This thesis focuses on swallow-wort, an invasive vine related to milkweeds, and the potential of Hypena opulenta for providing biological control in Michigan, as well as the indirect effects that the introduction of H. opulenta may have on the monarch butterfly. The first chapter covers the background of swallow-wort in its invasive range and outlines previous research done with H. opulenta in the United States and Canada.In the second chapter, the impact and the phenology of H. opulenta on black swallow-worts in Michigan is examined in common garden experiments. Swallow-wort survival and reproductive output are measured and compared when different adult densities are released in one study. The second study assessed the phenology of H. opulenta when releases took place at different dates either in sunny or shaded sites. In southern Michigan, H. opulenta is found to produce two generations per season, though overwintering could not be confirmed. Damage caused by larval feeding was higher in the shade but was not enough to reduce plant fitness regardless of release size or light availability. Swallow-worts can serve as oviposition sinks for monarchs, however, the presence of H. opulenta larvae may serve as an oviposition deterrent. Examination of the indirect effects of H. opulenta on monarch butterflies in the third chapter found no evidence that H. opulenta deters monarch oviposition. In addition, the utilization of swallow-wort by wild monarch butterflies as an oviposition host in Michigan was confirmed.
Read
