A tegula is a small

sclerite A sclerite (Greek language, Greek , ', meaning "hardness, hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instea ...

situated above the base of the costal vein in the wings of various

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s such as

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – gras ...

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

Hymenoptera Hymenoptera is a large order of insects, comprising the sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are parasitic. Females typi ...

Diptera Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advance ...

, and

Auchenorrhyncha The Auchenorrhyncha suborder of the Hemiptera contains most of the familiar members of what was called the "Homoptera" – groups such as cicadas, leafhoppers, treehoppers, planthoppers, and spittlebugs. The aphids and scale insects are the o ...

, and attached to the anterolateral portion of the

mesonotum The mesothorax is the middle of the three segments of the thorax of hexapods, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal), the mesosternum ( ventral), and the mesopleuron (lateral) ...

. It is densely innervated, with sensory bristles,

campaniform sensilla Campaniform sensilla are a class of mechanoreceptors found in insects, which respond to local stress and strain within the animal's cuticle. Campaniform sensilla function as Proprioception, proprioceptors that detect mechanical load as resistance ...

, as well as a

chordotonal organ Chordotonal organs are stretch receptor organs found only in insects and crustaceans. They are located at most joints and are made up of clusters of scolopidia that either directly or indirectly connect two joints and sense their movements relativ ...

in some species. The tegula in

locusts Locusts (derived from the Latin ''locusta'', locust or lobster) are various species of short-horned grasshoppers in the family Acrididae that have a Swarm behaviour, swarming phase. These insects are usually solitary, but under certain circu ...

is a model system for studying the role of feedback from

mechanoreceptors A mechanoreceptor, also called mechanoceptor, is a sensory receptor that responds to mechanical pressure or distortion. Mechanoreceptors are located on sensory neurons that convert mechanical pressure into electrical signals that, in animals, ar ...

during movement. In locusts, the tegula directly controls flight muscles. The

motor neurons A motor neuron (or motoneuron), also known as efferent neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly or ...

that control the activation of the wing elevator

muscles Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

are phase-locked to the

neurons A neuron (American English), neurone (British English), or nerve cell, is an membrane potential#Cell excitability, excitable cell (biology), cell that fires electric signals called action potentials across a neural network (biology), neural net ...

that innervate the tegula such that when the tegula is electrically stimulated the elevator muscles initiate an upstroke. When the tegula is removed, locust flight is clumsy and disordered at first but most animals adapt, suggesting the use of other mechanoreceptors to control flight. The tegula system is also a model for studying the role of

neuromodulation Neuromodulation is the physiological process by which a given neuron uses one or more chemicals to regulate diverse populations of neurons. Neuromodulators typically bind to metabotropic, G-protein coupled receptors (GPCRs) to initiate a sec ...

in state-dependent

motor control Motor control is the regulation of movements in organisms that possess a nervous system. Motor control includes conscious voluntary movements, subconscious muscle memory and involuntary reflexes, as well as instinctual taxes. To control ...

. Neural signals from the tegula only initiate wing muscle contraction when the animal is in flight (or fictive flight) due to endogenous release of the neuromodulator

octopamine Octopamine (OA), also known as ''para''-octopamine and norsynephrine among synonyms, is an organic chemical closely related to norepinephrine, and synthesized biologically by a homologous pathway. Octopamine is often considered the major "fig ...

.{{cite journal, last1=Ramirez, first1=J.M., last2=Pearson, first2=K.G., year=1991, title=Octopaminergic modulation of interneurons in the flight system of the locust, journal=Journal of Neurophysiology, volume=66, issue=5, pages=1522-1537, doi=10.1152/jn.1991.66.5.1522, pmid=1765792 This mechanism ensures that the animal does not initiate a wing stroke if the bristles are deflected by the wind as the animal is walking. Chalcid thorax

References

Insect anatomy la:Tegula