Background/Question/Methods
The black swallowtail butterfly, Papilio polyxenes, is a North American native and specialist on plants in the carrot family, Apiaceae. Female black swallowtails are known for laying eggs on common introduced species such as wild carrot, parsnip, and poison hemlock in Illinois and New York, and less so on the less common native species golden alexanders. With undergraduates in my lab, I have been looking at variation in leaf chemistry and female butterfly responses to leaves and chemical extracts of the leaves, as well as the relative distribution of wild carrot and golden alexanders within DuPage County, Illinois.
Results/Conclusions
Wild carrot is significantly more abundant within DuPage County when compared to the native golden alexanders. The latter is restricted to protected or planted prairie sites throughout the county, while carrot can be found commonly in yards, gardens, and forest preserves. There are differences in the contact chemical profiles of all four plant species, and the butterflies have a preference for non-volatile extracts of the native host, followed closely by wild carrot.