Raja N L Khan Women’s College, India
Rupa Dasgupta has completed her Ph.D from Kalyani University in 2012. She is currently working as Assistant Professor in Zoology in PG Department of Zoology, Raja N. L. Khan Women’s College. R Dasgupta has published more than 10 papers in reputed international and national Journals
"Medicinal Insecticides are major inputs in addition to seed, fertilizer and water in the modern agro-ecosystems to increase agricultural output. Globally, thousands of insecticide formulations are used in the agricultural fields. Are recommended agricultural dose (RAD) of these insecticides safe to sub-soil non-target organisms? Eco-toxicologists are searching this answer through varieties of bioassays using sensitive test organisms in the laboratory as well as in the field. The most common practice is to determine median lethal concentration (LC50) of the insecticides for the selected non-target organisms. But, it often gives false impression of the eco-toxicological hazards of an insecticide. Therefore, it is essential to assess ecological implications of the RAD of the insecticides. Earthworms constitute more than 80 % of invertebrate biomass in soil and are globally considered as model test organisms to evaluate eco-toxicological hazards of insecticides. Using epigeic earthworms Perionyx excavatus and Eisenia fetida as test organisms, bioassays were made to determine LC50 value of two carbamates (carbaryl and aldicarb), two organophosphates (monocrotophos and chlorpyrifos), one organochlorine (endosulfan) and one pyrethroid (cypermethrin) insecticides. Comparing LC50 values with the RAD it was revealed that LC50 value alone was inadequate to evaluate ecological risk of application of the insecticides in agro-ecosystems. Based on such comparison it was revealed that the carbamate insecticides aldicarb and carbaryl and the organochlorine insecticide endosulfan were most dangerous to earthworms, while the pyrethroid insecticide cypermethrin, though acutely toxic and the organophosphate insecticides chlorpyrifos and monocrotophos were ecologically safe. Chronic effects on biomass, reproduction and respiration of earthworms at sub lethal doses also indicated that carbaryl and endosulfan were more dangerous than chlorpyrifos. Based on the relative values of LC50 and RAD it was concluded that ban recently imposed on endosulfan in India is justified."