ИСТИНА

The study of microinsect flight is an area of modern entomology, closely related to biomechanics and aerodynamics. Some of the smallest body sizes among flying insects are found among parasitoid wasps of the family Trichogrammatidae. The body length of one of the smallest species of this family, Megaphragma vigianii, is only about 250 μm. As most other microinsects M. vigianii has bristled wings. We perform macro video recording of the flight of M. vigianii and reconstruct flight kinematics. Additionally, we perform CFD reconstruction of hovering flight. M. vigianii is capable of active maneuverable flight, the average and maximum flight speeds were 0.06 and 0.25 m/s (1000 body lengths/s), respectively. The average Reynolds number during the wing cycle is about 3, which means that viscous forces are very significant on vertical force generation, and the leakiness between the bristles must be quite low. Flight cycle of M. vigianii is characterized by the aerodynamic asymmetry. It consists of two power strokes, recovery stroke between upstroke and downstroke and supination between downstroke and upstroke. The most of the aerodynamic force produced during power strokes where angles of attack and wing speeds are maximal. During recovery stroke angles of attack and wing speeds are small to minimize drag. The estimated aerodynamic features revealed in our study and unusual kinematics of the operation of the microwasp wings are an important adaptation to flight at ultra-low Reynolds numbers, under conditions of prevalent viscous forces. This study was supported by the Russian Science Foundation (project no. 22-74-10010). KKeeyywwoorrddss:: flight, miniaturization, bristled wings, Hymenoptera, CFD