THE GEOGRAPHIC-VARIATION OF POPULATION-STRUCTURE IN OSTRINIA SPP LIVING ON DICOTYLEDONOUS HOST PLANTS AND THE FACTORS DETERMINING THE VARIATION

The population structure of Ostrinia nubilalis, O. narynensis, O. scapulalis and O. persica was studied using genetic factors determining the morphology of tibiae (Mt and i) in males. Larvae of borers were collected from fodder crops in more than 60 localities in the European part of the former USSR and 5 localities in the Asian one in 1976-1992. The papulation analysis confirmed the previous conclusions (Frolov, 1989) that the distribution of European com borer, naryn borer, brush-leg borer, and persian borer takes place in the form of polymorphous population structure. The wide areas occupied by practically monomorphous populations alternating with the territories occupied by polymorphous ones were detected and changes in the concentrations of the genes from near 0 to near 1 were observed within the spaces of about 50 to 60 km. The observed alternation of population structures correlates with the gradients of precipitation. The values of average precipitations in June and in May-August as well as of hydrothermic coefficient for June are reliably different for areas occupied by various species. The zones where the average precipitation in June is no less than 77 mm are inhabited by European com borer, the areas where it is 55 to 76 mm - by naryn and brush - leg borers, the areas with precipitation less than 50 mm - by persian borer. The areas with intermediate values of precipitation are occupied by polymorphous populations.