Effects of the insecticide esfenvalerate on zooplankton in an indoor synthetic model ecosystem.

Abstract

Effects of esfenvalerate on zooplankton and their recovery potential were studied using an indoor synthetic model ecosystem. Esfenvalerate was applied to the system by direct spiking to overlying water or the introduction of treated slurry soil to imitate drift and run-off exposure. Four zooplankton taxa, Daphnia magna (Cladocera), Heterocypris incongruens (Ostracoda), Cyclops sp. (Copepoda), and Brachionus calyciflorus (Rotifera), were exposed to esfenvalerate with Raphidocelis subcapitata (green alga). In a drift scenario, lower doses (0.02-0.5 µg/L) showed slight or negligible effects, but the results for the highest dose (5 µg/L) indicated direct effects, as remarkable population decreases were observed for three taxa (except rotifera). However, for the latter dose, results of weekly or single (Day-15) zooplankton re-introductions after dosing demonstrated resilient recovery. In a run-off scenario, a nominal dose of 20 µg/L, in which the measured water concentrations remained at 3-6%, had effects similar to those of the high drift exposure scenario for cladocera and ostracoda.