Sugonyaev, E.S., & Voinovich, N.D. 2001 Reversion of species diversity in chalcidoid parasites (Hymenoptera, Chalcidoidea) of the birch soft scale Eulecanium douglasi (Homoptera, Coccidae) in the subarctic.. Zoologicheskii Zhurnal 80(6): 680-687.

Notes: An intrinsic trait of hemicyclism (biennial life cycles) of Eulecanium douglasi Sulc (host), assumes differentiation of individuals by their seasonal development, is the basis for reversion of species diversity of parasites in the subarctic. The E. douglasi population under subarctic conditions is represented by two alternative factions that create a possibility for segregation of ecological niches in chalcidoid parasitic species infesting their host. The biotic heterogeneity of the host population in the subarctic stipulates the formation of a cline more saturated by parasitic species than in the Eurasian boreal plain forests (10 and 5 species, respectively).