The effect of methyl parathion on dietary discrimination ability was assessed in two‐week‐old northern bobwhite (Colinus virginianus). An initial oral dose of methyl parathion (0, 3 or 6 mg/kg: O,O‐dimethyl O‐(4‐nitrophenyl) ester) was given to two subgroups of bobwhite before a 6‐d food discrimination test; one group was tested with a choice of food treated with 45 ppm methyl parathion versus normal food and the second with a choice of 90 ppm treated food versus normal food. The average discrimination ratios (i.e., amount of treated to untreated food consumed) were used to indicate the chicks' ability to discriminate and avoid contaminated food. Chicks administered 6 mg/kg methyl parathion did not discriminate between treated and untreated food at either food treatment level and initially chose treated over untreated food (ratio = 1.28; p < 0.05). Brain cholinesterase activity in the 6 mg/kg groups averaged 50% of control levels, indicating high exposure to methyl parathion, which correlated with a behavioral disturbance (i.e., preference for treated food on day 1). Cholinesterase activity did not correlate with the discrimination ratios throughout the remainder of the 6‐d exposure period due to the strong side preference that developed in the treated groups. This study demonstrates that feeding behavior and taste discrimination ability of bobwhite chicks was impaired due to exposure to methyl parathion.
- Feeding behavior Acetylcholinesterase
- Methyl parathion