Meiramgul Mussina

Environmentally sound insect pest management strategies require continuous isolation and identification of effective biocontrol agents from different ecosystems. The quest for fungal isolates that are adapted to high temperatures is particularly significant, as they hold the potential to produce mycoinsecticides that are highly effective in semiarid and arid areas. This study aimed to collect new virulent isolates of entomopathogenic fungi (EPF) from Kazakhstan that show promise for controlling Colorado potato beetle (CPB) populations under arid conditions. Local isolates could be adapted to abiotic and biotic factors in the environment in which they survive. The findings of this study should provide insights into the species of EPF that inhabit a specific arid region of Kazakhstan, examining their traits in the regional climate, soil composition, and biological diversity. Throughout 2023–2024, a series of soil samples was collected from diverse locations within the Turkestan region of southern Kazakhstan for the isolation of EPF. The isolation of EPF was conducted using susceptible larvae of Tenebrio molitor (Coleoptera: Tenebrionidae), a host that does not have specificity for particular species of EPF. Using this insect bait, 41 pure cultures of EPF were isolated from soils in the arid zone of Kazakhstan. Polymerase chain reaction analysis based on the TEF1-α locus showed that all the isolates were indistinguishable from Beauveria bassiana ARSEF 2860 species. However, analysis of the ITS locus revealed two cryptic species: B. bassiana and B. pseudobassiana. For laboratory evaluation of biological activity EPF, the second and third instars of CPB were collected from potato fields in southern Kazakhstan and placed in plastic containers. Test CPB larvae were treated with conidia suspensions at 1 × 10⁷ spores/mL and survival was recorded daily for 3 weeks. The results of the bioassays revealed that all the new Kazakhstan isolates were pathogenic to larvae CPB and caused complete mortality by the end of the 11-day. These results showed that new isolates of EPF were highly virulent against larvae CPB.

This article presents the results of isolating and identifying EPF species and screening thermotolerant and highly virulent EPF strains that are promising for controlling Colorado potato beetle populations. Soil samples were collected from southern Kazakhstan for the isolation of fungi used in the experiments. Using the insect bait method, 41 isolates of EPF were obtained from the soils of southern Kazakhstan. PCR analysis based on ITS and TEF loci (elongation factor Ef1a) showed that all the isolates belong to the species B. bassiana. However, analysis of the ITS locus revealed two cryptic species: B. bassiana and B. pseudobassiana. No other fungal species were detected, likely due to the insufficient informativeness of the ITS and TEF loci in distinguishing species. Further studies with other loci are required. As a result of selecting natural isolates for virulence and thermotolerance, the following strains were identified: B13, B14, B15, B22, B23, B24, B25, B23-23, Bc4, Bc7, and Bc8. These strains showed high virulence (100% on the 11th day after treatment) and tolerance to suboptimal temperatures (+15°C and +30°C). Therefore, they are considered the most promising for use in the context of climate change. The data suggest that, despite the source of the isolates, EPF have great potential for controlling Colorado potato beetle populations, as the majority of isolates lead to fatal outcomes. Their geographical origin primarily influences their temperature preferences, which negatively affect their effectiveness in field conditions.

One of the key tasks of the agricultural policy of the Government of the Republic of Kazakhstan is the establishment of an efficient domestic agro-industrial sector that guarantees the nation's food security, its strong competitiveness in international agricultural production and in the food market. The current state of knowledge has defined the criteria for the production of crop goods in rainfed agroecosystems, which can be summarized as the following fundamental principles: achieving the highest yield of agricultural crops at the lowest expense; enhancing soil fertility primarily through the extensive application of biological methods for the regeneration of organic matter; development of optimized, highly productive agricultural landscapes with significant environmental capacity of regionally typical plant life forms. The realization of these principles is ensured by a range of measures, among which perennial grasses hold a prominent position. The most widespread species among all perennial grasses in the western region of the country is wheatgrass. Due to its distinctive biological characteristics, wheatgrass optimally utilizes the natural and climatic resources of the dry-steppe zone. The unique stability and effectiveness of wheatgrass as an environment-shaping crop in the agricultural systems of the dry-steppe zone underscore the necessity for further innovation and improvement in its cultivation techniques.