Acute toxicity of alpha-cypermethrin to oligochaete worm, Branchiura sowerbyi (Beddard, 1982) along with their behavioural responses.

Acute toxicity of alpha-cypermethrin to Branchiurasowerbyi and their behavioural changes were evaluated in the present study. The 24, 48, 72 and 96 h LC 50 values of alpha-cypermethrin to B. sowerbyi were 43.39, 39.75, 22.58 and 13.41 µg/l respectively. A significant variation (p<0.05) between mortality rate of worm and concentrations of the test chemical at all the exposure times (24, 48, 72 and 96 h) was observed. The mortality rate also significantly varies (p<0.05) with the exposure time at all the concentrations except 48h. In addition, a dose dependent change in the behavioural pattern of the worm was recorded. It was directly proportional to the increasing concentration of alpha-cypermethrin.