Invasive plants are responsible for millions of dollars in damages each year across the United States. Garlic mustard, Alliaria petiolata, is an invasive biennial herb introduced to North America from Europe in the 1800s. Since its introduction, it has spread across the eastern United States, often creating thick monocultures of plants in the forest understory. A. petiolata is known to "trick" adult native Pieris butterflies into ovipositing on their leaves; however, some species of Pieris caterpillars are unable to consume A. petiolata, and starve upon hatching. We investigated this relationship between A. petiolata and the native butterfly P. virginiensis.
Results/Conclusions
We found that P. virginiensis prefers to lay eggs on A. petiolata at about twice the rate that it does on its native host. Additionally, we observed no variation in larval mortality: all P. virginiesis larvae offered A. petiolata died within 5 days of hatching. We identified a major chemical causes of this mortality: alliarinoside, a compound unique to A. petiolata. Additionally, we will discuss other studies of native Pieridae butterflies and how they have responded to A. petiolata and its invasive relatives.