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Objective: Previous research has explored the pheromone release patterns of female moths, revealing species-specific release frequencies and the transmission of temporal information through odourant plumes in turbulent flows. Varying the release frequency during the orientation process results in distinct orientation behaviours. Studies on moth movement patterns have determined that encounters and deviations from odour plumes elicit distinct reactions; the time interval between each movement pattern is measured as the "reaction time," and the interval between each detection and loss of odourant plume is measured as the "gap length." Methods: We simulated turbulent flow at various release frequencies. Our efforts focused on establishing a model that could simulate the joint orientation movement under turbulent flow and intermittent plumes. We built an agent moving mechanism, including wind velocity information, with particular reference to the temporal parameter and orientation success efficiency. Results: We calculated the time threshold of each burst in different simulations under different wind velocities and release frequencies. The time structure characteristics of the plume along the turbulent flow vary depending on the distance from the source. We simulated walking agents in a turbulent environment and recorded their behaviour processes. The reaction time, release interval, and time threshold were related to the orientation results. Conclusion: On the basis of previous experimental results and our simulations, we conclude that the designated interval time likely enhances search efficiency. The complex and dynamic natural environment presents various opportunities for using this unique odour-source searching capability in different scenarios, potentially improving the control systems of odour-searching robots.

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OBJECTIVE: Excessive and unpleasant odours that emanate from the skin can induce bromhidrosis and substantially impair a person's quality of life. Enzymatic pathways generating unpleasant odours are well detailed, and among them, the C-S lyase is one of the enzymes involved in the conversion of non-volatile precursors into thiol-type malodorous volatile molecules such as 3M3SH. This study aimed to investigate the variation of axillary odour intensity correlated with Staphylococcus (S.) hominis C-S lyase activity within a group of volunteers after a physical activity. METHODS: First, a group of 24 volunteers from the same ethnicity with standardized hygienic and alimentary practices participated in a supervised indoor cycling activity. Following this session, worn T-shirts were recovered to enable the olfactory evaluation of axillary odours by qualified experts. To go further, the microbiota from the axillary zone of each volunteer was sampled and the bacterial relative abundance was investigated by using 16S rRNA metasequencing. Then, S. hominis isolates were obtained by culturomics from these microbiota samples and the C-S lyase activity was measured by spectrofluorometry in protein crude extracts. RESULTS: The evaluation of the odour intensity revealed that within the panel, two groups were significantly distinct. A non-odorous group and a malodorous one with volunteers having unpleasant odours. The 16S rRNA metasequencing reveals differences in bacterial communities between the two groups with a significant increase in the relative abundance of S. hominis in the malodorous group compared with the non-odorous one. The C-S lyase activities measured on S. hominis sampled on volunteers from the two groups demonstrate that for an equivalent quantity of protein, this enzymatic activity is significantly higher for the samples originating from the malodorous group. CONCLUSION: Hence, this study demonstrates that beyond the increase of S. hominis relative abundance, the C-S lyase enzymatic activity of this bacteria is also higher in volunteers with unpleasant axillary odours.

OBJECTIF: Les odeurs excessives et désagréables qui émanent de la peau peuvent induire une bromhidrose et altérer considérablement la qualité de vie d'une personne. Les voies enzymatiques générant des odeurs désagréables sont bien détaillées, et parmi elles, la C­S lyase est l'une des enzymes impliquées dans la conversion de précurseurs non volatils en molécules volatiles malodorantes de type thiols, telles que le 3M3SH. Cette étude avait pour objectif d'investiguer la variation de l'intensité de l'odeur axillaire corrélée à l'activité de la C­S lyase de Staphylococcus (S.) hominis d'un groupe de volontaires après la pratique d'une activité sportive. MÉTHODES: Un groupe de 24 volontaires de la même ethnie ayant des pratiques hygiéniques et alimentaires standardisées ont participé à une séance calibrée de vélo d'intérieur. Après cette activité, les t­shirts portés ont été récupérés pour permettre l'évaluation olfactive des odeurs axillaires par des experts qualifiés. Pour aller plus loin, le microbiote de la zone axillaire de chaque volontaire a été prélevé et l'abondance relative des bactéries a été étudiée par métaséquençage de l'ARNr 16S. Ensuite, des isolats de S. hominis ont été obtenus par culturomique à partir de ces échantillons de microbiote et l'activité de la C­S lyase a été mesurée par spectrofluorométrie dans des extraits protéiques totaux. RÉSULTATS: L'évaluation de l'intensité des odeurs a révélé qu'au sein du panel, deux groupes se distinguaient de manière significative. Un groupe non­odorant et un groupe malodorant avec des volontaires ayant des odeurs axillaires désagréables. Le métaséquençage de l'ARNr 16S révèle des différences dans les communautés bactériennes entre les deux groupes avec une augmentation significative de l'abondance relative de S. hominis dans le groupe malodorant par rapport au groupe non­odorant. L'activité enzymatique de la C­S lyase mesurée à partir d'isolats de S. hominis prélevés sur des volontaires des deux groupes démontrent que, pour une quantité équivalente de protéines, cette activité enzymatique est significativement plus élevée pour les échantillons provenant du groupe malodorant. CONCLUSION: Cette étude démontre qu'au­delà de l'augmentation de l'abondance relative de S. hominis, l'activité de la C­S lyase de cette bactérie est également plus élevée chez les volontaires présentant des odeurs axillaires désagréables.

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In recent decades, the compositions of preen oil and feathers have been studied to achieve insights into the chemistry of avian odours, which play a significant role in birds' social behaviour. Fewer studies are available regarding volatiles originating from other sources, such as faeces, eggs or a bird's whole body. The aims of this study were (i) to identify odour-active and further volatile compounds in zebra finch whole body odour and (ii) to semi-quantify selected volatiles and use the information to evaluate two different adsorbents for their suitability for whole body odour sampling. Volatiles from the headspace above zebra finches were sampled using an open loop system equipped with either activated charcoal or Tenax® TA. Samples were analysed by olfactory-guided approaches as well as gas chromatography-mass spectrometry. Using activated charcoal as sorbent, 26 odour-active and 73 further volatile compounds were detected, whereas with Tenax® TA 27 odour-active and 81 further volatile compounds were detected. In total, 104 compounds were (tentatively) identified, of which 22 had not been identified previously in zebra finch odour and 12 had not been described in any birds. Hints towards a chemical sex signature became evident for qualitative but not for quantitative differences. With the exception of some compounds, notably carboxylic acids and alkanes, relative peak areas obtained with the two adsorbent types were comparable. The approach described herein is proposed for future studies aiming to determine volatiles emitted by birds when, for example, parent birds are approaching the nest.

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Mate choice, and sex differences in romantic behaviours, represented one of the first major applications of evolutionary biology to human behaviour. This paper reviews Darwinian approaches to heterosexual mate assessment based on physical characteristics, placing the literature in its historical context (1871-1979), before turning (predominantly) to psychological research on attractiveness judgements based on physical characteristics. Attractiveness is consistently inferred across multiple modalities, with biological theories explaining why we differentiate certain individuals, on average, from others. Simultaneously, it is a judgement that varies systematically in light of our own traits, environment, and experiences. Over 30 years of research has generated robust effects alongside reasons to be humble in our lack of understanding of the precise physiological mechanisms involved in mate assessment. This review concludes with three questions to focus attention in further research, and proposes that our romantic preferences still provide a critical window into the evolution of human sexuality.

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Aroma is a crucial indicator of hop quality. This study analyzed the differences in aroma compound composition among six hop varieties from three regions: North America, Europe, and Asia. Descriptive analysis and sensomic approaches including gas chromatography-olfactometry/aroma extract dilution analysis, odour activity value calculation and aroma recombination were used for the detailed characterization and comparative analysis of hop aroma. A total of 55 aroma-active compounds were identified. Among them, linalool, geraniol, ß-myrcene, 2-undecanone, and methyl decanoate contributed significantly to hop aroma. Orthogonal partial least squares discriminant analysis revealed that, except for the SAAZ and XinYuan hops with some similarities in their aroma composition, the remaining hops exhibited unique aroma characteristics. A total of 16 compounds, including methyl 5-methylhexanoate and (E)-ß-farnesene, were identified as differentiating aroma compounds in the six hop samples. This study enriches the knowledge on hop flavour with different origins and provides valuable insights into its application.

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Previous research has shown a strong link between our sense of smell and emotion. More recently, the importance we attach to olfaction has been found to relate to our susceptibility to 'catch' the emotions of others. We explore this further by examining the relation between a newly developed measure of olfaction (social odour scale, SOS), which measures awareness of social odours, and emotional contagion susceptibility in female participants. The study therefore aimed to test the strength of this relationship and also help validate the English language version of the SOS. Female (n = 148) participants completed an online study that measured odour awareness [SOS; important of odour questionnaire, IOQ] and emotional contagion (EC). We found that the English version of the SOS yielded high reliability and supported the previous factor structure of the scale; additionally, we demonstrated a strong association between the SOS and IOQ which provides criterion validity for its usage. The study also revealed that whilst both the SOS and IOQ were positively associated with EC, the SOS was the more accurate predictor. These findings provide further validation for the use of the SOS and suggest that our subjective awareness of olfaction, especially concerning 'social odours' is an accurate predictor of emotional contagion.

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Although men's attraction to women's body odour has been suggested to vary over the ovulatory cycle, peaking around the fertile window, we still lack methodologically robust evidence corroborating this effect. Further, the chemical underpinnings of male preference for the odour of ovulating women remain unknown. Here, we combined perceptual and chemical analyses to investigate the axillary odour of naturally cycling women over 10 days, covering the gradual change in fertility across the ovulatory cycle with a focus on fertile days. The fertile state was confirmed by urinary ovulation tests as well as salivary oestradiol and progesterone levels. Men rated the scent of unfamiliar women, resembling a first encounter. We used multivariate analyses to relate variation in both odour ratings and chemical composition to female conception probability, temporal distance to ovulation and ovarian hormone levels. Our results provide no evidence that males prefer the odour of fertile women. Furthermore, the volatile analysis indicated no link between axillary odour composition and current fertility status. Together, our results showed no convincing support for a chemical fertility cue in women's axillary odour, questioning the presence of olfactory fertility information that is recognizable during first encounters in modern humans.

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In December 2019, a number of subjects presenting with an unexplained pneumonia-like illness were suspected to have a link to a seafood market in Wuhan, China. Subsequently, this illness was identified as the 2019-novel coronavirus (2019-nCoV) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the World Committee on Virus Classification. Since its initial identification, the virus has rapidly sperad across the globe, posing an extraordinary challenge for the medical community. Currently, the Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) is considered the most reliable method for diagnosing SARS-CoV-2. This procedure involves collecting oro-pharyngeal or nasopharyngeal swabs from individuals. Nevertheless, for the early detection of low viral loads, a more sensitive technique, such as droplet digital PCR (ddPCR), has been suggested. Despite the high effectiveness of RT-PCR, there is increasing interest in utilizing highly trained dogs and electronic noses (eNoses) as alternative methods for screening asymptomatic individuals for SARS-CoV-2. These dogs and eNoses have demonstrated high sensitivity and can detect volatile organic compounds (VOCs), enabling them to distinguish between COVID-19 positive and negative individuals. This manuscript recapitulates the potential, advantages, and limitations of employing trained dogs and eNoses for the screening and control of SARS-CoV-2.

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Control of algal blooms and associated biologically-induced water quality risks in drinking reservoirs is problematic. Copper sulphate (CuSO4) treatment is one intervention that has been utilised for >100 years. Evidence indicates a favourable short-term reduction in Cyanobacterial biomass (e.g. bloom termination), but here we indicate that it may also increase longer-term water quality risk. In 2022, we investigated the impacts of CuSO4 spraying on Cyanobacterial communities and nutrient levels within a drinking water supply reservoir using environmental DNA (eDNA) to assess community shifts, alongside monitoring nutrient fractions, orthophosphate (OP) and total phosphate (TP), post-treatment. CuSO4 application successfully reduced Cyanobacterial abundance, however elimination of Cyanobacteria resulted in a shift in bacterial dominance favouring Planctomycetota throughout the summer and a combination of Actinobacteriota and Verrucomicrobiota, throughout autumn. As Cyanobacterial abundance recovered post-treatment, Cyanobacterial genera demonstrated greater diversity compared to only three Cyanobacterial genera present across samples pre-treatment, and included taxa associated with water quality risk (e.g. taste and odour (T&O) metabolite and toxin producers). The increase in Cyanobacteria post-treatment was attributed to an increase in biologically available nutrients, primarily a significant increase in OP. Overall, findings suggest that the significant shift in biodiversity likely induces a less stable ecosystem with greater plasticity of response to changing environmental and biogeochemical variables. Legacy implications of CuSO4 spraying, in terms of shifts in ecosystem and nutrient balance over time, may have implications for drinking water quality, but importantly also for reservoir management options. As such, the effects of CuSO4 spraying should be considered carefully before consideration as a contender for in-reservoir biological control.

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Insect-plant interactions are shaped by the exchange of chemical cues called semiochemicals, which play a vital role in communication between organisms. Plants release a variety of volatile organic compounds in response to environmental cues, such as herbivore attacks. These compounds play a crucial role in mediating the interactions between plants and insects. This review provides an in-depth analysis of plant semiochemicals, encompassing their classification, current understanding of extraction, identification, and characterization using various analytical techniques, including gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy. The article also delves into the manner in which insects perceive and respond to plant semiochemicals, as well as the impact of environmental factors on plant odor emission and insect orientation. Furthermore, it explores the underlying mechanisms by which insects perceive and interpret these chemical cues, and how this impacts their behavioral responses, including feeding habits, oviposition patterns, and mating behaviors. Additionally, the potential applications of plant semiochemicals in integrated pest management strategies are explored. This review provides insight into the intricate relationships between plants and insects mediated by semiochemicals, highlighting the significance of continued research in this field to better understand and leverage these interactions for effective pest control.

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Although smell is sometimes treated with little regard, it is invested with cultural meaning and conveys a great deal of information, including about gender, sexuality and identity. This article draws on interviews with 11 transgender and nonbinary people who have accessed gender affirming hormone therapy (GAHT), and focuses on how they understand and explain changes in how their own bodies smell. Although it is well documented that GAHT causes changes in skin oiliness, changes in smell are inconsistently documented, and within the medical literature are often commented on only in passing. Taking a discourse analytic approach, the article finds that participants noticed changes in their own smell during hormonal transition, that in many cases this change was understood as significant in some way, and that these changes could be experienced as affirming. Understandings of what changes in bodily smell meant were often derived relationally or socially, although participants' discussion of the experience frequently focused on their own embodiment. Smell seems to form part of a process of (re)identification with the physical self and gender affirmation that can be facilitated by GAHT.

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Odour plumes in turbulent environments are intermittent and sparse. Laboratory-scaled experiments suggest that information about the source distance may be encoded in odour signal statistics, yet it is unclear whether useful and continuous distance estimates can be made under real-world flow conditions. Here, we analyse odour signals from outdoor experiments with a sensor moving across large spatial scales in desert and forest environments to show that odour signal statistics can yield useful estimates of distance. We show that achieving accurate estimates of distance requires integrating statistics from 5 to 10 s, with a high temporal encoding of the olfactory signal of at least 20 Hz. By combining distance estimates from a linear model with wind-relative motion dynamics, we achieved source distance estimates in a 60 × 60 m2 search area with median errors of 3-8 m, a distance at which point odour sources are often within visual range for animals such as mosquitoes.

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Currently, pathogenic microorganisms are becoming more active in public utility areas like parking lots and waste shelters due to the accumulation of organic waste. This uncontrolled waste leads to decay, altering its composition and presenting a microbiological risk to public health. Additionally, it emits unpleasant odors containing chemicals that irritate the mucous membranes, causing discomfort in the nose, throat, and eyes by stimulating the trigeminal nerve. These odors can have various negative effects on both quality of life and public health. The study investigated the physicochemical properties of oil composites enriched with natural additives and determined their effectiveness in reducing the intensity of nuisance odours. The research showed over 82% reduction in decaying meat odour and almost 65% reduction in ammonia odour. A higher impact of the given composites on reducing the odour from decaying meat than from ammonia was observed. This may be due to the biocidal properties of the additives used (turmeric, thymol, salicylic acid, hops and curly sorrel) and the higher intensity of ammonia odor compared to meat-derived odour. Despite the non-porous nature of the solids tested (with similar specific surface areas ranging from 0.66 to 0.88 m2/g), they were capable of sorbing NH3.

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The ventilated improved pit (VIP) latrine offers a promising route to safely managed sanitation to many households in developing countries. However, some technical guidelines must be followed in order to realise the technology's advantage of odour and fly nuisance control. This study sought to audit private VIP latrines in selected regions of Ghana to assess their compliance to conventional technical guidelines and to understand the major factors that influence the latrine designs. An inspection checklist was developed to assess 296 private VIP latrines in the Central, Ashanti and Northern Regions of Ghana while semi-structured interviews were conducted among the latrine owners to enquire the factors that influenced the designs of their latrines. The results show that provision of a window in the superstructure (86 %), and the avoidance of an insect screen in the window(s) (77 %) were the most complied guidelines. The use of 150 mm diameter vent pipe was the least satisfied guideline (5 %). On the average, a latrine satisfied about half (3.6) of the technical guidelines that were assessed. The decision or advice of local artisans is the most influential factor in the design of the latrines. Cost was the least mentioned factor cited by the latrine owners. There is the need to establish information desks at the various Metropolitan, Municipal and District Assemblies (MMDAs) to guide prospective owners on the proper design and construction of the VIP latrine. In addition, toilet construction should be incorporated in the curriculum for the basic training of building and construction students in Technical and Vocational Education and Training (TVET) institutions in Ghana. Further research is required to ascertain the basis of the decisions of local artisans and the potential impact of the use of accessories that are 'borrowed' from the WC toilet on odour and fly control in the latrine.

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In mammals, odour information within the olfactory bulb (OB) is processed by complex neural circuits before being ultimately represented in the action potential activity of mitral/tufted cells (M/Ts). Cholecystokinin-expressing (CCK+) superficial tufted cells (sTCs) are a subset of tufted cells that potentially contribute to olfactory processing in the OB by orchestrating M/T activity. However, the exact role of CCK+ sTCs in modulating odour processing and olfactory function in vivo is largely unknown. Here, we demonstrate that manipulating CCK+ sTCs can generate perception and induce place avoidance. Optogenetic activation/inactivation of CCK+ sTCs exerted strong but differing effects on spontaneous and odour-evoked M/T firing. Furthermore, inactivation of CCK+ sTCs disrupted M/T odour encoding and impaired olfactory detection and odour discrimination. These results establish the role of CCK+ sTCs in odour representation and olfactory behaviours. KEY POINTS: Mice could perceive the activity of CCK+ sTCs and show place avoidance to CCK+ sTC inactivation. Optical activation of CCK+ sTCs increased the percentage of cells with odour response but reduced the odour-evoked response in M/Ts in awake mice. Optical inactivation of CCK+ sTCs greatly decreased spontaneous firing and odour-evoked response in M/Ts. Inactivation of CCK+ sTCs impairs the odour decoding performance of M/Ts and disrupts odour detection and discrimination behaviours in mice. These results indicate that CCK+ sTCs participate in modulating the odour representation and maintaining normal olfactory-related behaviours.

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What makes an odour pleasant or unpleasant? The inherent properties of the constituent chemical compounds, or the nose of the beholder, driven by idiosyncratic differences and culture-specific learning? Here, 582 individuals, including Tanzanian Hadza hunter-gatherers, Amazonian Tsimane' horticulturalists, Yali from the Papuan highlands and two industrialized populations (Poles, Malaysians), rated the pleasantness of 15 odour samples. We find considerable similarities in odour assessments across cultures, but our data do not fully support a claim regarding the universality of smell preferences. Despite cross-cultural similarities in olfactory assessments, probably driven by odour properties, we suggest that odour availability in ecological and cultural niches bears an undeniable effect on human odour preferences.

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Two cultivars of wild rocket (Diplotaxis tenuifolia), cv. Denver and Marte, were subjected to chemical determination of flavour-related constituents, sensory descriptive analysis, and measurement of liking by consumer test. Consumers evaluated rocket leaves both as a single ingredient and in a recipe formed by a roll of bresaola with also Grana Padano cheese. Sensory analyses showed that Marte was characterized by a more intense bitterness, hotness, and pungency, which corresponded to a higher total GSL content, mainly due to a higher level of dimeric 4-mercaptobutyl GSL. Five clusters of consumers were identified based on their liking scores. When tasting rocket leaves as a single ingredient, three clusters showed a higher liking for the milder cultivar, one cluster showed an opposite preference, while flavour attributes, such as bitterness and hotness, appeared as the main drivers of liking. Differences in liking were no longer found between the two cultivars when rocket leaves were evaluated in the recipe. Therefore, as rocket leaves are generally consumed as a part of a recipe with other ingredients instead of as a single ingredient, in the assessment of consumer preferences, it should not be neglected the influence of the way in which the product is consumed.

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Scent rolling, a behaviour observed in various large carnivores like wolves, entails the animal lowering its chin and neck towards a scent, followed by rubbing the head, neck, shoulders, and back into it. This behaviour is prevalent among wolves exposed to diverse scents, though its exact purpose remains uncertain. In this study, captive wolves at Osijek Zoo responded differently to odours during olfactory enrichment sessions. In the initial year of this study, the highest level of interest, evidenced by both the frequency of responses and scent-rolling behaviour, was noted when the wolves encountered odours such as curry and rosemary, along with deer/mouflon and rat faeces. While certain odours, such as llama faeces and deer/mouflon faeces, garnered longer durations of interest in the second year of study, others, like guinea pig faeces and oregano, elicited shorter responses. Female wolves demonstrated a higher level of engagement with scents compared with males, particularly through scent rolling behaviour, which was exclusively observed in females during the second year of this study. Interestingly, certain odours did not trigger scent rolling, suggesting selective preferences. On the other hand, sheep's wool induced the longest duration of scent rolling, and a lack of significant differences in behaviour was observed between morning and afternoon sessions. Despite the existence of multiple hypotheses put forward to explain the causation of scent rolling in wolves, it seems to be elicited by unfamiliar odours.

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Waste treatment plants (WTPs) often generate odours that may cause nuisance to citizens living nearby. In general, people are becoming more sensitive to environmental issues, and particularly to odour pollution. Instrumental Odour Monitoring Systems (IOMSs) represent an emerging tool for continuous odour measurement and real-time identification of odour peaks, which can provide useful information about the process operation and indicate the occurrence of anomalous conditions likely to cause odour events in the surrounding territories. This paper describes the implementation of two IOMSs at the fenceline of a WTP, focusing on the definition of a specific experimental protocol and data processing procedure for dealing with the interferences of humidity and temperature affecting sensors' responses. Different approaches for data processing were compared and the optimal one was selected based on field performance testing. The humidity compensation model developed proved to be effective, bringing the IOMS classification accuracy above 95%. Also, the adoption of a class-specific regression model compared to a global regression model resulted in an odour quantification capability comparable with those of the reference method (i.e., dynamic olfactometry). Lastly, the validated models were used to process the monitoring data over a period of about one year.

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The mechanisms whereby environmental experiences of parents are transmitted to their offspring to impact their behaviour and fitness are poorly understood. Previously, we showed that naive Bicyclus anynana butterfly larvae, whose parents fed on a normal plant feed but coated with a novel odour, inherited an acquired preference towards that odour, which had initially elicited avoidance in the naive parents. Here, we performed simple haemolymph transfusions from odour-fed and control-fed larvae to naive larval recipients. We found that larvae injected with haemolymph from odour-fed donors stopped avoiding the novel odour, and their naive offspring preferred the odour more, compared to the offspring of larvae injected with control haemolymph. These results indicate that factors in the haemolymph, potentially the odour molecule itself, play an important role in odour learning and preference transmission across generations. Furthermore, this mechanism of odour preference inheritance, mediated by the haemolymph, bypasses the peripheral odour-sensing mechanisms taking place in the antennae, mouthparts or legs, and may mediate food plant switching and diversification in Lepidoptera or more broadly across insects.

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