Chemical nature of larval osmeterial secretions of papilionid butterflies in the generaParnassius,Sericinus andPachliopta

Volatile components of the larval osmeterial secretion ofParnassius glacialis (Parnassiinae, Parnassiini) consisted of isobutyric acid, 2-methylbutyric acid, and their methyl esters. In contrast, the osmeterial exudate ofSericinus montela (Parnassiinae, Zerynthiini) was characterized as monoterpene hydrocarbons comprising-myrcene (Major),-pinene, sabinene, limonene, and-phellandrene, whereas that ofPachliopta aristolochiae (Papilioninae, Troidini) was composed of numerous sesquiterpene hydrocarbons, including-himachalene,-amorphene, and germacrene-A, and a few oxygenated sesquiterpenoids. In these three species, the chemical nature of the secretions of the last and the penultimate instars was essentially of similar quality, suggesting that the three genera,Parnassius, Sericinus, andPachliopta, are assigned to homogeneous types.     

Aristolochic acids fromThottea spp. (Aristolochiaceae) and the osmeterial secretions of Thottea-feeding troidine swallowtail larvae (Papilionidae)

Two aristolochiaceous plants in the genusThottea were shown to contain aristolochic acids. Larvae of two Malaysian troidine swallowtail butterflies,Troides (Troides) amphrysus andPachliopta (Losaria) neptunus, that fed onThottea leaves were found to sequester corresponding aristolochic acid analogs in the osmeterial glands.     

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

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 α-pinene, sabinene, β-myrcene, limonene, β-phellandrene, (Z)-β-ocimene, (E)-β-ocimene, p-mentha-1,4(8)-diene, β-elemene, β-caryophyllene, (E)-β-farnesene, (3Z,6E)-α-farnesene, (Z)-α-bisabolene, germacrene-A, (E)-α-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.     

An Oviposition Stimulant for Spicebush Swallowtail Butterfly, Papilio troilus, from Leaves of Sassafras albidum

Female butterflies of the spicebush swallowtail, Papilio troilus, are specialists, ovipositing on plants in the family Lauraceae. Column chromatography and HPLC were used to isolate an oviposition stimulant from the leaves of one of its hosts, Sassafras albidum. The stimulant was identified as 3-trans-caffeoyl-muco-quinic acid on the basis of FAB-MS and ¹H NMR spectra as compared to a compound previously isolated from another plant. It was not active alone, but it increased the oviposition activity of butterflies when combined with other stimulant(s) at a concentration of 7 ng/mm² leaf surface area. Other caffeoylquinic acid isomers tested did not have this effect. This is the first report of a swallowtail contact oviposition stimulant from a plant in the family Lauraceae.     

Chemical defense secretions of some species of Malaysian rhinotermitidae (Isoptera,Rhinotermitidae)

The defense secretions of the soldiers of the Malaysian rhinotermitid,Parrhinotermes aequalis (Havilandi) andP. pygmaeus (John),Termitogeton planus (Havilandi) andSchedorhinotermes malaccensis (Holmgren) consist mainly of vinyl ketones, whereas that ofProrhinotermes flavus (Bugnion & Popoff) gives (E)-1-nitropentadecene. The chemistry of the defense secretions ofParrhinotermes andTermitogeton is documented and based on their chemical relationships;Termitogeton shows a closer affinity to the Rhinotermitinae than Heterotermitinae.     

Hydroxybenzoic Acid Derivatives in a Nonhost Rutaceous Plant, Orixa japonica, Deter Both Oviposition and Larval Feeding in a Rutaceae-Feeding Swallowtail Butterfly, Papilio xuthus L.

A Rutaceae-feeding swallowtail butterfly. Papilio xuthus L., feeds on various rutaceous plants but always rejects Orixa japonica Thunb. (Rutaceae). Females were strongly deterred from laying eggs by a methanolic extract of O. japonica leaves. Larvae also rejected a diet leaf medium impregnated with O. japonica leaf extracts. Several components in the water-soluble fraction of the leaf extract were found to deter both oviposition and feeding responses. Two major deterrent compounds were characterized as 5-[[2-O-(beta-D-apiofuranosyl)-beta-D-glucopyranosyl]oxy]-2-hydroxybenzoic acid and adisyringoyl aldaric acid. These compounds induced potent deterrence of both oviposition and larval feeding by P. xuthus, which suggests a congruent chemosensory mechanism of allomonal chemicals acting on both female tarsal chemoreceptors and larval maxillary taste receptors.     

Chemical defense secretions of the termite soldiers ofAcorhinotermes andRhinotermes (Isoptera,Rhinotermitinae)

The defense secretions of advanced nasutoid rhinotermitine soldiers from the New World contain enolic -ketoaldehydes as the major components. The secretions of minor soldiers ofRhinotermes hispidus (Emerson) andR. marginalis (Emerson) consist primarily of 3-keto-13-tetradecenal and 3-ketotetradecanal, but possess in addition C₁₃, C₁₄, C₁₅, and C₁₇ saturated and unsaturated ketones. Major soldiers lacked these compounds and in fact had virtually no frontal gland secretion. The defense secretion of the monomorphic soldiers ofAcorhinotermes subfusciceps (Emerson) contains mostly 3-keto-(Z)-9-hexadecenal and (Z)-8-pentadecen-2-one. Biosynthetic origins and interrelationships are postulated for these compounds, and the concomitant evolution of chemical weaponry and the modified labral brush is discussed.Fellow of the Alfred P. Sloan Foundation (1981–1983).     

Spruce Budworm Larval Processing of Piperidine Alkaloids from Spruce Needles

New needle bundles of Picea englemannii (Engelmann spruce) and Picea pungens (blue spruce) contain disubstituted piperidine alkaloids. No alkaloids were found in western spruce budworm larvae (Choristoneura occidentalis), which were feeding on the needles, but needle alkaloids were present in the budworm frass. Excretion of the alkaloids by the budworm larvae, either intact or after a metabolic change, was the common processing pathway. No sequestration could be demonstrated.     

Quantitative and qualitative effects of larval diet on male scent secretions ofEstigmene acrea,Phragmatobia foliginosa,andPyrrharctia isabella (Lepidoptera: Arctiidae)

In feeding experiments with insects reared in the laboratory, the presence of the dihydropyrrolizines hydroxydanaidal and danaidal in the male scent organs (coremata) of the arctiids,Estigmene acrea (Drury),Phragmatobia fuliginosa (L.), andPyrrharctia isabella (J.E. Smith), was shown to depend on the presence of a source of pyrrolizidine alkaloids (PAs) in the larval diet.Phragmatobia males given an artificial diet supplemented with the powdered roots of the PA-containing plantSymphytum officinale L. (comfrey) produced more hydroxydanaidal than danaidal, whereas males given an artificial diet supplemented with dried whole plants of another PA-containing species,Senecio vulgaris L., produced more danaidal than hydroxydanaidal.Pyrrharctia males produced hydroxydanaidal with little if any danaidal, whether the source of PAs was comfrey orS. vulgaris. A behavioral bioassay showed that the coremata of PA-deniedPyrrharctia male progeny of PA-denied parents were pheromonally inactive, whereas those of PA-denied male progeny of PA-supplied parents (male and/or female) were often active. This indicates that a small amount of pheromone is made from PAs transferred from the female to her eggs and that males effect copulatory transfers of PAs that are, in turn, passed to the eggs by the mated female. Field observations ofPhragmatobia andPyrrharctia larvae feeding on sources of PAs were reported. The PA monocrotaline was shown to be a feeding stimulant forPyrrharctia larvae.     

Responses by canids to scent gland secretions of the western diamondback rattlesnake (Crotalus atrox)

Many snakes discharge malodorous fluids from paired scent glands in the base of the tail when they are disturbed. A number of authors suggest that these secretions repel predators. Scent gland secretions of the western diamondback rattlesnake (Crotalus atrox), or dichloromethane extracts of them, were presented to coyotes (Canis latrans) in three field tests, and to domestic dogs (Canis familiaris) in two kennel tests, to determine whether responses of possible benefit to snakes are elicited. Free-ranging coyotes visited and rubbed and rolled at stations containing scent gland secretions in perforated plastic capsules more frequently than at those containing untreated or dichloromethane-treated capsules. Responses to dichloromethane extracts of scent gland secretions subjected to rotary evaporation were not significantly different from those to dichloromethane. Pure and mixed breeds of dogs presented with filter papers treated with dichloromethane or a dichloromethane extract of scent gland secretions mouthed (licked, bit, or ate) secretion-treated papers more frequently. Staffordshire terriers presented with filter papers treated with dichloromethane or dichloromethane extracts of snake scent gland and alligator (Alligator mississippiensis) paracloacal gland secretions exhibited urination postures to snake secretion-treated papers more frequently than to dichloromethane-treated papers, but responses to snake- and alligator-treated papers did not differ significantly. There was no indication that canids are repelled by scent gland secretions.     

Flavanone glycosides as oviposition stimulants in a papilionid butterfly,Papilio protenor

Identification of chemical compounds responsible for the oviposition behavior in a Rutaceae feeder,Papilio protenor demetrius, was undertaken with the epicarp of sour orange (Citrus natsudaidai) which exhibited potent stimulatory activity as did its leaves for egg-laying by the females. The stimulants were present in the hydrosoluble fraction, and the kairomonal activity displayed by the peel was regarded as originating from the synergistic effect of the total chemical complex. One of the active compounds was identified as a flavanone glycoside, naringin (naringenin-7-neohesperidoside), which, although showing no appreciable effectiveness when bioassayed alone, elicited positive response at the concentration of 0.2% either when admixed with other unidentified components or provided the females had been conditioned with them in advance. Another flavanone glycoside, hesperidin (hesperetin-7-rutinoside) that was contained in a trace amount in the peel also had a positive effect comparable to that of naringin under similar conditions, while their corresponding aglycones were less active or inactive. In contrast, a flavone glycoside, rhoifolin, coexisting in the peel, and some other flavones and flavonols tested as possible candidates for oviposition stimulants were all found entirely ineffective.     

Identification of thoracic gland constituents from maleXylocopa spp. latreille (Hymenoptera: Anthophoridae) from arizona

Some male carpenter bees (Xylocopa spp.) possess massive propodeal exocrine glands that produce copious quantities of multicomponent blends of lipoidal material. Some of these compounds are volatile, producing a flowery aroma that can be easily detected several meters downwind from a territorial male. Chemical characterization of these secretions showed them to be blends of terpenoid compounds or fatty acid derivatives. InX. varipuncta, the mixture is composed of alltrans-geranylgeraniol, alltrans-farnesal, and an isomer of 3,7, 11-trimethyl-2,7,10-dodecatrienal in an approximate 961 ratio. The secretion ofX. micheneri contains isopropyl oleate, (Z)-11-eicosen-1-ol, oleyl alcohol, and methyl palmitate at approximately 6324111. We hypothesize that these compounds act as pheromones that aid in attracting and holding conspecific females to symbolic nonresource encounter sites where mating occurs. They also appear to have utility as chemotaxonomic markers at the subgeneric level.Mention of a proprietary product does not constitute an endorsement or a recommendation for its use by USDA.     

Chemistry of metapleural gland secretions of three attine ants,Atta sexdens rubropilosa,Atta cephalotes,andAcromyrmex octospinosus (Hymenoptera: Formicidae)

The chemical composition of the secretions of the metapleural glands of workers and soldiers of twoAtta species,Atta sexdens rubropilosa andA. cephalotes, and workers ofAcromyrmex octospinosus, has been studied. As indicated by infrared spectrometry and confirmed by the ninhydrin test, the secretions contain chiefly proteins. Of the volatile acidic portion, which is present as ionized salts, phenylacetic acid is the major component in workers and soldiers ofA. s. rubropilosa andA. cephalotes. BothAtta species also contain 3-hydroxydecanoic acid and its homolog as minor components together with indoleacetic acid. While there are qualitative similarities in the acidic composition in the secretions ofA. s. rubropilosa andA. cephalotes, they differ quantitatively. The secretion ofAcromyrmex octospinosus contains 3-hydroxydecanoic and indoleacetic acids, but lacks phenylacetic acid. The bactericidal and fungicidal actions of the three major substances have been confirmed.     

Interspecific variation of diterpene composition ofCubitermes soldier defense secretions

Soldiers of the humivorous termite generaCubitermes andCrenetermes (Isoptera: Termitidae: Termitinae) secrete a mixture of unusual diterpene hydrocarbons from the fontanellar opening of the frontal gland. The defense secretions of sixCubitermes species and oneCrenetermes species show species-specific distributions of the five chemically identified major components and 12 unidentified minor components. The secretion is also present with its characteric terpene distribution in white presoldiers and newly molted soldiers, but is completely absent in workers.Fellow of the Alfred P. Sloan Foundation (1981–85) and Camille and Henry Dreyfus Teacher-Scholar (1981–86).     

Dermal gland secretions of tropical bont tick,Amblyomma variegatum (Acarina: Ixodidae): Biological activity on predators and pathogens

When they are mechanically disturbed, all instars of the tropical bont tickAmblyomma variegatum exude droplets of a liquid on the dorsal, lateral, and ventral cuticle. These spread out and quickly evaporate. In this study, the possible role of these secretions was investigated in relation to predators and pathogens. In laboratory bioassays, it was demonstrated that the secretions from engorged larvae, nymphs, and females have an antibiotic activity against the bacteria speciesBacillus thuringiensis andSerratia marcescens, combined with a repellent effect on a potential predator, the fire-antSolenopsis geminata.     

Defensive secretions of three species ofAcilius (Coleoptera: Dytiscidae) and their seasonal variations as determined by high-pressure liquid chromatography

A rapid, sensitive, stable, and quantitative high-pressure liquid chromatographic technique was developed for the analysis of defensive secretions obtained from the pygidial and prothoracic glands of dytiscids. Methods were developed for both normal phase (Porasil) and reverse phase (Bondapak C₁₈) columns. The applicability of this technique was demonstrated when defensive compounds ofAcilius semiculcatus, A. sylvanus andA. mediatus were isolated, identified, and quantitated. No major differences were found in the composition of the defensive secretions between the three species. The seasonal defensive titer ofA. semisulcatus was determined from June through October 1977. The pygidial defensive agents (benzoic acid,p-hydroxybenzaldehyde, and methylp-hydroxybenzoate varied from 9.0 to 67.8 g and exhibited a maximum in July, and a steroid from the prothoracic gland varied from 7.1 to 33.2 g and was maximum in October.     

Responses by domestic cats (Felis catus) to snake scent gland secretions

The scent gland secretions of snakes are thought to repel predators, but few predator species have been tested for responses to these exudates. Domestic cats (Felis catus) were tested for responses to scent gland secretions of the gray rat snake (Elaphe obsoleta), or to choloroform extracts of them, applied to filter paper or food. More cats salivated or rubbed on filter papers treated with scent gland secretions than on control papers. Scent gland exudates elicited rubbing and pawing in cats more frequently than did chemicals from a shed snake skin. Cats offered food pieces treated either with water or with scent gland secretions ate fewer of the latter; this result is consistent with the hypothesis that scent gland secretions deter feeding.     

Comparative metabolism of [3H]psoralen and [3H]isopsoralen by black swallowtail (Papilio polyxenes Fabr.) caterpillars

The comparative fate of tritiated preparations of a linear furanocoumarin (psoralen) and an angular furanocoumarin (isopsoralen) was determined in last-instar caterpillars of the black swallowtail butterfly (Papilio polyxenes Fabr.). Oral administration of either furanocoumarin at 5 g/g is followed by rapid metabolism, primarily through oxidative cleavage of the furan ring, and the metabolites are rapidly excreted. Isopsoralen is, however, metabolized at a somewhat slower rate than is psoralen, and levels of unmetabolized isopsoralen in body tissues of the treated caterpillars are about three-fold higher. These data are compatible with the hypothesis that a reduced detoxification rate accounts at least in part for the susceptibility ofP. polyxenes caterpillars to the deleterious effect of isopsoralens.     

Fate of iridoid glycosides in different life stages of the Buckeye,Junonia coenia (Lepidoptera: Nymphalidae)

The buckeye butterfly,Junonia coenia (Lepidoptera: Nymphalidae), specializes on plants that contain iridoid glycosides. To determine the fate of these compounds in larvae, pupae, and adults of this species, we reared larvae on artificial diets with and without iridoid glycosides, and on leaves of a host plant,Plantago lanceolata (Plantaginaceae). Quantification by gas chromatography showed that newly molted third-, fourth-, and fifth-instar larvae reared on leaves ofP. lanceolata contained means of 5.13, 2.88, and 6.83% dry weight iridoid glycoside. In contrast, the mean iridoid glycoside concentration of actively feeding fifth-instar larvae was 0.28% dry weight, that of pupae was 0.19% dry weight iridoids, and adults contained no detectable iridoids. Feeding experiments suggested that this reduction in actively feeding larvae was due to the metabolism of iridoid glycosides.P. lanceolata leaves in these experiments contained a mean of 1.00% dry weight iridoid glycoside, with a 2:1 ratio of aucubin to catalpol. Calculation of iridoid consumption and utilization indices showed that larvae fed artificial diets consumed, digested, and sequestered aucubin and catalpol in similar ways. When these indices were calculated for larvae fed leaves ofP. lanceolata, catalpol was sequestered twice as efficiently as aucubin.     

Shield Defense of a Larval Tortoise Beetle

Larvae of the folivorous tortoise beetle, Plagiometriona clavata, carry shields formed from feces and exuviae above their bodies. We used an ecologically relevant predatory ant, Formica subsericea, in a bioassay to determine if shields functioned as simple barriers, as previous studies indicated, or whether they were chemical defenses. Shields were necessary for larval survival; shield removal rendered larvae vulnerable. Shields produced by larvae reared on a substitute diet failed to provide protection. Solvent-leached shields also failed to deter ants, indicating the shield had a host-derived chemical component likely located in the feces, not in the exuviae. Solanum dulcamara, the larval host plant, contained free phytol, steroidal glycoalkaloids, and saponins. Shields contained partially deglycosylated metabolites of host steroidal glycoalkaloids and saponins, a suite of fatty acids, and derivatives of phytol, which together formed a deterrent barrier against ant attack. We compared the mobile shield of P. clavata to the stationary shield of another S. dulcamara-feeding leaf beetle, Lema trilinea. Both larval shield defenses were formed from a very similar array of host-derived compounds with deterrent properties. We concluded that convergent patterns of limited chemical transformation and selective incorporation of particular deterrent metabolites in shield defenses of two unrelated taxa represented responses to selection from invertebrate predators.