Genotype diversity and pathogenicity of Beauveria spp. Isolates from different ecoregions of Georgia

Abstract

In this study entomopathogenic fungi Beauveria spp. from various ecoregions of Georgia have been studied morphological and on the genome level. After morphological analysis of monocultures, 6 strains were selected for further investigations. Several DNA fragments of isolated strains were amplified and sequenced, ITS region (the rRNA gene cluster), EF1 (the Elongation Factor 1-alpha) and (the intergenic) Bloc region. A BLAST analysis of sequences strains and their morphological studies has shown that the strains belong to two species: (1) Beuveria bassiana (strain- Bb001; Bb006) and (2) Beauveria pseudobassiana (strain - Bb007; Bb009, Bb010; Bb011). The regional differences between strains were identified through phylogenic tree. Base on this research, it was confirmed that the samples taken from the same region were located at the same species on phylogenic tree. This is a first report where most virulent strains identified and their virulent against the fall webworm, Hyphantria cunea have been studied. Two entomopathogenic fungal strains: Bb001 and Bb011 evaluated the pathogenicity on the larvae (L5-L7) H. cunea. Both fungal isolate were pathogenic. The mortality 68% - 71 % for B.bassiana (Bb001) and 76.9% -87% for B.pseudobassiana (Bb010) were observed. Mortality caused by Bb001 was significantly different between the concentration (p<0,05). One-way Anova, Single factor, α=0.01: significance difference were found between the pairs of treatments: for Bb001 1x10⁸ and 1x10⁷: p=0,0025, F=18.7; for Bb010 1x10⁸ and x10⁷: p=0,000156, F=44.6; for Bb001 1x10⁸ and Bb010 1x10⁸: p=0,0001, F=46. B. pseudobassiana proved highly pathogenic. Maximum of larvae mortality were observed in 4-9 day after treatment, were as in variance Bb010 mortality indicate later 5 -13 day.