Feeding activity of Gammarus pulex under constant (treatment C) or pulsed (treatments A and B) exposure to imidacloprid.

1Pulsed treatment with a short interval in uncontaminated water between imidacloprid pulses (4 days).2Pulsed treatment with a long interval in uncontaminated water between imidacloprid pulses (8 days).3Pulsed treatment with a long interval in uncontaminated water between imidacloprid pulses (11 days).4Between control and treatment.5Among all treatments within one experiment.