RESUMEN
Flowering plants often use chemical signals to attract their pollinators, and compounds that elicit attraction are known for several groups of pollinators. For other pollinators such as gall midges, however, compounds responsible for their attraction to flowers are largely unknown. Here, we describe the pollination biology of Anthurium acutangulum, a Neotropical aroid species found to be attractive to gall midges. We collected and analyzed its floral scent by dynamic headspace collections and gas chromatography coupled to mass spectrometry, and identified compounds responsible for pollinator attraction. The inflorescences were almost exclusively visited by gall midges (females; Cecidomyiidae: Cecidomyiinae) and released a strong scent reminiscent of freshly cut cucumber, mainly (5S,7S)-trans-conophthorin, (E2,Z6)-2,6-nonadienal, and cis-conophthorin. Behavioral assays with the two most abundant compounds identified (E2,Z6)-2,6-nonadienal as being highly attractive to the female gall midge pollinators, whereas (5S,7S)-trans-conophthorin was not attractive. Overall, we introduce a new specialized gall midge pollination system and identify the chemical mediating communication between the pollinators and their host plants.
Asunto(s)
Araceae , Dípteros , Animales , Araceae/química , Femenino , Flores/química , Cromatografía de Gases y Espectrometría de Masas , PolinizaciónRESUMEN
With approximately 83,000 species described, Curculionidae is the largest family of beetles, comprising more than 80% of all weevil species worldwide. Many species of Curculionidae attack a wide range of native and orchards crops, as well as globally important stored products such as grains, flour, and seeds, being responsible for significant environmental and economic losses. This work provides an overview of the research in the identification of aggregation pheromones of Curculionidae, and their potential contributions to the development of semiochemical-based pest management strategies. The synergistic effect of the host plant volatiles in the attractiveness of weevil pheromones is also briefly reported, demonstrating the important role of these additional attractants in the chemical communication of curculionids.
Asunto(s)
Control de Insectos , Control Biológico de Vectores , Feromonas/farmacología , Gorgojos , AnimalesRESUMEN
The obligate pollination mutualism between Yucca and yucca moths is a classical example of coevolution. Oviposition and active pollination by female yucca moths occur at night when Yucca flowers are open and strongly scented. Thus, floral volatiles have been suggested as key sensory signals attracting yucca moths to their host plants, but no bioactive compounds have yet been identified. In this study, we showed that both sexes of the pollinator moth Tegeticula yuccasella are attracted to the floral scent of the host Yucca filamentosa. Chemical analysis of the floral headspace from six Yucca species in sections Chaenocarpa and Sarcocarpa revealed a set of novel tetranorsesquiterpenoids putatively derived from (E)-4,8-dimethyl-1,3,7-nonatriene. Their structure elucidation was accomplished by NMR analysis of the crude floral scent sample of Yucca treculeana along with GC/MS analysis and confirmed by total synthesis. Since all these volatiles are included in the floral scent of Y. filamentosa, which has been an important model species for understanding the pollination mutualism, we name these compounds filamentolide, filamentol, filamental, and filamentone. Several of these compounds elicited antennal responses in pollinating (Tegeticula) and non-pollinating (Prodoxus) moth species upon stimulation in electrophysiological recordings. In addition, synthetic (Z)-filamentolide attracted significant numbers of both sexes of two associated Prodoxus species in a field trapping experiment. Highly specialized insect-plant interactions, such as obligate pollination mutualisms, are predicted to be maintained through "private channels" dictated by specific compounds. The identification of novel bioactive tetranorsesquiterpenoids is a first step in testing such a hypothesis in the Yucca-yucca moth interaction.
Asunto(s)
Flores/metabolismo , Mariposas Nocturnas/fisiología , Feromonas/metabolismo , Sesquiterpenos/metabolismo , Yucca/metabolismo , Animales , FemeninoRESUMEN
Deception of floral visitors in pollination systems is widely distributed among flowering plants. In deceptive systems, the flower (or part of it) or inflorescence mimics either a specific or an unspecific model to attract pollinators. A previous study showed that Telipogon peruvianus flowers developed sexual deception for pollination. However, it was unknown which stimuli were playing a role in pollination. Therefore, we aim to throw some light onto these questions using colour and chemical analysis and biotests. Interestingly, using spectral reflectance, we show here that the flowers present high contrast similar to that produced by a female tachinid fly sitting on a daisy inflorescence, which is used as food resource. We also tested the role of chemical signals in pollinator attraction by collecting floral and female extracts for chemical and electrophysiological analyses, and carried out behavioural tests. For biotests, various treatments, including synthetic mixtures of the electrophysiologically active compounds found in common in females and flowers, have demonstrated that T. peruvianus flowers mimic the sexual pheromone of their pollinator's females. Thus, we give evidence that T. peruvianus flowers mimic a model composed of two organisms. Our study contributes to the understanding of the evolution of deceptive pollination.
Asunto(s)
Orchidaceae/fisiología , Polinización/fisiología , Clima Tropical , Animales , Conducta Animal , Color , Fenómenos Electrofisiológicos , Femenino , Flores/anatomía & histología , Insectos/fisiología , Masculino , Imitación Molecular , Pigmentación , Olfato/fisiologíaRESUMEN
Animal classification is primarily based on morphological characters, even though these may not be the first to diverge during speciation. In many cases, closely related taxa are actually difficult to distinguish based on morphological characters alone, especially when there is no substantial niche separation. As a consequence, the diversity of certain groups is likely to be underestimated. Lepidoptera -moths and butterflies- represent the largest group of herbivorous insects. The extensive diversification in the group is generally assumed to have its origin in the spectacular radiation of flowering plants and the resulting abundance of ecological niches. However, speciation can also occur without strong ecological divergence. For example, reproductive isolation can evolve as the result of divergence in mate preference and the associated pheromone communication system. We combined pheromone trapping and genetic analysis to elucidate the evolutionary relationships within a complex of primitive moth species (Lepidoptera: Eriocraniidae). Mitochondrial and nuclear DNA markers provided evidence that Eriocrania semipurpurella, as currently defined by morphological characters, includes three cryptic species in Northern and Western Europe. Male moths of these cryptic species, as well as of the closely related E. sangii, exhibited relative specificity in terms of their attraction to specific ratios of two major pheromone components, (2S,6Z)-nonen-2-ol and (2R,6Z)-nonen-2-ol. Our data suggest strong assortative mating in these species in the absence of apparent niche separation, indicating that Eriocrania moths may represent an example of non-ecological speciation. Finally, our study argues in favour of combining pheromone investigations and DNA barcoding as powerful tools for identifying and delimitating species boundaries.
Asunto(s)
Mariposas Nocturnas/genética , Atractivos Sexuales/química , Animales , ADN/aislamiento & purificación , ADN/metabolismo , Complejo IV de Transporte de Electrones/clasificación , Complejo IV de Transporte de Electrones/genética , Femenino , Variación Genética , Gliceraldehído 3-Fosfato Deshidrogenasa (NADP+)/clasificación , Gliceraldehído 3-Fosfato Deshidrogenasa (NADP+)/genética , Masculino , Mitocondrias/genética , Filogenia , Atractivos Sexuales/metabolismoRESUMEN
The hydrocarbon pattern in the floral scent of Yucca species was found to comprise a group of unbranched, mid-chain alkanes, alkenes, and an alkadiene. In Y. reverchonii, highly dominant (Z)-8-heptadecene is accompanied by (6Z,9Z)-6,9-heptadecadiene and heptadecane as minor components and by traces of other saturated and unsaturated hydrocarbons with similar chain length. Some of these volatiles proved to be perceived by the antennae of Tegeticula cassandra (pollinating seed-eater of Yucca) and Prodoxus decipiens (herbivore on Yucca). The possible biosynthesis of the compounds is discussed.
Asunto(s)
Alcadienos/metabolismo , Alcanos/metabolismo , Alquenos/metabolismo , Flores/metabolismo , Yucca/metabolismo , Alcadienos/análisis , Alcanos/análisis , Alquenos/análisis , Flores/química , Yucca/químicaRESUMEN
The pollen diet provided by adult bees to their offspring varies immensely. While some species collect pollen on several plants irrespective of their phylogenetic relatedness (polyleges), others collect only on plants within a genus or family (oligoleges). Floral scents play a central role in bee-plant interactions. To locate flowers, polyleges are assumed to rely on compounds commonly found as floral scent constituents, whereas oligoleges rely on unusual compounds to recognize host flowers unambiguously. Campanula flowers are visited by both polylectic and oligolectic species, and their scent bouquets consist of common and unusual (e.g., spiroacetals) volatiles. In a comparative approach, we performed electroantennographic analyses to investigate the antennal responses of three polyleges and three oligoleges to three common volatiles and four spiroacetals. We hypothesized that: 1) oligoleges and polyleges should respond similarly to common flower volatiles, and 2) Campanula oligoleges should be more sensitive to spiroacetals than are polyleges. In corroboration, we found that antennal sensitivity to common volatiles was similar among bees irrespective of pollen diet, whereas oligoleges of Campanula were more sensitive to spiroacetals than polyleges. Newly emerged bees of the Campanula oligolege Chelostoma rapunculi rely on spiroacetals for recognizing host-flowers, and our results suggest that this might also be true for other Campanula oligoleges, since Chelostoma campanularum and Hoplitis mitis also were able to perceive these specific volatiles at very low concentrations. Together, our results provide interesting insights into the significance of olfactory adaptations in oligolectic and polylectic bee species.
Asunto(s)
Abejas/fisiología , Campanulaceae , Flores/química , Odorantes/análisis , Polinización , Acetales/análisis , Animales , Antenas de Artrópodos/fisiología , Fenómenos Electrofisiológicos , Femenino , Especificidad de la Especie , Compuestos de Espiro/análisisRESUMEN
We present evidence that cerambycid species that are supposed mimics of vespid wasps also mimic their model's odor by producing spiroacetals, common constituents of vespid alarm pheromones. Adults of the North American cerambycids Megacyllene caryae (Gahan) and Megacyllene robiniae (Forster) are conspicuously patterned yellow and black, and are believed to be mimics of aculeate Hymenoptera, such as species of Vespula and Polistes. Adult males of M. caryae produce an aggregation-sex pheromone, but both sexes produce a pungent odor when handled, which has been assumed to be a defensive response. Headspace aerations of agitated females of M. caryae contained 16 compounds with mass spectra characteristic of spiroacetals of eight distinct chemical structures, with the dominant compound being (7E,2E)-7-ethyl-2-methyl-1,6-dioxaspiro[4.5]decane. Headspace samples of agitated males of M. caryae contained five of the same components, with the same dominant compound. Females of M. robiniae produced six different spiroacetals, one of which was not produced by M. caryae, (2E,7E)-2-ethyl-7-methyl-1,6-dioxaspiro[4.5]decane, and five that were shared with M. caryae, including the dominant (2E,8E)-2,8-dimethyl-1,7-dioxaspiro[5.5]undecane. The latter compound is the sole spiroacetal produced by both males and females of a South American cerambycid species, Callisphyris apicicornis (Fairmaire & Germain), which is also thought to be a wasp mimic. Preliminary work also identified spiroacetals of similar or identical structure released by vespid wasps that co-occur with the Megacyllene species.
Asunto(s)
Mimetismo Biológico , Escarabajos/metabolismo , Odorantes/análisis , Avispas/metabolismo , Acetales/análisis , Acetales/metabolismo , Animales , Femenino , Masculino , Feromonas/análisis , Feromonas/metabolismo , Compuestos de Espiro/análisis , Compuestos de Espiro/metabolismoRESUMEN
A new isoquinoline quinone system and its iodinated derivatives were isolated from the ascidian tunicate Ascidia virginea Müller 1776 (Phlebobranchia: Ascidiidae). Structures were elucidated by spectroscopic methods and derivatization reactions. Ascidine A (3,7-dihydro-1,8-dihydroxy-4-(4'-hydroxyphenyl)isoquinoline-3,7-dione (1), ascidine B (3,7-dihydro-1,8-dihydroxy-4-(4'-hydroxy-3'-iodophenyl)isoquinoline-3,7-dione (2), and ascidine C (3,7-dihydro-1,8-dihydroxy-4-(4'-hydroxy-3',5'-diiodophenyl)isoquinoline-3,7-dione (3) represent a novel type of tyrosine-derived alkaloids.
Asunto(s)
Productos Biológicos/química , Isoquinolinas/química , Quinonas/química , Urocordados/química , Animales , Productos Biológicos/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Isoquinolinas/aislamiento & purificación , Espectroscopía de Resonancia Magnética , Espectrometría de Masas , Estructura Molecular , Quinonas/aislamiento & purificación , EspectrofotometríaRESUMEN
Chilecomadia valdiviana (Philippi) (Lepidoptera: Cossidae) is an insect native to Chile. The larval stages feed on the wood of economically important fruit tree species such as apple, pear, olive, cherry, and avocado, and also on eucalyptus. This causes weakening and, in case of severe infestation, death of the tree. We report identification of the sex pheromone produced by females of this species. Hexane extracts of the abdominal glands of virgin females were analyzed by gas chromatography (GC) with electroantennographic detection, GC coupled with mass spectrometry, and GC coupled to infrared spectroscopy. The major pheromone component was identified as (7Z,10Z)-7,10-hexadecadienal (Z7,Z10-16:Ald), and minor components present in the extracts were (Z)-7-hexadecenal and (Z)-9-hexadecenal, hexadecanal, and (9Z,12Z)-9,12-octadecadienal. Structural assignments were carried out by comparison of analytical data of the natural products and their dimethyl disulfide adducts with those of authentic reference samples. In field tests, traps baited with Z7,Z10-16:Ald captured significantly more males than control traps.
Asunto(s)
Mariposas Nocturnas/química , Atractivos Sexuales/análisis , Aldehídos/análisis , Aldehídos/metabolismo , Alcadienos/análisis , Alcadienos/metabolismo , Animales , Cromatografía de Gases , Femenino , Cromatografía de Gases y Espectrometría de Masas , Masculino , Mariposas Nocturnas/metabolismo , Atractivos Sexuales/metabolismo , Espectrofotometría Infrarroja , Árboles/parasitologíaRESUMEN
It is unresolved as to whether fungi that share a common skin habitat might in principal interact. In in vitro screening tests with Candida albicans, Trichophytum rubrum and other common dermatophytes, we found C. albicans releases volatile compounds that inhibit growth of the dermatophytes. By applying (enantioselective) gas chromatography combined with mass spectrometry we identified 8 compounds among which stereochemically pure (3R,6E)-2,3-dihydrofarnesol (R-DHF) and (2E,6E)-farnesol (F-ol) were the main components. Synthetic R-DHF and its enantiomer, (3S,6E)-2,3-dihydrofarnesol (S-DHF), as well as F-ol were tested for their capacity to inhibit growth of dermatophytes in microtiter-plate assays over 62 h. All three compounds showed significant and concentration-dependent, to a certain extent even species-specific, inhibitory effects on T. rubrum, T. mentagrophytes, Microsporum canis and Epidermophyton floccosum. In general, S-DHF and F-ol had a pronounced effect on the dermatophytes, similar to or even stronger than that of fluconazole. E. floccosum was completely suppressed by 12.5 µg/ml dihydrofarnesol, as was the inhibition caused by 50 µg/ml fluconazole. Similarly, S-DHF- was more active against T. rubrum than fluconazole. To the best of our knowledge, 2,3-dihydrofarnesol has not yet been described as a volatile generated by microorganisms, and its inhibitory effect on dermatophytes is new to science. However, the relevance of this compound in interfungal interference in situ is unknown. In contrast, farnesol is a well-known semiochemical of C. albicans with intraspecific effects and a clear impact on other microorganisms. Mutual intermicrobial communication based on fungal volatiles therefore appears to be an exciting field for future investigations.
Asunto(s)
Antifúngicos/metabolismo , Arthrodermataceae/efectos de los fármacos , Arthrodermataceae/crecimiento & desarrollo , Candida albicans/metabolismo , Sesquiterpenos/metabolismo , Antibiosis , Cromatografía de Gases y Espectrometría de Masas , Pruebas de Sensibilidad MicrobianaRESUMEN
Representatives of the highly speciose tropical butterfly genus Bicyclus (Lepidoptera: Nymphalidae) are characterized by morphological differences in the male androconia, a set of scales and hair pencils located on the surface of the wings. These androconia are assumed to be associated with the release of courtship pheromones. In the present study, we report the identification and biosynthetic pathways of several novel esters from the wings of male B. martius sanaos. We found that the volatile compounds in this male butterfly were similar to female-produced moth sex pheromones. Components associated with the male wing androconial areas were identified as ethyl, isobutyl and 2-phenylethyl hexadecanoates and (11Z)-11-hexadecenoates, among which the latter are novel natural products. By topical application of deuterium-labelled fatty acid and amino acid precursors, we found these pheromone candidates to be produced in patches located on the forewings of the males. Deuterium labels from hexadecanoic acid were incorporated into (11Z)-11-hexadecenoic acid, providing experimental evidence of a Δ11-desaturase being active in butterflies. This unusual desaturase was found previously to be involved in the biosynthesis of female-produced sex pheromones of moths. In the male butterflies, both hexadecanoic acid and (11Z)-11-hexadecenoic acid were then enzymatically esterified to form the ethyl, isobutyl and 2-phenylethyl esters, incorporating ethanol, isobutanol, and 2-phenylethanol, derived from the corresponding amino acids L-alanine, L-valine, and L-phenylalanine.
Asunto(s)
Mariposas Diurnas/metabolismo , Ésteres/metabolismo , Atractivos Sexuales/metabolismo , Alas de Animales/metabolismo , Animales , Deuterio/metabolismo , Ésteres/química , Ácido Graso Desaturasas/metabolismo , Ácidos Grasos Monoinsaturados/metabolismo , Femenino , Masculino , Estructura Molecular , Ácido Palmítico/metabolismo , Atractivos Sexuales/química , Compuestos Orgánicos Volátiles/análisis , Compuestos Orgánicos Volátiles/químicaRESUMEN
Females of the parasitoid wasp Trichogramma turkestanica produce the putative polydeoxypropionates (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-diene and (2E,4E,6S,8S,10S)-4,6,8,10-tetramethyltrideca-2,4-dien-1-ol or their enantiomers as sex specific volatiles. The structures were assigned on the basis of GC-MS investigations using synthetic reference compounds.
RESUMEN
Many pollinators specialize on a few plants as food sources and rely on flower scents to recognize their hosts. However, the specific compounds mediating this recognition are mostly unknown. We investigated the chemical basis of host location/recognition in the Campanula-specialist bee Chelostoma rapunculi using chemical, electrophysiological, and behavioral approaches. Our findings show that Ca. trachelium flowers emit a weak scent consisting of both widespread and rare (i.e., spiroacetals) volatiles. In electroantennographic analyses, the antennae of bees responded to aliphatics, terpenes, aromatics, and spiroacetals; however, the bioassays revealed a more complex response picture. Spiroacetals attracted host-naive bees, whereas spiroacetals together with aliphatics and terpenes were used for host finding by host-experienced bees. On the intrafloral level, different flower parts of Ca. trachelium showed differences in the absolute and relative amounts of scent, including spiroacetals. Scent from pollen-presenting flower parts elicited more feeding responses in host-naive bees as compared to a scentless control, whereas host-experienced bees responded more to the nectar-presenting parts. Our study demonstrates the occurrence of learning (i.e., change in the bee's innate chemical search-image) after bees gain foraging experience on host flowers. We conclude that highly specific floral volatiles play a key role in host-flower recognition by this pollen-specialist bee, and discuss our findings into the broader context of host-recognition in oligolectic bees.
Asunto(s)
Abejas/fisiología , Campanulaceae , Flores/química , Odorantes/análisis , Compuestos Orgánicos Volátiles/análisis , Animales , Conducta Alimentaria , PolinizaciónRESUMEN
The family of cecidomyiid midges (Diptera: Cecidomyiidae) exhibits diversified patterns of life history, behavior, host range, population dynamics and other ecological traits. Those that feed on plants include many important agricultural pests; most cultivated plants are attacked by at least one midge species. Several features of the reproductive biology of cecidomyiid midges point to an important role for chemical communication, with this topic last reviewed comprehensively 12 years ago. Here, we review progress on identification of sex pheromones, chemicals involved in location of host plants, the neurophysiology of reception of volatile chemicals, and application of semiochemicals to management of pest species of cecidomyiid midges that has occurred during the last decade. We hope this review will stimulate and sustain further research in these fields.
Asunto(s)
Dípteros/química , Dípteros/metabolismo , Fenómenos Ecológicos y Ambientales , Comunicación Animal , Animales , Dípteros/fisiología , Odorantes , Control Biológico de Vectores , Atractivos Sexuales/análisis , Atractivos Sexuales/biosíntesis , Atractivos Sexuales/química , Atractivos Sexuales/metabolismoRESUMEN
The native leafmining moth Tischeria ekebladella (Lepidoptera: Tischeriidae) feeds on oaks and recently has become a pest of silviculture and urban green areas in central Europe. The behavioral responses of male moths to hexane extracts of whole bodies of calling females or males were tested under laboratory conditions. Only extracts of females elicited responses from males. Analysis of extracts by coupled gas chromatography/electroantennographic detection revealed the presence of two electroantennogram-active peaks. Structure elucidation of these compounds, by gas-chromatography/mass spectrometry and independent synthesis revealed them to be (3Z,6Z,9Z)-tricosa-3,6,9-triene and (3Z,6Z,9Z,19Z)-tricosa-3,6,9,19-tetraene. While the triene was present in both sexes, the tetraene was female-specific. The latter is a new structure for a pheromone component of Lepidoptera and a novel natural product. Field trapping tests, carried out in a mixed oak forest near Budapest (Hungary), using synthetic compounds applied to rubber dispensers, showed that the tetraene per se elicited catches of males in large numbers. When the triene was added to the tetraene in a ratio of 1:1, there was no increase in trap catch; the triene alone did not elicit catches of males. For monitoring this insect, the tetraene, applied to rubber dispensers at a dose of 300 µg, is a potent sex attractant.
Asunto(s)
Mariposas Nocturnas/química , Mariposas Nocturnas/fisiología , Atractivos Sexuales/aislamiento & purificación , Atractivos Sexuales/metabolismo , Animales , Antenas de Artrópodos/efectos de los fármacos , Femenino , Cromatografía de Gases y Espectrometría de Masas , Hungría , Masculino , Mariposas Nocturnas/efectos de los fármacos , Atractivos Sexuales/síntesis química , Conducta Sexual Animal/efectos de los fármacosRESUMEN
Starting from the enantiomers of limonene, all eight stereoisomers of trans-fused dihydronepetalactones were synthesized. Key compounds were pure stereoisomers of 1-acetoxymethyl-2-methyl-5-(2-hydroxy-1-methylethyl)-1-cyclopentene. The stereogenic center of limonene was retained at position 4a of the target compounds and used to stereoselectively control the introduction of the other chiral centers during the synthesis. Basically, this approach could also be used for the synthesis of enantiomerically pure trans-fused iridomyrmecins. Using synthetic reference samples, the combination of enantioselective gas chromatography and mass spectrometry revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain the enantiomerically pure trans-fused (4R,4aR,7R,7aS)-dihydronepetalactone as a minor component, showing an unusual (R)-configured stereogenic center at position 7.
RESUMEN
Following our earlier approach to the synthesis of dihydronepetalactones, all eight stereoisomers of trans-fused iridomyrmecins were synthesized starting from the enantiomers of limonene. Combined gas chromatography and mass spectrometry including enantioselective gas chromatography revealed that volatiles released by the endohyperparasitoid wasp Alloxysta victrix contain (4S,4aR,7S,7aR)-iridomyrmecin of 95-97% ee and stereochemically pure (4S,4aS,7R,7aS)-iridomyrmecin as a minor component.
RESUMEN
Xanthomonas campestris is a phytopathogenic bacterium and causes many diseases of agricultural relevance. Volatiles were shown to be important in inter- and intraorganismic attraction and defense reactions. Recently it became apparent that also bacteria emit a plethora of volatiles, which influence other organisms such as invertebrates, plants and fungi. As a first step to study volatile-based bacterial-plant interactions, the emission profile of Xanthomonas c. pv. vesicatoria 85-10 was determined by using GC/MS and PTR-MS techniques. More than 50 compounds were emitted by this species, the majority comprising ketones and methylketones. The structure of the dominant compound, 10-methylundecan-2-one, was assigned on the basis of its analytical data, obtained by GC/MS and verified by comparison of these data with those of a synthetic reference sample. Application of commercially available decan-2-one, undecan-2-one, dodecan-2-one, and the newly synthesized 10-methylundecan-2-one in bi-partite Petri dish bioassays revealed growth promotions in low quantities (0.01 to 10 µmol), whereas decan-2-one at 100 µmol caused growth inhibitions of the fungus Rhizoctonia solani. Volatile emission profiles of the bacteria were different for growth on media (nutrient broth) with or without glucose.
RESUMEN
An outstanding feature of orchids is the diversity of their pollination systems [1]. Most remarkable are those species that employ chemical deceit for the attraction of pollinators [2]. The orchid Epipactis helleborine is a typical wasp flower, exhibiting physiological and morphological adaptations for the attraction of pollinating social wasps [3]. As noted by Darwin [1], this species is almost entirely overlooked by other potential pollinators, despite a large nectar reward. Therefore, the mechanism for the attraction of pollinating social wasps was something of a mystery. By using a combination of behavioral experiments, electrophysiological investigations, and chemical analyses, we demonstrate for the first time that the flowers of E. helleborine and E. purpurata emit green-leaf volatiles (GLVs), which are attractive to foragers of the social wasps Vespula germanica and V. vulgaris. GLVs, emitted by damaged plant tissues, are known to guide parasitic wasps to their hosts [4]. Several E. helleborine GLVs that induced response in the antennae of wasps were also emitted by cabbage leaves infested with caterpillars (Pieris brassicae), which are common prey items for wasps [5]. This is the first example in which GLVs have been implicated in chemical mimicry for the attraction of pollinating insects.