Variation in preference and specificity in monophagous and oligophagous swallowtail butterflies

Abstract

Analysis of a locally monophagous butterfly species, Papilio oregonius, and a locally oligophagous species, P. zelicaon, showed significant variation in oviposition preference within populations of both species. Females of both species chose primarily their native hosts, but the percentages of eggs laid by individual females among the plant species and the number of plant species on which individual females laid eggs differed significantly among isofemale strains within populations. Moreover, some females within all isofemale strains of both species laid a few eggs on Foeniculum vulgare, an umbelliferous species that does not occur in the native habitats of these populations but is a host for Papilio species in other geographic areas. Local monophagy and oligophagy in these species probably reflect the relative ranking among potential plant species. Both populations harbor variation in oviposition choice that could allow for host shifts if these populations invaded new habitats. -from Author