| Abstract: | The effect of some pesticides on the rhythmic and tonic activity of adductor muscle of fresh-water mussel (Anodonta cygnea) larvae was investigated in short-term experiments. In the examined concentration range, Dimecron-50 does not influence the rhythmic activity of adductor muscles, while high concentrations of Gramoxone (is greater than 1 ml/l), Thimet-10 G (is greater than 5 x 10(-1) g/l) and Hungaria L-7 (is greater than 10(-1) g/l) cause a slight increase in it. These substances also induce a prolonged tonic contraction of a small proportion (10%) of larvae. Hungaria L-7 makes an exception, causing considerable contracture (30%). The concentrations inhibiting the TA activation by 50% are: 6x 10(-1) ml/l Dimecron-50; 2.5 x 10(-1) ml/l Gramoxone; 10(-1) g/l Hungaria L-7 and 8x 10(-2) g/l Thimet-10 G, while the 50% inhibition of the nonspecific ACh activation is resulted by 2 x 10(-1) ml/l D-50. It is concluded that contamination of environmental waters with Dimecron-50, Thimet-10 G or Hungaria L-7 may be injurious also for Pelecypoda larvae, that may contribute to the unbalancing of the water ecosystem. |
