Troidini

Abstract: The use of unpalatability as a defense strategy of butterflies has been studied since the time of Bates (1862). Most studies have focused primarily on the role of unpalatability in mimicry systems, rather than on the defensive function of unpalatability itself. Unpalatable butterflies have been found primarily in five major groups: (1) the tribe Troidini of the family Papilionidae, whose members feed on plants in the Aristolociaceae, and the following subfamilies of the Nymphalidae: (2) the Danainae, feeding on milkweeds (Asclepiadaceae); (3) the Ithomiinae, which feed on solanaceous plants; (4) the Acraeinae and (5) the Heliconiinae, both of which feed on plants in the family Passifloraceae. Some pierids (Pieridae) are unpalatable as well (Finn, 1895, 1897a, 1897b; Swynnerton, 1919; Pough and Brower, 1977), but unpalatability does not seem to be common in this group. Research on unpalatable North American butterflies has considered primarily three species: the Monarch, Danaus plexippus (Danainae), and the Queen, Danaus gilippus (Danainae), both feeding on milkweeds which contain cardiac glycosides (J. Brower, 1958a, 1958c; Roeske et al., 1975); and the Pipevine Swallowtail, Battus philenor (Papilionidae), which sequesters aristolochic acids from its foodplants in the Aristolochiaceae (J. Brower, 1958b; Rothschild et al., 1970; Platt et al., 1971). Other North American butterflies have been neglected in studies on unpalatabil-

Abstract: It has long been assumed that the North American pipevine swallowtail, Battus philenor (L.) (Papilionidae, Troidini), is protected from natural enemies by aristolochic acids sequestered from its Aristolochia food plants. This study confirmed that populations of B. philenor from Virginia and east Texas sequester these compounds. A comparison of the aristolochic acid profiles of the Virginia butterflies and their A. macrophylla food plants revealed several differences. The aristolochic acid fraction of the foliage was dominated by aristolochic acids I and II, whereas the insects had a much lower proportion of aristolochic acid II and contained, in addition, substantial amounts of aristolochic acids Ia and IVa, which were not detected in the plants. The eggs, larval integument, osmeterial glands, pupal cuticle, and adults (wings and bodies) all contained aristolochic acids. These findings help explain the abundant ecological data indicating that both immature and adult B. philenor are unpalatable and protected from natural enemies.

Abstract: Phylogenetic relationships among the Japanese papilionid butterflies were analyzed by comparing 783 nucleotide sequences of the mitochondrial gene encoding NADH dehydrogenase subunit 5 (ND5). Phylogenetic trees of the representative species from each family in the superfamily Papilionoidea revealed that the species of the family Papilionidae and those of all other families formed distinct clusters, with a few species of the family Hesperiidae (Hesperioidea) as an outgroup. In the phylogenetic trees of most Japanese species of the family Papilionidae with Nymphalis xanthomelas (Nymphalidae) as an outgroup, the tribe Parnassiini (Parnassiinae) formed a cluster, and the rest formed the other cluster in which the tribe Zerynthiini (Parnassiinae) and the subfamily Papilioninae formed different subclusters. In the Papilioninae cluster, the tribes Troidini and Graphiini formed a subcluster, and the tribe Papilionini formed the other subcluster. These results generally agree with the traditional classification of the papilionid butterflies based on their morphological characteristics and support the proposed evolutionary genealogy of the butterflies based on their morphology, behavior, and larval host plants, except that the tribes Parnasiini and Zerynthiini (both Parnassiinae) are not in the same cluster.