Many aspects of insect flight performance rival or surpass that of birds, bats, and man-made aircraft; yet unlike these other groups, insects have little active control over the three-dimensional shape of their wings. Insect wings bend and twist passively during flight, and until recently it wasn't known whether these wing deformations are an inevitable drawback of ultra-light, flapping wings, or whether wings have evolved to bend in ways that benefit flight performance. Recent studies have shown that flexible wings can produce higher aerodynamic forces than stiff ones, but the effects of flexibility on other aspects of flight performance remain unknown. In this study, a powerful new technique developed by the researchers to stiffen the wings of live bumblebees and mason bees will be used, along with tests of several aspects of flight performance, including maximum force production, efficiency, stability in windy environments, and maneuverability, to develop a more comprehensive understanding of wing flexibility and design in insects. In addition, the effects of body size on wing flexibility and flight performance will be quantified. This work will have broad implications and spur future research in biomechanics, animal behavior, evolution, physics, and robotics. The project will provide training for undergraduate and graduate students and post-doctoral researchers at two institutions, a small liberal arts college and a large, diverse, public university. In addition, to address the declining representation of female scientists at higher career stages, five early-career, female biomechanists will be recruited for a three-year peer mentoring program.
Recent studies have shown that the passive deformations of flexible insect wings can enhance aerodynamic force production. However, the effects of flexibility on other aspects of flight performance involving more complex environments or behaviors have received little attention, as these are difficult to simulate with computational or physical modeling approaches. In this study, a technique developed by the investigators to alter the stiffness of ultra-light insect wings without adding significant mass (by "splinting" a flexible wing-vein joint) will be used, along with tests of multiple aspects of flight performance, to develop a more comprehensive understanding of wing flexibility and design. This project has three main goals: (1) test how chordwise wing flexibility in bumblebees affects all major aspects of flight performance, including maximum force production, energetic efficiency, stability in unsteady flow, and maneuverability during voluntary tracking and collision avoidance, (2) examine the relative importance of spanwise versus chordwise flexibility to force production and energetic efficiency in mason bees, and (3) explore how the effects of flexibility on passive wing deformations and maximum force production vary with size in bumblebees. This work will have broad implications and spur future research in numerous fields, and will provide training for undergraduate and graduate students and post-doctoral fellows. The researchers will also create a mentoring program aimed at addressing the "leaky pipeline" phenomenon, targeting five early-career, female biomechanists to participate in a three-year peer mentoring circle that will provide monthly discussions, feedback, and support, as well as funding to attend an annual biomechanics conference.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
