PhD "ZOOM" SEMINAR

Monday May 6

Hind-Wing Flexibility in the Scarab Beetles

Yonatan Meresman

Animal locomotion is strongly linked to their ecology. Flying species that hover or land precisely on top of flowers (e.g., for feeding) require higher maneuverability and control than those flying merely to reach distant areas. The flight style is affected by the wing shape. While birds and bats control the wing shape using muscles and joints within the wing itself, insects have more restricted control. Their wings lack intrinsic muscles. Instead, they are composed of a thin membrane reinforced by stiffer veins. These veins elastically deform during flight as a result of inertial and aerodynamic loads. In turn, these deformations affect the aerodynamic forces acting on the wings.
The flexibility of insect wings might have been under natural selection to match various flight demands. One way by which wing elasticity can change in the course of evolution is by adjusting the wing veins. Indeed, insects vary in the size number and arrangement of their wing veins, resulting in changes in the wings' structural stiffness. However, despite a growing interest in flexible wing aerodynamics in biological and engineering disciplines, empirical data, acquired from free-flying animals, are scarce, and the interpretation of these data is complex due to structural, energetic, and aerodynamic trade-offs in the adaptation of wings for specific flight styles.
In the upcoming talk, I will discuss how the wing flexibility affects elastic wing deformation in scarab beetles, its function in free-flying beetles, and the divergence of wing structure to match various flight styles. I will present results from our studies showing that elastic wing deformations are adjusted to conserve a favorable wing shape during flight within a species. During aerial maneuvers, the flexibility augments the torque generated by each wing but attenuates the asymmetry between the left and right wings, thus contributing to stabilization and, finally, how morphological diversification has led to inter-specific variation in elastic wing deformation during flight in scarab beetles.
Our multidisciplinary, comparative approach allows an in-depth look at the mechanisms of flight by flexible wings. It unveils evolutionary links between wing form and function and provides a deeper understanding of the evolution of insect wings, flight biomechanics, and mechanisms for flight control.