B CHROMOSOME POLYMORPHISM OF BLACKFLIES (DIPTERA, SIMULIIDAE) FROM THE NORTH-WESTERN REGION OF RUSSIA
L. A. Chubareva, N. A. Petrova
Zoological Institute RAS, St. Petersburg;
e-mail: chironom@zin.ru
We have studied karyofonds of natural populations and B-chromosome morphology of 8 species of blackflies from
the North-Western region of Russia: Odagmia ornata Mg., Hellichiella crassa Rubz.,
Simulium morsitans Edw., Simulium argyreatum Mg., Shoenbaueria pusilla Fries,
Cnetha fontinalis Radzv., Stegopterna duodecimata Rubz. and Archesimulium tuberosum Lundstr.
For this purpose we made slides of squashed blackflies larvae with salivary gland polytene chromosomes stained by
aceto-orcein, in addition to similarly stained slides with mitotic chromosomes from gonads and ganglia. Morphology
of polytene B-chromosomes of Shoenbaueria pusilla Fries., Cnetha fontinalis Radzv., Stegopterna
duodecimata Rubz., and Archesimulium tuberosum Lundstr. has been first described. B-chromosome
polymorphism was found in all species, but the number of B-chromosomes was conserved within each differences in
polytene individual. Stable and distinct interspecific differences in the morphology of polytene B-chromosomes were
demonstrated, and these characters are advisable to use to distinguish the species. We have investigated for the
first time karyofonds of Od. ornata populations from Arkhangelsk Region (Solovetskie Islands) and Leningrad
Region (railway station Sablino), and those of S. argyreatum populations from Murmansk Region (Kandalaksha
environs) and Karelia (railway station Chupa). A long term study of Od. ornata and S. argyrestum
population from North-Western Russia revealed interspecific and interpopulation dynamics of the occurrence of
specimens with B-chromosomes. Some populations showed an increased percentage of individuals with B-chromosomes.
It is suggested that B-chromosomes may play a role in adaptation of polulations to severe environmental conditions.
Key words: Simuliidae, North-Western region of Russia, polytene chromosomes, B-chromosomes
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