SOME CHARACTERISTICS OF GENETIC-VARIANTS OF TUBIFEX-TUBIFEX (MULLER, 1774) (OLIGOCHAETA, TUBIFICIDAE) IN LABORATORY CULTURES

Genetic variants of the oligochaete Tubifex tubifex were identified with enzyme electrophoresis and subsequently reared in laboratory cultures. Three types are abundant in field populations. Individuals that show homozygotic bands of glucosephosphate-isomerase (GPI) 22 together with isocitrate-dehydrogenase (IDH) 35 were labeled Type A. Type B is characterized by GPI 23 together with IDH 11 and Type C is characterized by GPI 11 with either IDH 34 or IDH 33. Initial results on freshweights of adults and cocoon production revealed differences between the two main types, A and B. In the same period, Type B reached higher weights and produced five times as many cocoons as Type A, whereas number of eggs per cocoon were not different between these Types. Type B also had the lowest mortality in 16-week experiments with changing temperatures.