Population growth of Brachionus calyciflorus affected by deltamethrin and imidacloprid insecticides

Abstract

Rotifers due to their relatively short lifespan, high fecundity and high rate of population increase are ideal for chronic toxicity tests. The aim of this research was determine the lethal concentrations (LC50 24 h) of deltamethrin and imidaclopride and their impacts on reproduction and growth of the freshwater rotifer, Brachionus calyciflorus. Experiments carried out statically based on standard method (O.E.C.D.). Based on LC50 levels of pesticides, different concentration treatment groups designated and rotifer population responses in the five different concentrations of deltamethrin (0.00, 0.05, 0.10, 0.21 and 0.53 mgl-1) and imidacloprid (0.00, 6.22, 12.45, 24.91 and 62.27 mg l-1) with three replicates per each concentration during ten days were studied. The LC50 24h of deltamethrin and imidacloprid for freshwater rotifer determined as 1.06 mg l-1 and 124.54 mg l-1, respectively. The density of rotifers in all treatment groups of pesticides compare to the control group at tenth day decreased significantly (p<0.05). The ovigerous females to nonovigerous females ratio (OF/NOF) and mictic females to amictic females ratio (mic/amic) significantly affected (p<0.05) in all concentrations for both insecticides. This study suggested that B. calyciflorus are severely sensitive to deltamethrin rather than to imidacloprid pesticide.