Vol 46, No 5 (2019)

Students, colleagues, and friends of Bella Rafailovna Striganova as well as the Editorial Board of the journal Biology Bulletin, which she headed for many years, dedicate this issue of the journal to her memory. The subjects of the articles represent the most important areas of research for B.R. Striganova: regularities of geographic changes in taxonomic diversity, abundance, and landscape distribution of soil communities; trophic relations of pedobionts and zoomicrobial relationships; functioning of detrital food webs; the importance, conservation, and rational use of the biological diversity of natural systems; soil zoology and problems of the national economy; problems of evolutionary theory.

It has been established that three earthworm species inhabit tundra landscapes of Eastern Europe: the Eastern European–Siberian Eisenia n. nordenskioldi, cosmopolitan Lumbricus rubellus (sporadic occurrences near the forest edge), and cosmopolitan Dendrobaena octaedra. In the Palaearctic zonal tundra, D. octaedra does not occur east of Tazovskii Peninsula, while E. n. nordenskioldi was not found west of Pechora Bay. The two species coexist in the Arctic only in Nenets and Yamalo-Nenets Autonomous okrugs. New earthworm records in the northern part of Eastern Europe have been reported. The significant habitat plasticity of D. octaedra and E. n. nordenskioldi in tundra landscapes is demonstrated. It is found that the cold-resistant soil-litter E. n. nordenskioldi prefers open habitats (dwarf shrub tundras, meadows, and marshes), while the less cold-tolerant (in the worm phase) litter D. octaedra is more abundant under the shrub or crooked forest canopy, possibly, because of the milder wintering conditions there (i.e., the presence of leaf litter and snow retention). It is suggested that the habitat area of E. n. nordenskioldi in Eastern Europe was much larger during the last glacial epoch.

The use of isotopic analysis for reconstructing the structure of food webs requires determination of the trophic fractionation of carbon and nitrogen stable isotopes (Δ¹³C and Δ¹⁵N). Fungi and mycophagous animals play a key role in soil communities, but there are very limited field data on the degree of isotope fractionation in animals that feed on fungi. We studied the bulk isotopic composition of mycetophagous Diptera larvae inhabiting fruit bodies of saprotrophic and mycorrhizal macromycetes, as well as larva feeding on parasitic rust fungi. Trophic enrichment in ¹³С and ¹⁵N was at the minimum (0.0 and 0.9‰, respectively) in the larvae of gall midges Mycodiplosis sp. feeding on rust fungi (Pucciniales). In the larvae of dipterans inhabiting fruiting bodies of saprotrophic and mycorrhizal macromycetes, the Δ¹³C and Δ¹⁵N values averaged 0.9 and 3.4‰, respectively. This corresponds to the values usually observed in grazing food chains. The accumulation of ¹⁵N was more pronounced in the larvae that fed on saprotrophic fungi, but no clear relationship was found between the degree of trophic fractionation and the taxonomic affiliation of animals or fungi. As suggested by our data and the analysis of published studies, the variations in the trophic fractionation in mycophages are strong, but they are not likely to impede the identification of the “mycorrhizal” and “saprotrophic” energy channels in the soil food webs.

Among the factors modifying the structure of associations and activity of earthworms, the influence of intra- and interspecific interactions has been studied insufficiently. In field experiments the relative importance of these interactions has been compared in lumbricid species that are trophic competitors: in the soil detritophages Allolobophora chlorotica and Aporrectodea caliginosa and in the leaf litter consumers Lumbricusrubellus and L. terrestris. For each species the relative significance of the intra- and interspecific interactions were evaluated by comparison of the state of lumbricid individuals in conditions of low (control) and high population densities in one- or two-species populations. The increase in population density (due to either conspecifics or species-competitor) usually negatively affected the important parameters of the current earthworm generation (growth, mortality, and fecundity), and also of the subsequent generation (numbers and size of the cocoons produced). For three species (except for L. terrestris), trends were revealed indicating the greater strength of intraspecific than interspecific interactions. The species reactions were determined by different factors: by the trophic competition for the litter-dwelling L. rubellus, whereas for the soil dwellers Al. chlorotica and A. caliginosa (in conditions of a surplus of food resources) they were presumably determined by competition for the space.

Intraracial differences in the Carpathian honeybee race Apis mellifera carpatica from Russia and Tajikistan with the race standard (Vuchkovski line from Transcarpathian oblast of Ukraine) are compared by morphometric and molecular-genetic study. The most informative features, the “cubital index” and the “discal displacement,” are shown to deviate significantly from the standard. However, the calculated genetic distance between datasets from different regions indicates the uniformity of the Carpathian race across its distribution range. The nucleotide composition of the mtDNA COI gene (1535 bp) reveals two groups of haplotypes associated with the apiary foundation time and differing by the amino acid composition of the COI protein (group I, asparagine; group II, serine). In addition to honeybee samples from different regions, group I includes honeybees from an isolated apiary in the mountain-forest zone of Crimea, which originated from the honeybee line 77 from the Transcarpathian. Group II includes honeybee samples of the modern “Vuchkovski” standard line.

In four habitats of the city of Kaluga, 64 ground beetle species were found. Only 17 species have a complete demographic structure in at least one of the habitats. These species are considered residential and form a stable component in the taxocenoses studied. Only 5–9 species were resident in the habitats considered. The labile component (migrants and sporadic species) were more diverse in all the habitats. The stable component was significantly more abundant than the labile component. Apparently, no more than half of the Carabidae species found in cities are permanent inhabitants of urban landscapes. The composition of the stable and labile components in Carabidae taxocenoses in Kaluga is more similar to that in the taxocenoses of the azonal habitats. At the same time, the urban taxocenoses of ground beetles are formed mainly by the species of the nearest zonal communities.