The Susceptibility of Fingerlings of Oreochromis Niloticus (L.) to Three Synthetic Insecticides Commonly used in Ghana

Abstract

The acute toxicities of three synthetic insecticides, Thiodan 35EC, Cymbush 10EC and Roxion 40EC, used in the control of agricultural pests in Ghana to the fingerlings of Oreochromis niloticus were investigated in freshwater at 26 -28°C under static bioassay test conditions. The 96-hr LC50's of Thiodan and Roxion were 2.66 ppb and 12,232.07 ppb respectively; the fingerlings of 0. niloticus are thus about 4600 times more susceptible to Thiodan, an organochlorine insecticide than to an organophosphate insecticide. The 12-hr LC5O of Cymbush was 446.68 ppb. The general trend of sequential events in the reaction of 0. niloticus to the various concentrations of the test chemical were: high excitability, erratic and uncoordinated movements, loss of equilibrium and finally death.