Combined Effects of Warming and Imidacloprid on Survival, Reproduction and Population Growth of Brachionus calyciflorus (Rotifera).

Global warming and pesticide contamination are two stressors of high concern, but their combined effects on freshwater biota are controversial. This study investigated the combined effects of warming and imidacloprid (IMI) on survival (measured as life expectancy at hatching), reproduction (net reproductive rate), population growth (intrinsic rate of population increase) and sexual reproduction (proportion of sexual offspring) of Brachionus calyciflorus using a life table experiment. The results showed that compared with controls, treatments with IMI at 50-100 mg/L significantly decreased survival, reproduction and population growth of the rotifers at 20℃. The inhibiting effect at higher IMI concentrations on survival increased with increasing temperatures, but those on reproduction and population growth increased only when the temperature increased from 25℃ to 30℃. The proportion of sexual offspring decreased with increasing temperatures. When monitoring the ecological effects of pollutants, environmental temperature and the possible adaptation of rotifers to it should be taken into consideration.