Globalization of trade has made understanding the biology of invasive species a high priority. Many weeds utilize toxins to fend off consumers, but in areas of invasion plants freed from their insect enemies often lose toxicity over time. When their ancestral enemies catch up with them through accidental or deliberate introduction, however, renewed damage may bring about increased investment in chemical defense. Because plants also rely on chemicals to attract pollinators, escape from and subsequent reacquaintance with ancestral enemies may also influence the ability of invasive weeds to produce seed and expand their range. These relationships will be examined in the flower-feeding parsnip webworm and its hostplant wild parsnip. Although native to Europe, this interaction is invasive in North America and, since 2004, in New Zealand. The recent invasion of New Zealand provides an extraordinary opportunity to document evolutionary responses in an invasive weed to re-association with an adapted specialist. Methodological approaches include reciprocal transplant experiments, phytochemical analyses, and quantitative selection analysis to measure impacts of herbivory on phytochemicals involved in pollinator and webworm attraction.
Broader impacts of this work include providing interdisciplinary graduate training to insure 21st century scientific competitiveness and providing professional development projects for middle/high school math/science teachers, popular science publications, public lectures, a user-friendly website, and a book for the general public. This work can also contribute to designing programs for invasive species management, biodiversity conservation, and restoration ecology.
