Comparative toxicity of petroleum and two synthetic oils to the large milkweed bug, Oncopeltus fasciatus

Effects of petroleum and two synthetic oils on mortality and reproduction of the large milkweed bug, Oncopeltus fasciatus (Dallas), were compared. Reproduction was investigated because of its importance in the maintenance of population levels and the sensitivity of the reproductive system to toxicants.

Adult milkweed bugs were dosed topically with the test oils to measure acute toxicity. Chronic toxicity was determined by mean survival after chronic exposure, starting with the fifth instar. The ability of sublethal levels of the test oils to affect reproduction was measured by the number of eggs laid and their percent hatch.

The two synthetic oils were found to be more acutely and chronically toxic than petroleum. Egg production was not affected by petroleum but was reduced approximately 20% by sublethal levels of both synthetic oils. Egg viability was not affected.