Responses of North American Papilio troilus and P. glaucus to potential hosts from Australia

We tested the abilities of neonate larvae of the Lauraceae-specialist, P. troilus, and the generalist Eastern tiger swallow-tail, Papilio glaucus (both from Levy County, Florida) to eat, survive, and grow on leaves of 22 plant species from 7 families of ancient angiosperms in Australia, Rutaceae, Magnoliaceae, Lauraceae, Monimiaceae, Sapotaceae, Winteraceae, and Annonaceae. Clearly, some common Papilio feeding stimulants exist in Australian plant species of certain, but not all, Lauraceae. Three Lauraceae species (two introduced Cinnamomum species and the native Litsea leefeana) were as suitable for the generalist F. glaucus as was observed for F. troilus. While no ability to feed and grow was detected for the Lauraceae-specialized P. troilus on any of the other six ancient Angiosperm families, the generalist R. glaucus did feed successfully on Magnoliaceae and Winteraceae as well as Lauraceae. In addition, some larvae of one R. glaucus family attempted feeding on Citrus (Rutaceae) and a small amount of feeding was observed on southern sassafras (Antherosperma moschatum; Monimiaceae), but all P. glaucus (from 4 families) died on Annonaceae and Sapotaceae. Surprisingly, the North American Lauraceae-specialist (P. troilus) died on all Lauraceae species by day #12, but some generalist P. glaucus larvae survived. Most of the generalist (P. glaucus) offspring survived and grew very well on all 3 species of Magnoliaceae assayed (Magnolia virginiana, Michelia champaca, & Michelia doltsopa) and on Tasmannia insipida (Winteraceae). The ability of these larvae to feed and grow on T. insipida but not T. lanceolata suggests significant phytochemical differences may exist within the Winteraceae. Two Monimiaceae "sassafras" plant species were unsuitable to both North American Papilio species despite their very close phylogenetic relationship with the Lauraceae.