Volatile Odorants Research Articles

In the arm-in-cage test, topical repellents activate mosquitoes to disengage upon contact instead of repelling them at distance

Topical repellents provide protection against mosquito bites and their efficacy is often assessed using the arm-in-cage test. The arm-in-cage test estimates the repellent’s protection time by exposing a repellent-treated forearm to host-seeking mosquitoes inside a cage at regular intervals until the first confirmed mosquito bite. However, the test does not reveal the repellents’ behavioural mode of action. To understand how mosquitoes interact with topical repellents in the arm-in-cage test, we used a 3D infrared video camera system to track individual Aedes aegypti and Anopheles stephensi females during exposure to either a repellent-treated or an untreated forearm. The repellents tested were 20% (m/m) ethanolic solutions of N, N-diethyl-meta-toluamide, p-menthane-3,8-diol, icaridin and ethyl butylacetylaminopropionate. All four repellents substantially reduced the number of bites compared to an untreated forearm, while the flight trajectories indicate that the repellents do not prevent skin contact as the mosquitoes made multiple brief contacts with the treated forearm. We conclude that, in the context of the arm-in-cage test, topical repellents activate mosquitoes to disengage from the forearm with undirected displacements upon contact rather than being repelled at distance by volatile odorants.

Evaluation of High Vacuum Flavor Extraction Device as a Novel Technique for the Extraction of Volatile Compounds

In this study, a high vacuum flavor extraction (HVE) device was developed to address the limitations of traditional extraction methods, such as extended extraction times and artifact generation during high-temperature processes. Firstly, the repeatability and precision of the HVE method were evaluated through quantitative analysis of twelve volatile odor compounds across seven replicate extractions using gas chromatography–flame ionization detection (GC-FID). The results showed that the HVE system achieved a mean relative standard deviation (RSD) of 11.60 ± 1.79% and a recovery rate of 90.55 ± 4.56%, demonstrating its precision and reproducibility. Secondly, the performance of HVE was compared with solvent-assisted flavor evaporation (SAFE) and simultaneous distillation–extraction (SDE) for extracting flavor compounds from fried tilapia mince. The results indicated that HVE was more effective, particularly in extracting aldehydes and pyrazines, which are key contributors to the flavor profile. Finally, sensory evaluations supported these findings, showing that the odor profiles obtained through HVE were most similar to the original sample, with a similarity score of 72.55%, compared to 69.25% for SAFE and 60.29% for SDE. These findings suggest that HVE is a suitable method for the extraction and analysis of volatile compounds in complex food matrices such as fried tilapia mince.

Metabolomics reveals a differential attitude in phytochemical profile of black tea (Camellia Sinensis Var. assamica) during processing

Black tea's quality and flavor are largely influenced by its processing stages, which affect its volatile and non-volatile phytochemicals. This study aimed to optimized black tea manufacturing by investigating withering time, fermentation time, and temperature's impact on sensory quality. Using a U*15 (157) uniform design, optimal conditions were determined: 14 h of withering, 5.6 h of fermentation, and a 34 °C temperature. A verification experiment analyzed the volatile and non-volatile profiles. HPLC, GC–MS, and LC-MS revealed dynamic changes in phytochemicals. Among 157 VOCs and 2642 metabolites, 19 VOCs (VIP > 1.5) were crucial for aroma, while 50 (VIP > 1.5, p < 0.01) characteristic metabolites were identified. During processing, fragrant volatile compounds like linalool oxides, geraniol, benzeneacetaldehyde, benzaldehyde, methyl salicylate, and linalyl acetate increased, contributing to rose and honey like aromas. These changes were crucial in developing the characteristic flavor and color of black tea. Twenty-four new compounds formed, while 80 grassy odor volatiles decreased. Non-volatile metabolites changed notably, with decreased catechins and increased gallic acid. Theaflavin compounds rose initially but declined later. This study outlines metabolite changes in Yunkang 10 black tea, crucial for flavor enhancement and quality control.

Rapid Lactic Acid Content Detection in Secondary Fermentation of Maize Silage Using Colorimetric Sensor Array Combined with Hyperspectral Imaging

Lactic acid content is a crucial indicator for evaluating maize silage quality, and its accurate detection is essential for ensuring product quality. In this study, a quantitative prediction model for the change of lactic acid content during the secondary fermentation of maize silage was constructed based on a colorimetric sensor array (CSA) combined with hyperspectral imaging. Volatile odor information from maize silage samples with different days of aerobic exposure was obtained using CSA and recorded by a hyperspectral imaging (HSI) system. Subsequently, the acquired spectral data were subjected to preprocessing through five distinct methods before being modeled using partial least squares regression (PLSR). The coronavirus herd immunity optimizer (CHIO) algorithm was introduced to screen three color-sensitive dyes that are more sensitive to changes in lactic acid content of maize silage. To minimize model redundancy, three algorithms, such as competitive adaptive reweighted sampling (CARS), were used to extract the characteristic wavelengths of the three dyes, and the combination of the characteristic wavelengths obtained by each algorithm was used as an input variable to build an analytical model for quantitative prediction of the lactic acid content by support vector regression (SVR). Moreover, two optimization algorithms, namely grid search (GS) and crested porcupine optimizer (CPO), were compared to determine their effectiveness in optimizing the parameters of the SVR model. The results showed that the prediction accuracy of the model can be significantly improved by choosing appropriate pretreatment methods for different color-sensitive dyes. The CARS-CPO-SVR model had better prediction, with a prediction set determination coefficient (RP2), root mean square error of prediction (RMSEP), and a ratio of performance to deviation (RPD) of 0.9617, 2.0057, and 5.1997, respectively. These comprehensive findings confirm the viability of integrating CSA with hyperspectral imaging to accurately quantify the lactic acid content in silage, providing a scientific and novel method for maize silage quality testing.

Analysis of flower volatile compounds and odor classification of 17 tree peony cultivars

As one of the significant ornamental characteristics of tree peony, floral fragrance has garnered considerable attention. In this study, 65 cultivars of tree peony were classified into three groups based on their sensory evaluation scores: strong fragrance, medium fragrance, and no/light fragrance and 9 strong fragrance cultivars, 6 medium fragrance cultivars, and 2 light/no fragrance cultivars were selected for substance analysis. Using gas chromatography-mass spectrometry (GC–MS), 77 volatile organic compounds (VOCs) were identified and classified from 17 tree peony cultivars, they were terpenoids, benzenoids/phenylpropanoids, and fatty acid derivatives. Monoterpenoids were the main volatile compounds in the cultivars ‘Souvenir de Maxime Cornu’, ‘Okan’, ‘Chromatella’, ‘Yapianzi’, and ‘Liuli Guanzhu’, while benzenoids/phenylpropanoids were the main volatile compounds in ‘Shaonvqun’ and ‘Binglingzi’. Through the calculation of odor activity value (OAV), 17 cultivars were categorized into four distinct groups: flower-sweet scent, flower-rose scent, herb scent and mixed scent. This investigation presented the composition and classification of fragrant compounds of 17 tree peony cultivars and classified the odor profiles based on the contribution of flower volatiles to the overall olfactory experience, offering valuable materials for genetic enhancement of tree peony floral fragrance.

Pseudomonas aeruginosa modulates both Caenorhabditis elegans attraction and pathogenesis by regulating nitrogen assimilation

Detecting chemical signals is important for identifying food sources and avoiding harmful agents. Like many animals, C. elegans use olfaction to chemotax towards their main food source, bacteria. However, little is known about the bacterial compounds governing C. elegans attraction to bacteria and the physiological importance of these compounds to bacteria. Here, we address these questions by investigating the function of a small RNA, P11, in the pathogen, Pseudomonas aeruginosa, that was previously shown to mediate learned pathogen avoidance. We discovered that this RNA also affects the attraction of untrained C. elegans to P. aeruginosa and does so by controlling production of ammonia, a volatile odorant produced during nitrogen assimilation. We describe the complex regulation of P. aeruginosa nitrogen assimilation, which is mediated by a partner-switching mechanism involving environmental nitrates, sensor proteins, and P11. In addition to mediating C. elegans attraction, we demonstrate that nitrogen assimilation mutants perturb bacterial fitness and pathogenesis during C. elegans infection by P. aeruginosa. These studies define ammonia as a major mediator of trans-kingdom signaling, implicate nitrogen assimilation as important for both bacteria and host organisms, and highlight how a bacterial metabolic pathway can either benefit or harm a host in different contexts.

Does Maternal Diet Influence Future Infant Taste and Odor Preferences? A Critical Analysis.

The dietary choices a mother makes during pregnancy offer her developing fetus its earliest exposure to the family's culinary preferences. This comprehensive literature review synthesizes five decades of research, which has provided valuable insights into fetal flavor learning. Converging evidence across various species supports the functionality of fetal chemoreceptive systems by the end of gestation, enabling the detection of an extensive array of chemosensory cues derived from the maternal diet and transmitted to the amniotic fluid. The fetus effectively encodes these flavors, resulting in their enhanced acceptance after birth. While existing studies predominantly concentrate on fetal learning about odor volatiles, limited evidence suggests a capacity for learning about gustatory (i.e., taste) properties. Examining whether these prenatal odor, taste, and flavor experiences translate into enduring shifts in dietary behaviors beyond weaning remains a crucial avenue for further investigation.

Biodetection of an odor signature in white-tailed deer associated with infection by chronic wasting disease prions.

Chronic wasting disease (CWD) has become a major concern among those involved in managing wild and captive cervid populations. CWD is a fatal, highly transmissible spongiform encephalopathy caused by an abnormally folded protein, called a prion. Prions are present in a number of tissues, including feces and urine in CWD infected animals, suggesting multiple modes of transmission, including animal-to-animal, environmental, and by fomite. CWD management is complicated by the lack of practical, non-invasive, live-animal screening tests. Recently, there has been a focus on how the volatile odors of feces and urine can be used to discriminate between infected and noninfected animals in several different species. Such a tool may prove useful in identifying potentially infected live animals, carcasses, urine, feces, and contaminated environments. Toward this goal, dogs were trained to detect and discriminate CWD infected individuals from non-infected deer in a laboratory setting. Dogs were tested with novel panels of fecal samples demonstrating the dogs' ability to generalize a learned odor profile to novel odor samples based on infection status. Additionally, dogs were transitioned from alerting to fecal samples to an odor profile that consisted of CWD infection status with a different odor background using different sections of gastrointestinal tracts. These results indicated that canine biodetectors can discriminate the specific odors emitted from the feces of non-infected versus CWD infected white-tailed deer as well as generalizing the learned response to other tissues collected from infected individuals. These findings suggest that the health status of wild and farmed cervids can be evaluated non-invasively for CWD infection via monitoring of volatile metabolites thereby providing an effective tool for rapid CWD surveillance.

Oxytocin induces the formation of distinctive cortical representations and cognitions biased toward familiar mice

Social recognition is essential for the formation of social structures. Many times, recognition comes with lesser exploration of familiar animals. This lesser exploration has led to the assumption that recognition may be a habituation memory. The underlying memory mechanisms and the thereby acquired cortical representations of familiar mice have remained largely unknown, however. Here, we introduce an approach directly examining the recognition process from volatile body odors among male mice. We show that volatile body odors emitted by mice are sufficient to identify individuals and that more salience is assigned to familiar mice. Familiarity is encoded by reinforced population responses in two olfactory cortex hubs and communicated to other brain regions. The underlying oxytocin-induced plasticity promotes the separation of the cortical representations of familiar from other mice. In summary, neuronal encoding of familiar animals is distinct and utilizes the cortical representational space more broadly, promoting storage of complex social relationships.

Examination of the Odor-Eliminating Effect of a Deodorizing Spray on the Volatile Odorants of Malignant Wounds.

This study aimed to compare the odor components before and after spraying a deodorizing spray (DS) on volatile odorants in malignant wounds (MWs) in women with breast cancer; a secondary aim was to evaluate the deodorizing effect of the DS. This is an observational study. We investigated 3 patients who had MWs resulting from breast cancer. Participants were recruited from outpatient clinics in the Breast Surgery Department, University Hospital, Kanagawa, Japan. The target material was exudate-containing dressings collected from MWs. After collection, the odor components (air) were collected into a sampling bag by using a handheld pump. Then, after 5 sprays of a DS, air was collected in the same manner. All odor components were analyzed objectively by gas chromatography-mass spectrometry-olfactometry (GC/MS-O). The concentration in parts per million (ppm) of the main odor components in the air before and after spraying DS was compared, and the residual concentration rate (%) was calculated. Sniffing tests before and after spraying were also conducted to determine the subjective deodorizing effect of DS. Of the possible hundreds of volatile odorants, 3 to 11 main components of volatile odorants were detected per subject. After DS spraying, the odorants dimethyl disulfide, dimethyl trisulfide, and benzyl alcohol were reduced according to GC/MS-O. The residual concentration of the following main odor components was also reduced: benzyl alcohol (30%), octanal (56%), p-dichlorobenzene (56%), isovaleric acid (56%), propylene glycol (63%), and nonanal (66%). DS was effective against some volatile odorants in MWs, but no clear deodorizing effect was observed. Since there are individual differences in the type and number of odorants in MWs, the use of DS needs to be examined and verified in a larger number of cases.

Earthy/musty odour bioaccumulation in Plecoglossus altivelis grown in a land-based aquaculture fed by reclaimed secondary effluent in wastewater treatment plant

ABSTRACT Reclaimed wastewater (RWW) has been used globally for centuries, though its application in aquaculture is less extensive. Limited study has addressed impacts of RWW-derived volatile odour compounds (VOCs), such as 2,4,6-trichloroanisole (TCA), 2-methylisoborneol (MIB), and geosmin (GSM), on fish quality. This study aims to (1) assess the feasibility of reusing secondary effluent from a municipal wastewater treatment plant (WWTP) for Plecoglossus altivelis aquaculture in a land-based flow-through system and (2) evaluate the sensory effects of selected VOCs on fish quality. Results showed that increased temperature and ammonia levels in summer RWW negatively affected fish growth, while autumn RWW did not. Heavy metals in fish did not cause health issues. TCA, MIB, and GSM concentrations in fish tissues were 4.7–5.7, 0.3–40.5, and 1.1–1.9 mg kg−1, respectively. TCA emerged as the most concerning odorant, with higher relative odour intensity than MIB and GSM in RWW-cultured fish, regardless of seasonal change. This study is the first to report on a self-constructed aquaculture system using RWW at a WWTP, recommending effective VOC and ammonia removal for sustainable RWW use in aquaculture. Additionally, the study highlighted TCA's impact as an anthropogenic indicator in aquatic environments amid increasing WWTP prevalence in developed cities.

Mechanisms underlying the formation of main volatile odor sulfur compounds in foods during thermal processing.

Volatile sulfur compounds (VSCs) significantly influence food flavor and garner considerable attention in flavor research due to their low sensory thresholds, diverse odor attributes, and high reactivity. Extensive research studies have explored VSC formation through thermal processes such as the Maillard reaction, thermal pyrolysis, oxidation, and enzymatic reactions. However, understanding of the specific reaction mechanisms and processes remains limited. This is due to the dispersed nature of existing studies, the undefined intermediates involved, and the complexity of the matrices and processing conditions. Given these limitations, the authors have shifted their focus from foods to sulfides. The structure, source, and chemical characteristics of common precursors (sulfur-containing amino acids and derivatives, thiamine, thioglucoside, and lentinic acid) and their corresponding reactive intermediates (hydrogen sulfide, thiol, alkyl sulfide, alkyl sulfenic acid, and thial) are provided, and the degradation mechanisms, reaction rules, and matrix conditions are summarized based on their chemical characteristics. Additionally, the VSC formation processes in several typical foods during processing are elucidated, adhering to these identified rules. This article provides a comprehensive overview of VSCs, from precursors and intermediates to end products, and is crucial for understanding the mechanisms behind VSC formation and managing the flavor qualities of processed foods.

Molecular Characterization of Chemosensory Protein (CSP) Genes and the Involvement of AgifCSP5 in the Perception of Host Location in the Aphid Parasitoid Aphidius gifuensis.

Aphidius gifuensis is the dominant parasitic natural enemy of aphids. Elucidating the molecular mechanism of host recognition of A. gifuensis would improve its biological control effect. Chemosensory proteins (CSPs) play a crucial role in insect olfactory systems and are mainly involved in host localization. In this study, a total of nine CSPs of A. gifuensis with complete open reading frames were identified based on antennal transcriptome data. Phylogenetic analysis revealed that AgifCSPs were mainly clustered into three subgroups (AgifCSP1/2/7/8, AgifCSP3/9, and AgifCSP4/5/6). AgifCSP2/5 showed high expression in the antennae of both sexes. Moreover, AgifCSP5 was found to be specifically expressed in the antennae. In addition, fluorescent binding assays revealed that AifCSP5 had greater affinities for 7 of 32 volatile odor molecules from various sources. Molecular docking and site-directed mutagenesis results revealed that the residue at which AgifCSP5 binds to these seven plant volatiles is Tyr75. Behavior tests further confirmed that trans-2-nonenal, one of the seven active volatiles in the ligand binding test, significantly attracted female adults at a relatively low concentration of 10 mg/mL. In conclusion, AgifCSP5 may be involved in locating aphid-infested crops from long distances by detecting and binding trans-2-nonenal. These findings provide a theoretical foundation for further understanding the olfactory recognition mechanisms and indirect aphid localization behavior of A. gifuensis from long distances by first identifying the host plant of aphids.

NAD activates olfactory receptor 1386 to regulate type I interferon responses in Plasmodium yoelii YM infection

Olfactory receptors (Olfr) are G protein-coupled receptors that are normally expressed on olfactory sensory neurons to detect volatile chemicals or odorants. Interestingly, many Olfrs are also expressed in diverse tissues and function in cell-cell recognition, migration, and proliferation as well as immune responses and disease processes. Here, we showed that many Olfr genes were expressed in the mouse spleen, linked to Plasmodium yoelii genetic loci significantly, and/or had genome-wide patterns of LOD scores (GPLSs) similar to those of host Toll-like receptor genes. Expression of specific Olfr genes such as Olfr1386 in HEK293T cells significantly increased luciferase signals driven by IFN-β and NF-κB promoters, with elevated levels of phosphorylated TBK1, IRF3, P38, and JNK. Mice without Olfr1386 were generated using the CRISPR/Cas9 method, and the Olfr1386-/- mice showed significantly lower IFN-α/β levels and longer survival than wild-type (WT) littermates after infection with P. yoelii YM parasites. Inhibition of G protein signaling and P38 activity could affect cyclic AMP-responsive element promoter-driven luciferase signals and IFN-β mRNA levels in HEK293T cells expressing the Olfr1386 gene, respectively. Screening of malaria parasite metabolites identified nicotinamide adenine dinucleotide (NAD) as a potential ligand for Olfr1386, and NAD could stimulate IFN-β responses and phosphorylation of TBK1 and STAT1/2 in RAW264.7 cells. Additionally, parasite RNA (pRNA) could significantly increase Olfr1386 mRNA levels. This study links multiple Olfrs to host immune response pathways, identifies a candidate ligand for Olfr1386, and demonstrates the important roles of Olfr1386 in regulating type I interferon (IFN-I) responses during malaria parasite infections.

Characterization of Key Odor-Active Compounds in Draft Beers for the Chinese Market Using Molecular Sensory Science Approaches.

Beer is a popular alcoholic beverage worldwide. However, limited research has been conducted on identifying key odor-active components in lager-type draft beers for the Chinese market. Therefore, this study aims to elucidate the odor characteristics of the four most popular draft beer brands through a sensory evaluation and an electronic nose. Subsequently, the four draft beers were analyzed through solid-phase microextraction and liquid-liquid extraction using a two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GC×GC-O-MS). Fifty-five volatile odor compounds were detected through GC×GC-O-MS. Through an Aroma Extract Dilution Analysis, 22 key odor-active compounds with flavor dilution factors ≥ 16 were identified, with 11 compounds having odor activity values > one. An electronic nose analysis revealed significant disparities in the odor characteristics of the four samples, enabling their distinct identification. These findings help us to better understand the flavor characteristics of draft beer and the stylistic differences between different brands of products and provide a theoretical basis for objectively evaluating the quality differences between different brands of draft beer.

Development of active hydrogel absorbent pads based on sodium alginate/potassium-doped carbon dots for chilled pork preservation

In this study, potassium-doped carbon dots (K-CDs) were added to sodium alginate (NaAlg) hydrogel to yield high-strength, antibacterial, antioxidant NaAlg hydrogel absorbent pads (NaAlg/K-CDs) to absorb chilled pork exudate during storage. The results revealed that the swelling rates of the NaAlg/K-CDs peaked at 3286.83%, a figure exceeding that of the commercial absorbent pads. Based on the bacterial diversity and richness results, Pseudomonas aeruginosa (P. aeruginosa) was evidently the dominant spoilage organism during chilled pork storage. On storage day 6, the P. aeruginosa population in the NaAlg/K-CDs hydrogel absorbent pad group was 82% of that in the control group. The total volatile basic nitrogen (TVB-N) value of the NaAlg/K-CDs group remained lower than 0.15 mg/g on day 8. The pH, TVB-N, total viable count (TVC), cooking loss, and volatile odour values of the chilled pork in the NaAlg/K-CDs hydrogel absorbent pad group were significantly lower than those in other absorbent pad groups. Moreover, the colour change and shear force values of the chilled pork in the NaAlg/K-CDs hydrogel absorbent pad group were lower than those in the control and wood fiber paper absorbent pad groups. These results indicate that the shelf life of the NaAlg/K-CDs-packaged chilled pork was extended by 2 days compared with that of the control. Therefore, the NaAlg/K-CDs hydrogel absorbent pads potentially inhibited microbial growth and improved the storage quality of chilled pork. This study provides an alternative solution against traditional chilled pork absorbent pads, further promoting the advancement of fresh meat preservation techniques.

Accentuation of the browning characteristics and functional properties of aged tomatoes (Solanum lycopersicum cv.)

Moisture-assisted aging technology (MAAT) is a green process that improves browning characteristics and functionalities. This study investigated the physicochemical and functional characteristics of aged tomatoes. MAAT modulated carotenoids biotransformation from esterified to free form (Fourier-transform infrared spectroscopy 1738, 2851, and 2922 cm−1) and generated primary and secondary oxidation volatiles, such as 4-terpineol, α-terpineol, and γ-terpineol (Headspace solid-phase microextraction gas chromatography-mass), which contributed woody and clove odors. Total flavonoids and α-glucosidase activity inhibitory were significantly increased from 1207.729 to 2318.204 mg RE/100 g DW and 77.703% to 86.851%, respectively. We discovered different synthesis pathways of 5-HMF and furfural under different water activities; this breakthrough may set furfural as an important factor in quality control of MAAT products in the future. Thus, MAAT can modulate the chemical form of tomato carotenoids, improve functionalities, and generate unique woody odor volatiles. These results may be applied to health food development in the food industry.

The impacts of cold plasma on the taste and odor formation of dried silver carp products

This study investigated non-thermal pretreatment (cold plasma, CP) on the flavor (taste and odor) profiles of dried fish products. CP treatment of 5 min contributed to accumulation of umami nucleotides adenosine 5′-monophosphate (AMP) from 30.96 to 40.82 μg/g and inosine 5′-monophosphate (IMP) from 2009.29 to 2132.23 μg/g, and significant reduction of bitter hypoxanthine ribonucleoside (HxR) and hypoxanthine (Hx), respectively (P < 0.05) in the dried fish products. A noticeable enhancement in sweet glycine (from 429.41 to 490.03 mg/100 g) and umami glutamic acid (from 55.68 to 67.76 mg/100 g) accompanied with the CP treatment (P < 0.05) based on taste activity value (TAV > 1). And the characteristic odor volatiles (nonanal, hexanal and 1-octen-3-ol) were strengthened 2.13-, 2.16- and 2.17- folds, respectively (P < 0.05). The results of equivalent umami concentration and Gibbs free energy calculation, combining with the correlation analysis, indicate that nucleotides and free amino acids synergically enhanced the taste improvement of dried fish products. Moderate lipids oxidation favored the formation of characteristic volatiles. The CP pretreatment offered new strategies for enhancing flavor of dried fish products.

Antifungal activity of bio-active cell-free culture extracts and volatile organic compounds (VOCs) synthesised by endophytic fungal isolates of Garden Nasturtium

Antimicrobial resistance in fungal pathogens (both human and plant) is increasing alarmingly, leading to massive economic crises. The existing anti-fungal agents are becoming ineffective, and the situation worsens on a logarithmic scale. Novel antifungals from unique natural sources are highly sought to cope sustainably with the situation. Metabolites from endophytic microbes are the best-fitted alternatives in this case. Endophytes are the untapped sources of ‘plants’ internal microbial population’ and are promising sources of effective bio-therapeutic agents. Fungal endophytes were isolated from Tropaeolum majus and checked for antifungal activity against selected plant and human pathogens. Bioactive metabolites were identified through chromatographic techniques. The mode of action of those metabolites was evaluated through various spectroscopic techniques. The production of antifungal metabolite was optimized also. In particular VOCs (volatile organic compounds) of TML9 were tested in vitro for their anti-phytopathogenic activity. Ethyl acetate (EA) extract of cell-free culture components of Colletotrichum aenigma TML3 exhibited broad-spectrum antifungal activity against four species of Candida and the major constituents reported were 6-pentyl-2H-pyran-2-one, 2-Nonanone, 1 propanol 2-amino. The volatile metabolites, trans-ocimene, geraniol, and 4-terpinyl acetate, produced from Curvularia lunata TML9, inhibited the growth of some selected phyto pathogens. EA extract hampered the biofilm formation, minimised the haemolytic effect, and blocked the transformation of Candida albicans (MTCC 4748) from yeast to hyphal form with a Minimum Fungicidal Concentration (MFC) of 200–600 µg mL−1. Central carbohydrate metabolism, ergosterol synthesis, and membrane permeability were adversely affected and caused the lethal leakage of necessary macromolecules of C. albicans. Volatile metabolites inhibited the growth of phytopathogens i.e., Rhizoctonia solani, Alternaria alternata, Botrytis cinerea, Cercospora beticola, Penicillium digitatum, Aspergillus fumigatus, Ceratocystis ulmi, Pythium ultimum up to 89% with an IC50 value of 21.3–69.6 µL 50 mL−1 and caused leakage of soluble proteins and other intracellular molecules. Citrusy sweet odor volatiles of TML9 cultured in wheat-husk minimised the infections of Penicillium digitatum (green mold), in VOC-exposed sweet oranges (Citrus sinensis). Volatile and non-volatile antifungal metabolites of these two T. majus endophytes hold agricultural and pharmaceutical interests. Metabolites of TML3 have strong anti-Candida activity and require further assessment for therapeutic applications. Also, volatile metabolites of TML9 can be further studied as a source of antifungals. The present investigational outcomes bio-prospects the efficacy of fungal endophytes of Garden Nasturtium.

Olfactory Responses of Asproparthenis punctiventris Germar to Leaf Odours of Amaranthaceae Plants.

Understanding the stimuli used by insect pests to find their food plants can be a first step towards manipulating their behaviour and, thus, controlling them. We investigated the responses of the sugar beet weevil Asproparthenis punctiventris (Coleoptera: Curculionidae) to the volatile leaf odours of its food plants, including Beta vulgaris subsp. vulgaris (Altissima and Cicla groups), Atriplex hortensis, Chenopodium album, and Amaranthus retroflexus, in a four-arm olfactometer. A bioassay procedure was developed, and the frequency of visits and time spent by adult weevils in the quadrant of the olfactometer with leaf volatiles was recorded, as was their first choice of quadrant. Females and males were equally attracted to the leaf odours of young B. vulgaris subsp. vulgaris plants, i.e., sugar beet and chard, as indicated by the overall picture of the behavioural parameters analysed. Males, but not females, responded positively to the leaf odour of the garden orache (A. hortensis), and no response was observed when the weevils were tested with the leaf odours of fat hen (C. album) or common amaranth (A. retroflexus). These results suggest that A. punctiventris uses leaf odours to locate sugar beet and other food plants. Knowledge of the olfactory responses of this pest can provide a basis for improved monitoring or mass trapping strategies.