Search Results (105)

Environmental enrichment is essential for promoting species-specific behaviors and enhancing the welfare of zoo-housed animals. This study examined the behavioral responses of two juvenile male binturongs (Arctictis binturong) at the Minnesota Zoo to three enrichment stimuli: lavender oil (olfactory), thawed fish (olfactory and dietary), and hard-boiled egg (olfactory and dietary). Their behaviors were recorded using scan sampling before and after enrichment exposure, focusing on locomotion, foraging, resting, and visitor visibility. Food-based enrichments, particularly the hard-boiled egg, significantly increased foraging behavior, while lavender oil and thawed fish produced minimal behavioral changes. Locomotion and visibility remained stable across the conditions, although a slight increase in resting was observed with lavender oil. No evidence of scent-marking disruption was noted, and individual differences appeared to influence inactivity levels. These findings highlight the potential of biologically relevant, food-based enrichment to stimulate natural behaviors in binturongs and emphasize the importance of species-specific enrichment strategies. Future research should explore a broader range of olfactory cues, assess long-term behavioral responses, and incorporate physiological measures to further evaluate enrichment impacts on binturong welfare. Full article

The parasitoid wasp Dolichogenidea gelechiidivoris is a key koinobiont solitary endoparasitoid of the invasive agricultural pest Tuta absoluta. This study investigates both the morphological and molecular foundations of sex-specific olfactory differentiation in this species. Morphological analysis revealed that males possess significantly longer antennae (2880.8 ± 20.36 μm) than females (2137.23 ± 43.47 μm), demonstrating pronounced sexual dimorphism. Scanning electron microscopy identified similar sensilla types on both sexes, but differences existed in the length and diameter of specific sensilla. Transcriptomic analysis of adult antennae uncovered molecular differentiation, identifying 11 odorant-binding proteins (OBPs) and 20 odorant receptors (ORs), with 27 chemosensory genes upregulated in females and 4 enriched in males. Integrating morphological and molecular evidence demonstrates complementary sexual specialization in the olfactory apparatus of D. gelechiidivoris. Linking these findings to the potential functions of different sensilla types, as discussed in the context of prior research, provides crucial insights into the sex-specific use of volatile cues. These findings provide critical insights into the use of volatile signals in this highly relevant species for biological control targeting T. absoluta. Full article

Prejudices, particularly those related to social biases, are shaped by various cognitive and sensory mechanisms. This study investigates the interaction between olfactory perception and propensity and implicit or explicit prejudices through three experimental protocols in a metaverse condition. Experiment 1 examines the impact of five different odors on proxemic behavior when interacting with individuals from stigmatized social groups. Experiment 2 integrates electroencephalography (EEG) to analyze the neural correlates of prejudice-related responses to olfactory stimuli. Experiment 3 explores implicit biases through the Implicit Association Test (IAT) in relation to different fragrances, without employing virtual reality. The proposed protocol is expected to demonstrate a significant relationship between olfactory cues, linked to social relationships, and implicit or explicit prejudices, with variations based on individual differences. These insights will contribute to psychological, neuroscientific, and social interventions, offering new perspectives on the unconscious mechanisms of bias formation. Additionally, this study highlights the potential of virtual reality and olfactory stimuli as innovative tools for studying and addressing social biases in controlled environments. Full article

The black fig fly, Silba adipata (Diptera: Lonchaeidae), is an invasive pest recently introduced to Mexico, where it has rapidly spread across fig-producing regions. Despite its economic importance, effective monitoring strategies remain poorly studied. The present study evaluated the response of S. adipata adults to visual (color) and olfactory (attractant) cues under laboratory and field conditions in fig orchards. No significant color preferences were observed in laboratory choice tests using nine colors or in field trials using traps of four different colors. In the laboratory, traps containing 2% ammonium sulfate solution, torula yeast + borax, or Captor + borax, captured similar numbers of flies, whereas CeraTrap^® was less attractive. Traps containing 2% ammonium sulfate were more effective than 2% ammonium acetate, though attraction was comparable when ammonium acetate was diluted to 0.2% or 0.02%. In the field, torula yeast + borax and 2% ammonium sulfate mixed with fig latex outperformed the 2% ammonium sulfate solution alone, although seasonal variation influenced trap performance. A high proportion of field-captured females were sexually immature. Torula yeast + borax attracted high numbers of non-target insects and other lonchaeid species, which reduced its specificity. In contrast, traps containing fig latex mixtures showed higher selectivity, although some S. adipata adults could not be sexed due to specimen degradation. These findings highlight the value of torula yeast pellets and 2% ammonium sulfate plus fig latex for monitoring this pest, but merit validation in field studies performed over the entire crop cycle across both wet and dry seasons. Future studies should evaluate other proteins, ammonium salt combinations and fig latex volatiles in order to develop effective and selective monitoring or mass trapping tools targeted at this invasive pest. Full article

Chemical communication is based on the release of chemical cues, including odorants, tastants and semiochemicals, which can be perceived by animals and trigger physiological and behavioral responses. These compounds exhibit a wide size and properties range, spanning from small volatile molecules to soluble proteins, and are perceived by various chemosensory receptors (CRs). The structure of these receptors is very well conserved across all organisms and within the family to which they belong, the G-protein-coupled receptor (GPCR) family. It is characterized by highly conserved seven-transmembrane (7TM) α-helices. However, the characteristics of these proteins and the methods used to study their structures are limiting factors for resolving their structures. Due to the importance of CRs—especially olfactory and taste receptors, responsible for two of our five basic senses—alternative methods are utilized to overcome these structural challenges. Indeed, in silico structural biology is an expanding field that is very useful for CR structural studies. Since the 1960s, many algorithms have been developed and improved in an attempt to resolve protein structure. We review the current knowledge regarding different vertebrate CRs in this study, with an emphasis on the in silico structural methods employed to improve our understanding of CR structures. Full article

Lampreys are primitive fish that rely significantly on olfactory cues throughout their complex life cycle. The olfactory system of the sea lamprey (Petromyzon marinus) is among the best characterized in vertebrates. In recent decades, tremendous advances have been made by isolating individual compounds from sea lampreys that can replicate natural behavior when artificially applied in the wild. In no other aquatic vertebrate has the olfactory ecology been described in such extensive detail. In the first section, we provide a comprehensive review of olfactory behaviors induced by specific, individual odorants during every major developmental stage of the sea lamprey in behavioral contexts such as feeding, predator avoidance, and reproduction. Moreover, pheromonal inputs have been shown to induce neuroendocrine responses through the hypothalamic-pituitary-gonadal axis, triggering remarkable developmental and physiological effects, such as gametogenesis and increased pheromone release. In the second section of this review, we describe a hypothetical endocrine signaling pathway through which reproductive fitness is increased following pheromone detection. In the final section of this review, we focus on the neuronal circuits that transform olfactory inputs into motor output. We describe specific brain signaling pathways that underlie odor-evoked locomotion. Furthermore, we consider possible modulatory inputs to these pathways that may induce plasticity in olfactory behavior following changes in the external or internal environment. As a whole, this review synthesizes previous and recent progress in understanding the behavioral, endocrine, and neuronal responses of lampreys to chemosensory signals. Full article

This paper introduces a novel nature-inspired optimization algorithm called the Grizzly Bear Fat Increase Optimizer (GBFIO). The GBFIO algorithm mimics the natural behavior of grizzly bears as they accumulate body fat in preparation for winter, drawing on their strategies of hunting, fishing, and eating grass, honey, etc. Hence, three mathematical steps are modeled and considered in the GBFIO algorithm to solve the optimization problem: (1) finding food sources (e.g., vegetables, fruits, honey, oysters), based on past experiences and olfactory cues; (2) hunting animals and protecting offspring from predators; and (3) fishing. Thirty-one standard benchmark functions and thirty CEC2017 test benchmark functions are applied to evaluate the performance of the GBFIO, such as unimodal, multimodal of high dimensional, fixed dimensional multimodal, and also the rotated and shifted benchmark functions. In addition, four constrained engineering design problems such as tension/compression spring design, welded beam design, pressure vessel design, and speed reducer design problems have been considered to show the efficiency of the proposed GBFIO algorithm in solving constrained problems. The GBFIO can successfully solve diverse kinds of optimization problems, as shown in the results of optimization of objective functions, especially in high dimension objective functions in comparison to other algorithms. Additionally, the performance of the GBFIO algorithm has been compared with the ability and efficiency of other popular optimization algorithms in finding the solutions. In comparison to other optimization algorithms, the GBFIO algorithm offers yields superior or competitive quasi-optimal solutions relative to other well-known optimization algorithms. Full article

Spotted hyenas live in fission–fusion social societies, requiring them to adopt a flexible multimodal communication system across variable spatial scales. However, researchers have extensively studied acoustic and olfactory signals for conspecific communication compared to visual signals, especially in wild populations. Here, we reviewed 46 articles on the Web of Science on social communication in wild and captive spotted hyena populations to synthesize our collective knowledge of the extent to which spotted hyenas utilize sensory cues to communicate and how flexible they are between captive and wild populations. Across all articles, 54% focused on acoustic communication (n = 25), 33% on olfaction (n = 15), leaving only 13% on vision (n = 6). Most of this research studied wild populations (82%; n = 38), leaving an intriguing gap in our knowledge of captive populations and their potential for developing behavioral innovations due to their robust social cognition (i.e., modifying behavioral form and/or function observed in wild populations to better accommodate the captive performer’s environment and social needs). Improving our understanding of innovation development in this species has possible benefits for studying behavioral evolution and improving captive welfare (e.g., identifying normal vs. stereotypic behavior) in this social carnivore. Full article

All animals require the ability to use visual, auditory, tactile, and olfactory information to survive through activities including locating and identifying conspecifics including potential mates, locating food or shelter, or noticing an approaching predator. Detecting such information invariably requires sensory organs. The morphology of sensory organs evolves under natural selection to optimise the ability to detect salient cues and signals against the background noise in the natural environment. The rapidly proliferating anthropogenic impacts on almost all natural environments include light, noise, and chemical pollution, which can interfere with an animal’s ability to detect visual, acoustic or seismic, and olfactory information, respectively. Many studies examine the resulting changes in the characteristics of signals or the behavioural responses to them in affected natural populations, but very few examine the resulting changes in the sensory organs required to detect the signals; those that do all find evidence of morphological changes. Here, I review the current knowledge on the impact of anthropogenic pollution on sensory organ morphology in wild and captive populations, highlighting knowledge gaps and future directions for addressing them. This is especially important in the context of the growing recognition of the cruciality of sensory ecology in the design of effective threatened species conservation programs and invasive species management strategies. Full article

Wildlife behavior can be influenced by the deployment of sensory cues in a landscape, but different cues vary in the strength and duration of their effectiveness. We aimed to identify the most effective and cost-efficient countermeasures (sensory cues) to deter wild boar (Sus scrofa) entry and damage to cornfields in Hunchun, Jilin Province, China. These cornfields have experienced severe damage by wild boars during the critical 30-day period when this crop was ripening. From 2016 to 2021, different countermeasures were applied sequentially seeking to control this damage by using either (1) visual deterrents, i.e., solar blinkers of different colors; (2) auditory deterrents, i.e., playbacks of Amur tiger (Panthera tigris altaica) calls, wild boar calls, or wolf (Canis lupus) calls; (3) tactile deterrents, i.e., electric fencing; (4) olfactory deterrents, i.e., Adult Amur tiger feces; or (5) various combined deterrents. We first evaluated the effectiveness of these broad categories, then performed a detailed analysis of the individual countermeasures to assess their specific deterrence effectiveness and duration. A cost-effective analysis was subsequently performed on the most effective countermeasures to evaluate the best option for practical applications. Across the broad categories of deterrents, the tactile group proved the most effective overall. For individual deterrents, the seven countermeasures showing significantly higher effectiveness than the others tested included the following: (1) 1000 mA red solar blinker (32.25 ± 4.22 days), (2) 1000 mA yellow solar blinker (29.67 ± 4.58 days), (3) 1000 mA green solar blinker (29.58 ± 5.60 days), (4) electric fencing with three wires (29.67 ± 0.58 days), (5) electric fencing with two wires (28.00 ± 2.00 days), (6) Adult Amur tiger calls for 15 s and wild boar calls for 15 s plus a combined 30 s plus a blank recording for 5 min (26.50 ± 2.38 days), and (7) Adult Amur tiger feces and calls (27.34 ± 2.94 days). Except for the Adult Amur tiger feces and calls, each countermeasure would cover most of the period over which control is necessary (30 days). The 1000 mA red solar blinker of achieved the highest repellency per cost ratio (0.31) at 30.29 IUS$/hm² but showed reduced effectiveness over time. Although electric fencing with three wires offers longer deterrence, its cost-effectiveness ratio was lower (0.27) due to higher installation and maintenance costs at 319.69 IUS$/hm². The 1000 mA red solar blinker offers a highly cost-effective short-term deterrent, while the electric fencing with three wires provides durable, long-term protection despite its higher costs. Balancing cost and duration can optimize wild boar deterrence strategies across different management needs. Full article

Electroencephalography (EEG)-basedpersonal identification has gained significant attention, but fluctuations in emotional states often affect model accuracy. Previous studies suggest that multisensory stimuli, such as video and olfactory cues, can enhance emotional responses and improve EEG-based identification accuracy. This study proposes a novel deep learning-based model, CNN-BiLSTM-Residual Network (CBR-Net), for EEG-based identification and establishes a multisensory emotional EEG dataset with both video-only and olfactory-enhanced video stimulation. The model includes a convolutional neural network (CNN) for spatial feature extraction, Bi-LSTM for temporal modeling, residual connections, and a fully connected classification module. Experimental results show that olfactory-enhanced video stimulation significantly improves the emotional intensity of EEG signals, leading to better recognition accuracy. The CBR-Net model outperforms video-only stimulation, achieving the highest accuracy for negative emotions (96.59%), followed by neutral (94.25%) and positive emotions (95.42%). Ablation studies reveal that the Bi-LSTM module is crucial for neutral emotions, while CNN is more effective for positive emotions. Compared to traditional machine learning and existing deep learning models, CBR-Net demonstrates superior performance across all emotional states. In conclusion, CBR-Net enhances identity recognition accuracy and validates the advantages of multisensory stimuli in EEG signals. Full article

Ocean acidification (OA) associated with climate change is expected to lower the ocean’s pH by 0.5 units by 2100. Whilst associated effects such as coral bleaching and shell calcification are well documented, lesser-known impacts are the ‘invisible’ effects on animal sensory systems. Olfactory disruption impacts the behaviour towards chemical cues in many marine species, including crustaceans. We examine the effects of microplastic odour and additional stressors on the European green crab C. maenas. Using uridine diphosphate (UDP) and uridine triphosphate (UTP) as a sex pheromone bouquet, glutathione (GSH) as a food cue, and polyethylene (PE) as plastic odour, cues were mixed with carboxycellulose to create slow-release gels. Crabs were exposed to gels in seawater pH values of 8.2, 7.6, and 7.2. Crabs took longer to react to all odours in reduced pH conditions (pH 8.2 to pH 7.2, p = 0.0017). At a low pH, PE-exposed crabs exhibited attraction towards microplastic odour and changed behavioural responses by burying. The study confirms low pH as disruptive to olfaction and highlights that plastic derivatives can become more bioactive at reduced pH levels, potentially increasing the threat posed by microplastic pollution. Further research is required to determine the potential long-term impacts of the combined threat of microplastics and reduced pH in the environment. Full article

Over the last three decades, adult neurogenesis in mammals has been a central focus of neurobiological research, providing insights into brain plasticity and function. However, interest in this field has recently waned due to challenges in translating findings into regenerative applications and the ongoing debate about the persistence of this phenomenon in the adult human brain. Despite these hurdles, significant progress has been made in understanding how adult neurogenesis plays a critical role in the adaptation of brain circuits to environmental stimuli regulating key brain functions. This review focuses on the role of olfactory neurogenesis in the brain’s response to social reproductive cues in rodents, highlighting its influence on animal behaviors critical for survival. We also address open questions and propose future directions to advance our understanding of the relationship between adult neurogenesis and reproductive function regulation. Full article

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) (FAW), is an invasive and destructive polyphagous pest that poses a significant threat to global agricultural production. The FAW mainly damages maize, with a particular preference for V3–V5 (third to fifth leaf collar) plant stages in northern China. How the FAW moth precisely locates maize plants in the V3–V5 stage at night remains unclear. The aims of this study were to evaluate the visual and olfactory cues used by the FAW to identify its host plant, maize, in order to select attractants with better trapping efficacy. Hyperspectral analysis of maize plants at different growth stages using the ASD Fieldspec 4 spectrometer was performed using mimics (moths or maize leaves sealed with transparent plastic sheets) and black cloth-covered plants for single visual and single olfactory attraction experiments. Gas chromatography–mass spectrometry (GC-MS) was used to analyze volatiles emitted from V3–V5 stage maize leaves. Volatile organic chemicals (VOCs) were screened using electroantennography (EAG) and Y-tube. Attractor efficacy was validated using mimics + VOCs. Results showed very little variance in the spectral reflectance curve of the maize at different growth stages. Fifteen VOCs were identified in the V3–V5 stage leaves of three different maize varieties, of which cis-3-hexenyl acetate and myrcene were found in relatively high concentrations in these maize varieties. The frequency of visits attracted by single visual stimuli was significantly lower than that attracted by single olfactory or olfactory + visual cues. The attractiveness of foliar cis-3-hexenyl acetate increased as its concentration decreased. The combination of mimics + cis-3-hexenyl acetate (1 ng/μL) increased host detection efficiency and stimulated mating behavior. These results indicate that the nocturnal insect FAW primarily uses olfactory cues for host identification, with visual cues serving as a complementary modality. The synergistic effect of olfactory and visual cues increases the efficiency of host recognition. We found that cis-3-hexenol acetate at a concentration from maize leaves is a reliable olfactory signal for the FAW. When using host plant VOCs as attractants to control adult FAWs, the role of visual cues must be considered. Full article

Color vision, which varies among species, plays an important role in foraging, mating, and habitat selection among insects. Protaetia brevitarsis (Coleoptera: Scarabaeidae, Lewis) is an omnivorous beetle that damages both crops and fruit. Here, to understand the effect of vision and olfaction in host selection, experiments were conducted on the spectral wavelength preference, color preference, and associative learning ability of adult P. brevitarsis using LED lights and grapes. In our experiments, adults showed the strongest spontaneous preference toward the red spectrum, particularly 730 nm. Non-preferred lights were used to train adults with a food reward (grapes). Green-trained adults had an increasing tendency to prefer green light, and blue-trained adults had a clear preference for blue light. Furthermore, adults significantly preferred red grapes in the absence of olfactory cues, but their selectivity for grapes differed in the presence of olfactory cues, indicating that vision was not the only factor in foraging decisions, but that olfactory cues also influenced their decision making. The results lay the groundwork for revealing their host localization mechanism and provide promising avenues for biological control in the field. Full article