Tegula (insect anatomy) explained

A tegula is a small sclerite situated above the base of the costal vein in the wings of various insects such as Orthoptera, Lepidoptera, Hymenoptera, Diptera, and Auchenorrhyncha, and attached to the antero-lateral portion of the mesonotum.^[1] It is densely innervated, with sensory bristles, campaniform sensilla, as well as a chordotonal organ in some species.^[2]

The tegula in locusts is a model system for studying the role of feedback from mechanoreceptors during movement.^{[3] [4] [5]} In locusts, the tegula directly controls flight muscles. The motor neurons that control the activation of wing elevator muscles are phase-locked to the neurons that innervate the tegula such that when the tegula is electrically stimulated the elevator muscles initiate an upstroke.^[6] 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.^{[7] [8] [9]}

The tegula system is also a model for studying the role of neuromodulation for state-dependent motor 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.^[10] This mechanism ensures that the animal does not initiate a wing stroke if the bristles are deflected by wind as the animal is walking.

References

1. Web site: Fischer, Wolf and Büschges . The locust tegula: kinematic parameters and activity pattern during the wing stroke . 2010-08-31 . Journal of Experimental Biology.
2. Book: Fudalewicz-Niemczyk, Władysława . L'innervation et les organes sensoriels des ailes des Diptères et comparaison avec l'innervation des ailes d'insectes d'autres ordres . 1963.
3. Ramirez, J. M., & Pearson, K. G. (1993). Alteration of bursting properties in interneurons during locust flight. Journal of neurophysiology, 70(5), 2148-2160.
4. Pearson, K. G. and Wolf, H. Connections of hindwing tegulae with flight neurones in the locust, Locusta migratoria. J. Exp. Biol. 135:381-409, 1988
5. Wolf, H. "The Locust Tegula: significance for flight rhythm generation, wing movement control and aerodynamic force production." Journal of Experimental Biology 182.1 (1993): 229-253.
6. Wolf, H. "The Locust Tegula: significance for flight rhythm generation, wing movement control and aerodynamic force production." Journal of Experimental Biology 182.1 (1993): 229-253.
7. Recovery of the flight system following ablation of the tegulae in immature adult locusts, C Gee, R Robertson, Journal of Experimental Biology 1996 199: 1395-1403.
8. Kien, J., Altman, J.S. Connections of the locust wing tegulae with metathoracic flight motoneurons. J. Comp. Physiol. 133, 299–310 (1979). https://doi.org/10.1007/BF00661132
9. Büschges, A., & Pearson, K. G. (1991). Adaptive modifications in the flight system of the locust after the removal of wing proprioceptors. Journal of Experimental Biology, 157(1), 313-333.
10. Ramirez, J. M., & Pearson, K. G. (1991). Octopaminergic modulation of interneurons in the flight system of the locust. Journal of Neurophysiology, 66(5), 1522-1537.