Biology subjects

Sane, S. P.

Publications and source records attributed to Sane, S. P..

3 recordsLinked to original sources

bioRxiv2018

Visual control of landing maneuvers in houseflies on vertical and inverted surfaces

Landing maneuvers in flies are complex behaviors that may be conceptually decomposed into a sequence of modular behaviors such as body deceleration, extension of legs, and body rotations which are coordinated to ensure controlled touchdown. The composite nature of these behaviors means that there is variability in the kinematics of landing maneuvers, making it difficult to identify the general rules that govern this behavior. Many previous studies have relied on tethered preparations to study landing behaviors, but tethering constrains some behavioral modules to operate in an open feedback control loop while others remain in closed-loop, thereby inducing experimental artefacts. On the other hand, freely flying insects are hard to precisely control, which may also increase behavioral variability. One approach towards understanding the general rules underlying landing behavior is to determine the common elements of landing kinematics on surfaces that are oriented in different ways. We conducted a series of experiments in which the houseflies, Musca Domestica, were lured to specific visual targets on either vertical or inverted horizontal substrates. These conditions elicited landing behaviors in the flies that could be captured accurately using multiple high-speed video cameras. We filmed the houseflies landing on surfaces oriented along two directions: vertical (vertical landings), and upside down (inverted landings). Our experiments reveal that flies that are able to land feet-first in a controlled manner must satisfy specific criteria, failing which their landing performance is compromised causing their heads to bump into the surface during landing. Flies landing smoothly on both surfaces initiate deceleration at approximately fixed distances from the substrate and in direct proportion to the component of flight velocity normal to the landing surface. The ratio of perpendicular distance to the substrate and velocity at the onset of deceleration was conserved, despite the large differences in the mechanics of the vertical vs. inverted landings. Flies extend their legs independently of distance from the landing surface or their approach velocity normal to the surface, regardless of the orientation of the landing substrate. Together, these results show that the visual initiation of deceleration is robust to orientation of the landing surface, whereas the initiation of leg-extension may be context-dependent and variable which allows flies to land on substrates of various orientations in a versatile manner. These findings may also be of interest to roboticists that are interested in developing flapping robots that can land on surfaces of different orientations.

animal behavior and cognition↗

bioRxiv2018

Independent control of slow and fast flight manoeuvres in insects: the roles of vision and antennal mechanoreception

Flying animals need constant sensory feedback about their body position and orientation for flight control. The visual system provides essential but slow feedback. In contrast, mechanosensory channels can provide feedback at much shorter timescales. How the contributions from these two senses are integrated remains an open question in most insect groups. In Diptera, fast mechanosensory feedback is provided by organs called halteres, and is crucial for the control of rapid flight manoeuvres, while vision controls manoeuvres in lower temporal frequency bands. Here we have investigated the visual-mechanosensory integration in an insect which lacks halteres: the hawkmoth Macroglossum stellatarum. They represent a large group of insects that use Johnstons organs in their antennae to provide mechanosensory feedback on perturbations in body position. High-speed videos of freely-flying hawkmoths hovering at stationary or oscillating artificial flowers showed that positional fidelity during flight was reduced in flagella ablated animals, but was recovered after flagella re-attachment. Our experiments show that antennal mechanosensory feedback specifically mediates fast flight manoeuvres, but not slow ones. Differences in the latency of visual feedback (in different light intensities) affected all antennal conditions equally, suggesting there was no compensatory interaction between antennal and visual feedback under the tested conditions. These results establish the importance of antennal mechanosensors in providing rapid mechanosensory feedback for finer control of flight manoeuvres, acting in parallel to visual feedback.

neuroscience↗

bioRxiv2017

Odor source localization in complex visual environments by fruit flies

Flying insects routinely forage in complex and cluttered sensory environments. Their search for a food or a pheromone source typically begins with a whiff of odor, which triggers a flight response, eventually bringing the insect in the vicinity of the odor source. The precise localization of an odor source, however, requires the use of both visual and olfactory modalities, aided by air currents that trap odor molecules into turbulent plumes, which the insects track. Here, we investigated odor tracking behavior in fruit flies (Drosophila melanogaster) presented with low- or high-contrast visual landmarks, which were either paired with or separate from an attractive odor cue. These experiments were conducted either in a gentle air stream which generated odor plumes, or in still air in which odor dissipates uniformly in all directions. The trajectories of the flies revealed several novel features of their odor-tracking behavior in addition to those that have been previously documented (e.g. cast- and-surge maneuvers). First, in both moving and still air, odor-seeking flies rely on the co-occurrence of visual landmarks with olfactory cues to guide them to putative odorant objects in the decisive phase before landing. Second, flies abruptly decelerate when they encounter an odor plume, and thereafter steer towards nearby visual objects that had no inherent salience in the absence of odor. This indicates that the interception of an attractive odor increases their salience to nearby high-contrast visual landmarks. Third, flies adopt distinct odor tracking strategies during flight in moving vs. still air. Whereas they weave in and out of plumes towards an odor source when airflow is present, their approach is more gradual and incremental in still air. Both strategies are robust and flexible, and can ensure that the flies reliably find the odor source under diverse visual and airflow environments. Our experiments also indicate the possibility of an olfactory \" working memory\" that enables flies to continue their search even when the olfactory feedback is reduced or absent. Together, these results provide insights into how flies determine the precise location of an odor source.

animal behavior and cognition↗