Notes: Methyl parathion-d6 is an internal standard for the quantification of methyl parathion (Item No. 25786) by GC- or LC-MS. Methyl parathion is an organophosphate insecticide.{41949} Methyl parathion is lethal to lab strains and field isolates of tobacco budworm larvae (LD50s = 7 and 81.8-128.3 μg/g, respectively).{45030} It reduces the number of stink bugs (C. sayi) caught per 100 net sweeps when applied to alfalfa fields at a concentration of 0.4 pounds per acre.{45031} Methyl parathion increases sister chromatid exchange (SCE) in a concentration-dependent manner and induces cell cycle arrest at the M1 phase in V79 cells at a concentration of 40 μg/ml.{42227} It is toxic to rats (LD50 = 14 mg/kg).{41949}