RESUMEN
Pollinators use their sense of smell to locate flowers from long distances, but little is known about how they are able to discriminate their target odor from a mélange of other natural and anthropogenic odors. Here, we measured the plume from Datura wrightii flowers, a nectar resource for Manduca sexta moths, and show that the scent was dynamic and rapidly embedded among background odors. The moth's ability to track the odor was dependent on the background and odor frequency. By influencing the balance of excitation and inhibition in the antennal lobe, background odors altered the neuronal representation of the target odor and the ability of the moth to track the plume. These results show that the mix of odors present in the environment influences the pollinator's olfactory ability.
Asunto(s)
Datura/fisiología , Flores/fisiología , Manduca/fisiología , Neuronas/fisiología , Odorantes , Neuronas Receptoras Olfatorias/fisiología , Animales , Antenas de Artrópodos/inervación , Antenas de Artrópodos/fisiología , Conducta Animal , Encéfalo/fisiología , Fenómenos Electrofisiológicos , Conducta Alimentaria , Vuelo Animal , Interneuronas/fisiología , Masculino , Inhibición Neural , Vías Olfatorias/fisiología , Percepción Olfatoria , Néctar de las Plantas , Polinización , Olfato , Compuestos Orgánicos VolátilesRESUMEN
Insect antennae are sensory organs involved in a variety of behaviors, sensing many different stimulus modalities. As mechanosensors, they are crucial for flight control in the hawkmoth Manduca sexta. One of their roles is to mediate compensatory reflexes of the abdomen in response to rotations of the body in the pitch axis. Abdominal motions, in turn, are a component of the steering mechanism for flying insects. Using a radio controlled, programmable, miniature stimulator, we show that ultra-low-current electrical stimulation of antennal muscles in freely-flying hawkmoths leads to repeatable, transient changes in the animals' pitch angle, as well as less predictable changes in flight speed and flight altitude. We postulate that by deflecting the antennae we indirectly stimulate mechanoreceptors at the base, which drive compensatory reflexes leading to changes in pitch attitude.
Asunto(s)
Antenas de Artrópodos/fisiología , Vuelo Animal , Manduca/fisiología , Mecanotransducción Celular , Animales , Antenas de Artrópodos/citología , Antenas de Artrópodos/inervación , Estimulación Eléctrica , Manduca/citología , Mecanorreceptores/fisiología , Músculos/fisiología , Tecnología InalámbricaRESUMEN
Direct gating of mechanoelectrical transduction channels by mechanical force is a basic feature of hair cells that assures fast transduction and underpins the mechanical amplification of acoustic inputs, but the associated non-linearity - the gating compliance - inevitably distorts signals. Because reducing distortion would make the ear a better detector, we sought mechanisms with that effect. Mimicking in vivo stimulation, we used stiff probes to displace individual hair bundles at physiological amplitudes and measured the coherence and phase of the relative stereociliary motions with a dual-beam differential interferometer. Although stereocilia moved coherently and in phase at the stimulus frequencies, large phase lags at the frequencies of the internally generated distortion products indicated dissipative relative motions. Tip links engaged these relative modes and decreased the coherence in both stimulated and free hair bundles. These results show that a hair bundle breaks into a highly dissipative serial arrangement of stereocilia at distortion frequencies, precluding their amplification.
Asunto(s)
Estimulación Acústica , Células Ciliadas Auditivas Internas/fisiología , Distorsión de la Percepción/fisiología , Estereocilios/fisiología , Animales , Femenino , Activación del Canal Iónico/fisiología , Canales Iónicos/fisiología , Masculino , Mecanorreceptores/fisiología , Modelos Animales , Rana catesbeianaRESUMEN
Flying insects rely on the integration of feedback signals from multiple sensory modalities. Thus, in addition to the visual input, mechanosensory information from antennae is crucial for stable flight in the hawkmoth Manduca sexta. However, the nature of compensatory reflexes mediated by mechanoreceptors on the antennae is unknown. In this study we describe an abdominal flexion response mediated by the antennal mechanosensory input during mechanical body rotations. Such reflexive abdominal motions lead to shifts in the animal's center of mass, and therefore changes in flight trajectory. Moths respond with abdominal flexion both to visual and mechanical rotations, but the mechanical response depends on the presence of the mass of the flagellum. In addition, the mechanically mediated flexion response is about 200° out of phase with the visual response and adds linearly to it. Phase-shifting feedback signals in such a manner can lead to a more stable behavioral output response when the animal is faced with turbulent perturbations to the flight path.