Electroantennogram response and attraction of Anastrepha suspensa to volatiles of various sugar sources and aged sugar solutions

With the aim of finding new, sugar‐based volatile attractants for economically important tephritid fruit fly species, we used electroantennography (EAG) to quantitate olfactory responses of female Caribbean fruit fly, Anastrepha suspensa (Loew) (Diptera: Tephritidae), to volatiles of six sugar sources (refined white and brown cane sugar, coconut sugar, date sugar, date jaggery, and cane panela). Laboratory‐strain and wild flies, both sexually immature and mature, were tested for EAG responses to the volatiles of dry crystallized sugar sources and 10% (wt/vol) aqueous solutions that had aged in the laboratory for 0–7 days. In general, wild flies exhibited higher EAG responses than laboratory flies, and immature females responded more strongly than mature females. With the exception of date jaggery and cane panela, volatiles of dry sugar sources and 0‐ and 1‐day‐old solutions elicited lower EAG responses than any of the aged solutions. Most solution volatiles elicited the strongest EAG response after 2 days of aging. Of the treatments evaluated, volatiles of the 5‐day‐old date jaggery solution elicited the highest‐amplitude EAG responses (39%) in A. suspensa females. On the basis of the latter, we tested the attraction response of mature and immature females to date‐jaggery solutions aged over 2 and 4 days in two‐choice flight tunnel bioassays. With both mature and immature females, the 2‐day‐old solution was more attractive than the 4‐day‐old jaggery solution, but significantly more mature females (70% of captures) were attracted to 2‐day‐old jaggery solution. We discuss our results with respect to the improvement of fruit fly lures and attractants by incorporating elements from aged date‐jaggery sugar.     

Gas chromatography column as an ambient‐temperature volatile trap

Open‐tube volatile traps have largely been shunned in favor of solid adsorbent containing traps for the collection of volatile pheromones and attractants. Solid adsorbents require large solvent rinses and glass capillaries can be difficult to maneuver for the collection of volatiles from small or hard‐to‐reach odor sources. A gas chromatograph (GC) column (DB‐1), an open‐tube glass capillary, and a SuperQ^®‐containing capillary were compared for their collection efficiencies from rubber septa and live calling insects. All three traps captured similar ratios of test compounds from septa at airflows >10 ml per min. Eluting analytes from a packed adsorbent, SuperQ, required at least 30× more solvent than was required to collect all the pheromone from the open‐tube glass capillaries, and the GC column enjoyed an additional three‐fold reduced solvent volume compared to the glass capillary. Thus, analytes could be eluted from the GC‐column trap and directly analyzed on GC without solvent evaporation. We placed glass wool ‘plugs’ in both GC columns and glass capillaries and found no volatiles in these plugs, indicating that breakthrough did not occur during 1‐h collections at 25 ml per min. We demonstrate here that at ambient laboratory temperatures, a DB‐1 GC column effectively collects Oriental fruit moth sex pheromone volatiles from a rubber septum and live pheromone‐releasing moths. Release ratios of pheromone from rubber septa are consistent with earlier reports from static air systems, whereas the release ratio of the (Z)‐8‐dodecenyl alcohol (Z8‐12:OH) from female Grapholita molesta Busck (Lepidoptera: Tortricidae) differed from published results and is likely due to different collection methods or moth‐strain origin.     

Host selection by Ibalia leucospoides based on temporal variations of volatiles from the hosts’ fungal symbiont

Insect parasitoids locate hosts via reliable and predictable cues such as volatile emissions from hosts and/or host plants. For insects that depend on mutualistic organisms, such as many wood‐boring insects, symbiont‐derived semiochemicals may represent a source of such cues to be exploited by natural enemies. Ultimately, exploitation of these signals may increase fitness by optimizing foraging efficiency. Female parasitoids of Ibalia leucospoides use volatiles from the fungal symbiont Amylostereum areolatum of their host Sirex noctlio to find concealed host eggs and young larvae within the xylem. We hypothesize that the temporal pattern of fungal emissions may indicate not only the presence of host larvae but also be used as a cue that indicates host suitability and age. Such information would allow female parasitoids to discern more efficiently between hosts within ovipositor reach from those already buried too deep into the xylem and out of reach. In this context, we assessed the behaviour of I. leucospoides females to volatiles of A. areolatum in a ‘Y’‐tube olfactometer at regular intervals over 30 days. We concurrently examined the fungal volatiles by headspace sampling through solid‐phase microextraction (SPME) followed by gas chromatography mass spectrometry (GC‐MS). We observed that females were attracted to volatiles produced by two‐week‐old fungal cultures, a period that matches when older larvae are still within ovipositor reach. Four chemical compounds were detected: ethanol, acetone, acetaldehyde and the sesquiterpene 2,2,8‐trimethyltricyclo[6.2.2.01,6]dodec‐5‐ene, with each compounds’ relative abundance changing over time. Results are discussed in the context of parasitoids fitness. Future studies involving electrophysiology, different collection techniques and further behavioural assays will help in identifying the compounds that convey temporal information to female parasitoids and have the potential for being used in integrated pest management programmes.     

Olfactory response of Anastrepha striata (Diptera: Tephritidae) to guava and sweet orange volatiles

The behavioral responses of virgin and mated female Anastrepha striata Schiner (Diptera: Tephritidae) to guava (Psidium guajava L.) or sweet orange (Citrus sinensis L.) were evaluated separately using multilure traps in two‐choice tests in field cages. The results showed that flies were more attracted to guava and sweet orange volatiles than to control (unbaited trap). The physiological state (virgin or mated) of females did not affect their attraction to the fruit volatiles. Combined analysis of gas chromatography coupled with electroantennography (GC‐EAD) of volatile extracts of both fruits showed that 1 and 6 compounds from orange and guava, respectively elicited repeatable antennal responses from mated females. The EAD active compounds in guava volatile extracts were identified by gas chromatography‐mass spectrometry (GC‐MS) as ethyl butyrate, (Z)‐3‐hexenol, hexanol, ethyl hexanoate, hexyl acetate, and ethyl octanoate. Linalool was identified as the only antennal active compound in sweet orange extracts. In field cage tests, there were no significant differences between the number of mated flies captured by the traps baited with guava extracts and the number caught by traps baited with the 6‐component blend that was formulated according to the relative proportions in the guava extracts. Similar results occurred when synthetic linalool was evaluated against orange extracts. From a practical point of view, the compounds identified in this study could be used for monitoring A. striata populations.     

Behavioural responses of stable flies to cattle manure slurry associated odourants

Stable flies (Stomoxys calcitrans [Diptera: Muscidae] L.) are blood‐feeding synanthropic pests, which cause significant economic losses in livestock. Stable fly antennae contain olfactory sensilla responsive to host and host environment‐associated odours. Field observation indicated that the abundance of stable flies increased significantly in grasslands or crop fields when cattle manure slurry was applied. Major volatile compounds emanating from manure slurry were collected and identified. Behavioural responses of stable flies to those compounds were investigated in laboratory bioassays and field‐trapping studies. Results from olfactometer assays revealed that phenol, p‐cresol and m‐cresol were attractive to adult stable flies. When tested individually, attraction was higher with lower dosages. Stable flies were most attracted to blends of phenol and m‐cresol or p‐cresol. Traps with binary blend lures caught more stable flies in field trials as well.     

Chemical composition and antimicrobial activity of volatiles from Degenia velebitica, a European stenoendemic plant of the Brassicaceae family

Free and glucosidic bound leaf volatiles of Degenia velebitica were isolated and fractionated simultaneously into H₂O‐soluble, H₂O‐insoluble, and highly volatile compounds by hydrodistillation–adsorption (HDA) and analyzed by GC/MS. Among the 24 constituents identified, the main compounds obtained by the HDA method were S‐ and/or N‐atom containing compounds, i.e., 6‐(methylsulfanyl)hexanenitrile ( 10 ; 26.78%), dimethyl trisulfide ( 6 ; 26.35%), 3,4,5‐trimethylpyrazole ( 17 ; 13.33%), hex‐5‐enenitrile ( 2 ; 10.11%), dimethyl tetrasulfide ( 8 ; 4.93%), and pent‐4‐enyl isothiocyanate ( 7 ; 4.45%). In addition, O‐glycosidically bound volatiles and free volatiles were isolated by solvent extraction. Sixteen volatile O‐aglycones and twelve free volatile components were identified. The main O‐aglycones were eugenol ( 19 ; 24.15%), 2‐methoxy‐4‐vinylphenol ( 11 ; 11.50%), and benzyl alcohol ( 20 ; 9.49%), and the main free volatiles were (9Z,12Z)‐octa‐9,12‐dienic acid (38.35%), hexadecanoic acid (22.64%), and phytol (5.80%). The H₂O‐soluble volatile fraction obtained by HDA, containing mostly glucosinolate degradation products and 3,4,5‐trimethylpyrazole ( 17 ), was evaluated for antimicrobial activity by determining inhibition zones with the diffusion method as well as minimal inhibitory concentrations (MIC) and minimal microbicidal concentrations (MMC) with the micro‐dilution method. The fraction expressed activity against the tested Gram‐positive and Gram‐negative bacteria as well as against yeast, with MIC values equal to or lower than 16.7 μg/ml.     

Electrophysiological and behavioral identification of a volatile blend involved in host location of female strawberry sap beetle,Stelidota geminata

The strawberry sap beetle (SSB), Stelidota geminata (Say) (Coleoptera: Nitidulidae), is a serious direct pest of strawberries in the northeastern USA. To date, however, no food or pheromone‐based attractants for SSB have been identified. A combination of solid‐phase microextraction, adsorbent sampling, gas chromatography coupled with electroantennographic detection (GC–EAD), and gas chromatography–mass spectrometry was used to identify volatile compounds from strawberry fruit acting as behavioral attractants for female SSB. Consistent EAD activity was obtained for 16 ester compounds. In Y‐tube olfactometer bioassays, the blend of these 16 compounds mixed at a ratio observed from strawberry headspace was significantly more attractive to adult female SSB than a control. Female SSB showed no difference in response levels between the 16‐component blend and a strawberry volatile adsorbent extract. Our data indicate that the combination of the ethyl acetate with some or all of the remaining 15 compounds is necessary for this ester blend to be attractive to female SSB. Previously identified host volatiles found for other species of sap beetles included mostly alcohols associated with over‐ripe fruit rather than the esters identified from ripe strawberries for SSB. A highly attractive synthetic food odor will be useful for developing new management options for SSB.     

Electrophysiological responses of Batocera horsfieldi (Hope) adults to plant volatiles

The olfactory stimuli from the maturation feeding‐plant, Rosa multiflora Thunb., and larval‐host plant, Populus deltoides, of the longhorned beetle, Batocera horsfieldi (Hope), were investigated by using TCT‐GC/MS (Thermal desorption and cold trap, and GC/MS) and electroantennogram recordings (EAG). A total of 20 plant compounds were identified from plant headspace volatile, including aliphatic, aromatic and terpenoid compounds. Five compounds were common to both plants. Eight compounds eliciting strong EAG response were E‐3‐hexenyl acetate, 3‐carene, 1‐penten‐3‐ol, 3‐pentanol, Z‐2‐penten‐1‐ol, hexanal and E‐2‐hexenal. Female and male B. horsfieldi exhibited broad overlap in their EAG responses to individual plant odour, and there was no clear pattern of difference between responses of female and male antennae to different compounds. Mating status had little effect on the EAG responses of females.     

Volatiles from soil‐borne fungi affect directional growth of roots

Volatiles play major roles in mediating ecological interactions between soil (micro)organisms and plants. It is well‐established that microbial volatiles can increase root biomass and lateral root formation. To date, however, it is unknown whether microbial volatiles can affect directional root growth. Here, we present a novel method to study belowground volatile‐mediated interactions. As proof‐of‐concept, we designed a root Y‐tube olfactometer, and tested the effects of volatiles from four different soil‐borne fungi on directional growth of Brassica rapa roots in soil. Subsequently, we compared the fungal volatile organic compounds (VOCs) previously profiled with Gas Chromatography–Mass Spectrometry (GC–MS). Using our newly designed setup, we show that directional root growth in soil is differentially affected by fungal volatiles. Roots grew more frequently toward volatiles from the root pathogen Rhizoctonia solani, whereas volatiles from the other three saprophytic fungi did not impact directional root growth. GC–MS profiling showed that six VOCs were exclusively emitted by R. solani. These findings verify that this novel method is suitable to unravel the intriguing chemical cross‐talk between roots and soil‐borne fungi and its impact on root growth.     

Identification of stable fly attractant compounds in vinasse,a byproduct of sugarcane–ethanol distillation

The stable fly, Stomoxys calcitrans (Diptera: Muscidae), is a worldwide pest of livestock. Recent outbreaks of stable flies in sugarcane fields in Brazil have become a serious problem for livestock producers. Larvae and pupae found inside sugarcane stems after harvesting may indicate that stable flies use these stems as potential oviposition or larval development sites. Field observations suggest that outbreaks of stable flies are associated with the vinasse and filter cake derived from biomass distillation in sugarcane ethanol production that are used as fertilizers in sugarcane fields. Adult stable flies are attracted to vinasse, which appears to present an ideal larval development site. The primary goal of the present study is to demonstrate the role of vinasse in influencing the sensory physiological and behavioural responses of stable flies, and to identify its associated volatile attractant compounds. Both laboratory and field studies showed that vinasse is extremely attractive to adult stable flies. Chemical analyses of volatiles collected revealed a wide range of carboxylic acids, alcohols, phenols and aldehydes as potential attractant compounds. These newly identified attractants could be used to develop a tool for the attractant‐baited mass trapping of stable flies in order to reduce infestations.     

Phosphoproteomic analysis of chromoplasts from sweet orange during fruit ripening

Like other types of plastids, chromoplasts have essential biosynthetic and metabolic activities which may be regulated via post‐translational modifications, such as phosphorylation, of their resident proteins. We here report a proteome‐wide mapping of in vivo phosphorylation sites in chromoplast‐enriched samples prepared from sweet orange [Citrus sinensis (L.) Osbeck] at different ripening stages by titanium dioxide‐based affinity chromatography for phosphoprotein enrichment with LC‐MS/MS. A total of 109 plastid‐localized phosphoprotein candidates were identified that correspond to 179 unique phosphorylation sites in 135 phosphopeptides. On the basis of Motif‐X analysis, two distinct types of phosphorylation sites, one as proline‐directed phosphorylation motif and the other as casein kinase II motif, can be generalized from these identified phosphopeptides. While most identified phosphoproteins show high homology to those already identified in plastids, approximately 22% of them are novel based on BLAST search using the public databases PhosPhAt and P³DB. A close comparative analysis showed that approximately 50% of the phosphoproteins identified in citrus chromoplasts find obvious counterparts in the chloroplast phosphoproteome, suggesting a rather high‐level of conservation in basic metabolic activities in these two types of plastids. Not surprisingly, the phosphoproteome of citrus chromoplasts is also characterized by the lack of phosphoproteins involved in photosynthesis and by the presence of more phosphoproteins implicated in stress/redox responses. This study presents the first comprehensive phosphoproteomic analysis of chromoplasts and may help to understand how phosphorylation regulates differentiation of citrus chromoplasts during fruit ripening.     

Olfactory response of a predatory mirid to herbivore induced plant volatiles: multiple herbivory vs. single herbivory

Plants infested with a single herbivore species can attract natural enemies through the emission of herbivore‐induced plant volatiles (HIPVs). However, under natural conditions plants are often attacked by more than one herbivore species. We investigated the olfactory response of a generalist predators Macrolophus caliginosus to pepper infested with two‐spotted spider mites, Tetranychus urticae, or green peach aphid, Myzus persicae, vs. plants infested with both herbivore species in a Y‐tube olfactometer set up. In addition, the constituents of volatile blends from plants exposed to multiple or single herbivory were identified by gas chromatography‐mass spectrometry (GC‐MS). The mirid bugs showed a stronger response to volatiles emitted from plants simultaneously infested with spider mites and aphids than to those emitted from plants infested by just one herbivore, irrespective of the species. Combined with results from previous studies under similar conditions we infer that this was a reaction to herbivore induced plant volatiles. The GC‐MS analysis showed that single herbivory induced the release of 22 additional compounds as compared with the volatiles emitted from clean plants. Quantitative analyses revealed that the amount of volatile blends emitted from pepper infested by both herbivores was significantly higher than that from pepper infested by a single herbivore. Moreover, two unique substances were tentatively identified (with a probability of 94% and 91%, respectively) in volatiles emitted by multiple herbivory damaged plants: α‐zingiberene and dodecyl acetate.     

Roles of plant volatiles in defence against microbial pathogens and microbial exploitation of volatiles

Plants emit a large variety of volatile organic compounds during infection by pathogenic microbes, including terpenes, aromatics, nitrogen‐containing compounds, and fatty acid derivatives, as well as the volatile plant hormones, methyl jasmonate, and methyl salicylate. Given the general antimicrobial activity of plant volatiles and the timing of emission following infection, these compounds have often been assumed to function in defence against pathogens without much solid evidence. In this review, we critically evaluate current knowledge on the toxicity of volatiles to fungi, bacteria, and viruses and their role in plant resistance as well as how they act to induce systemic resistance in uninfected parts of the plant and in neighbouring plants. We also discuss how microbes can detoxify plant volatiles and exploit them as nutrients, attractants for insect vectors, and inducers of volatile emissions, which stimulate immune responses that make plants more susceptible to infection. Although much more is known about plant volatile–herbivore interactions, knowledge of volatile–microbe interactions is growing and it may eventually be possible to harness plant volatiles to reduce disease in agriculture and forestry. Future research in this field can be facilitated by making use of the analytical and molecular tools generated by the prolific research on plant–herbivore interactions.     

Volatile compounds emitted by Triatoma dimidiata,a vector of Chagas disease: chemical analysis and behavioural evaluation

In this study, we evaluated the responses of Triatoma dimidiata Latreille (Hemiptera: Reduviidae) to volatiles emitted by conspecific females, males, mating pairs and metasternal gland (MG) extracts with a Y‐tube olfactometer. The volatile compounds released by mating pairs and MGs of T. dimidiata were identified using solid‐phase microextraction and coupled gas chromatography‐mass spectrometry (GC‐MS). Females were not attracted to volatiles emitted by males or MG extracts; however, they preferred clean air to their own volatiles or those from mating pairs. Males were attracted to volatiles emitted by males, females, mating pairs, pairs in which the male had the MG orifices occluded or MG extracts of both sexes. However, males were not attracted to volatiles emitted by pairs in which the female had the MG orifices occluded. The chemical analyses showed that 14 and 15 compounds were detected in the headspace of mating pairs and MG, respectively. Most of the compounds identified from MG except for isobutyric acid were also detected in the headspace of mating pairs. Both females and males were attracted to octanal and 6‐methyl‐5‐hepten‐2‐one, and males were attracted to 3,5‐dimethyl‐2‐hexanol. Males but not females were attracted to a seven‐compound blend, formulated from compounds identified in attractive MG extracts.     

NMR,HS‐SPME‐GC/MS,and HPLC/MSn Analyses of Phytoconstituents and Aroma Profile of Rosmarinus eriocalyx

In this work, a comprehensive study on the chemical constituents of the aerial parts of Rosmarinus eriocalyx (Lamiaceae), an aromatic shrub traditionally consumed as a food and herbal remedy in Algeria, is presented. The aroma profile was analysed by headspace solid phase microextraction (HS‐SPME) coupled with gas chromatography‐mass spectrometry (GC/MS), whereas the crude extract constituents were analyzed by ¹H‐NMR and by high performance liquid chromatography coupled with mass spectrometry (HPLC/MSⁿ). Thirty‐nine volatile compounds, most of them being monoterpenes, have been identified, with camphor, camphene, and α‐pinene as the most abundant constituents. ¹H‐NMR analysis revealed the presence of phenolic compounds and betulinic acid while HPLC/MSⁿ allowed the identification of glycosilated and aglyconic flavonoids as well as phenylpropanoid derivatives. Some of these constituents, namely as betulinic acid, rosmanol, and cirsimaritin were reported for the first time in R. eriocalyx.     

Comprehensive two‐dimensional gas chromatography–mass spectrometry analysis of volatile constituents in Thai vetiver root oils obtained by using different extraction methods

Introduction – Vetiver root oil is known as one of the finest fixatives used in perfumery. This highly complex oil contains more than 200 components, which are mainly sesquiterpene hydrocarbons and their oxygenated derivatives. Since conventional GC‐MS has limitation in terms of separation efficiency, the comprehensive two‐dimensional GC‐MS (GC × GC‐MS) was proposed in this study as an alternative technique for the analysis of vetiver oil constituents. Objective – To evaluate efficiency of the hyphenated GC × GC‐MS technique in terms of separation power and sensitivity prior to identification and quantitation of the volatile constituents in a variety of vetiver root oil samples. Methodology – Dried roots of Vetiveria zizanioides were subjected to extraction using various conditions of four different methods; simultaneous steam distillation, supercritical fluid, microwave‐assisted, and Soxhlet extraction. Volatile components in all vetiver root oil samples were separated and identified by GC‐MS and GC × GC‐MS. The relative contents of volatile constituents in each vetiver oil sample were calculated using the peak volume normalization method. Results – Different techniques of extraction had diverse effects on yield, physical and chemical properties of the vetiver root oils obtained. Overall, 64 volatile constituents were identified by GC‐MS. Among the 245 well‐resolved individual components obtained by GC × GC‐MS, the additional identification of 43 more volatiles was achieved. Conclusion – In comparison with GC‐MS, GC × GC‐MS showed greater ability to differentiate the quality of essential oils obtained from diverse extraction conditions in terms of their volatile compositions and contents. Copyright © 2009 John Wiley & Sons, Ltd.     

Synergism between aromatic compounds and green leaf volatiles derived from the host plant underlies female attraction in the oriental fruit moth

Blends of volatile compounds emitted by host plants are known to mediate the attraction of gravid female herbivores to oviposition sites, but the role of individual odor components is still little understood. We characterized the olfactory response of mated female Cydia (Grapholita) molesta (Busck) (Lepidoptera: Tortricidae) to synthetic mixtures of compounds emitted by peach shoot, a key host plant of this herbivore, and investigated the role of important constituents of bioactive mixtures in moth attraction. Relative ratios of constituents of the mixtures corresponded to the natural ratio of volatile compounds collected in the plant's headspace. A significant attractant effect was found for a comparatively complex 10‐compound mixture that included four green leaf volatiles [(Z)‐3‐hexen‐1‐ol, 1‐hexanol, (E)‐2‐hexenal, and (Z)‐3‐hexen‐1‐yl acetate], five aromatics (benzaldehyde, methyl salicylate, methyl benzoate, benzonitrile, and phenylacetonitrile), and a carboxylic acid (valeric acid). Using a subtraction approach, the number of compounds was progressively decreased, resulting in a bioactive 5‐compound mixture composed of two constituents, green leaf volatiles and aromatic compounds. Further evaluations revealed that benzaldehyde and benzonitrile must be present in association with three distinct green leaf volatiles to produce an attractant effect on the female moths. This 5‐compound mixture was as attractive as natural peach shoot volatiles, which are known to comprise over 20 compounds. Results are discussed in light of the documented synergistic effect between the three general green leaf volatiles and the two specific aromatic compounds.     

藏药镰形棘豆挥发性成分研究(英文)

本文通过水蒸气蒸馏、超临界CO2萃取和顶空萃取三种方法并结合GC和GC/MS技术分析藏药镰形棘豆(Oxytropis falcate Bunge)中的挥发性成分,共鉴定出58个化合物,分别占71.0%,85.6%和84.5%。烷烃类、黄酮类和醛类化合物为主要挥发性成分。3种方法得到的挥发性成分在保留时间值上具有一定的连续性,能更完全地阐述清楚藏药镰形棘豆的挥发性成分,为进一步开发利用这种药用植物提供科学依据。