Toxicity of Pyrethroids to Grapsid Crab (Pseudograpsus sp.) Collected from the Sundarbans Mangrove Ecosystem, Bangladesh

Grapsid crab (Pseudograpsus sp.) was exposed to three synthetic pesticides (pyrethroids eg. cypermethrin, deltamethrin and fenvalerate) to observe the toxicity on this crab. The crabs were exposed to 8 concentrations of cypermethrin, 4 concentrations of fenvalerate and 6 concentrations of deltamethrin and a control. For each treatment there were three replicates and they were stocked in glass aquaria with dechlorinated tap water and aeration at a density of 1 crab/l. Cent percent mortality were recorded at 0.16 ppm and 0.004 ppm for fenvalerate and deltamethrin respectively within 72 hrs. Lethal concentrations (LC 50) for cypermethrin, deltamethrin and fenvalerate to grapsid crab at 48 hrs exposure periods were 0.00332 ppm, 0.00137 ppm and 0.06976 ppm respectively; 0.00208 ppm, 0.00101 ppm and…