Changing pattern of insecticide use and its impact on environment and biodiversity : An evaluation in Indian perspectives

A drastic change in cropping pattern during the middle of twentieth century marked the beginning of green revolution. Development of high yielding varieties of crop invited application of huge input of fertilizers, insecticides and irrigation water. More efficient insecticide formulations were invented and total use of insecticides increased to many fold resulting in adverse impacts on environment, biodiversity and human health. Carbaryl, chlorpyrifos and endosulfan representing respectively carbamate, organophosphate and organochlorine compounds are the three most common insecticides that are widely used in the agricultural fields in India and cause serious damages to soil subsystem. Earthworms being the dominant constituent of the non-target invertebrate biomass in the soil are the worst victims of this environmental pollution and existence of these ecologically important soil organisms is threatened by the escalating use of these insecticides in the country. Application of carbaryl and chlorpyrifos also needs careful monitoring because earthworms were found sensitive to doses close to 10 % and 60 % of RAD of these two insecticides respectively.

There are reports that target insects have developed resistance to pyrethroids. As a result, farmers often use pyrethroids in combination with carbamates and organophosphates, the more toxic and persistent group of insecticides. High yielding varieties of crops are known to tolerate high level of these insecticides, but contain residue at level much higher than the permissible limit. Implementation of eco-friendly methods of cultivation is urgently needed to protect environment, biodiversity and human health from the indiscriminate use of modern insecticides.