investigation of lc50, noec and loec of glyphosate, deltamethrin and pretilachlor in guppies (poecilia reticulata)

background: the presence of pesticides is very prevalent in surface waters of iran. these toxic substances may accumulate in the food chain and cause serious ecological and health problems. the aim of this study was to determine the acute toxicity of glyphosate, deltamethrin and pretilachlor as potential dangerous organic pesticides to assess lethal effects of these chemicals agents to the guppy (poecilia reticulata). methods: fish samples were exposed to different concentrations of glyphosate (41%) (0, 2, 5, 10, 15 and 25 ppm), deltamethrin (2.5%) (0, 0.01, 0.02, 0.04, 0.10 and 0.30 ppm) and pretilachlor (50%) (0, 2, 4, 8, 16 and 32 ppm) for 96 h and cumulative mortality of the guppies was calculated with 24 h intervals. results: lc50-96h was 12.01±1.00, 0.08±0.47 and 8.24±0.42 for glyphosate, deltamethrin and pretilachlor respectively. the very low lc50 obtained for glyphosate (12.01±1.00 ppm), deltamethrin (0.08±0.47 ppm) and pretilachlor (8.24±0.42 ppm) indicate that glyphosate, deltamethrin and pretilachlor are highly toxic to guppies. conclusion: our results demonstrated that deltamethrin and glyphosate had the lowest and highest rate of mortality on the guppy respectively.