Biodiversity of entomopathogenic fungi genus Beauveria in the soils of arid zone

Abstract

BACKGROUND AND OBJECTIVES: In recent years, there has been an increased need to reduce chemical pollutants, and studies of entomopathogenic fungi, which are natural regulators for several harmful insects, has become widespread. Entomopathogenic fungi are inexhaustible source of natural strains that have a broad range of virulence in many species of harmful insects. Among entomopathogenic anamorphic ascomycetes, those fungi from the genus Beauveria are most studied. Studies have been conducted for the past two hundred years, meaning that most mycoinsecticides are based on the results of these studies. Although these fungi are considered well-studied, research into the cryptic species composition of genus Beauveria and their geographical distribution remains relevant for identifying promising strains for pest control. This study aims to investigate the biodiversity of the genus Beauveria prevalent in the soils of southern Kazakhstan (Turkestan region). METHODS: Entomopathogenic fungi of the genus Beauveria are widespread in the natural ecosystem, including soil. Therefore, during 2023-2024 soil samples from various locations in southern Kazakhstan (Turkestan region) were collected to isolate entomopathogenic fungi. The insect bait method was used to isolate entomopathogenic fungi. Larvae of Tenebrio molitor (Coleoptera: Tenebrionidae) were used as baits, with five replicates per sample, and placed in soil samples inside plastic containers. After infection, dead larvae were transferred to a moist chamber to promote mycosis development. Fungal conidia were then transferred to Sabouraud’s agar medium. Species identification of the isolated fungi was conducted using classical light microscopy and molecular genetic analysis of internal transcribed spacer regions and the translation elongation factor 1 alpha gene.FINDINGS: 41 isolates were isolated into pure culture, of which 36 were fully identified. Polymerase chain reaction analysis of the translation elongation factor 1-alpha gene revealed that all isolates belong to Beauveria bassiana. However, analysis of the internal transcribed spacer region identified two cryptic species within the genus Beauveria: Beauveria bassiana and Beauveria pseudobassiana. The majority of the isolates were identified as Beauveria bassiana – 84 percent (31 isolates), while Beauveria pseudobassiana accounted for 16 percent (5 isolates).CONCLUSION: The species composition of entomopathogenic fungi in the soils of southern Kazakhstan (Turkestan region) turned out to be quite modest and sparse, which explains the soil and climatic conditions of the region. A distinctive feature of the climate of the study region is aridity. Only fungi of the genus Beauveria were isolated, which are considered cosmopolitan. Isolation of viable entomopathogenic fungi demonstrates adaptation to arid conditions, which is very important in the context of climate change.

Keywords

• bait insect
• beauveria bassiana
• beauveria pseudobassiana
• biodiversity
• entomopathogenic fungi (epf)
• soil microorganisms