Novel flight style and light wings boost flight performance of tiny beetles

Abstract

Flight speed is positively correlated with body size in animals1. However, miniature featherwing beetles can fly at speeds and accelerations of insects three times their size2. Here we show that this performance results from a reduced wing mass and a previously unknown type of wing-motion cycle. Our experiment combines three-dimensional reconstructions of morphology and kinematics in one of the smallest insects, the beetle Paratuposa placentis (body length 395 μm). The flapping bristled wings follow a pronounced figure-of-eight loop that consists of subperpendicular up and down strokes followed by claps at stroke reversals above and below the body. The elytra act as inertial brakes that prevent excessive body oscillation. Computational analyses suggest functional decomposition of the wingbeat cycle into two power half strokes, which produce a large upward force, and two down-dragging recovery half strokes. In contrast to heavier membranous wings, the motion of bristled wings of the same size requires little inertial power. Muscle mechanical power requirements thus remain positive throughout the wingbeat cycle, making elastic energy storage obsolete. These adaptations help to explain how extremely small insects have preserved good aerial performance during miniaturization, one of the factors of their evolutionary success.

Distinct forms of resonant optimality within insect indirect flight motors

“…Second, with reference to energetic optimality: if, as is often thought [14,46–48], the purpose of thoracic elasticity is to absorb negative power requirements, then this purpose is fulfilled over frequency ranges, not only at a single frequency. These frequency ranges are sufficient to explain most currently reported wingbeat frequency variations.…”

“…If these variations represent switches between distinct resonant frequencies, then finely tuned resonant frequency control via pleurosternal and tergopleural muscular actuation [9,[22][23][24][25][26] would not be required. Second, with reference to energetic optimality: if, as is often thought [14,[46][47][48], the purpose of thoracic elasticity is to absorb negative power requirements, then this purpose is fulfilled over frequency ranges, not only at a single frequency. These frequency ranges are sufficient to explain most currently reported wingbeat frequency variations.…”

“…The insight that thoracic elasticity can absorb flight motor negative work and thereby decrease motor muscular power consumption [14,46–48] is connected to a more general phenomenon of linear and nonlinear dynamics: the generalized energy-based conception of resonance sometimes referred to as global resonance [27–30]. In a general system, the core condition of global resonance is the absence of negative work in the system overall power requirement: pfalse(tfalse)≥0, normal∀ t.If this condition is satisfied—e.g.…”

“…We have not yet characterized the flight motor power consumption, and the frequencies at which the flight motor is most efficient. The role of thoracic elasticity, and structural resonance, in reducing motor muscular power consumption can be seen through the lens of negative work absorption: the potential for thoracic elasticity to absorb negative work-work done by the wing on the flight motor-and then release this stored energy at other points during the wingbeat cycle [14,[46][47][48]. To compute the frequency at which this effect is optimal, we require a more sophisticated analysis.…”

Amoeba-Size Beetle Has a Novel Method of Flying!

“…In contrast, the flight of tinier insects has remained a mystery. This recently changed with an elegant study by an international group lead by Sergey Farisenkov, Dmitry Kolomenskiy, and Alexey Polilov [1]. They studied the flight of the miniature featherwing beetle Paratuposa placentis .…”