Preference and performance of the wild indigo duskywing (erynnis baptisiae) on its native host yellow wild indigo (baptisia tinctoria) and on the introduced plant crown vetch (securigera varia)

Susan D. McMahon

Additional committee member: Barb Barton, M.S.


The Wild Indigo Duskywing butterfly (Erynnis baptisiae) shifted from its native host plant Yellow Wild Indigo (Baptisia tinctoria) to the introduced plant Crown Vetch (Securigera varia). This study examined the effects of this host shift by comparing butterfly preference (larval feeding and female oviposition) and performance (pupal weight and pupation success) of two distinct butterfly populations, on both native and introduced plants. Caterpillars reared on the native plant had significantly greater pupal weight regardless of the population origin. Larval feeding preference was significantly affected by the plant fed upon; larvae from both populations strongly preferred to feed on the native plant. Neither population origin nor host plant significantly affected pupation success or oviposition preference. Greater performance on and feeding preference for the native plant emphasizes that increasing the B. tinctoria population will likely increase the butterfly population.