Volatile Blends Research Articles

Attraction of Sweet Potato Whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), and Two Generalist Predators to Green Leaf Volatile Compounds.

Traditionally, olfaction was thought to play a minor role in the behavioral ecology of the sweet potato whitefly, Bemisia tabaci (Gennadius). However, recent research is uncovering significant potential for whitefly management based on olfaction. Incorporating chemical attractants with standard whitefly management programs could significantly improve control. The integration of attractants with biological control is exceptionally promising. Therefore, the behavioral response of B. tabaci and two generalist predators to the green leaf volatiles (E)-2-hexenal, (Z)-3-hexenal, (Z)-3-hexenyl acetate, and (Z)-3-hexe-1-ol were investigated in Y-tube olfactometers. Three of the four green leaf volatiles resulted in the attraction of female B. tabaci. Blend optimization indicated a two-chemical blend to be the most attractive blend for female B. tabaci. In addition, this blend was attractive to female Macrolophus praeclarus (Distant) but did not elicit a behavioral response from either male or female Delphastus catalinae (Horn). The two-chemical blend of green leaf volatiles could be further developed as a lure to attract B. tabaci and its predator, M. praeclarus.

Metabolic engineering of a 1,8-cineole synthase from Nicotiana suaveolens, confers enhanced resistance to Meloidogyne incognita by synergistic blend of root volatiles

Root-knot nematodes (RKNs) pose a significant threat to global crop production. Given the detrimental effects of fumigants and conventional chemical nematicides, there is a growing interest in exploring biological nematicides as a promising alternative for pest control. In this study, we present data demonstrating the role of root volatiles in enhancing resistance against Meloidogyne incognita (M. incognita) in tobacco plants overexpressing NsCINS (NsCINS-OE). The NsCINS gene, derived from Nicotiana suaveolens, encodes a 1,8-cineole synthase induced by M. incognita infection and predominantly localized to the chloroplast. The roots of NsCINS-OE plants exhibited deterrent properties to infective second-stage juveniles (J2s) of M. incognita. Moreover, NsCINS-OE plants showed enhanced resistance against M. incognita, as evidenced by reduced gall numbers and egg mass counts compared to wild type (WT) plants. Notably, the emission of root volatiles from NsCINS-OE plants, including 1,8-cineole, α-terpineol, terpinene-4-ol, and furfural, was significantly higher than that of WT. In vitro assays confirmed that a mixture of commercially available volatile organic compounds (VOCs) had a deterrent effect on infective J2s. Furthermore, the natural root volatiles emitted by NsCINS-OE plants effectively enhanced tobacco's resistance against M. incognita. Our findings provide valuable insights into the role of NsCINS in volatile-based defense and highlight the potential of metabolic engineering of monoterpene synthase genes to control M. incognita by enhancing root volatile emissions.

Volatile Organic Compound Emissions in the Changing Arctic

Arctic ecosystems have long been thought to be minimal sources of volatile organic compounds (VOCs) to the atmosphere because of their low plant biomass and cold temperatures. However, these ecosystems experience rapid climatic warming that alters vegetation composition. Tundra vegetation VOC emissions have stronger temperature dependency than current emission models estimate. Thus, warming, both directly and indirectly (via vegetation changes) likely increases the release and alters the blend of emitted plant volatiles, such as isoprene, monoterpenes, and sesquiterpenes, from Arctic ecosystems. Climate change also increases the pressure of both background herbivory and insect outbreaks. The resulting leaf damage induces the production of volatile defense compounds, and warming amplifies this response. Soils function as both sources and sinks of VOCs, and thawing permafrost is a hotspot for soil VOC emissions, contributing to ecosystem emissions if the VOCs bypass microbial uptake. Overall, Arctic VOC emissions are likely to increase in the future with implications for ecological interactions and atmospheric composition.

Composition, Bioactivities, Microbiome, Safety Concerns, and Impact of Essential Oils on the Health Status of Domestic Animals

Essential oils (EOs) are highly concentrated and volatile blends of nonpolar substances that are derived from aromatic plant components and comprise terpenes, terpenoids, and phenylpropanoids, exhibiting diverse biological and pharmacological properties. The burgeoning pet industry is interested in EOs as a potential solution for common health issues in domestic animals, particularly in addressing antimicrobial resistance. The present literature review summarizes the composition, properties, benefits, safety considerations, and effects of EOs on domestic animals. The applications of EOs range from antimicrobial effects to antioxidant, anti-inflammatory, and anticancer activities, etc. The chemical constituents of EOs, exemplified by eucalyptus EO and rosemary EO, highlight their distinct aromatic profiles and potential benefits. Nevertheless, understanding the chemical makeup of EOs is fundamental to assessing their potential impacts on biological systems. The gut microbiota plays a crucial role in regulating various metabolic processes in the host, including energy homeostasis, glucose metabolism, and lipid metabolism. Safety considerations, including potential toxicity risk awareness, are essential when incorporating EOs into animal care routines. The feed additives incorporating EOs have shown promise in influencing gut microbiota balance, reducing inflammation, and acting as antioxidants. However, considering the potential risks associated with high doses or multiple administrations, cautious application is paramount. Preliminary studies suggest low toxicity levels, but further research is required to evaluate the safety of EOs. Though studies have reported the beneficial effects of EOs on pets and animals, further research is needed to validate the findings in real-world conditions. The paper also discussed the regulatory considerations and future perspectives on applying EOs in veterinary medicine.

Volatiles emitted by pepper weevil-infested plants and fruit strongly attract the pteromalid parasitoid Jaliscoa hunteri

Among the many ways arthropod pests may signal their whereabouts to natural enemies, the release of specific volatiles by either pests themselves or their infested host plants may represent some of the most valuable cues that dictate biocontrol agent host-attraction, trophic impact and host-specificity. In this study, we sought to elucidate how plant and insect host-specific volatiles mediate attraction of pteromalid wasp, Jaliscoa hunteri to immature pepper weevil, Anthonomus eugenii, an economically important and challenging-to-control pest of cultivated Capsicum sp. pepper crops across North America. To begin, we used an air-entrainment system to collect volatiles released by whole pepper plants infested or not by either egg, L1 or L3 stages of pepper weevil and in the presence or absence of parental adults. The chemical analysis of sample volatiles from pepper plants infested or not with A. eugenii larvae were then compared, and among these, five compounds were identified that had their emission increased from 1.5 to 8.1 times relative to the blend of volatiles emitted by undamaged pepper plants including: linalool, 1-hexanol, 4,8-dimethylnona-1,3,7-triene (DMNT), methyl salicylate, and 4,8,12-trimethyltrideca-1,3,7,11-tetraene (TMTT). We next conducted Y olfactometer bioassays to compare the attractive potential of volatiles emitted by pepper fruit, infested or not by L1 or L3 immature pepper weevil, as well as by the alternative J. hunteri-rearing host, L3 or L4 immature Callosobruchus maculatus as they developed within infested chickpeas. Olfactometer bioassays showed that J. hunteri females preferred and consistently oriented towards the volatiles derived from pepper fruit infested by both larval stages of pepper weevil compared to the odour of undamaged pepper fruit. The females of J. hunteri also preferred for the odour emitted by chickpeas infested with C. maculatus compared to air. Ultimately this work highlights the considerable value of studying the composition of volatile headspace captures for pest-infested fruit and complimentary Y-tube assays for measuring or even improving the attraction potential of natural enemies to economically or ecologically important host species.

Testing the joint effects of arbuscular mycorrhizal fungi and ants on insect herbivory on potato plants

Main conclusionAnts, but not mycorrhizae, significantly affected insect leaf-chewing herbivory on potato plants. However, there was no evidence of mutualistic interactive effects on herbivory.Plants associate with both aboveground and belowground mutualists, two prominent examples being ants and arbuscular mycorrhizal fungi (AMF), respectively. While both of these mutualisms have been extensively studied, joint manipulations testing their independent and interactive (non-additive) effects on plants are rare. To address this gap, we conducted a joint test of ant and AMF effects on herbivory by leaf-chewing insects attacking potato (Solanum tuberosum) plants, and further measured plant traits likely mediating mutualist effects on herbivory. In a field experiment, we factorially manipulated the presence of AMF (two levels: control and mycorrhization) and ants (two levels: exclusion and presence) and quantified the concentration of leaf phenolic compounds acting as direct defenses, as well as plant volatile organic compound (VOC) emissions potentially mediating direct (e.g., herbivore repellents) or indirect (e.g., ant attractants) defense. Moreover, we measured ant abundance and performed a dual-choice greenhouse experiment testing for effects of VOC blends (mimicking those emitted by control vs. AMF-inoculated plants) on ant attraction as a mechanism for indirect defense. Ant presence significantly reduced herbivory whereas mycorrhization had no detectable influence on herbivory and mutualist effects operated independently. Plant trait measurements indicated that mycorrhization had no effect on leaf phenolics but significantly increased VOC emissions. However, mycorrhization did not affect ant abundance and there was no evidence of AMF effects on herbivory operating via ant-mediated defense. Consistently, the dual-choice assay showed no effect of AMF-induced volatile blends on ant attraction. Together, these results suggest that herbivory on potato plants responds mainly to top-down (ant-mediated) rather than bottom-up (AMF-mediated) control, an asymmetry in effects which could have precluded mutualist non-additive effects on herbivory. Further research on this, as well as other plant systems, is needed to examine the ecological contexts under which mutualist interactive effects are more or less likely to emerge and their impacts on plant fitness and associated communities.

Plasticity in inhibitory networks improves pattern separation in early olfactory processing.

By combining computational modeling, machine learning, and analysis of calcium imaging data, we demonstrate that associative and non-associative plasticity in the honeybee antennal lobe (AL) - first relay of the insect olfactory system - work together to enhance the contrast between rewarded and unrewarded odors. Training the AL's inhibitory network within specific odor environments enables the suppression of neural responses to common odor components, while amplifying responses to distinctive ones. This study sheds light on the olfactory system's ability to adapt and efficiently learn new odor-reward associations across varying environments, and it proposes innovative, energy-efficient principles applicable to artificial intelligence.

Too hot to handle: temperature-induced plasticity influences pollinator behaviour and plant fitness.

Increased temperature can induce plastic changes in many plant traits. However, little is known about how these changes affect plant interactions with insect pollinators and herbivores, and what the consequences for plant fitness and selection are. We grew fast-cycling Brassica rapa plants at two temperatures (ambient and increased temperature) and phenotyped them (floral traits, scent, colour and glucosinolates). We then exposed plants to both pollinators (Bombus terrestris) and pollinating herbivores (Pieris rapae). We measured flower visitation, oviposition of P. rapae, herbivore development and seed output. Plants in the hot environment produced more but smaller flowers, with lower UV reflectance and emitted a different volatile blend with overall lower volatile emission. Moreover, these plants received fewer first-choice visits by bumblebees and butterflies, and fewer flower visits by butterflies. Seed production was lower in hot environment plants, both because of a reduction in flower fertility due to temperature and because of the reduced visitation of pollinators. The selection on plant traits changed in strength and direction between temperatures. Our study highlights an important mechanism by which global warming can change plant-pollinator interactions and negatively impact plant fitness, as well as potentially alter plant evolution through changes in phenotypic selection.

Olfactory preference of the litchi fruit borer for oviposition on two litchi varieties.

The litchi fruit borer Conopomorpha sinensis Bradley is a major destructive pest of litchi and longan plants in China, India and South East Asia. Given its strong olfactory-based oviposition behaviour, interfering with the chemical communication between this insect pest and its host plant may serve as a potential control strategy. However, the chemical compounds associated with its egg-laying behaviour remain poorly understood. In this study, we investigated the olfactory preference of female C. sinensis for oviposition on intact mature fruits of the Feizixiao (FZX) and Guiwei (GW) varieties. Results showed that female C. sinensis preferred to lay eggs on FZX compared with GW fruits, and this preference was olfactory-induced. In addition, we identified differences in the chemical composition of the volatile blend and proportions between FZX and GW fruits, with terpenes being the main volatile components contributing to this divergence. Compounds that induced electrophysiological activity in female borers were subsequently screened from FZX. d-Limonene exhibited the strongest oviposition attraction among four candidates. Furthermore, this compound served as a volatile olfactory cue for recognition and orientation in female C. sinensis. The results of this study provide a deeper understanding of the olfactory preferences of female C. sinensis for oviposition on specific litchi varieties. © 2024 Society of Chemical Industry.

Aphid-Induced Volatiles and Subsequent Attraction of Natural Enemies Varies among Sorghum Cultivars.

The production of herbivore-induced plant volatiles (HIPVs) is a type of indirect defense used by plants to attract natural enemies and reduce herbivory by insect pests. In many crops little is known about genotypic variation in HIPV production or how this may affect natural enemy attraction. In this study, we identified and quantified HIPVs produced by 10 sorghum (Sorghum bicolor) cultivars infested with a prominent aphid pest, the sorghum aphid (Melanaphis sorghi Theobald). Volatiles were collected using dynamic headspace sampling techniques and identified and quantified using GC-MS. The total amounts of volatiles induced by the aphids did not differ among the 10 cultivars, but overall blends of volatiles differed significantly in composition. Most notably, aphid herbivory induced higher levels of methyl salicylate (MeSA) emission in two cultivars, whereas in four cultivars, the volatile emissions did not change in response to aphid infestation. Dual-choice olfactometer assays were used to determine preference of the aphid parasitoid, Aphelinus nigritus, and predator, Chrysoperla rufilabris, between plants of the same cultivar that were un-infested or infested with aphids. Two aphid-infested cultivars were preferred by natural enemies, while four other cultivars were more attractive to natural enemies when they were free of aphids. The remaining four cultivars elicited no response from parasitoids. Our work suggests that genetic variation in HIPV emissions greatly affects parasitoid and predator attraction to aphid-infested sorghum and that screening crop cultivars for specific predator and parasitoid attractants has the potential to improve the efficacy of biological control.

Enhanced parasitisation of caterpillars and aphids on field‐grown Brassica oleracea plants upon soil amendment with insect exuviae

Abstract Multitrophic plant–insect interactions are mediated by plant volatiles. The emission of herbivore‐induced plant volatiles is influenced by environmental conditions, such as soil microbes and nutrient composition, with consequences for above‐ground trophic interactions. Here, we investigated whether insect exuviae in the soil alter the plant's volatile blend and attraction of parasitoids in the laboratory and whether this attraction also occurs in the field. We studied the effects of soil amendment with exuviae originating from three insect species, Tenebrio molitor, Acheta domesticus and Hermetia illucens, on the proportion of parasitised Plutella xylostella caterpillars and Brevicoryne brassicae aphids in the field in three consecutive years. In the laboratory, we collected and analysed the volatile blend of amended plants infested with caterpillars or aphids. The attraction of the parasitoids Diadegma semiclausum and Diaeretiella rapae, respectively, towards these volatile blends was assessed in an olfactometer. Our study shows that insect exuviae‐amended soil enhanced the proportion of parasitised herbivores of two species in the field. Relative amounts of several components of the plant volatile blend were affected by soil amendment. Soil amendment with Acheta domesticus or Tenebrio molitor exuviae resulted in an increased attraction of the two parasitoid species in the olfactometer. Soil amendment with insect exuviae altered the plant volatile blend leading to enhanced attraction of parasitoids in laboratory assays. These effects were sustained under the complex and variable biotic and abiotic conditions in the field. Our results underline the importance of belowground processes, such as the decomposition of insect exuviae, on aboveground volatile‐mediated multitrophic interactions. Read the free Plain Language Summary for this article on the Journal blog.

High-resolution kinetics of herbivore-induced plant volatile transfer reveal clocked response patterns in neighboring plants.

Volatiles emitted by herbivore-attacked plants (senders) can enhance defenses in neighboring plants (receivers), however, the temporal dynamics of this phenomenon remain poorly studied. Using a custom-built, high-throughput proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) system, we explored temporal patterns of volatile transfer and responses between herbivore-attacked and undamaged maize plants. We found that continuous exposure to natural blends of herbivore-induced volatiles results in clocked temporal response patterns in neighboring plants, characterized by an induced terpene burst at the onset of the second day of exposure. This delayed burst is not explained by terpene accumulation during the night, but coincides with delayed jasmonate accumulation in receiver plants. The delayed burst occurs independent of day:night light transitions and cannot be fully explained by sender volatile dynamics. Instead, it is the result of a stress memory from volatile exposure during the first day and secondary exposure to bioactive volatiles on the second day. Our study reveals that prolonged exposure to natural blends of stress-induced volatiles results in a response that integrates priming and direct induction into a distinct and predictable temporal response pattern. This provides an answer to the long-standing question of whether stress volatiles predominantly induce or prime plant defenses in neighboring plants, by revealing that they can do both in sequence.

High-resolution kinetics of herbivore-induced plant volatile transfer reveal clocked response patterns in neighboring plants

Volatiles emitted by herbivore-attacked plants (senders) can enhance defenses in neighboring plants (receivers), however, the temporal dynamics of this phenomenon remain poorly studied. Using a custom-built, high-throughput proton transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) system, we explored temporal patterns of volatile transfer and responses between herbivore-attacked and undamaged maize plants. We found that continuous exposure to natural blends of herbivore-induced volatiles results in clocked temporal response patterns in neighboring plants, characterized by an induced terpene burst at the onset of the second day of exposure. This delayed burst is not explained by terpene accumulation during the night, but coincides with delayed jasmonate accumulation in receiver plants. The delayed burst occurs independent of day:night light transitions and cannot be fully explained by sender volatile dynamics. Instead, it is the result of a stress memory from volatile exposure during the first day and secondary exposure to bioactive volatiles on the second day. Our study reveals that prolonged exposure to natural blends of stress-induced volatiles results in a response that integrates priming and direct induction into a distinct and predictable temporal response pattern. This provides an answer to the long-standing question of whether stress volatiles predominantly induce or prime plant defenses in neighboring plants, by revealing that they can do both in sequence.

Evaluation of HOOK SWD attract-and-kill on captures, emergence, and survival of Drosophila suzukii in Florida

Abstract Attract-and-kill can be a useful tactic in managing insect pests as part of an integrated pest management (IPM) program. An attractant, usually a pheromone or food-based volatile blend, is mixed with a killing agent, usually an insecticide, in some form of applicator or dispenser. HOOK® products utilize a SPLAT® gel matrix (ISCA, Riverside, California). HOOK® SWD has been developed for the management of Drosophila suzukii Matsumura (Diptera: Drosophilidae), a major pest of thin-skinned fruit and berry crops. The attractant is a blend of food-based volatiles, and the killing agent is spinosad. This study looked at the use of HOOK® SWD in combination with insecticide applications to manage D. suzukii in conventional and organic blackberries and blueberries. The experiment was conducted on four farms: a conventional commercial blueberry farm, a commercial organic blueberry farm, a conventional u-pick blackberry farm, and a conventional organic blackberry farm all in north-central Florida. HOOK® SWD applied at 7- and 14-day intervals demonstrated efficacy in reducing D. suzukii trap catch and emergence at the organic blackberry and conventional blueberry farms. Drosophila suzukii trap catch and emergence counts at the conventional u-pick blackberry and the organic blueberry farms were not significantly different among treatments. Several factors may have contributed to this lack of efficacy including understory weeds, proximity of unmanaged areas, etc. Therefore, HOOK® SWD shows promise as a D. suzukii management tactic, but further research is needed to optimize its efficacy.

Behavioral responses of Ixodiphagus hookeri (Hymenoptera; Encyrtidae) to Rhipicephalus sanguineus nymphs (Ixodida: Ixodidae) and dog hair volatiles

Abstract The wasp Ixodiphagus hookeri (Howard; Hymenoptera: Encyrtidae) parasitizes the larvae and nymphs of several tick species worldwide. In this study, we investigated whether I. hookeri females are attracted to Rhipicephalus sanguineus Latreille (Ixodida: Ixodidae) nymphs, hair samples from non-infested and infested Schnauzer dog volatiles, and a synthetic blend of compounds isolated from dog hair in a Y-tube glass olfactometer. We also studied the acceptance of fed and unfed R. sanguineus nymphs by female wasps. Our results showed that I. hookeri females were not attracted to R. sanguineus nymphs. In contrast, they were attracted to dog hair samples and extracts from non-infested and R. sanguineus-infested Schnauzer dog hair. Wasps were more attracted to hair samples from R. sanguineus-infested dogs than to those from non-infested dogs. In addition, I. hookeri females were attracted to a synthetic blend composed of hexanal, heptanal, and isovaleric acid, compounds previously isolated from dog hair. In contrast, I. hookeri females were not attracted to binary blends or individual compounds. Female wasps showed a higher acceptance of live-fed and live-unfed R. sanguineus nymphs than of dead fed nymphs washed with dichloromethane. Our results suggests that the host seeking behavior of I. hookeri females is attributable to a blend of volatiles from infested and non-infested schnauzer dogs, used to attack R. sanguineus nymphs.

Simulated Herbivory Affects the Volatile Emissions of Oak Saplings, while Neighbourhood Affects Flavan-3-ols Content of Their Leaves.

To what extent particular plant defences against herbivorous insects are constitutive or inducible will depend on the costs and benefits in their neighbourhood. Some defensive chemicals in leaves are thought to be costly and hard to produce rapidly, while others, including volatile organic compounds that attract natural enemies, might be cheaper and can be released rapidly. When surrounding tree species are more closely related, trees can face an increased abundance of both specialist herbivores and their parasitoids, potentially increasing the benefits of constitutive and inducible defences. To test if oaks (Quercus robur) respond more to herbivore attacks with volatile emission than with changes in leaf phenolic chemistry and carbon to nitrogen ratio (C: N), and whether oaks respond to the neighbouring tree species, we performed an experiment in a forest in Poland. Oak saplings were placed in neighbourhoods dominated by oak, beech, or pine trees, and half of them were treated with the phytohormone methyl jasmonate (elicitor of anti-herbivore responses). Oaks responded to the treatment by emitting a different volatile blend within 24h, while leaf phenolic chemistry and C: N remained largely unaffected after 16 days and multiple treatments. Leaf phenolics were subtly affected by the neighbouring trees with elevated flavan-3-ols concentrations in pine-dominated plots. Our results suggest that these oaks rely on phenols as a constitutive defence and when attacked emit volatiles to attract natural enemies. Further studies might determine if the small effect of the neighbourhood on leaf phenolics is a response to different levels of shading, or if oaks use volatile cues to assess the composition of their neighbourhood.

Field evaluation of electrophysiologically-active dung volatiles as chemical lures for trapping of dung beetles

Dung beetles are economically important beneficial insects that process dung. To locate this source, they use volatile organic compounds (VOCs). The objectives of the study were to evaluate the attractiveness of ten electrophysiologically-active dung volatiles (phenol, skatole, indole, p-cresol, butanone, butyric acid, eucalyptol, dimethyl sulphide, dimethyl disulphide, and toluene) to dung beetles in the field and to investigate how the composition of volatile blends influences efficacy as lures for use in traps. Six combinations of the compounds were compared with field collected cattle dung bait and a negative control, across three seasons. Both dung and synthetic baits captured all exotic dung beetle species present in the study area. A six-compound mix (M1), comprising major dung volatiles, served as an attractive chemical mixture. The addition of dimethyl sulphide, dimethyl disulphide (M2) and toluene (M4) enhanced attractancy of M1 for dung beetles, while eucalyptol (M3) decreased the attractancy. The degree of attraction by various dung beetle species to synthetic baits varied, but baits proved to be effective, especially for summer trapping. The trap design used in this study presented a convenient and practical way to sample dung beetle and other associated scarabs from open pastures. The attraction of introduced dung beetle species to synthetic baits is documented here for the first time in Australia. In addition, necrophagous Omorgus sp. is reported here for the first time to be attracted to synthetic baits. They showed a significant attraction to the mixture containing dimethyl sulphide and dimethyl disulphide (M2). The current study represents a promising first step towards formulating a synthetic chemical lure for dung beetles, offering a consistent, standardised, and bio-secure trapping method compared to use of naturally occurring dung baits, especially as a multi-species lure.

Metabolite profiling reveals the influence of grapevine genetic distance on the chemical signature of juices.

Yield, disease tolerance, and climate adaptation are important traits in grapevine genetic breeding programs. Selection for these characteristics causes unpredictable changes in primary and specialized metabolism, affecting the physicochemical properties and chemical composition of the berries and their processed products, juice, and wine. In this study, we investigated the influence of the genetic distance between grapevine genotypes on the chemical signatures of the juices, by integrating comprehensive metabolic profiling to genetic analyses. The studied grapevine cultivars exhibited low genetic diversity. Breeding for agronomic traits promoted higher contents of soluble sugars, total phenolics, and anthocyanins in the juices. Untargeted juice metabolomics identified a total of 147 metabolites, consisting of 30 volatiles, 21 phenolics, and 96 ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) features. Juices from grapes of the most recent cultivars exhibited increased levels of trans-resveratrol, catechin, and luteolin. The blend of volatiles from juices of later cultivars was also more complex, consisting of 29 distinct metabolites in 'BRS Magna'. Grapes from 'BRS Carmem', an intermediate cultivar, gave the most divergent UHPLC-MS juice profile. Contents of soluble solids, total phenolics, and anthocyanins in grape juices were increased by controlled crosses and hybrid selection. Integrative analyses demonstrated that the juices' metabolic profiles accurately represent the cultivars' genetic distances. Juices from 'BRS Violeta' and 'BRS Magna' show relevant positive association with health-related phenolics and a distinct set of odor volatiles, although these characteristics were specifically sought by breeding. © 2023 Society of Chemical Industry.

Taxonomic insights from floral scents of western North American sessile-flowered Trillium.

Chemical composition of floral volatiles can be an important complement to morphological characters in describing and identifying species. Four of the five species of western sessile-flowered Trillium are challenging to distinguish morphologically due to wide intraspecific variation and overlapping characters among taxa. Characterizing their floral volatile compositions could aid future taxonomic, ecological, and evolutionary studies of Trillium and related taxa. We addressed two major questions: How do western sessile Trillium taxa vary in floral chemistry? Can floral scent be used to distinguish species? We collected petals from 600 individuals at 42 wild populations of four sessile Trillium species across California, Oregon, and Washington. Volatile organic compounds from the petals were extracted using solid-phase microextraction, and the volatiles were identified and quantified by gas chromatography-mass spectrometry. The utility of floral scent composition in distinguishing species was tested using nonmetric multidimensional scaling and random forest analysis. Floral volatiles of the white-petaled T. albidum were dominated by oxygenated monoterpenes and showed considerable geographic variation that paralleled morphological variation. The maroon-petaled T. angustipetalum and T. kurabayashii produced floral scents characterized by aliphatic esters, but each had a distinct chemical composition. Petal color of Trillium chloropetalum is highly variable, as were its scent compositions, which were blends of volatiles from both white-petaled and maroon-petaled congeneric taxa. Differences in floral scent compositions are consistent with current taxonomy of the western sessile Trillium group. In cases where species delimitations are difficult based on morphology, floral scent composition provides taxonomic insight and suggests a potential hybrid origin for T. chloropetalum.

Rugose spiralling whitefly, Aleurodicus rugioperculatus Martin infested host plant volatiles elicit a host locating behavior of aphelinid parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae)

Parasitoids find their hosts by using cues released by herbivores and their host plants. In crop fields, these semiochemicals could be used for insect pest control by attracting and retaining natural enemies. The hymenopteran aphelinidae endoparasitoid, Encarsia guadeloupae (E. guadeloupae), selectively parasitizes rugose spiralling whitefly (RSW), Aleurodicus rugioperculatus Martin, an invasive pest of coconut in India, thus offering an effective way to improve RSW control under natural field conditions. However, the chemical interactions that occur in between the RSW infected host plants and E. guadeloupae were unknown. Hence, using olfactometer assays and chemical analyses, we investigated the volatile organic compounds (VOCs) mediating attraction of the parasitoid to RSW infested host plants. To investigate the attraction of the E. guadeloupae towards the healthy and RSW infected leaves of coconut (Cocos nucifera L), banana (Musa paradisiaca L) and custard apple (Annona squmosa L), we employed a six-arm olfactometer. The E. guadeloupae preferred the volatile compounds from RSW-infested host plants rather than healthy plants. A higher percent response rate of E. guadeloupae was observed in RSW-infected banana (35.83 %), followed by healthy banana (24.33 %), RSW-infested custard apple (16.33 %), and RSW-infested coconut (9.00 %) leaf volatiles, respectively. The volatile compounds emitted from RSW-infested and healthy plants have been studied using GC–MS with thermal desorption (TD). The results revealed more than 20 volatile compounds belonging to seven chemical classes were identified and characterized from infested plants by RSW. Of these, α-Ocimene, α-Pinene, 3-Carene, trans-α-Ocimene, and (E)-hex-3-ene-2, 5-diol were emitted at higher levels than other compounds its proven through PCA and Heat map analysis. These five compounds elicited the greatest attraction of E. guadeloupae towards RSW damaged plants. The synthetic blend of the above volatiles could be used as attractants to enhance the population of E. guadeloupae to manage RSW under field conditions.