Cypermethrin induced Respiratory and behavioural Responses of Estuarine clam, Katelysia opima (Gmelin)

摘要

A static renewal bioassay method was conducted to determine the acute toxicity (LC50) of technical grade pyrethroid insecticide, cypermethrin (25% EC) in estuarine clam, Katelysia opima. The clams were exposed to different concentrations of cypermethrin for 96 h. The acute toxicity value was found to be 2.79 g/L . Behavioural patterns and oxygen consumption were studied in lethal and sub-lethal concentrations. During the experimental period, clams from higher concentration group isolated their body from the stressful environment by closing their shell valves for a considerable period. Mucilage secretion was observed in higher concentration groups. Variation in oxygen consumption was observed in both lethal and sub-lethal concentrations of cypermethrin respectively. Clams from LC group showed an elevation in the rate of oxygen consumption after initial 12 hours and fluctuated up to 96 hours. Rate of respiration was severely hampered in LC50 group. Change in oxygen consumption may be due to respiratory distress as a consequence of impairment in oxidative metabolism.