Mechanics of the thorax in flies

Insects represent more than 60% of all multicellular life forms, and are easily among the most diverse and abundant organisms on earth. They evolved functional wings and the ability to fly, which enabled them to occupy diverse niches. Insects of the hyper-diverse orders show extreme miniaturization of their body size. The reduced body size, however, imposes steep constraints on flight ability, as their wings must flap faster to generate sufficient forces to stay aloft. Here, we discuss the various physiological and biomechanical adaptations of the thorax in flies which enabled them to overcome the myriad constraints of small body size, while ensuring very precise control of their wing motion. One such adaptation is the evolution of specialized myogenic or asynchronous muscles that power the high-frequency wing motion, in combination with neurogenic or synchronous steering muscles that control higher-order wing kinematic patterns. Additionally, passive cuticular linkages within the thorax coordinate fast and yet precise bilateral wing movement, in combination with an actively controlled clutch and gear system that enables flexible flight patterns. Thus, the study of thoracic biomechanics, along with the underlying sensory-motor processing, is central in understanding how the insect body form is adapted for flight

Wing Video and Reconstruction Data

The “UpSampled_Generalized Base Displacement.mat” and “Generalized Base Displacement.mat” files contain the generalized wing base displacement transformed from the wing tip displacement. The first file is upsampled so that the sampling rate of the data is 40 kHz, while the later file is sampled at 1 kHz. The “Tip Motor Stim.mat” and “Motor Tip Displacement.mat” files contain the wing tip displacements of one 10-second white noise segement (first file) and for 10 10-second white noise repeats (later file). Each tip displacement file is sample at 40 kHz. Each “Moth Wing Video” folder contains the 3D high-speed videography data of that moth wing. A total of four moth wings (2 males (files labeled with M16 or M27) and 2 females (files labeled with M26 or M28)) were used to transform their wing base and tip displacements into a generalizable wing base displacement. Each “Moth Wing Video” folder contains a “DLTcoefs.csv” file (calibration file), two “.cine” files (Video data of each camera sampled at 1000 fps), and a “xyzpts.csv” file that contains the reconstructed 3D coordinates of the digitized points at each frame. The remaining files are output files not used in further analyses. Calibration and Digitization was performed with custom matlab codes by the Hedrick laboratory at UNC. High-speed videography was conducted using phantom software

Data from: Neural evidence supports a dual sensory-motor role for insect wings

Flying insects use feedback from various sensory modalities including vision and mechanosensation to navigate through their environment. The rapid speed of mechanosensory information acquisition and processing compensates for the slower processing times associated with vision, particularly under low light conditions. While halteres in dipteran species are well known to provide such information for flight control, less is understood about the mechanosensory roles of their evolutionary antecedent, wings. The features that wing mechanosensory neurons (campaniform sensilla) encode remains relatively unexplored. We hypothesized that the wing campaniform sensilla of the hawkmoth, Manduca sexta, rapidly and selectively extract mechanical stimulus features in a manner similar to halteres. We used electrophysiological and computational techniques to characterize the encoding properties of wing campaniform sensilla. To accomplish this, we developed a novel technique for localizing receptive fields using a focused IR laser that elicits changes in the neural activity of mechanoreceptors. We found that (i) most wing mechanosensors encoded mechanical stimulus features rapidly and precisely, (ii) they are selective for specific stimulus features, and (iii) there is diversity in the encoding properties of wing campaniform sensilla. We found that the encoding properties of wing campaniform sensilla are similar to those for haltere neurons. Therefore, it appears that the neural architecture that underlies the haltere sensory function is present in wings, which lends credence to the notion that wings themselves may serve a similar sensory function. Thus, wings may not only function as the primary actuator of the organism but also as sensors of the inertial dynamics of the animal

Mechanics of the thorax in flies

Insects represent more than 60% of all multicellular life forms, and are easily among the most diverse and abundant organisms on earth. They evolved functional wings and the ability to fly, which enabled them to occupy diverse niches. Insects of the hyper-diverse orders show extreme miniaturization of their body size. The reduced body size, however, imposes steep constraints on flight ability, as their wings must flap faster to generate sufficient forces to stay aloft. Here, we discuss the various physiological and biomechanical adaptations of the thorax in flies which enabled them to overcome the myriad constraints of small body size, while ensuring very precise control of their wing motion. One such adaptation is the evolution of specialized myogenic or asynchronous muscles that power the high-frequency wing motion, in combination with neurogenic or synchronous steering muscles that control higher-order wing kinematic patterns. Additionally, passive cuticular linkages within the thorax coordinate fast and yet precise bilateral wing movement, in combination with an actively controlled clutch and gear system that enables flexible flight patterns. Thus, the study of thoracic biomechanics, along with the underlying sensory-motor processing, is central in understanding how the insect body form is adapted for flight

Biomechanical basis of wing and haltere coordination in flies

The spectacular success and diversification of insects rests critically on two major evolutionary adaptations. First, the evolution of flight, which enhanced the ability of insects to colonize novel ecological habitats, evade predators, or hunt prey; and second, the miniaturization of their body size, which profoundly influenced all aspects of their biology from development to behavior. However, miniaturization imposes steep demands on the flight system because smaller insects must flap their wings at higher frequencies to generate sufficient aerodynamic forces to stay aloft; it also poses challenges to the sensorimotor system because precise control of wing kinematics and body trajectories requires fast sensory feedback. These tradeoffs are best studied in Dipteran flies in which rapid mechanosensory feedback to wing motor system is provided by halteres, reduced hind wings that evolved into gyroscopic sensors. Halteres oscillate at the same frequency as and precisely antiphase to the wings; they detect body rotations during flight, thus providing feedback that is essential for controlling wing motion during aerial maneuvers. Although tight phase synchrony between halteres and wings is essential for providing proper timing cues, the mechanisms underlying this coordination are not well understood. Here, we identify specific mechanical linkages within the thorax that passively mediate both wing–wing and wing–haltere phase synchronization. We demonstrate that the wing hinge must possess a clutch system that enables flies to independently engage or disengage each wing from the mechanically linked thorax. In concert with a previously described gearbox located within the wing hinge, the clutch system enables independent control of each wing. These biomechanical features are essential for flight control in flies

Modeling strain sensing by the gyroscopic halteres, in the dipteran soldier fly, hermetia illucens

Dipteran insects are known to receive mechanosensory feedback on their aerial rotations from a pair of vibratory gyroscopic organs called halteres. Halteres are simple cantilever-like structures with an end mass that evolved from the hind wings of the ancestral four-winged insects form. In most Diptera, including the soldier fly Hermetia illucens, the halteres vibrate at the same frequency as the wings. These vibrations occur in a vertical plane such that any rotation about this plane imposes orthogonal Coriolis forces on the halteres causing their plane of vibration to shift laterally by a small degree. This motion results in strain variation at the base of the haltere shaft, which is sensed by the campaniform sensilla. This strain variation is, therefore, a key parameter for sensing body rotations. In this paper, we present a study of the basic mechanism of soldier fly halteres to demonstrate its use as a vibratory gyroscope. First, we use a static force sensor to determine the stiffness of the haltere, to evaluate the natural frequency along the flapping direction, followed by nanoindentation-based measurement of its elastic modulus. We then model the haltere as a simple structure with the measured material properties and carry out an analysis to estimate the gyroscopic strain. We also use Finite Element simulations to verify our estimates. This study is intended to provide a better understanding of the mechanism of the natural vibratory gyroscope

Raw Extracellular Neural Data and Stimulus Data

Column one and two for the files labeled M1 through M25 are the raw neural voltage data and the corresponding motor voltage stimulus sampled at 40 kHz. M# indicates the particular moth used for experimentation. The raw neural data and stimulus data for M26 through M33 (both sampled at 40 kHz) were split into two files respectively called “M#_Raw Neural Data.txt” and “M#_ Stimulus Data.txt”. Files labeled M13, M15, M18, M19, and M20 had an additional step stimulus preceding the delivery of the white noise stimulus. A 0.2 Hz square wave stimulus of 4 V amplitude was interjected between the sinusoidal and white noise stimulus segments. The duration of the step stimulus was 16 seconds (640000 samples). There was a rest period of 1 second between the sinusoidal and the step function as well as between the step and white noise stimulus. Moreover, the Raw Neural Data files for M26, M28, M31, M32, and M33 contained multiple columns. Each column represented the neural data recorded from a particular recording site on the multi-site extracellular electrode. Having neural data from multiple recoding sites on the electrode improved spike sorting. These Data were acquired and saved in Matlab. Moreover, these data consisted of multiple chunks (6 chunks), which were concatenated together

Spike Sorted Neural Data (time stamps of spiking)

Each file contains the spike timestamps of the units isolated from the extracellular data of a particular moth (M# refers to a particular moth). Each column represents a unit and each row corresponds to a timestamp of when a unit spiked. The last column of each file contains the unsorted spike timestamps, and therefore, was not used for further analyses. Spike sorting was performed using Offline Sorter V4 and timestamp data was exported from NeuroExplorer V5

Wand Calibration Data

We verified the wing motion reconstruction data through cross validating that the measured length of a physical wand object can be reconstructed through 3D high-speed videography. The “20150615 Calibration file_20pt.csv” file contains the physical measurements of our calibration object and is used to calibrate the volume of space that the wand moved through. The “cal01_WandDLTcoefs.csv” file contains the calibrated volume coefficients. “M1_Wand.cine” and “M2_Wand.cine” are the recorded video files (using phantom software) that capture the wand movement through the calibrated space. “Digitized_Wandxyzpts.csv” contains the 3D coordinates of the wand position at each frame. The cameras were set at 1000 fps.The remaining files are output files not used in further analyses. Calibration and Digitization was performed with custom matlab codes by the Hedrick laboratory at UNC

Wing deformation movie from Neural evidence supports a dual sensory-motor role for insect wings

High speed video of wing deformations during experimental manipulatio