Effects of the Duration and Timing of Dietary Methyl Parathion Exposure on Bobwhite Reproduction

Effects of Methyl Parathion on Reproduction in the Japanese Quail

“…In avian reproductive testing the production of viable chicks is the most important endpoint (OECD 1995). Concentrations of methyl parathion greater than 28 ppm produced unacceptably high levels of mortality in bobwhite after five weeks of treatment (Bennett et al 1990). In the Japanese quail, 48 ppm of methyl parathion administered for six weeks did not increased the mortality rate.…”

“…Exposing high concentrations of methyl parathion to northern bobwhite (Colinus virginianus) in their natural habitats may increase susceptibility to predation (Buerger et al 1991). Test diets containing 0, 14, 20, 28 or 40 ppm of methyl parathion exposed to bobwhite during the egg producing period caused a dose related reduction in body weight, egg production, and egg weight as well as eggshell strength and thickness (Bennett and Bennett 1990).…”

“…The study was carried out under the conditions of the draft test guideline, prepared by a working group of German toxicologists and intended to replace the existing OECD guideline 206 (OECD, 1994). The results obtained were compared to that of Bennett et al (1990) on bobwhite. An analysis of available data on the relative sensitivity of bobwhite and Japanese quail to reproductive toxicants was recommended by a Working group of the SETAC/OECD Workshop Avian Toxicity Testing (OECD 1995).…”

Accounting for Differing Exposure Patterns between Laboratory Tests and the Field in the Assessment of Long-term Risks of Pesticides to Terrestrial Vertebrates

“…The potential for recovery should also be considered. For example, studies by Stromberg (1986) and Bennett et al (1990) indicate that organophosphate insecticides may cause an effect on egg production, but that egg-laying returns to normal after exposure ceases. Intuitively, brief bouts of exposure above a toxic threshold pose less risk than longer bouts of equally high exposure, and readily reversible toxic effects are of less concern than long-lasting effects.…”

Selecting surrogate endpoints for estimating pesticide effects on avian reproductive success

“…For this reason, reduced egg production should be seen as a broader indicator of adult well‐being during the egg‐laying phase that could ultimately affect reproductive success and that may be expressed in several ways in the field. Because some pesticides can affect egg production and eggshell thickness rapidly after initial exposures (Bennett, Dominguez et al ; Bennett, Bentley et al ; Bennett et al ), Bennett et al () proposed that both endpoints be compared to the estimated dietary dose (i.e., 1‐day EDD) on each day during the egg‐laying phase. If evidence exists for a pesticide indicating that a longer period of exposure is necessary to produce effects on these endpoints, an exposure estimate based on a longer time‐weighted average may be appropriate.…”