Effects of Fenitrothion on Life History Parameters of the Rotifer Brachionus calyciflorus

The effects of fenitrothion on life history parameters, the production of resting eggs and hatching of resting eggs of the rotifer Brachionus calyciflorus were studied on the individual and population level. Neonates (<4 h-old) were individually cultured in six concentrations (0.1, 1, 10, 100, 1,000 and 2,000 mu g L-1) of fenitrothion. Life history parameters including duration time of the juvenile period, hatching time of the first neonate, reproductive period, post-reproduction period, lifespan, and lifetime reproduction were evaluated. Fenitrothion significantly prolonged the juvenile period at 0.1 mu g L-1 and extended hatching time of the first neonate at 1,000 mu g L-1. Rotifers exposed to fenitrothion at concentrations of 0.1, 1, 10, and 100 mu g L-1 had longer reproductive periods and produced more offspring than controls. Exposure to 1,000 mu g L-1 significantly reduced the number of resting eggs produced. Low concentrations of fenitrothion caused an increase in the duration of the juvenile period, reproductive period, and lifetime reproduction of B. calyciflorus.