Fig 4.

Effect of (a) imidacloprid, (b) fipronil and (c) fipronil sulfone on feeding activity of S. frequens larvae after 48-h exposure. Asterisks indicate a significant difference compared to control; **p < 0.01, ***p < 0.001. Time to capture in fipronil (100 and 1000 μg/L) and fipronil sulfone (10, 100 and 1000 μg/L) treatments exceeded the 5-min time limit, and Dunnett's test could not be applied to these treatments because the variance was zero due to setting the time to 5 min. Values for these treatment groups were interpreted as being significantly higher than in the control based on the 5-min time limit being much higher than the highest time to capture in the 10 μg/L (fipronil) and 1 μg/L (fipronil sulfone) treatments, which were significantly higher than the respective controls. The large variation observed particularly in the imidacloprid treatment and in the control is probably due to individual differences in locomotor activity.