Journal of Agriculture
and Environmental Sciences

A Review: Effect of Ozone on Milkweeds (Asclepias spp.) in USA and Potential Implications for Monarch Butterflies
Donald D. Davis, Dennis R. Decoteau

Abstract
Ozone is the most important phytotoxic air pollutants in the U.S., in both agricultural and ecological settings. Common milkweed (Asclepias syriaca L.) isone of the most important ozone-sensitive, native, bioindicatorplants in the U.S that is capable of detecting phytotoxic levels of ambient ozone. Diagnostic ozone-induced symptoms on milkweed foliage are brown to black spots (“stipples”) on the axial leaf surface, in addition to prematuredefoliation (accelerated senescence). OtherAsclepias spp.in the U.S.might also serve asozone-sensitive bioindicators, butfew have been tested.We suggest testing them, and also suggest that ozone injury to milkweedsmig htinfluence the monarch butterfly (Danaus plexippus L.) life cycle, since adult female monarchsoviposit only onmilkweed leaves and resulting caterpillars feed exclusively on milkweed leaves. We hope this review will stimulate new research and provide a framework for further studies in the complicated, interwoven, tripartite interaction among ambient ozone, milkweeds, and monarch butterflies. This review discusses sources, concentrations, and dispersion of the air pollutant ozone in the U.S.; the time frame for the historical development of ozone-sensitive bioindicator plants; and the lack of data regarding ozone-sensitivity among milkweed species in the U.S.

Full Text: PDF     DOI: 10.15640/jaes.v7n2a16