Trends in the formation of biotopic complexes of bumblebees (Hymenoptera, Apidae: Bombini) in northern taiga karst landscapes of the Western Russian Plain

Main trends in the formation of biotopic complexes of bumblebees in the northern taiga zone are analyzed. It is proposed that Eurasian forest species of bumblebees (Bombus (Th.) schrencki, B. (Mg.) consobrinus, etc.) are coadaptively connected with entomophilous plant species belonging to the synusia of Eurosiberian riverine-mountain meadow tall herbage, with the numbers of species in both biotic groups (pollinating insects and plants) and their abundance being greater in the landscape characterized by a high degree of karstification. In the biotopic bumblebee complex of a large river valley, the relative abundance of forest bumblebee species is 2.5–5.3 times lower than in other complexes, whereas that of meadow species is two orders of magnitude higher due to favorable thermal conditions and a large number of habitats with mesophilic herbage and legumes. Each of the distinct ecogeographic groups of bumblebees and the corresponding synusiae (each comprising entomophilous plants of different taxonomic groups) appear to be coadapted. This is probably a result of the diffuse coevolution of pollinators and plants belonging to the genetically unified biota.