Goncharova M. Morphophysiological and cytogenetic alterations in midges Chironomus riparius Meigen under the effects of anthropogenic factors

Role of essential ecological factors in ontogenesis of Chironomus riparius has been studied. Peculiarities of development in simulated conditions and the changes occurring on the cellular and organism level under the effect of toxic substances have been described. Electivity of Chironomus riparius on different ontogenesis stages regarding to gradation of several physical-chemical factors has been investigated. Both on imaginal and larval stages it demonstrates preference to water and sediments with higher organic matter contents, but does not possess the ability to avoid toxic environment. Morphological and cytogenetic alterations in Chironomus riparius under the effect of toxic substances in spiked and natural contaminated sediments have been studied. Dose-dependent decrease in survival, larval weight and delay of imago emergence is registered beginning with copper (Cu II) contents 10 mg/kg dry substrate weight, 20 mg/kg caused morphological deformities of larval mouthparts (abnormal antennas structure, gaps and anomalies of mentum and epipharynx teeth) and structural and functional alterations in the polytene chromosomes of the salivary glands (inversions, chromosome decondensation, appearance of new puffs, reducing of the nucleolus activity). Morphological deformities appear at the first larval stage and remain with successive moltings. Presence of puffs in polytene chromosomes correlate with morphological mouthparts deformities. The multispecies method for assessing of freshwater sediment toxicity using Chironomus riparius larvae has been developed. The toxicity of different type water bodies of Ukraine using this method has been investigated and toxicity identification evaluation procedure has been carried out. Survival, rate of morphological mouthparts deformities and structural and functional alterations in the polytene chromosomes demonstrate high correlations with level of sediments contamination.