Odor Plume Tracking Research Articles

Analysis of Odor-Tracking Performance of Silk Moth Using a Sensory-Motor Intervention System.

Animals can adaptively behave in different environmental conditions by converting environmental information obtained from their sensory organs into actions. This sensory-motor integration enables the accomplishment of various tasks and is essential for animal survival. This sensory-motor integration also plays an important role in localization to females, relying on sex pheromones floating in space. In this study, we focused on the localization behavior of the adult male silk moth, Bombyx mori. We investigated sensory-motor integration against time delay using odor plume tracking performance as an index when we set a certain time delay for the sensory and motor responses. Given that it is difficult to directly intervene in the sensory and motor functions of the silk moth, we constructed an intervention system based on a mobile behavior measurement system controlled by them. Using this intervention system, not only can timing the detection of the odor in the environment and timing the presentation of the odor to the silk moth be manipulated, but timing the reflection of the movement of the silk moth can also be manipulated. We analyzed the extent to which the localization strategy of the silk moth could tolerate sensory delays by setting a delay to the odor presentation. We also evaluated behavioral compensation by odor sensory feedback by setting a delay to the motor. The results of the localization experiment have shown that the localization success rate did not decrease when there was a motor delay. However, when there was a sensory delay, the success rate decreased depending on the time delay. Analysis of the change in behavior after detection of the odor stimulus has shown that the movement was more linear when we set a motor delay. However, the movement was accompanied by a large rotational movement when there was a delay in the sensory input. This result has suggested that behavior is compensated for the delay in motor function by feedback control of odor sensation, but not when accompanied by sensory delay. To compensate for this, the silk moth may acquire appropriate information from the environment by making large body movements.

Near-surface wind variability over spatiotemporal scales relevant to plume tracking insects.

Odor plume tracking is important for many organisms, and flying insects have served as popular model systems for studying this behavior both in field and laboratory settings. The shape and statistics of the airborne odor plumes that insects follow are largely governed by the wind that advects them. Prior atmospheric studies have investigated aspects of microscale wind patterns with an emphasis on characterizing pollution dispersion, enhancing weather prediction models, and for assessing wind energy potential. Here, we aim to characterize microscale wind dynamics through the lens of short-term ecological functions by focusing on spatial and temporal scales most relevant to insects actively searching for odor sources. We collected and compared near-surface wind data across three distinct environments (sage steppe, forest, and urban) in Northern Nevada. Our findings show that near-surface wind direction variability decreases with increasing wind speeds and increases in environments with greater surface complexity. Across environments, there is a strong correlation between the variability in the wind speed (i.e., turbulence intensity) and wind direction (i.e., standard deviation in wind direction). In some environments, the standard deviation in the wind direction varied as much as 15°-75° on time scales of 1-10 min. We draw insight between our findings and previous plume tracking experiments to provide a general intuition for future field research and guidance for wind tunnel design. Our analysis suggests a hypothesis that there may be an ideal range of wind speeds and environment complexity in which insects will be most successful when tracking odor plumes over long distances.

Dehydrated Drosophila melanogaster track a water plume in tethered flight

Perception of sensory stimuli can be modulated by changes in internal state to drive contextually appropriate behavior. For example, dehydration is a threat to terrestrial animals, especially to Drosophila melanogaster due to their large surface area to volume ratio, particularly under the energy demands of flight. While hydrated D.melanogaster avoid water cues, while walking, dehydration leads to water-seeking behavior. We show that in tethered flight, hydrated flies ignore a water stimulus, whereas dehydrated flies track a water plume. Antennal occlusions eliminate odor and water plume tracking, whereas inactivation of moist sensing neurons in the antennae disrupts water tracking only upon starvation and dehydration. Elimination of the olfactory coreceptor eradicates odor tracking while leaving water-seeking behavior intact in dehydrated flies. Our results suggest that while similar hygrosensory receptors may be used for walking and in-flight hygrotaxis, the temporal dynamics of modulating the perception of water vary with behavioral state.

A comparison of odor plume-tracking behavior of walking and flying insects in different turbulent environments.

Many animals locate food, mates and territories by following plumes of attractive odors. There are clear differences in the structure of this plume-tracking behavior depending on whether an animal is flying, swimming, walking or crawling. These differences could arise from different control rules used by the central nervous system during these different modes of locomotion or one set of rules interacting with the different environments while walking on the surface versus flying or swimming. Flow speeds and turbulence that characterize the environments where walking and flying insects track plumes may alter the structure of odor plumes in an environment-specific way that results in the same control rules generating behaviors that appear quite different. We tested these ideas by challenging walking male cockroaches, Periplaneta americana, and flying male moths, Manduca sexta, to track plumes of their species' sex pheromones in low wind speeds characteristic of cockroach experimental environments, higher wind speeds characteristic of moth experimental environments, and conditions ranging from low to high turbulence. Introducing a turbulence-generating structure into the flow significantly improved the flying plume tracker's ability to locate the odor source, and changed the structure of the behavior of both flying and walking plume trackers. Our results support the idea that plume trackers moving slowly along the substrate may use the spatial distribution of odor, while faster moving flying plume trackers may use the timing of odor encounters to steer to locate the source.

Experimental and theoretical probe on mechano- and chemosensory integration in the insect antennal lobe.

In nature, olfactory signals are delivered to detectors-for example, insect antennae-by means of turbulent air, which exerts concurrent chemical and mechanical stimulation on the detectors. The antennal lobe, which is traditionally viewed as a chemosensory module, sits downstream of antennal inputs. We review experimental evidence showing that, in addition to being a chemosensory structure, antennal lobe neurons also respond to mechanosensory input in the form of wind speed. Benchmarked with empirical data, we constructed a dynamical model to simulate bimodal integration in the antennal lobe, with model dynamics yielding insights such as a positive correlation between the strength of mechanical input and the capacity to follow high frequency odor pulses, an important task in tracking odor sources. Furthermore, we combine experimental and theoretical results to develop a conceptual framework for viewing the functional significance of sensory integration within the antennal lobe. We formulate the testable hypothesis that the antennal lobe alternates between two distinct dynamical regimes, one which benefits odor plume tracking and one which promotes odor discrimination. We postulate that the strength of mechanical input, which correlates with behavioral contexts such being mid-flight versus hovering near a flower, triggers the transition from one regime to the other.

A reinforcement learning fuzzy system for continuous control in robotic odor plume tracking

AbstractIn dynamic outdoor environments characterized by turbulent airflow and intermittent odor plumes, robotic odor plume tracking remains challenging, because existing algorithms heavily rely on manually tuning or learning from expert experience, which are hard to implement in an unknown environment. In this paper, a multi-continuous-output Takagi–Sugeno–Kang fuzzy system was designed and tuned with reinforcement learning to solve the robotic odor source localization problem in dynamic odor plumes. Based on the Lévy Taxis plume tracking controller, the proposed fuzzy system determined the parameters of the controller based on the robot’s observation and guided the robot to turn and move towards the odor source at each searching step. The trained fuzzy system was tested in simulated filament-based odor plumes dispersed by a changing wind field. The results showed that the performance of the proposed fuzzy system-based controller trained with reinforcement learning can achieve a similar success rate and higher efficiency compared with a manually tuned and well-designed fuzzy system-based controller. The fuzzy system-based plume tracking controller was also validated through real robotic experiments.

Opening the chemosensory world of the lobster, Homarus americanus

The natural history of the American lobster, Homarus americanus H. Milne-Edwards, 1837, was described in detail as part of the general interest in marine biology in the late 19th century. A half-century ago, lobsters gained prominence in the biological analysis of underwater chemical sensing, using neurobiological, behavioral, and ecological approaches. Lobsters made us recognize different chemical sensing organs, each with their unique signal-filtering properties and behavioral functions, and they showed how they generate and control information currents for both odor dispersal and reception. This led to better understanding of the constraints that fluid motion places on odor signal analysis and sensor design. This, in turn, spurred construction of a lobster-inspired electronic nose to measure the temporal resolution of chemoreceptor organs used in odor plume analysis and tracking. Simultaneously, long-term field and naturalistic tank observations revealed their social structure involving sheltering, dominance fights, individual recognition by urine signals, courtship displays, cohabitation, and mating behavior. While most investigations focused on chemical signals, flow sensors were analyzed as part of antennule flicking and odor-flow coincidence detection. Mechanoreception plays an important role in smelling and tasting. Lobster vision contributes to opponent size estimates and recognition. Multisensory analysis will become increasingly important as is the chemical identification of the signals. Lobsters remain significant contributors to underwater sensory biology, influencing many other model systems, including other crustaceans, mollusks, sharks, and reef fish larvae. It has always been my privilege to work with so many inspiring students and colleagues.

An Airflow Analysis Study of Quadrotor Based Flying Sniffer Robot

Wheeled based sniffer robots have been using in current research trend of odor plume tracking, but they have a serious pitfall because they only perform2D odor plume tracking which is ineffective. The main reason of being ineffective is because wheeled sniffer robots ignore the fact that the majority of odor plumes are released into 3D space instead of 2D space. Therefore, a flying sniffer robot is needed to overcome 3D odor plume tracking problem. In this paper, we propose to use a quadrotor as the locomotion of a flying sniffer robot. In order to make sure the quadrotor based flying sniffer robot can perform well in odor plumes tracking, we have carried out a detail study in airflow simulation analysis by using Computational Fluid Dynamics (CFD) software. Besides, we also conducted experiments to determine the odor sensing ability of quadrotor based flying sniffer robot. From our experiments, we are able to identify the odor sensing region of quadrotor based flying sniffer robot in quantitative measurement. From airflow analysis simulation study and experiments, we proved that a quadrotor based flying sniffer robot is a feasible solution for 3D odor plume tracking.

The role of vision in odor-plume tracking by walking and flying insects

The walking paths of male cockroaches, Periplaneta americana, tracking point-source plumes of female pheromone often appear similar in structure to those observed from flying male moths. Flying moths use visual-flow-field feedback of their movements to control steering and speed over the ground and to detect the wind speed and direction while tracking plumes of odors. Walking insects are also known to use flow field cues to steer their trajectories. Can the upwind steering we observe in plume-tracking walking male cockroaches be explained by visual-flow-field feedback, as in flying moths? To answer this question, we experimentally occluded the compound eyes and ocelli of virgin P. americana males, separately and in combination, and challenged them with different wind and odor environments in our laboratory wind tunnel. They were observed responding to: (1) still air and no odor, (2) wind and no odor, (3) a wind-borne point-source pheromone plume and (4) a wide pheromone plume in wind. If walking cockroaches require visual cues to control their steering with respect to their environment, we would expect their tracks to be less directed and more variable if they cannot see. Instead, we found few statistically significant differences among behaviors exhibited by intact control cockroaches or those with their eyes occluded, under any of our environmental conditions. Working towards our goal of a comprehensive understanding of chemo-orientation in insects, we then challenged flying and walking male moths to track pheromone plumes with and without visual feedback. Neither walking nor flying moths performed as well as walking cockroaches when there was no visual information available.

An olfactory circuit increases the fidelity of visual behavior.

Multimodal integration allows neural circuits to be activated in a behaviorally context-specific manner. In the case of odor plume tracking by Drosophila, an attractive odorant increases the influence of yaw-optic flow on steering behavior in flight, which enhances visual stability reflexes, resulting in straighter flight trajectories within an odor plume. However, it is not well understood whether context-specific changes in optomotor behavior are the result of an increased sensitivity to motion inputs (e.g., through increased visual attention) or direct scaling of motor outputs (i.e., increased steering gain). We address this question by examining the optomotor behavior of Drosophila melanogaster in a tethered flight assay and demonstrate that whereas olfactory cues decrease the gain of the optomotor response to sideslip optic flow, they concomitantly increase the gain of the yaw optomotor response by enhancing the animal's ability to follow transient visual perturbations. Furthermore, ablating the mushroom bodies (MBs) of the fly brain via larval hydroxyurea (HU) treatment results in a loss of olfaction-dependent increase in yaw optomotor fidelity. By expressing either tetanus toxin light chain or diphtheria toxin in gal4-defined neural circuits, we were able to replicate the loss of function observed in the HU treatment within the lines expressing broadly in the mushroom bodies, but not within specific mushroom body lobes. Finally, we were able to genetically separate the yaw responses and sideslip responses in our behavioral assay. Together, our results implicate the MBs in a fast-acting, memory-independent olfactory modification of a visual reflex that is critical for flight control.

Three-dimensional characterization of the wind-borne pheromone tracking behavior of male hawkmoths, Manduca sexta

We studied the relationship between vertical and lateral movements during free flight odor plume tracking by male moths, Manduca sexta, in a wind tunnel with the "horizon" set at different altitudes. Three-dimensional recordings revealed that the plume tracking males generated roughly equivalent movements vertically and laterally regardless of horizon height. We hypothesized that the moths' tracks would be narrower in the vertical plane when they were presented with visual patterns on the tunnel's side walls. Instead, we discovered that their tracks tended to be wider in the horizontal plane. Anecdotal observations of other moth species describe plume tracking flight in three dimensions as "spiraling", suggesting a specific predictable relationship between vertical and lateral movements. However, we found that the relative phase, frequency, and amplitude of the vertical versus lateral movements vary on a maneuver-by-maneuver basis with no predictable temporal or spatial relationship. Our analyses suggest that a moth's trajectory in 3D can best be described as progressing upwind toward the source while cutting through the plume from all directions with loops of different radii. This is a more precise description than the terms "zigzagging" and "counter-turning" which were derived from 2D analyses of this behavior.

An initial study on the effects of signal intermittency on the odor plume tracking behavior of the American lobster, Homarus americanus.

of the world after each molt. That is, ommatidia viewing the most anterior region of the animal's visual space now sample a more lateral region of visual space. As a consequence, the retinotopic map in the brain must undergo comparable rearrangements to accommodate inputs from new ommatidia sampling visual space in front of the animal. The retinotopic map has been determined for adult animals at the first two synaptic layers in the brain (6), but that of the juvenile remains to be studied. The retinotopic map must be plastic to accommodate the changing retinal mosaic as the eye grows. Supported by grants from the National Science Foundation, National Eye Institute, and the National Institutes of Mental Health. C. McGuiness and S. Meadors received REU Fellowships from the National Science Foundation. We thank the f the world after each molt. That is, ommatidia viewing the most terior egion f the animal's visual space now sample a more ateral region f visual space. As a consequence, the retinotopic ap in the brain must undergo comparable rear ng ments to ccommodate inputs from new ommatidia sampling visual space front of the animal. The retinotopic map has been determined for dult animals at the first two synaptic layers n the b ain (6), but at of the juvenil remains to be studied. The retinotopic map ust be plastic o accommodate the changing retinal mosaic as the Monomoy National Wildlife Refuge, Morris Island, Chatham, Massachusetts.