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EFFECTS OF THE DURATION AND TIMING OF DIETARY METHYL PARATHION EXPOSURE ON BOBWHITE REPRODUCTION
Citation:
Bennett, R., R. Bentley, T. Shiroyama, AND J. Bennett. EFFECTS OF THE DURATION AND TIMING OF DIETARY METHYL PARATHION EXPOSURE ON BOBWHITE REPRODUCTION. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-90/402 (NTIS PB91171587).
Description:
Two northern bobwhite (colinus virginianus) reproduction tests were conducted concurrently to evaluate how the duration and time of initiation of methyl parathion exposure affeCted dose-response relationships of reproductive parameters. n the long-term exposure test, pairs of adult bobwhite were fed methyl parathion-amended diets (0,7,10,14,20 or 28 ppm) for 25 weeks: 10 weeks prior to the onset of laying, 6 weeks as they came into laying condition and 9 weeks during egg laying. n the short-term exposure test, quail received amended diets (0,10, 14,20,28, or 40 ppm) for only three weeks during the egg laying period, followed by a three-week posttreatment period. ourteen birds died in the long-term test, compared to two in the short-term test. Significant dose-related reductions in daily food consumption, egg production and the number of 4-d-old chicks were observed in both tests during the treatment periods. o dose-related effects on fertility, hatchability or chick weights were detected. n the long-term test there were dose-related decreases in adult body weight, brain and serum cholinesterase activity and female serum calcium concentrations. holinesterase and calcium were not measured in the short-term test. ggshell weights were significantly decreased in both tests, but a dose-related decrease in eggshell strength and thickness was detected only in the short-term test. uring the posttreatment period of the short-term test, no dose-related effects on reproductive parameters were observed, except that egg production did not recover until the third week after treatment. xcept for the number of adult mortalities, all dose-related effects observed in the long-term exposure test also were observed in the short-term test. he short-term test design had two advantages that reduced variability unrelated to the chemical treatments: nfertile and incompatible pairs could be removed from the experiment and pretreatment values could be obtained to serve as controls for each pair.