Aristolochic acid content of South-East Asian troidine swallowtails (Lepidoptera: Papilionidae) and of Aristolochia plant species (Aristolochiaceae)

Summary. Analysis of South-East Asian troidine swallowtails revealed high variability in the content of aristolochic acids among individuals. The presence or absence of these compounds depends on the Aristolochia species available as food plant for the larvae. Only one plant species (Aristolochia philippinensis) contained a high concentration of aristolochic acids, while other species from various localities contained none or only marginal amounts. Whether aristolochic acids have a distinct function in chemical defense of these swallowtails is still an open question. Received 11 December 2000; accepted 4 August 2001.     

The occurrence of aristolochic acids in neotropical troidine swallowtails (Lepidoptera: Papilionidae)

Summary. Analysis of individuals of 17 troidine species demonstrated the presence of aristolochic acids in these butterflies in varying concentrations. Although aristolochic acids do not occur in Aristolochia galeata leaves, they were present in Battus polydamas larvae reared on these leaves, and thus may be synthesized by the larvae from chemical precursors in the plant. Received 17 August 1999; accepted 20 January 2000     

Oviposition stimulants for the pipevine swallowtail butterfly,Battus philenor (Papilionidae), from anAristolochia host plant: Synergism between inositols,aristolochic acids and a monogalactosyl diglyceride

Aristolochia macrophylla (Lam.) is a major host of the pipevine swallowtail butterfly,Battus philenor (L.), in the eastern United States. The female butterflies use a synergistic mixture of inositols, acids and a lipid as oviposition cues in recognizing this plant on contact. The acids and lipid, all isolated from the Et₂O-CHCl₃ fraction of an alcoholic extract of fresh foliage, were identified as aristolochic acid I (1), aristolochic acid II (2) and 1,2-[di(9Z,12Z,15Z)-octadeca-9, 12, 15-trienoyl]-3-galactosyl-sn-glycerol (3). Identifications were facilitated by UV, MS (EI and FAB) and NMR (1D and 2D) spectral techniques and by analysis of the hydrolysis products of 3. The active inositols were identified as D-(+)-pinitol, reported previously, and sequoyitol. Though this is apparently the first report of oviposition responses to a diacyl glycerol glycoside by a phytophagous insect, responses to aristolochic acids and sequoyitol have been reported previously for anAristolochia-feeding swallowtail of a different genus in Japan. This indicates substantial evolutionary conservatism in chemical oviposition cues within the tribe Troidini.     

Chemical basis for differential acceptance of two sympatric rutaceous plants by ovipositing females of a swallowtail butterfly, Papilio polytes (Lepidoptera, Papilionidae)

Summary. In the natural habitat of Papilio polytes, a Rutaceae feeder utilizing Toddalia asiatica as a major host plant, some other rutaceous plants such as Murraya paniculata (abundant) and Glycosmis citrifolia (relatively rare) occur sympatrically as potential hosts. Whereas G. citrifolia is occasionally infested in the field, M. paniculata remains entirely unexploited by the butterfly. We thus examined the phytochemical mechanisms that can explain the differential acceptance of the two plants by ovipositing females of P. polytes. The foliage of G. citrifolia was found to readily induce oviposition and females deposited eggs in response to a methanolic extract of the plant. Stimulatory activity-directed fractionation of the extract revealed the presence of two characteristic compounds, trans-4-hydroxy-N-methylproline and 2-C-methylerythronic acid, known to serve as oviposition stimulants for the butterfly. In addition, larvae performed as well or better onG. citrifolia as on T. asiatica. Similar examination of the inhibitory chemical constituents of M. paniculata led to the isolation of an oviposition deterrent. The compound, identified as trigonelline (N-methylpyridine- 3-carboxylic acid), exhibited moderate oviposition deterrency to females. These results combined with our previous data are in agreement with the observed differential utilization of the two plants by P. polytes in the field.     

Sequestration of aristolochic acids by the pipevine swallowtail, Battus philenor (L.): evidence and ecological implications

Summary. 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. Received 7 April 2000; accepted 31 May 2000     

Oviposition stimulant for the zebra swallowtail butterfly, Eurytides marcellus, from the foliage of pawpaw, Asimina triloba

Summary. We have isolated a caffeoylcyclohexane-1-carboxylic acid derivative, 3-caffeoyl-muco-quinic acid (3-CmQA), as a contact oviposition stimulant for the zebra swallowtail butterfly, Eruytides marcellus (Papilionidae), from the foliage of its primary host plant, Asimina triloba (Annonaceae). This compound alone was as active in stimulating oviposition by females as were the parent ethanolic plant extract and the host plant itself. Other tested isomers of 3-CmQA, including 5-caffeoylquinic acid (5-CQA or trans-chlorogenic acid), were inactive. We found, however, that experienced female butterflies responded strongly to host volatiles, which enhanced landing rates and hence oviposition.? This is the first report of an oviposition stimulant for a swallowtail butterfly of the tribe Graphiini. We found 3-CmQA to be the major caffeoylcyclohexane-1-carboxylic acid isomer in plants of the genus Asimina. These plants lack appreciable amounts of 5-CQA, which has been shown previously to be one of the oviposition stimulants for certain Rutaceae- or Apiaceae-feeding swallowtails of the related tribe Papilionini.? Our findings, along with earlier results from the tribes Troidini and Papilionini, suggest that responses by swallowtails to hydroxycinnamic acid derivatives as oviposition cues date back at least to the ancestor of the subfamily Papilioninae. Received 24 March 1998; accepted 27 May 1998.     

Comparative electrophysiological analysis of plant odor perception in females of threePapilio species

Summary Antennae of femalePapilio butterflies perceive many volatile plant constituents with widely differing, constituent-specific sensitivities. We compared the responses of threePapilio species to volatiles from host and non-host plants to assess species-specificity and the degree of evolutionary conservatism in olfactory responses.Since previous studies had demonstrated that the polar constituents in odor fromDaucus carota stimulate oviposition behavior inPapilio polyxenes, we collected headspace volatiles fromD. carota, Pastinaca sativa (both Apiaceae) andArtemisia dracunculus (Asteraceae) and separated the polar fraction of these volatiles by gas chromatography. GC-coupled electroantennograms (GC-EAG) were recorded from the speciesPapilio polyxenes, P. machaon hippocrates andP. troilus. In addition, the responses of the three species to five compounds known as generally occurring constituents of plant odor were recorded. The relative sensitivities for these compounds were nearly identical in all threePapilio species. The response spectra to the separated plant volatiles also showed considerable similarities among the species.From the limited set of GC peaks evoking a response in one of the species, 64% (D. carota), 44% (P. sativa) and 29% (A. dracunculus) also evoked a response in both of the other species. The responses of the two closely related Apiaceae feeders (P. polyxenes, P. m. hippocrates) to volatiles fromD. carota were more similar to each other than was either to the response ofP. troilus, which feeds on Lauraceae. However, this was not true for the responses to volatiles fromP. sativa. The least congruence among the three species was found in the responses to volatiles fromA. dracunculus, a non-host for all of them. The differences and similarities found in the response profiles of the threePapilio species are discussed with respect to evolutionary adaptation to host odor versus evolutionary conservatism in adaptation of olfactory receptors.