Cytotaxonomical variability of Chironomus plumosus L. and C-anthracinus Zett. (Diptera, Chironomidae) from industrial and municipal polluted areas ofFinland

Chironomid larvae were collected from different localities of industrial po lluted area of Finland. By the cytogenetical and external larval morphologi cal analysis the material studied could be referred to either as Chironomus plumosus L. or as C. anthracinus Zett. The effect of an industrial and a m unicipal contamination on the appearance of structural and functional alter ations in the polytene chromosomes of both studied species was shown. Chrom osome and genome polymorphism of Chironomus lumosus L, in different localit ies of industrial polluted areas of Lohjanjaveri, south Finland is describe d. A high chromosome polymorphism involving para-and pericentric inversions was established. A polymorphic system exists in all studied localities and it is characterised by the transition of one homozygous inversion into ano ther through heterozygote formation. The studying areas were characterised by an increasing frequency of inverted homozygous inversions in arms A,C,D. The genome polymorphism is expressed by an additional " B" chromosome whic h varies in frequency and morphology. This polymorphism may provide the pop ulation with better chance to surviving under extreme polluted conditions. Structural-functional alterations in C. anthracinus were observed. New para and pericentric inversions, were found in the studied polluted areas. Balb iani ring system (BR) of C.plumosus and nucleolus (N) of C. anthracinus wer e very sensitive to the pollution. Together with a normal activity of BR sy stem of C.plumosus and N of C.anthracinus we observed a clear reversed leve l: there were number of individuals and cells which BR and N were in hetero zygous state or collapsed. Their potential for detecting genotoxic agents i n ecosystems are discussed and some morphological deformities of both studi ed species were described. However, no correlation between the rate of chro mosome rearrangements and rate of morphological deformities were establishe d.