Morphological deformities occurring in Belarusian chironomids (Diptera : Chironomidae) subsequent to the Chernobyl nuclear disaster

1. Chironomid larvae and adults were collected from several freshwater habi tats around the Chernobyl site from 1990 to 1994 (4-8 years after a nuclear accident) and examined for morphological deformities. 2. Deformities were found in larvae of nine of the 13 species collected, an d were most obvious in headcapsule structures, particularly the antennae, m entum, mandibles and epipharyngeal pectens. 3. In species of Chironomus, the most abundant genus, there was a positive linear relationship between the incidence of deformity and radiation level. Indices of severity of deformity showed similar trends, It is suggested th at these deformities resulted largely from ingestion of irradiated, plant-d erived, fine particulate food. 4. Among adult male Ch. riparius, the deformity index decreased both with i ncreasing time from the accident and with increasing distance from the reac tor, although these trends were not statistically significant. There was al so a trend of increased severity of deformity closer to the accident, both in time and space. 5. Overall, there was a greater incidence of deformity in the larvae than i n the adults (e.g. 60 versus 20%, respectively, at the Krasnoselye site and 33 versus 20%, respectively, at the more distant Dron'ki site). 6. It was not possible to determine whether the deformities were inherited from previous generations or were somatic occurrences in each new generatio n as a consequence of the radiation that continues to pervade the region.