, Hemiptera, Aleyrodidae). The efficacies of the tested B. bassiana strains for third instar white grub larvae varied, with only two strains showing high entomopathogenic activity. At 25 °C, mortality reached 73% for Bav.5-Gal and 74% for Bav.1-Lep at 55 d post-infection, but was lower, 27% and 29%, respectively, at 12 °C. These two strains produced significantly higher mortality in adult and whitefly nymphs, with 65–75% mortality 6 d post-infection. Based on morphological characters, including production of ellipsoidal conidia, and molecular characters (ITS, partial 18S (SSU rDNA) and EF1-α sequences), the isolates were identified as Beauveria bassiana belonging to Clade E from Asia. Our results add to data on the diversity of ecosystems inhabited by B. bassiana and provide a local resource for pest control efforts.