Defensive secretion ofTenebrio molitor (Coleoptera: Tenebrionidae)

The defensive secretion ofTenebrio molitor contains a mixture of 2-methyl-1,4-benzoquinone andm-cresol. The phenol had not previously been detected in the secretion, although some investigators reported presence of 2-ethyl-1,4-benzoquinone as a second component. We failed to detect the latter quinone in secretion samples from three laboratory populations ofT. molitor.Paper No. 100 of the seriesDefense Mechanisms of Arthropods; No. 99 is Storey et al.,J. Chem. Ecol., 17, 687–693 (1991).     

Genetic Analysis of Benzoquinone Production in Tribolium confusum

Many species of tenebrionid beetles produce and secrete benzoquinones from specialized prothoracic and postabdominal glands. Tribolium confusum produces two compounds methyl-1,4-benzoquinone (MBQ) and ethyl-1,4-benzoquinone (EBQ). These compounds are hypothesized to function as external defense compounds, killing microbes and deterring predators, and their ability to evolve by natural selection depends on both selection and the genetic vs. environmental contribution to phenotypic variation. We crossed a strain of T. confusum that produces high quantities of benzoquinones, b-Pakistan, with a low-producing strain, b-+, and measured both the internal and external quantities of MBQ and EBQ for the two extreme strains and their F1 progeny. Internal amounts show a clear pattern of inheritance, with at least 50% of the phenotypic variation attributed to genotype. Additive and dominance coefficients for internal amounts indicate that the trait is additive with no significant dominance. In contrast, external quantities show little pattern of inheritance. The role of genetics and environment in determining quantities of secretory defensive compounds is important to elucidating the ecology and evolutionary potential of chemical defenses.     

Defensive Secretion Components of the Host Parastizopus armaticeps as Kairomones for the Cleptoparasite Eremostibes opacus

The subsocial tenebrionid Parastizopus armaticeps Pér. is parasitized by the closely related Eremostibes opacus Koch (Coleoptera: Tenebrionidae). We found that the pygidial defensive secretions of both species are similar and contain a mixture of 1,4-benzoquinones, 1-alkenes, and monoterpene hydrocarbons. The 1-alkenes are dominated by 1-undecene, with admixtures of 1-tridecene in both species and 1-pentadecene in P. armaticeps only. Methyl- and ethyl-1,4-benzoquinone are the major quinones of the secretions of both species. The monoterpene fractions consist of (−)-α-pinene, (−)-camphene, sabinene, (−)-β-pinene, and (−)-limonene. Volatiles trapped with Porapak Q at the entrance to the breeding burrows of P. armaticeps were identified as components of the defensive secretion. However, in contrast to the secretion, the 1,4-benzoquinones were almost completely absent in the volatiles. Bioassays investigating attraction showed that the cleptoparasite E. opacus was drawn to the monoterpene hydrocarbons, produced by P. armaticeps, and deterred by the 1,4-benzoquinones. The 1-alkenes had no effect. Among the monoterpenes, only (−)-camphene was attractive to E. opacus. This is one of the rare cases of chemical exploitation of defensive allomones, and the first based on odor homology. We have drawn an evolutionary scenario including various functional changes in the defensive secretion compounds, leading to the kairomonal exploitation.     

Chemical Defense in Harvestmen (Arachnida,Opiliones): Do Benzoquinone Secretions Deter Invertebrate and Vertebrate Predators?

Two alkylated 1,4-benzoquinones were identified from the defensive secretion produced by the neotropical harvestman Goniosoma longipes (Gonyleptidae). They were characterized as 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. We tested the effectiveness of these benzoquinone secretions against several predator types, including invertebrates and vertebrates. Different predators were exposed to the harvestmen's gland secretion or to distilled water in laboratory bioassays. Our results indicate that secretions containing the 1,4-benzoquinones released by G. longipes can be an effective defense against predation, and that the effectiveness of the secretion is dependent on the predator type. The scent gland secretion repelled seven ant species, two species of large wandering spiders, and one frog species, but was not an effective defense against an opossum. Our study also demonstrates that the scent gland secretion of G. longipes can work as a chemical shield preventing the approach of three large predatory ants for at least 10 min. The chemical shield may protect the harvestman against successive attacks of the same ant worker and also allow the harvestman to flee before massive ant recruitment. Our data support the suggestion that chemical defenses may increase survival with some but not all potential predators. This variation in defense effectiveness may result from many interacting factors, including the attack strategy, size, learning ability, and physiology of the predators, as well as the chemical nature of the defensive compounds, type of emission, and amount of effluent released by the prey.     

Production and Predator-Induced Release of Volatile Chemicals by the Plant Bug Lygus hesperus

Both sexes of adult western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), released three volatile chemicals in relatively large amounts when attacked by ants (Pogonomyrmex rugosus and Solenopsis xyloni) or when grabbed by forceps, as determined by solid-phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). The relative amounts of the volatile compounds, hexyl butyrate, (E)-4-oxo-2-hexenal, and (E)-2-hexenyl butyrate, absorbed by SPME as a percentage of the largest were 100%, 44%, and 4%, respectively, from females, and 83%, 37%, and 3% from males. Both ant species were repelled by the defensive discharges (confirmed by SPME) when the ants attacked L. hesperus adults. Sexually mature L. hesperus were individually extracted in pentane to quantify the mean amounts of hexyl butyrate (14.9 μg/female; 10.3 μg/male), (E)-4-oxo-2-hexenal (2.7 μg/female; 3.1 μg/male), and (E)-2-hexenyl butyrate (1.2 μg/female; 0.6 μg/male). (E)-4-Oxo-2-hexenal was unstable in solvent when in contact with a macerated adult, but relatively stable when the solution was decanted within minutes. The production of the three major volatile components began soon after the emergence of the adult and amounts increased for about 5–10 d with little or no increase thereafter. Minor additional constituents were cross-correlated in many cases with the three major ones. A cost of defensive secretion is suggested for females but not for males, because heavier females produced more volatile compounds than lighter females. The initial discharge percentage, defined as the proportion of volatile compounds initially present that is discharged to defend against predation was estimated at about 50% in males and 70% in females. Newly eclosed adults did not produce volatile chemicals until 2 d after molting.     

Inter- and Intraspecific Variation in Floral Scent in the Genus <Emphasis Type="Italic">Salix</Emphasis> and its Implication for Pollination

The floral scent composition of 32 European and two Asian Salix L. species (Salicaceae) was analyzed. Intra- and interspecific variation was compared for a subset of 8 species. All Salix species are dioecious and floral scent was collected from both male and female individuals by using a dynamic headspace MicroSPE method, and analyzed by GC-MS. A total of 48 compounds were detected, most of them being isoprenoids and benzenoids. Commonly occurring compounds included trans-β-ocimene, cis-β-ocimene, benzaldehyde, d-limonene, α-pinene, cis-3-hexenyl aceatate, linalool, 1,4-dimethoxybenzene, and β-pinene. Two compounds, 1,4-dimethoxybenzene and trans-β-ocimene, were responsible for most of the interspecific variation. In a subset of eight extensively sampled species, six had a characteristic floral scent composition; half of the pairwise species comparisons confirmed significant differences. In three of these eight species, intraspecific variability could be explained by sex differences. Variation in Salix floral scent may provide specific signals that guide pollinators and thus contribute to the reproductive isolation of compatible and cooccurring species.     

Amphibian Chemical Defense: Antifungal Metabolites of the Microsymbiont <Emphasis Type="Italic">Janthinobacterium lividum</Emphasis> on the Salamander <Emphasis Type="Italic">Plethodon cinereus</Emphasis>

Disease has spurred declines in global amphibian populations. In particular, the fungal pathogen Batrachochytrium dendrobatidis has decimated amphibian diversity in some areas unaffected by habitat loss. However, there is little evidence to explain how some amphibian species persist despite infection or even clear the pathogen beyond detection. One hypothesis is that certain bacterial symbionts on the skin of amphibians inhibit the growth of the pathogen. An antifungal strain of Janthinobacterium lividum, isolated from the skin of the red-backed salamander Plethodon cinereus, produces antifungal metabolites at concentrations lethal to B. dendrobatidis. Antifungal metabolites were identified by using reversed phase high performance liquid chromatography, high resolution mass spectrometry, nuclear magnetic resonance, and UV-Vis spectroscopy and tested for efficacy of inhibiting the pathogen. Two metabolites, indole-3-carboxaldehyde and violacein, inhibited the pathogen’s growth at relatively low concentrations (68.9 and 1.82 μM, respectively). Analysis of fresh salamander skin confirmed the presence of J. lividum and its metabolites on the skin of host salamanders in concentrations high enough to hinder or kill the pathogen (51 and 207 μM, respectively). These results support the hypothesis that cutaneous, mutualistic bacteria play a role in amphibian resistance to fungal disease. Exploitation of this biological process may provide long-term resistance to B. dendrobatidis for vulnerable amphibians and serve as a model for managing future emerging diseases in wildlife populations. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Influence of oleoresin constituents fromPinus ponderosa andPinus jeffreyi on growth of mycangial fungi fromDendroctonus ponderosae andDendroctonus jeffreyi

Dendroctonus jeffreyi andD. ponderosae are morphologically similar sympatric species of pine bark beetles over portions of their geographic ranges; however,D. jeffreyi is monophagous onP. jeffreyi whileD. ponderosae is highly polyphagous. Both species carry a species of mycangial fungi that are also very similar in appearance. Growth of the two mycangial fungi and of the fungusLeptographium terebrantis (associated with the polyphagous and non-tree-killingDendroctonus valens) in the presence of oleoresin constituents of host and nonhost conifers was tested by placing individual chemicals on agar growth medium and by growing the cultures in saturated atmospheres of the chemicals. The fungus associated withD. jeffreyi showed greater tolerance for chemical constituents placed on the growth medium than the other two fungi, and growth after three days was enhanced by heptane, the dominant constituent ofP. jeffreyi oleoresin. Growth of all three species of fungi was reduced by the resin constituents when the chemicals were presented as saturated atmospheres. The results suggest that the influence of the tree on growth of the symbiotic fungi of the bark beetles during the initial attack process may be different than after colonization by the beetles is complete. The difference in the responses of the apparently related species of mycangial fungi may provide some new insight into the evolutionary history of these beetle/mycangial fungus/host tree systems.     

Byrsonic Acid—the Clue to Floral Mimicry Involving Oil-Producing Flowers and Oil-Collecting Bees

Tetrapedia diversipes and other Apidae (Anthophoridae) may be deceived by floral similarities between Malpighiaceae and Orchidaceae of the Oncidiinae subtribe. The latter do not usually exudate floral oils. Thus, visitors may pollinate the flowers in a deceit/food/pollination syndrome. We studied the chemical compositions of Byrsonima intermedia (Malpighiaceae) floral oil and T. diversipes (Anthophoridae) cell provisions. From B. intermedia floral oil, we isolated a novel fatty acid (3R, 7R)-3,7-diacetoxy-docosanoic acid, here named byrsonic acid, and from T. diversipes cell provisions we isolated two novel fatty acid derivatives 3,7-dihydroxy-eicosanoic acid and 3,7-dihydroxy-docosanoic acid, here named tetrapedic acids A and B, respectively. The three fatty acid derivatives have common features: possess long chains (20 or 22 carbon atoms) with no double bond and either hydroxy or acetoxy groups at carbons 3 and 7. This characteristic was also encountered in the fatty acid moiety of oncidinol (2S, 3′R, 7′R)-1-acetyl-2-[3′, 7′-diacetoxyeicosanyl)-glycerol, a major floral oil constituent of several Oncidiinae species (Orchidaceae). Thus, both tetrapedic A (C20) and B (C22) could be the biotransformation products of oncidinol and byrsonic acid by T. diversipes hydrolases. These are the chemical clues for bee visitation and oil collecting from both plant species. The results indicate that the deceit/pollination syndrome should not be applied to all Oncidiinae flowers.     

Dihydropyrrolizine attractants for arctiid moths that visit plants containing pyrrolizidine alkaloids

Adults of three species of arctiid moths (Cisseps fulvicollis, Ctenucha virginia, andHalysidota tessellaris) are attracted to plants that contain pyrrolizidine alkaloids (PAs). The moths use olfactory cues to locate these plants, then feed on leaves, flowers, and roots with the proboscis. To investigate the chemical basis of attraction, sticky traps were baited with roots of a PA-containing plant,Eupatorium maculatum, alkaloids ofE. maculatum, and several derivatives of these alkaloids. Volatile derivatives of the bicyclic pyrrolizidine skeleton attracted all three arctiid species. The dihydropyrrolizines, (S)-(+)-hydroxydanaidal and (R)-(–)-hydroxydanaidal, proved to be the most attractive compounds tested, accounting for over 70% of the moths captured. Different alkaloid derivatives attracted different proportions of male and femaleCisseps. Both (S)-(+)-hydroxydanaidal (52% male) and (R)-(–)-hydroxydanaidal (71% male) attracted a significantly lower percentage ofCisseps males thanE. maculatum roots (87% male).Cisseps males possess eversible scent organs (coremata) that are displayed during courtship. Analysis of corematal extracts revealed the presence of hydroxydanaidal.Cisseps moths thus resemble danaine and ithomiine butterflies, both in their attraction to PA sources and in the presence of PA derivatives in the male scent organs.     

Reaction of Mutualistic and Granivorous Ants to Ulex Elaiosome Chemicals

It has been proposed that chemicals on plant elaiosomes aid seed detection by seed-dispersing ants. We hypothesized that the chemical interaction between ants and elaiosomes is more intimate than a generic attraction, and that elaiosome chemicals will attract mutualistic but not granivorous ant species. We investigated this by using two gorse species, Ulex minor and U. europaeus, and two associated ant species from European heathlands, the mutualist Myrmica ruginodis and the granivore Tetramorium caespitum. Behavioral studies were conducted with laboratory nests and foraging arenas. Both ants will take Ulex seeds, but while M. ruginodis showed increased antennation toward ether extracts of elaiosome surface chemicals compared with controls, T. caespitum showed no response. Elaiosome extracts were separated into seven lipid fractions. M. ruginodis showed increased antennation only toward the diglyceride fractions of both Ulex species, whereas T. caespitum showed no consistent reaction. This indicates that M. ruginodis can detect the elaiosome by responding to its surface chemicals, but T. caespitum is unresponsive to these chemicals. Responses to surface chemicals could increase the rate of seed detection in the field, and so these results suggest that Ulex elaiosomes produce chemicals that facilitate attraction of mutualistic rather than granivorous ant species. This could reduce seed predation and increase Ulex fitness.     

Defensive and pheromonal secretion of the tergal gland of Aleochara curtula

The defensive secretion from the tergal gland of the staphylinid beetle,Aleochara curtula, acting as a supplementary mating stimulant, was investigated by gas-liquid chromatography, mass spectrometry, and IR spectroscopy. The reservoir contains a complex mixture of hydrocarbons, aliphatic aldehydes, and substituted 1,4-benzoquinones.n-Undecane, 1-undecene, and (Z)-4-tridecene were identified as the major hydrocarbon components. The main aldehydes aren-dodecanal and (Z)-5-tetradecenal, and the chief quinones are toluquinone and 2-methoxy-3-methyl-1,4-benzoquinone, the latter being established structurally by comparison of the mass spectra of the three synthesized isomers. Quantitative GLC analyses revealed no sex specificity of the relative concentrations of the compounds.Coleoptera: Staphylinidae (Aleocharinae)     

The Identification of 2,4-diacetylphloroglucinol as an Antifungal Metabolite Produced by Cutaneous Bacteria of the Salamander <Emphasis Type="Italic">Plethodon cinereus</Emphasis>

Beneficial bacteria that live on salamander skins have the ability to inhibit pathogenic fungi. Our study aimed to identify the specific chemical agent(s) of this process and asked if any of the antifungal compounds known to operate in analogous plant–bacteria–fungi systems were present. Crude extracts of bacteria isolated from salamander skin were exposed to HPLC, UV-Vis, GC-MS, and HR-MS analyses. These investigations show that 2,4-diacetylphloroglucinol is produced by the bacteria isolate Lysobacter gummosus (AB161361), which was found on the red-backed salamander, Plethodon cinereus. Furthermore, exposure of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (isolate JEL 215), to different concentrations of 2,4-diacetylphloroglucinol resulted in an IC₅₀ value of 8.73 μM, comparable to crude extract concentrations. This study is the first to show that an epibiotic bacterium on an amphibian species produces a chemical that inhibits pathogenic fungi.     

Ontogeny and Environment as Determinants of the Secondary Chemistry of Three Species of White Birch

This study investigates variation in the secondary chemistry of the bark of three closely related, winter-dormant species of white birch (Betula resinifera, B. pendula, and B. platyphylla) at different ontogenetic stages by using different plant parts (top and base). The experimental birches were grown for 4 years in two growing conditions (pot and field) at different nutrient levels. There was considerable species-specific quantitative and qualitative variation in the secondary chemicals in bark, but this was also affected by fertilization and the age of the plant. In general, there was greater chemical diversity in saplings than in seedlings. The study revealed three new components, secoisolariciresinol 9-O-β-glucopyranoside and two of its derivatives, that have not been reported previously for the bark of white birches. Principal component analysis showed that the species studied had a similar chemical composition at the juvenile stage, but as the plants grew, they became more clearly differentiated, which indicates that the species of older plants can be identified by chemotaxonomy. Evidently, the secondary chemistry of birches is under genetic control, but it is affected by properties of growing conditions and ontogeny. Electronic Supplementary Material Supplementary material to this paper is available in electronic form at     

Reinvestigation of the polymethylene-interrupted 18:2 and 20:2 acids of Ginkgo biloba seed lipids

The fatty acid composition of Ginkgo biloba seed lipids was reinvestigated with particular emphasis on the polymethylene-interrupted octadecadienoic and eicosadienoic acids. Analysis of the picolinyl esters and 4,4-dimethyloxazoline derivatives by capillary gas-liquid chromatography on a highly polar cyanopropyl polysiloxane stationary phase coupled with mass spectrometry revealed the presence of three such acids, with the structures 5,9–18:2, 5,11–18:2, and 5,11–20:2. This indicated that in G. biloba seeds, cis-vaccenic (11–18:1) acid may be a substrate for the Δ5-desaturase characteristic of gymnosperms. The 5,11-18:2 acid was not limited to G. biloba, as it may occur in a few other species. The 5,11-20:2 acid is a common component of the seed lipids from almost all gymnosperm species analyzed so far.     

Coadaptation ofDrosophila and yeasts in their natural habitat

The mutualistic interactions of cactophilicDrosophila and their associated yeasts in the Sonoran Desert are studied as a system which has evolved within the framework of their host cactus stem chemistry. Because theDrosophila-yeast system is saphrophytic, their responses are not thought to directly influence the evolution of the host. Host cactus stem chemistry appears to play an important role in determining where cactophilicDrosophila breed and feed. Several chemicals have been identified as being important. These include sterols and alkaloids of senita as well as fatty acids and sterol diols of agria and organpipe cactus. Cactus chemistry appears to have a limited role in directly determining the distribution of cactus-specific yeasts. Those effects which are known are due to unusual lipids of organpipe cactus and triterpene glycosides of agria and organpipe cactus.Drosophilayeast interactions are viewed as mutualistic and can take the form of (1) benefits to theDrosophila by either direct nutritional gains or by detoxification of harmful chemicals produced during decay of the host stem tissue and (2) benefits to the yeast in the form of increased likelihood of transmission to new habitats. Experiments on yeast-yeast interactions in decaying agria cactus provide evidence that the yeast community is coadapted. This coadaptation among yeasts occurs in two manners: (1) mutualistic increases in growth rates (which are independent of the presence ofDrosophila larvae) and (2) stabilizing competitive interactions when growth reaches carrying capacity. This latter form is dependent on larval activity and results in benefits to the larvae present. In this sense, the coadapted yeast community is probably also coadapted with respect to itsDrosophila vector.     

Pentacyclic Triterpenes with Selective Bioactivity from <Emphasis Type="Italic">Sebastiania adenophora</Emphasis> Leaves,Euphorbiaceae

Six known pentacyclic triterpenes possessing oleanane, lupane, or taraxerane-type skeletons were isolated from the leaves of Sebastiania adenophora (Euphorbiaceae) and are reported for the first time in this species. These compounds include 3-epi-β-amyrin, β-amyrinone, 3-epi-lupeol, lupenone, taraxerol, and taraxerone. Structures were elucidated by comparison with literature data. The bioactivities of these compounds were tested on the root growth of Amaranthus hypochondriacus, amaranth (Amaranthaceae), Lycopersicon esculentum, tomato (Solanaceae), and Echinochloa crus-galli, barnyard grass (Poaceae). All six triterpenes were selectively bioactive. An important stimulatory effect was observed on amaranth root growth (23% to 56%) for almost all tested triterpenes (250 μg/ml). These triterpenes significantly inhibited the root growth of barnyard grass (28% to 78%) and tomato (23% to 49%). Aqueous leachate and organic extracts of S. adenophora leaves significantly inhibited the root growth of all test species. The possible ecological role of the allelochemicals isolated is discussed.     

Cyclohexene dehydrogenation and hydrogenation on Pt(111) monitored by SFG surface vibrational spectroscopy: different reaction mechanisms at high pressures and in vacuum

The hydrogenation and dehydrogenation reactions of cyclohexene on Pt(111) crystal surfaces were investigated by surface vibrational spectroscopy via sum frequency generation (SFG) both under vacuum and high pressure conditions with 10 Torr cyclohexene and various hydrogen pressures from 30 up to ~600 Torr. At high pressures, the gas composition and turnover rate (TOR) were measured by gas chromatography. In vacuum, cyclohexene on Pt(111) undergoes a change from π/σ‐bonded, σ‐bonded cyclohexene and c‐C₆H₉ surface species to adsorbed benzene when the surface was heated from 130 to 330 K. A site‐blocking effect was observed at saturation coverage of cyclohexene that caused dehydrogenation to shift to somewhat higher surface temperature. At high pressures, however, none of the species observed in vacuum conditions were detectable. 1,4‐cyclohexadiene (1,4‐CHD) was found to be the major species on the surface at 295 K, even with the presence of nearly 600 Torr of hydrogen. Hydrogenation was the only detectable reaction at the temperature range between 300 and 400 K with 1,3‐cyclohexadiene (1,3‐CHD) on the surface, as revealed by SFG. Further increasing the surface temperature results in a decrease in hydrogenation reaction rate and an increase in dehydrogenation reaction rate and both 1,3‐CHD and 1,4‐CHD were present on the surface simultaneously. The simultaneous observation of the reaction kinetic data and the chemical nature of surface species allows us to postulate a reaction mechanism at high pressures: cyclohexene hydrogenates to cyclohexane via a 1,3‐CHD intermediate and dehydrogenates to benzene through both 1,4‐CHD and 1,3‐CHD intermediates. Isomerisation of the 1,4‐CHD and 1,3‐CHD surface species is negligible. This revised version was published online in July 2006 with corrections to the Cover Date.     

Sequestration of Furostanol Saponins by <Emphasis Type="Italic">Monophadnus</Emphasis> Sawfly Larvae

Sawfly larvae of the tribe Phymatocerini (Hymenoptera: Tenthredinidae), which are specialized on toxic plants in the orders Liliales and Ranunculales, exude a droplet of deterrent hemolymph upon attack by a predator. We investigated whether secondary plant metabolites from Ranunculaceae leaves are sequestered by phymatocerine Monophadnus species, i.e., Monophadnus alpicola feeding upon Pulsatilla alpina and Monophadnus monticola feeding upon Ranunculus lanuginosus. Moreover, two undescribed Monophadnus species were studied: species A collected from Helleborus foetidus and species B collected from Helleborus viridis. Comparative high-performance liquid chromatographic–photodiode array detection–electrospray ionization–mass spectrometric analyses of plant leaf and insect hemolymph extracts revealed the presence of furostanol saponins in all samples. Larvae of species A and B actively sequestered (25R)-26-[(α-l-rhamnopyranosyl)oxy]-22α-methoxyfurost-5-en-3β-yl O-β-d-glucopyranosyl-(1→3)-O-[6-acetyl-β-d-glucopyranosyl-(1→3)]-O-β-d-glucopyranoside (compound 1). This compound occurred at a 65- to 200-fold higher concentration in the hemolymph of the two species (1.6 and 17.5 μmol/g FW, respectively) than in their host plant (0.008 and 0.268 μmol/g FW, respectively). In M. monticola, compound 1 was found at a concentration (1.2 μmol/g FW) similar to that in the host plant (1.36 μmol/g FW). The compound could not be detected consistently in M. alpicola larvae where, however, a related saponin may be present. Additional furostanol saponins were found in H. foetidus and H. viridis, but not in the two Monophadnus species feeding on them, indicating that sequestration of compound 1 is a highly specific process. In laboratory bioassays, crude hemolymph of three Monophadnus species showed a significant feeding deterrent activity against a potential predator, Myrmica rubra ant workers. Isolated furostanol saponins were also active against the ants, at a concentration range similar to that found in the hemolymph. Thus, these compounds seem to play a major role for chemical defense of Monophadnus larvae, although other plant secondary metabolites (glycosylated ecdysteroids) were also detected in their hemolymph. Physiological and ecological implications of the sequestered furostanol saponins are discussed. Dedicated to the memory of Professor Ivano Morelli (1940–2005)     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.