Fecundity and Progeny Growth Following Subacute Insecticide Ingestion by the Mallard

The influences of subtoxic levels of dieldrin and parathion on the fecundity and progeny development of the Mallard were investigated. Five trios each of mallards received either 4.0 p.p.m. of dieldrin or 10.0 p.p.m. of parathion in their diets; six additional trios constituted controls. The diets were fed ad libitum for 90 days, which included approximately 30 days prior to and 60 days following the onset of egg production. Egg production, fertility, hatchability and progeny development to six weeks of age were evaluated. No significant influences on either egg production or fertility were disclosed. Hatchability of fertile eggs from dieldrin fed trios was significantly depressed to less than 50 percent of control or parathion levels. Egg shell thickness was significantly depressed in eggs from parathion treated individuals. A non-significant depression of shell thickness was also noted in dieldrin shells. Shell thinning per se apparently was not responsible for the reduced hatchability of dieldrin embryos. Progeny from treated and control groups demonstrated equivalent hatching weights and rates of growth to six weeks of age.