Florida red bay (Persea borbonia) leaf extracts deter oviposition of a sympatric generalist herbivore, Papilio glaucus (Lepidoptera: Papilionidae)

Summary. The ability to perceive and respond to phytochemicals that reliably indicate poor suitability of a potential host plant confers a selective advantage to ovipositing female swallowtail butterflies. Papilio glaucus females are generalists that nonetheless do not oviposit on red bay (Persea borbonia: Lauraceae). Red bay is toxic to P. glaucus neonates but is commonly found in habitats alongside their principal host plant, Magnolia virginiana, in central Florida. The hypothesis that deterrent compounds present in the leaves of red bay mediate its rejection by P. glaucus was evaluated in our study. Florida populations of P. glaucus did not oviposit on host leaves sprayed with the methanol extract of red bay foliage, although they accepted solvent-treated and untreated tulip tree leaves in 3 choice bioassays. Additionally, tulip tree leaves sprayed with methanolic extracts of red bay also deterred oviposition by P. glaucus females from Ohio, Kentucky and Pennsylvania, although these populations do not naturally encounter red bay. Clearly, deterrent compounds found within this non-host are the basis of its rejection by populations of P. glaucus and such recognition is fundamental to the species, not just a reflection of local adaptations. Received 2 April 1999; accepted 11 June 1999.