BACKGROUND Black soldier fly larvae (BSFL) offer very good prospects for the production of cheap and high‐quality dietary protein. This insect is able to consume low‐quality substrates, including food waste. The properties and safety of the compost obtained are largely determined by its microbiome. However, while the bacterial component of the BSFL‐compost microbiome has been much studied, little is known about its fungal component. In plant‐based rearing substrates both the biomass and the metabolic activity of fungi often exceed the biomass and the activity of prokaryotes. So, the purpose of this study was to investigate the fungal community of the compost produced by BSF larvae reared on a food waste substrate. RESULTS Community structure was determined by metabarcoding of the ITS (internal transcribed spacer) region. Species composition and abundance were determined using the plating technique and subsequent identification of the isolated pure cultures. It was found that the primary mycobiome of the food waste substrate that was used consisted of 19 families, represented mainly by phytopathogenic and endophytic genera. Larva incubation led to the complete elimination of all mycelial fungi from the resulting compost. The final mycobiome consisted of only two yeast species, Pichia kudriavzevii and Diutina rugosa, with a total abundance of 1.2 × 107 CFU g−1. CONCLUSIONS The rearing of BSFL led to the complete elimination of mycelial fungi from its feed substrate. The final compost lacked harmful fungi, including molds. This information may be crucial for BSF compost utilization. The phenomenon was also an interesting aspect of zoomicrobial interactions in nature and agriculture. © 2021 Society of Chemical Industry.

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The prospects for application of metagenomic technologies in environmental studies are discussed. The advantages in investigating the taxonomic composition of aquatic and terrestrial ecosystems, as well as examples of trophic and phoric relationships found in ecosystems using the metagenomic approach, are described. The capabilities of metagenomics to study prokaryotic communities in complicated environments such as soils or animal intestines are shown. The role of relic DNA in the metagenome and the possibilities to study ancient organisms are highlighted. Particular attention is paid to the criticism of metagenomic technologies related to the low reproducibility of the sequencing data. Common methodological mistakes in bioinformatics processing of metagenomic data leading to misleading results are considered.

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When investigating and refining problems of determining the economic efficiency of alternatives of hydraulic construction, selecting optimal types and designs of structures and equipment, developing methods of technical and economic calculations, and deriving calculation formulas, the authors used both the basic recommendations of "Standard Procedure for Determining Economic Efficienty of Investments and New Technology" and their own investigations in the area of economics of water management and hydropower engineering.The authors correctly point out the following characteristics of economic investigations and calculations in the area of hydraulic construction: the need for comparison of nonsimukaneous expenditures during construction and operation of water management projects, consideration of related investments, the need for distribution of expenditures between participants of the water management complex, the need to compare planned hydroelectric power stations with thermal electric power stations, and also the fact that during the period of operation of hydraulic complexes the costs of production are generally quite negligible in comparison with investments for their const.ruction. On the basis of this the authors conclude that in hydraulic construction the problem of proper consideration of the effect of investments on cost and cost of production is of great significance (p. 11).Recognizing the value of using modern computers and mathematical methods when solving many complex engineering and economic problems for conditions corresponding to prescribed optimization requirements, the authors of the book validly note that "...this can be accomplished only if the effect of all acting factors can be represented in the form of definite analytic, graphic, or probability relations," which in a number of cases are difficult to establish. For example, the "effect of geological and topographic factors which must be taken into account when solving the problem of the optimal scheme of energy utilization of a stretch of the river and the representation of which in any form suitable for input into a computer, represents enormous difficukies" (pp. 14-15).Examining the economic indexes in the area of water management and water power, the authors use as basic indexes the size of the investments in individual structures and for the complex, the annual expenses for operating individual structures, and for the entire complex which determines the production cost of the product and the economically founded selling cost (p. 16). In this case it is correctly noted that "an economically profitable water management project should, due to the quantity 8c, which is the cost of production equated by the authors to its selling price (rate), completely compensate all expenses for operating the project and, furthermore, yield the necessary profit (p. 19).