From Terpenoids to Aliphatic Acids: Further Evidence for Late-Instar Switch in Osmeterial Defense as a Characteristic Trait of Swallowtail Butterflies in the Tribe Papilionini

Abstract

We compared the chemical compositions of the osmeterial secretions of fourth and fifth (last) instars of eight swallowtail species of the tribe Papilionini. Four species (Papilio demoleus, P. polytes, P. paris, and P. macilentus) are Asian Rutaceae-feeding swallowtails. The other four (Chilasa epicydes, C. agestor, P. troilus, and P. glaucus) represent more distant clades within the Papilionini and species with larval hosts in other plant families. We conducted a quantitative analysis for six species, but only qualitative analysis for P. glaucus and C. agestor. In all eight species, regardless of larval host plant, secretions of the fourth instar principally consisted of mono- and sesquiterpene hydrocarbons, whereas those of the fifth instar comprised aliphatic acids and their esters. Consistent with earlier findings, our results suggest that this "heterogeneous" pattern of osmeterial chemistry, not seen in other tribes, may characterize the Papilionini as a whole. Unlike those of most Papilio species, the fourth and fifth instars of Chilasa species resemble each other in body coloration. Thus, the heterogeneous osmeterial pattern is not necessarily associated with color change in papilionid larvae. The major terpenoids identified in fourth instar larval secretions from the six species were alpha-pinene, sabinene, beta-myrcene, limonene, beta-phellandrene, (Z)-beta-ocimene, (E)-beta-ocimene, p-mentha-1,4(8)-diene, beta-elemene, beta-caryophyllene, (E)-beta-farnesene, (3Z,6E)-alpha-farnesene, (Z)-alpha-bisabolene, germacrene-A, (E)-alpha-bisabolene, and germacrene-B. The profiles for individual species differed both qualitatively and quantitatively from one another, and certain species also secreted methyl 3-hydroxy-n-butyrate and oxygenated sesquiterpenes in relatively large proportions. Secretions from fifth instars were composed of varying proportions of isobutyric, 2-methylbutyric, and acetic acids, and methyl and ethyl (minor) esters of both isobutyric and 2-methylbutyric acids. The heterogeneity of osmeterial chemistry in the tribe Papilionini may represent fine-tuning of chemical defense in response to shifting predation pressures as the larvae age and grow.

Biosynthesis of volatile terpenes that accumulate in the secretory cavities of young leaves of Japanese pepper (<i>Zanthoxylum piperitum</i>): Isolation and functional characterization of monoterpene and sesquiterpene synthase genes

“…It is most likely that volatile terpenes accumulated in the secretory cavities are involved in defense against insect damage. On the other hand, it is well known that volatile terpenesproducing Citrus plants including Japanese pepper are hosts for the larvae of a swallowtail butterflies (Honda and Hayashi 1995;Ômura et al 2006). When the chemical composition in the osmeterial secretions from larvae of some swallowtail species of the tribe Papilionini was analyzed, volatile terpenes including D-limonene, β-phellandrene, and β-caryophyllene were detected, suggesting that ZpTPSs might contribute to ecological interaction between a swallowtail and Japanese pepper via volatile terpenes.…”

The Prosternal Gland in Pacific Northwest Butterfly Larvae with Preliminary Chemical Analyses of Emissions

“…In contrast, examination of lycaenid and papilionid larvae showed no evidence of prosternal glands. However, papilionid larvae are well documented to possess an analogous bifurcate eversible dorsal gland just behind the head, which secretes defensive chemicals (Eisner & Meinwald 1965;Omura et al 2006).…”

“…samples as well as in N. menapia and P. sonora, and likely have a defensive function. Terpenoids dominate the osmeterial secretions of early-mid instar papilionid larvae whose major enemies are invertebrate predators (Omura et al 2006), and also were found in prosternal glands of nymphalid larvae, Dione juno and Abanote hylonome (Osborn & Jaffe 1998). All Argynnis spp.…”

Sequestration of aristolochic acids from meridic diets by larvae of Battus polydamas archidamas (Papilionidae: Troidini)

“…The presence of deterrent and toxic compounds is reported in the osmeterial secretions of several Troidini (Honda, 1980(Honda, , 1983Omura et al, 2006). The presence of AAs in this organ is also widespread in the tribe Troidini; nevertheless, their ecological role is not well established (Nishida, 1995;Sime et al, 2000).…”