Variation in cuticular lipid profiles of black butterflies of the genus Papilio in Japan

Abstract

Insect (epi)cuticular lipids characterize sex and species and often play an important role in mating behavior. We previously revealed that two black-colored swallowtail butterflies, Papilio polytes and Papilio protenor, show sexual dimorphism and species specificity in cuticular lipid composition and that P. polytes males use specific monoene components for mate discrimination. These findings suggest that their closely related species may have different profiles of cuticular lipids. We examined the cuticular lipid compositions of five Papilio species (P. bianor, P. maackii, P. helenus, P. macilentus, and P. memnon), closely related and sympatric to P. polytes and P. protenor, and discussed whether it is possible to discriminate between sexes, and between species based on their chemical profiles. The cuticular lipids consist mainly of C23–C31 aliphatic hydrocarbons, in which n-tricosane, n-heptacosane, and n-nonacosane are predominant. Several aliphatic ketones, aliphatic acids, and oxygenated terpenoids were also identified as major components shared by several species. There were no components exclusive to a particular species. Conspecific males and females shared most of the components but were mostly distinguishable based on their composition. Moreover, P. helenus males, P. polytes females, and P. protenor females had two different phenotypes of lipid composition. Although unrelated to the genetic lineage, the seven species were classified into four clusters based on their lipid profiles. The first cluster was composed of only P. memnon. The other six species were broadly classified into three clusters consisting of subclusters for each species: 1) P. polytes, P. helenus, P. macilentus, and several P. protenor females; 2) P. bianor and P. protenor; and 3) P. maackii and several P. helenus males. These results indicate that cuticular lipid profiles characterize the species and sex of the Papilio species and may be responsible for mate discrimination among them.