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1.
Science ; 369(6500): 188-193, 2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32647000

RESUMO

Seven decades of research on the "cognitive map," the allocentric representation of space, have yielded key neurobiological insights, yet field evidence from free-ranging wild animals is still lacking. Using a system capable of tracking dozens of animals simultaneously at high accuracy and resolution, we assembled a large dataset of 172 foraging Egyptian fruit bats comprising >18 million localizations collected over 3449 bat-nights across 4 years. Detailed track analysis, combined with translocation experiments and exhaustive mapping of fruit trees, revealed that wild bats seldom exhibit random search but instead repeatedly forage in goal-directed, long, and straight flights that include frequent shortcuts. Alternative, non-map-based strategies were ruled out by simulations, time-lag embedding, and other trajectory analyses. Our results are consistent with expectations from cognitive map-like navigation and support previous neurobiological evidence from captive bats.


Assuntos
Quirópteros/fisiologia , Voo Animal/fisiologia , Orientação Espacial/fisiologia , Navegação Espacial/fisiologia , Animais , Cognição , Conjuntos de Dados como Assunto
2.
Science ; 368(6491): 634-637, 2020 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-32381721

RESUMO

Some flying animals use active sensing to perceive and avoid obstacles. Nocturnal mosquitoes exhibit a behavioral response to divert away from surfaces when vision is unavailable, indicating a short-range, mechanosensory collision-avoidance mechanism. We suggest that this behavior is mediated by perceiving modulations of their self-induced airflow patterns as they enter a ground or wall effect. We used computational fluid dynamics simulations of low-altitude and near-wall flights based on in vivo high-speed kinematic measurements to quantify changes in the self-generated pressure and velocity cues at the sensitive mechanosensory antennae. We validated the principle that encoding aerodynamic information can enable collision avoidance by developing a quadcopter with a sensory system inspired by the mosquito. Such low-power sensing systems have major potential for future use in safer rotorcraft control systems.


Assuntos
Acidentes Aeronáuticos/prevenção & controle , Aeronaves , Culicidae/fisiologia , Voo Animal/fisiologia , Visão Noturna/fisiologia , Animais , Antenas de Artrópodes/fisiologia , Biônica , Simulação por Computador , Robótica/métodos
3.
PLoS One ; 15(4): e0232193, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32348334

RESUMO

Insect wings are highly evolved structures with aerodynamic and structural properties that are not fully understood or systematically modeled. Most species in the insect order Odonata have permanently deployed high aspect ratio wings. Odonata have been documented to exhibit extraordinary flight performance and a wide range of interesting flight behaviors that rely on agility and efficiency. The characteristic three-dimensional corrugated structures of these wings have been observed and modeled for a small number of species, with studies showing that corrugations can provide significant aerodynamic and structural advantages. Comprehensive museum collections are the most practical source of Odonata wing, despite the risk of adverse effects caused by dehydration and preservation of specimens. Museum specimens are not to be handled or damaged and are best left undisturbed in their display enclosures. We have undertaken a systematic process of scanning, modeling, and post-processing the wings of over 80 Odonata species using a novel and accurate method and apparatus we developed for this purpose. The method allows the samples to stay inside their glass cases if necessary and is non-destructive. The measurements taken have been validated against micro-computed tomography scanning and against similar-sized objects with measured dimensions. The resulting publicly available dataset will allow aeronautical analysis of Odonata aerodynamics and structures, the study of the evolution of functional structures, and research into insect ecology. The technique is useable for other orders of insects and other fragile samples.


Assuntos
Odonatos/anatomia & histologia , Asas de Animais/anatomia & histologia , Animais , Bases de Dados Factuais , Voo Animal/fisiologia , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional/instrumentação , Imageamento Tridimensional/métodos , Microscopia Eletrônica de Varredura , Modelos Anatômicos , Museus , Odonatos/classificação , Odonatos/fisiologia , Fotogrametria/instrumentação , Austrália do Sul , Asas de Animais/fisiologia , Asas de Animais/ultraestrutura , Microtomografia por Raio-X
4.
PLoS One ; 15(3): e0229746, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32126133

RESUMO

Dynamic soaring is a flight technique used by albatrosses and other birds to cover large distances without the expenditure of energy, which is extracted from the available wind conditions, as brightly perceived five centuries ago by Leonardo da Vinci. Closed dynamic soaring trajectories use spatial variations of wind speed to travel, in principle, indefinitely over a prescribed area. The application of the concept of closed dynamic soaring trajectories to aerial vehicles, such as UAVs, may provide a solution to improve the endurance in certain missions. The main limitation of dynamic soaring is its dependence on the wind characteristics. More than one century ago, Lord Rayleigh proposed a very simple model, based on the repeated crossing of a step wind profile, presently known as Rayleigh cycle, that provides a clear explanation of the physical phenomenon. The present paper studies the feasibility of closed, single-loop, energy-neutral trajectories for a broad set of wind and vehicle conditions. Through the use of trajectory optimization methods, it was possible to see how the shape of the wind profile, the initial flight conditions and the vehicle constraints influence the required wind strength to perform dynamic soaring trajectories and consequently their feasibility. It was possible to conclude that there are optimal values for the initial airspeed and initial height of the vehicle, that minimize the required wind strength. In addition, it was seen how the structural and aerodynamic constraints of the vehicle affect dynamic soaring at high and low airspeeds respectively. Finally, some new trajectories that can be performed in conditions of excess wind are proposed. The purpose is to maximize the time spent aloft and the path length while maintaining the concept of single-loop, energy-neutral trajectories, making them especially useful for aerial vehicles surveillance applications.


Assuntos
Aviação/métodos , Aves/fisiologia , Voo Animal/fisiologia , Modelos Teóricos , Vento , Animais , Estudos de Viabilidade , Asas de Animais/fisiologia
5.
PLoS One ; 15(3): e0230262, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32176713

RESUMO

Although there is a consensus about the evolutionary drivers of animal migration, considerable work is necessary to identify the mechanisms that underlie the great variety of strategies observed in nature. The study of differential migration offers unique opportunities to identify such mechanisms and allows comparisons of the costs and benefits of migration. The purpose of this study was to compare the characteristics of short and long-distance migrations, and fitness consequences, in a long-lived seabird species. We combined demographic monitoring (survival, phenology, hatching success) of 58 Northern Gannets (Morus bassanus) breeding on Bonaventure Island (Canada) and biologging technology (Global Location Sensor or GLS loggers) to estimate activity and energy budgets during the non-breeding period for three different migration strategies: to the Gulf of Mexico (GM), southeast (SE) or northeast (NE) Atlantic coast of the U.S. Survival, timing of arrival at the colony and hatching success are similar for short (NE, SE) and long-distance (GM) migrants. Despite similar fitness consequences, we found, as expected, that the overall energetic cost of migration is higher for long-distance migrants, although the daily cost during migration was similar between strategies. In contrast, daily maintenance and thermoregulation costs were lower for GM migrants in winter, where sea-surface temperature of the GM is 4-7o C warmer than SE and NE. In addition, GM migrants tend to fly 30 min less per day in their wintering area than other migrants. Considering lower foraging effort and lower thermoregulation costs during winter for long-distance migrants, this suggests that the energetic benefits during the winter of foraging in the GM outweigh any negative consequences of the longer-distance migration. These results support the notion that the costs and benefits of short and long-distance migration is broadly equal on an annual basis, i.e. there are no apparent carry-over effects in this long-lived bird species, probably because of the favourable conditions in the furthest wintering area.


Assuntos
Migração Animal/fisiologia , Aves/fisiologia , Metabolismo Energético/fisiologia , Animais , Cruzamento , Canadá , Voo Animal/fisiologia , Golfo do México , Oceanos e Mares , Estações do Ano , Análise de Sobrevida , Temperatura
6.
J Insect Sci ; 20(1)2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-32104893

RESUMO

Different densities prerelease packing and times of lethargy in the fruit fly parasitoids Diachasmimorpha longicaudata (Ashmead) were evaluated in order to standardize the process of chilled insect technique for this species. Adults were kept at densities of 0.048, 0.072, 0.096, 0.120, and 0.144 parasitoids/cm2 before release in a México tower, where thermal lethargy was induced at a temperature of 2 ± 2°C for 45 min. Samples of parasitoids were collected to evaluate mortality, survival, fecundity, and flight capacity. All densities showed a similar mortality, both for males (ca. >10%) and females (ca. <7). There was no effect of density on survival and flight capacity in both sexes. On the other hand, fecundity increased with density, 1.66 sons/♀/day, similar to the control. We conclude that a density of 30,000 pupae per cage (0.144 parasitoids/cm2) is adequate for the massive prerelease packaging of the parasitoid D. longicaudata. Regarding the thermal lethargy period, 180 min under 2 ± 2°C conditions, considered as time for management, does not affect the survival, fecundity, and flight capacity of adults. The results obtained are of great utility to establish prerelease packaging parameters for D. longicaudata used in the biological control of Tephritidae fruit fly populations.


Assuntos
Temperatura Baixa , Controle Biológico de Vetores/métodos , Vespas/fisiologia , Animais , Feminino , Fertilidade/fisiologia , Voo Animal/fisiologia , Masculino , Tephritidae/parasitologia
7.
PLoS One ; 15(1): e0226689, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31914127

RESUMO

Many animals display morphological adaptations of the nose that improve their ability to detect and track odors. Bilateral odor sampling improves an animals' ability to navigate using olfaction and increased separation of the nostrils facilitates olfactory source localization. Many bats use odors to find food and mates and bats display an elaborate diversity of facial features. Prior studies have quantified how variations in facial features correlate with echolocation and feeding ecology, but surprisingly none have asked whether bat noses might be adapted for olfactory tracking in flight. We predicted that bat species that rely upon odor cues while foraging would have greater nostril separation in support of olfactory tropotaxis. Using museum specimens, we measured the external nose and cranial morphology of 40 New World bat species. Diet had a significant effect on external nose morphology, but contrary to our predictions, insectivorous bats had the largest relative separation of nostrils, while nectar feeding species had the narrowest nostril widths. Furthermore, nasal echolocating bats had significantly narrower nostrils than oral emitting bats, reflecting a potential trade-off between sonar pulse emission and stereo-olfaction in those species. To our knowledge, this is the first study to evaluate the evolutionary interactions between olfaction and echolocation in shaping the external morphology of a facial feature using modern phylogenetic comparative methods. Future work pairing olfactory morphology with tracking behavior will provide more insight into how animals such as bats integrate olfactory information while foraging.


Assuntos
Adaptação Fisiológica , Evolução Biológica , Quirópteros/anatomia & histologia , Ecologia , Voo Animal/fisiologia , Nariz/anatomia & histologia , Olfato/fisiologia , Animais , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Quirópteros/fisiologia , Ecolocação , Nariz/fisiologia , Filogenia , Comportamento Predatório
8.
Nat Commun ; 10(1): 5593, 2019 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811150

RESUMO

Complex behaviours may be viewed as sequences of modular actions, each elicited by specific sensory cues in their characteristic timescales. From this perspective, we can construct models in which unitary behavioural modules are hierarchically placed in context of related actions. Here, we analyse antennal positioning reflex in hawkmoths as a tuneable behavioural unit. Mechanosensory feedback from two antennal structures, Böhm's bristles (BB) and Johnston's organs (JO), determines antennal position. At flight onset, antennae attain a specific position, which is maintained by feedback from BB. Simultaneously, JO senses deflections in flagellum-pedicel joint due to frontal airflow, to modulate its steady-state position. Restricting JO abolishes positional modulation but maintains stability against perturbations. Linear feedback models are sufficient to predict antennal dynamics at various set-points. We modelled antennal positioning as a hierarchical neural-circuit in which fast BB feedback maintains instantaneous set-point, but slow JO feedback modulates it, thereby elucidating mechanisms underlying its robustness and flexibility.


Assuntos
Movimentos do Ar , Voo Animal/fisiologia , Mariposas/fisiologia , Reflexo/fisiologia , Asas de Animais/fisiologia , Animais , Comportamento Animal/fisiologia , Sinais (Psicologia) , Feminino , Flagelos , Masculino , Mariposas/anatomia & histologia , Neurônios Motores/fisiologia , Fenômenos Fisiológicos do Sistema Nervoso , Estimulação Física , Asas de Animais/inervação
9.
PLoS Comput Biol ; 15(12): e1007550, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31856162

RESUMO

Most objects and vegetation making up the habitats of echolocating bats return a multitude of overlapping echoes. Recent evidence suggests that the limited temporal and spatial resolution of bio-sonar prevents bats from separately perceiving the objects giving rise to these overlapping echoes. Therefore, bats often operate under conditions where their ability to localize obstacles is severely limited. Nevertheless, bats excel at avoiding complex obstacles. In this paper, we present a robotic model of bat obstacle avoidance using interaural level differences and distance to the nearest obstacle as the minimal set of cues. In contrast to previous robotic models of bats, the current robot does not attempt to localize obstacles. We evaluate two obstacle avoidance strategies. First, the Fixed Head Strategy keeps the acoustic gaze direction aligned with the direction of flight. Second, the Delayed Linear Adaptive Law (DLAL) Strategy uses acoustic gaze scanning, as observed in hunting bats. Acoustic gaze scanning has been suggested to aid the bat in hunting for prey. Here, we evaluate its adaptive value for obstacle avoidance when obstacles can not be localized. The robot's obstacle avoidance performance is assessed in two environments mimicking (highly cluttered) experimental setups commonly used in behavioral experiments: a rectangular arena containing multiple complex cylindrical reflecting surfaces and a corridor lined with complex reflecting surfaces. The results indicate that distance to the nearest object and interaural level differences allows steering the robot clear of obstacles in environments that return non-localizable echoes. Furthermore, we found that using acoustic gaze scanning reduced performance, suggesting that gaze scanning might not be beneficial under conditions where the animal has limited access to angular information, which is in line with behavioral evidence.


Assuntos
Quirópteros/fisiologia , Ecolocação/fisiologia , Modelos Biológicos , Robótica/instrumentação , Acústica , Algoritmos , Animais , Aprendizagem da Esquiva/fisiologia , Comportamento Animal/fisiologia , Quirópteros/psicologia , Biologia Computacional , Simulação por Computador , Sinais (Psicologia) , Voo Animal/fisiologia , Robótica/estatística & dados numéricos
10.
Nature ; 575(7782): 324-329, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31686057

RESUMO

Flying insects capable of navigating in highly cluttered natural environments can withstand in-flight collisions because of the combination of their low inertia1 and the resilience of their wings2, exoskeletons1 and muscles. Current insect-scale (less than ten centimetres long and weighing less than five grams) aerial robots3-6 use rigid microscale actuators, which are typically fragile under external impact. Biomimetic artificial muscles7-10 that are capable of large deformation offer a promising alternative for actuation because they can endure the stresses caused by such impacts. However, existing soft actuators11-13 have not yet demonstrated sufficient power density to achieve lift-off, and their actuation nonlinearity and limited bandwidth create further challenges for achieving closed-loop (driven by an input control signal that is adjusted based on sensory feedback) flight control. Here we develop heavier-than-air aerial robots powered by soft artificial muscles that demonstrate open-loop (driven by a predetermined signal without feedback), passively stable (upright during flight) ascending flight as well as closed-loop, hovering flight. The robots are driven by multi-layered dielectric elastomer actuators that weigh 100 milligrams each and have a resonance frequency of 500 hertz and power density of 600 watts per kilogram. To increase the mechanical power output of the actuator and to demonstrate flight control, we present ways to overcome challenges unique to soft actuators, such as nonlinear transduction and dynamic buckling. These robots can sense and withstand collisions with surrounding obstacles and can recover from in-flight collisions by exploiting material robustness and vehicle passive stability. We also fly two micro-aerial vehicles simultaneously in a cluttered environment. They collide with the wall and each other without suffering damage. These robots rely on offboard amplifiers and an external motion-capture system to provide power to the dielectric elastomer actuators and to control their flight. Our work demonstrates how soft actuators can achieve sufficient power density and bandwidth to enable controlled flight, illustrating the potential of developing next-generation agile soft robots.


Assuntos
Voo Animal/fisiologia , Músculos/fisiologia , Animais , Próteses e Implantes , Robótica , Asas de Animais
11.
Nat Commun ; 10(1): 5354, 2019 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-31767856

RESUMO

The lift that animal wings generate to fly is typically considered a vertical force that supports weight, while drag is considered a horizontal force that opposes thrust. To determine how birds use lift and drag, here we report aerodynamic forces and kinematics of Pacific parrotlets (Forpus coelestis) during short, foraging flights. At takeoff they incline their wing stroke plane, which orients lift forward to accelerate and drag upward to support nearly half of their bodyweight. Upon landing, lift is oriented backward to contribute a quarter of the braking force, which reduces the aerodynamic power required to land. Wingbeat power requirements are dominated by downstrokes, while relatively inactive upstrokes cost almost no aerodynamic power. The parrotlets repurpose lift and drag during these flights with lift-to-drag ratios below two. Such low ratios are within range of proto-wings, showing how avian precursors may have relied on drag to take off with flapping wings.


Assuntos
Fenômenos Biomecânicos/fisiologia , Aves/fisiologia , Voo Animal/fisiologia , Asas de Animais/fisiologia , Algoritmos , Animais , Fenômenos Mecânicos , Modelos Biológicos , Fenômenos Físicos
12.
PLoS One ; 14(10): e0214168, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31647815

RESUMO

Bioacoustic sensors, sometimes known as autonomous recording units (ARUs), can record sounds of wildlife over long periods of time in scalable and minimally invasive ways. Deriving per-species abundance estimates from these sensors requires detection, classification, and quantification of animal vocalizations as individual acoustic events. Yet, variability in ambient noise, both over time and across sensors, hinders the reliability of current automated systems for sound event detection (SED), such as convolutional neural networks (CNN) in the time-frequency domain. In this article, we develop, benchmark, and combine several machine listening techniques to improve the generalizability of SED models across heterogeneous acoustic environments. As a case study, we consider the problem of detecting avian flight calls from a ten-hour recording of nocturnal bird migration, recorded by a network of six ARUs in the presence of heterogeneous background noise. Starting from a CNN yielding state-of-the-art accuracy on this task, we introduce two noise adaptation techniques, respectively integrating short-term (60 ms) and long-term (30 min) context. First, we apply per-channel energy normalization (PCEN) in the time-frequency domain, which applies short-term automatic gain control to every subband in the mel-frequency spectrogram. Secondly, we replace the last dense layer in the network by a context-adaptive neural network (CA-NN) layer, i.e. an affine layer whose weights are dynamically adapted at prediction time by an auxiliary network taking long-term summary statistics of spectrotemporal features as input. We show that PCEN reduces temporal overfitting across dawn vs. dusk audio clips whereas context adaptation on PCEN-based summary statistics reduces spatial overfitting across sensor locations. Moreover, combining them yields state-of-the-art results that are unmatched by artificial data augmentation alone. We release a pre-trained version of our best performing system under the name of BirdVoxDetect, a ready-to-use detector of avian flight calls in field recordings.


Assuntos
Acústica/instrumentação , Ecolocação/fisiologia , Redes Neurais de Computação , Processamento de Sinais Assistido por Computador/instrumentação , Vocalização Animal/fisiologia , Animais , Aves/fisiologia , Voo Animal/fisiologia , Ruído , Reprodutibilidade dos Testes
13.
PLoS One ; 14(9): e0222214, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31491008

RESUMO

Light traps are used to determine the temporal and spatial dynamics of the migratory brown planthoppers (BPHs) Nilaparvata lugens. But very little is known whether newly emerged adults respond to local light traps during the emigration period. Thus, it is important to evaluate the efficiency of light traps in attracting emigrant and immigrant populations to improve forecasting and control of this pest. The migration periods of N. lugens were determined by field surveys in Fuyang, Zhejiang province in 2012 and Yongfu, Guangxi Zhuang Autonomous Region in 2013. Mark-release-recapture experiments with both newly emerged (unflown) and flight experienced (flown) N. lugens were conducted at the two study sites. The marking method did not have any significant effect on the survival or flight capability of the N. lugens. A total of 4800 marked flown and 8400 unflown BPHs were released at a distance of 10, 20 and 30 m from 45-watt fluorescent actinic light traps. The results showed that without wind (< 3.2 m/s) or rainfall conditions, the overall recapture rate of flown BPHs was higher than that of unflown BPHs (9.60% and 0.92%, respectively; χ21 = 589.66, P < 0.0001). Curve estimation regression analysis showed that flown BPHs were attracted to the light source at a distance of 19.77 m, and unflown BPH at a distance of 5.35 m, with these distances corresponding to a 5% recapture rate. Given that the population dynamics of BPHs in the light traps were not synchronous with that in the fields, our results indicate that only a few emerging BPHs in an infested site can be captured locally by light traps. Therefore, care must be taken in estimating the abundance of the sample to absolute local abundance during sedentary and emigration period.


Assuntos
Migração Animal/fisiologia , Hemípteros/fisiologia , Fototaxia/fisiologia , Animais , Voo Animal/fisiologia
14.
Horm Behav ; 116: 104586, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31473198

RESUMO

Glucocorticoids are commonly associated with responses to stress, but other important functions include homeostatic regulation, energy metabolism and tissue remodeling. At low circulating levels, glucocorticoids bind to high-affinity mineralocorticoid receptors (MR) to activate tissue repair and homeostasis (anabolic pathways), whereas at elevated levels, glucocorticoids bind to glucocorticoid receptors (GR) to activate catabolic pathways. Long distance migrations, such as those performed by Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii), require modification of anatomy, physiology and behavior. Plasma corticosterone (CORT) increases in association with impending departure and flight and may promote muscle-specific anabolic states. To test this idea, we explored glucocorticoid signaling in the pectoralis (flight) and gastrocnemius (leg) muscles of male sparrows on the wintering grounds at three stages leading up to spring departure: winter (February), pre-nuptial molt (March), and pre-departure (April). CORT was detected in plasma and in both muscles, but measures of CORT signaling differed across muscles and stages. Expression of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) Type 2 (inactivates CORT) increased in the pectoralis at pre-departure, whereas 11ß-HSD Type 1 (regenerates CORT) did not change. Neither of the two 11ß-HSD isoforms was detectable in the gastrocnemius. Expression of MR, but not GR, was elevated in the pectoralis at pre-departure, while only GR expression was elevated at pre-nuptial molt in gastrocnemius. These data suggest that anabolic functions predominate in the pectoralis only while catabolic activity is undetected in either muscle at pre-departure.


Assuntos
Migração Animal/fisiologia , Voo Animal/fisiologia , Glucocorticoides/metabolismo , Músculo Esquelético/metabolismo , Pardais/fisiologia , Animais , Variação Biológica Individual , Corticosterona/sangue , Masculino , Muda , Fenótipo , Receptores de Glucocorticoides/metabolismo , Estações do Ano , Transdução de Sinais/fisiologia , Fatores de Tempo
15.
PLoS One ; 14(7): e0220563, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31365584

RESUMO

The BG-Malaria trap (BGM) is an adaptation of the well-known BG-Sentinel trap (BGS) with greater trapping efficiencies for anopheline and culicine mosquitoes. Its continued optimization requires greater understanding of mosquito flight behaviors near it. We used three high-resolution infrared cameras (68 frames/second) to track flight behaviors of laboratory-reared Anopheles arabiensis females in vicinity of the BGM in comparison with BGS. Additional comparisons were done for BGM at 20, 40 and 80cm heights, and for BGMs baited with Ifakara blend plus CO2, CO2 alone, or no bait. More mosquitoes were observed near BGM than BGS. Both BGMs installed 20cm above the floor and baited with CO2 received more visits by host-seeking mosquitoes than the other BGMs evaluated in their respective experiments. Trap designs, height and attractants all influence mosquito activity in vicinity of the traps which can be readily visualized using infrared cameras to accelerate trap development and testing. The greater activity of host-seeking mosquitoes near BGM than BGS supports the proven superiority of BGM traps in field and semi-field settings.


Assuntos
Comportamento Animal/efeitos dos fármacos , Voo Animal/fisiologia , Malária/prevenção & controle , Malária/parasitologia , Controle de Mosquitos/instrumentação , Controle de Mosquitos/métodos , Plasmodium falciparum/fisiologia , Animais , Anopheles , Feminino , Voo Animal/efeitos dos fármacos , Odorantes , Plasmodium falciparum/efeitos dos fármacos
16.
Bioinspir Biomim ; 14(5): 055005, 2019 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-31365904

RESUMO

Chimney swifts (Chaetura pelagica) are highly aerial, small, insectivorous birds well known for roosting en masse in chimneys during their autumn migration. These roosting events require hundreds to thousands of birds to enter a small opening (here 0.64 m2) within a short amount of time (15-30 min). Thus, these entry events pose a complex navigational and behavioral challenge as birds identify their entry route, cooperate with other birds present to form an entry flock, and compete with other birds at the time of chimney entry. We used six synchronized cameras to capture and reconstruct the 3D flight trajectories of swifts before and during chimney entry. Navigation into the chimney is consistent with use of a relative retinal expansion velocity cue, which results in an entry/non-entry decision point about 1.5 m above the chimney, or 0.4 s at typical entry speeds. Entries were highly clustered with 91 of 136 entries occurring within 1 s of another entry. We observed both synchronous (entry within 0.2 s) and sequential entry behavior (entry separated by ~0.4 s). Birds entering the chimney flew in close proximity to other birds (median minimum distance 0.51 m; 1.7 wingspans). In cases where two birds appeared to attempt a near-simultaneous entry, the bird either slightly to the rear or with a velocity vector bringing it closer to the current position of the other bird tended to make an avoidance maneuver and abandon its entry attempt. Overall, these results show how groups of animals execute complex landing and collision avoidance maneuvers in a natural setting without central control authority.


Assuntos
Comportamento Animal/fisiologia , Aves/fisiologia , Comportamento Competitivo/fisiologia , Comportamento Cooperativo , Voo Animal/fisiologia , Animais , Retina/fisiologia , Gravação em Vídeo
17.
PLoS One ; 14(8): e0219861, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31412069

RESUMO

Landing maneuvers of flies are complex behaviors which can be conceptually decomposed into sequences of modular actions, including body-deceleration, leg-extension, and body rotations. These behavioral 'modules' must be coordinated to ensure well-controlled landing. The composite nature of these behaviors induces kinematic variability, making it difficult to identify the central rules that govern landing. Many previous studies have relied on tethered preparations to study landing behaviors, but tethering induces experimental artefacts by forcing some behaviors to operate in open-feedback control loop while others remain closed-loop. On the other hand, it is harder for the experimenter to control the stimuli experienced by freely-flying insects. One approach towards understanding general mechanisms of landing is to determine the common elements of their kinematics on surfaces of different orientations. We conducted a series of experiments in which the houseflies, Musca domestica, were lured to land on vertical (wall landings) or inverted (ceiling landings) substrates, while their flight was recorded with multiple high-speed cameras. We observed that, in both cases, well-controlled landings occurred when the distance at which flies initiated deceleration was proportional to flight velocity component in the direction of substrate. The ratio of substrate distance and velocity at onset of deceleration (tau) was conserved, despite substantial differences in mechanics of vertical vs. ceiling landings. When these conditions were not satisfied, their landing performance was compromised, causing their heads to collide into the substrate. Unlike body-deceleration, leg-extension in flies was independent of substrate distance or approach velocity. Thus, the robust reflexive visual initiation of deceleration is independent of substrate orientation, and combines with a more variable initiation of leg-extension which depends on surface orientation. Together, these combinations of behaviors enable flies to land in a versatile manner on substrates of various orientations.


Assuntos
Aprendizagem da Esquiva/fisiologia , Voo Animal/fisiologia , Moscas Domésticas/fisiologia , Atividade Motora/fisiologia , Orientação Espacial/fisiologia , Animais , Fenômenos Biomecânicos , Desaceleração
18.
Bioinspir Biomim ; 14(6): 065001, 2019 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-31412322

RESUMO

We have designed a bio-hybrid fly-robot interface (FRI) to study sensorimotor control in insects. The FRI consists of a miniaturized recording platform mounted on a two-wheeled robot and is controlled by the neuronal spiking activity of an identified visual interneuron, the blowfly H1-cell. For a given turning radius of the robot, we found a proportional relationship between the spike rate of the H1-cell and the relative distance of the FRI from the patterned wall of an experimental arena. Under closed-loop conditions during oscillatory forward movements biased towards the wall, collision avoidance manoeuvres were triggered whenever the H1-cell spike rate exceeded a certain threshold value. We also investigated the FRI behaviour in corners of the arena. The ultimate goal is to enable autonomous and energy-efficient manoeuvrings of the FRI within arbitrary visual environments.


Assuntos
Voo Animal/fisiologia , Robótica/instrumentação , Algoritmos , Animais , Aprendizagem da Esquiva , Materiais Biomiméticos , Interface Usuário-Computador
19.
Bioinspir Biomim ; 14(5): 056015, 2019 08 29.
Artigo em Inglês | MEDLINE | ID: mdl-31357180

RESUMO

Birds fly in dynamic flight conditions while maintaining aerodynamic efficiency. This agility is in part due to specialized feather systems that function as flow control devices during adverse conditions such as high-angle of attack maneuvers. In this paper, we present an engineered three-dimensional leading-edge device inspired by one of these specialized groups of feathers known as the alula. Wind tunnel results show that, similar to the biological alula, the leading-edge alula-inspired device (LEAD) increases the wing's ability to maintain higher pressure gradients by modifying the near-wall flow. It also generates tip vortices that modify the turbulence on the upper-surface of the wing, delaying flow separation. The effect of the LEAD location and morphology on lift production and wake velocity profile are investigated using force and hot-wire anemometer measurements, respectively. Results show lift improvements up to 32% and 37% under post and deep stall conditions, respectively. Despite the observed drag penalties of up to 39%, the aerodynamic efficiency, defined as the lift-to-drag ratio, is maintained and sometimes improved with the addition of the LEAD to a wing. This is to be expected as the LEAD is a post-stall device, suitable for high angles of attack maneuvers, where maintaining lift production is more critical than drag reduction. The LEAD also accelerates the flow over the wing and reduces the wake velocity deficit, indicating attenuated flow separation. This work presents a detailed experimental investigation of an engineered three dimensional leading-edge device that combines the functionality of traditional two dimensional slats and vortex generators. Such a device can be used to not only extend the flight envelope of unmanned aerial vehicles (UAVs), but to also study the role and function of the biological alula.


Assuntos
Biomimética/instrumentação , Plumas/anatomia & histologia , Asas de Animais/anatomia & histologia , Animais , Fenômenos Biomecânicos , Voo Animal/fisiologia , Vento
20.
Proc Natl Acad Sci U S A ; 116(30): 15033-15041, 2019 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-31289235

RESUMO

Flying birds maneuver effectively through lateral gusts, even when gust speeds are as high as flight speeds. What information birds use to sense gusts and how they compensate is largely unknown. We found that lovebirds can maneuver through 45° lateral gusts similarly well in forest-, lake-, and cave-like visual environments. Despite being diurnal and raised in captivity, the birds fly to their goal perch with only a dim point light source as a beacon, showing that they do not need optic flow or a visual horizon to maneuver. To accomplish this feat, lovebirds primarily yaw their bodies into the gust while fixating their head on the goal using neck angles of up to 30°. Our corroborated model for proportional yaw reorientation and speed control shows how lovebirds can compensate for lateral gusts informed by muscle proprioceptive cues from neck twist. The neck muscles not only stabilize the lovebirds' visual and inertial head orientations by compensating low-frequency body maneuvers, but also attenuate faster 3D wingbeat-induced perturbations. This head stabilization enables the vestibular system to sense the direction of gravity. Apparently, the visual horizon can be replaced by a gravitational horizon to inform the observed horizontal gust compensation maneuvers in the dark. Our scaling analysis shows how this minimal sensorimotor solution scales favorably for bigger birds, offering local wind angle feedback within a wingbeat. The way lovebirds glean wind orientation may thus inform minimal control algorithms that enable aerial robots to maneuver in similar windy and dark environments.


Assuntos
Agapornis/fisiologia , Retroalimentação Sensorial/fisiologia , Voo Animal/fisiologia , Orientação/fisiologia , Desempenho Psicomotor/fisiologia , Percepção Espacial/fisiologia , Animais , Escuridão , Feminino , Masculino , Músculos do Pescoço/fisiologia , Percepção Visual/fisiologia , Vento , Asas de Animais/anatomia & histologia , Asas de Animais/fisiologia
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