[Species composition and population dynamics of fleas on the small suslik in stable foci of plague on the Ergenin ridge].

The paper presents results of investigations of fleas from Citellus pygmaeus obtained during epizootological surveys in 1972-1974 (the Ergenin ridge, Kalmyk ASSR). The most high number of the main species of fleas of C. pygmaeus was observed in the first year of epizootic on the background of great abundance of the host (over 30 specimens per 1 hectare). In the following years the decrease in the number of C. pygmaeus was accompanied by the fall in the fleas number. The distribution of different species of fleas in a microbiotope is uneven in various periods. In all periods in nests fleas of N. setosa were dominant while fleas of C. tesquorum were most abundant on the host. In burrows there was noted a change of dominant species: in the period of intensive epizootic of 1972 they were Ct. pollex and C. tesquorum, in 1973 during a slump of epizootic--C. tesquorum and N. setosa and in 1974 when epizootic was not discovered at all--N. setosa.