A comparison of preference and performance of Erynnis baptisiae (Lepidoptera: Hesperiidae) on a native and an introduced host plant

摘要

The increasing number of introduced and invasive plant species present phytophagous insects with many novel host plants. The butterfly Erynnis baptisiae (Forbes) (Lepidoptera: Hesperiidae) shifted from a native host plant, Baptisia tinctoria (L.), to an introduced host, Securigera varia (L.). Critical information about the biology of E. baptisiae, a species of special concern in Michigan, and the impact of its host shift is lacking. The purpose of this study was to compare preference and performance of two distinct populations of E. baptisiae on its native host and on an introduced plant. Preference was assessed based on female oviposition and larval feeding. Oviposition choice experiments demonstrated no significant preference by females for laying eggs on the native versus the introduced plant. Despite this, larvae from both populations strongly preferred to feed on the native plant, as measured by the number of leaves damaged in feeding choice experiments. Performance was assessed based on pupal weight, pupation success and development time. In rearing experiments, pupal weight was significantly higher when larvae fed on the native plant, regardless of the original host plant. There were no significant differences in the percentage of larvae successfully pupating and emerging as adults. Total development time was significantly shorter for caterpillars feeding on the native plant. Although the introduced plant S. varia is an adequate host plant, E. baptisiae preferred to feed on the native plant B. tinctoria, and also performed better on it. This implies that an increase in the number of B. tinctoria plants may increase the fitness of E. baptisiae, which may lead to a population increase and stabilization of the state population of E. baptisiae.