抄録
Marine rotifer Brachionus plicatilis exposed to 2-ppm of fenitrothion, a representative organophosphorus insecticide, was cultivated on a minute alga Tetraselimis tetrathele by a water-flow continuous cultivation system constructed in a laboratory for 1037 days. The fenitrothion-exposed B. plicatilis was used to examine the influences on tolerance to fenitrothion and other organophosphorus insecticides, such as salithion, phenthoate, dichlofenthion, cyanophos, diazinon and malathion. Tolerance was estimated at the 50 % lethal concentration (LC50 value) of an insecticide for B. plicatilis. The LC50 value of fenitrothion for B. plicatilis exposed for 1,037 days was 9.2 ppm and that for non-exposed B. plicatilis was 5.4 ppm. The tolerance to fenitrothion by B. plicatilis was certainly increased. The exposed B. plicatilis showed an increased tolerance to salithion, dichlofenthion, cyanophos and diazin on, but a decreased tolerance to phenihnate. The influence on tolerance to malathion could not be estimated in tested concentrations. lt was made clear that B. plicatilis exposed to fenitrothion increased tolerance to fenitrothion, moreover it changed the resistance activity to other organophosphorus insecticides.
