Toxic effect of the mosquito killer, S‐Deltamethrine, on the development and respiratory electron transport system activity of the embryos of bream (Abramis brama L.), roach (Rutilus rutilus), barbell (Barbus barbus) and pike (Esox lucius)

The effect of the insecticide, S-Deltamethrine (DM, LC50 for mosquito larvae: 0.02 ppb), in the concentration range between 0.025 and 2500 ppb was examined in both embryogenesis and embryonic evolution of the electron transport system (ETS) of the bream, roach, barbel and pike. A 0.025 ppb concentration of DM caused 10-25% death of the embryos in the first 2 days of incubation. Fifty per cent of the roach embryos died by the end of a 144 h incubation period when the concentration was 0.025 ppb. In 2.5 ppb, 50% of the embryos died after 120 h. In 25 ppb, 50% death was registered after 96 h, and in 250 and 2500 ppb, 50% death was detected after 48 h. Fifty per cent of the barbel embryos died after a 48 h long incubation time in 250 and 2500 ppb. The same mortality was detected for the embryos of pike in 2500 ppb after a longer (148 and 168 h) incubation time. Half of the bream embryos died after 24 and 48 h at a concentration of 2500 ppb. Larvae showed a more sensitive response to treatments than did embryos. After hatching, 30-84% of the larvae died in 0.025 ppb. Compared to embryos, larvae moved less in a concentration of 0.025 ppb and could not swim as easily as controls. In a concentration >0.25-2.5 ppb, larvae were passive and often malformed. S-Deltamethrine inhibited ETS activity in a concentration-dependent manner. Electron transport system activity of larvae was reduced by 50% in 250 ppb concentration.