Studies on Toxicity of some Agricultural Chemicals to Tadpoles of Frog, Rana tigrina

The present investigation is aimed to study the toxic effects of three agro-chemicals, endosulfan, indofil and dhanusan-50 on the tadpoles of Indian bullfrog, Rana tigrina. By following standard procedure for toxicity determination, it has been found that 96 hr/ LC₅₀ value of endosulfan was 1.5ppm, whereas for that of indofil and dhanusan-50, it was respectively 6.5 ppm and 8.0 ppm showing that endosulfan was most toxic and dhanusan-50 was least toxic. Some remarkable changes in the behaviour of the tadpoles in the toxic media of all the three agro-chemicals were observed such as agitated movement, hyperexcitability, bending and looping of body, surfacing movement, muscular weakness and finally death. The loss of these fish-food organisms have consequent effects on the ecosystem because of interrelationship of the organisms in the sense of food chain, and this adverse situation is destined to have an impact on the prospects of fish yields from the contaminated water areas.