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Title: An Insect Wing: Expansion, Hemodynamics, and Venation Patterns
Abstract: Almost one million species of insects have been described to date, with most being winged and capable of flight. Wing venation patterns are highly diverse, with some wings partitioned into just a few “domains” (vein-bounded regions) and others into many thousands. Insect wings are also dynamic living structures composed of stiff tubular veins, which supply hemolymph to veins containing trachea and nerves. There are several key phases in the life of an insect wing: development, emergence and expansion, maturation and maintenance during adulthood. Emergence and wing expansion require seamless transitions between hormonal, neuronal and mechanical cues. A bottleneck to sexual maturity, an expanding wing must be accurately elongated and stiffened. Once the wing is primed, scleratized and ready for flight, maintenance begins. Sensory hairs, mechanosenosors, and more require a continuous supply of hemolymph. Wing flexibility is achieved through hydration of resilin, a highly elastic protein found throughout the wing. In this thesis, I use experimental and computational approaches to explore an insect wing from emergence, through adult hemodynamics and comparative venation geometries. Chapters 1 and 2 focus on the Schistocerca americana, the North American Grasshopper. In Chapter 1, I explore wing unfolding during emergence and expansion, specifically during autoexpansion, a phenomena in which a wing can unfold even when separated from its host insect. In Chapter 2, I quantify hemolymph flow dynamics within the adult wing and its relationship to accessory pulsatile organs such as wing hearts. In Chapter 3, I utilize quantitative approaches to explore the diversity of venation patterns seen across insect wings, amassing an unprecedented dataset of wing venation geometries to tackle the challenge of comparing geometries and topologies across insect orders. Taken together, this work highlights the diversity and multifunctionality of wings, reflected on their development, function and form, all of which play a role in the phylogenetic and functional diversity of insect wings.
Committee: L. Mahadevan (Advisor), Andy Biewener, Stacey Combes, Missy Holbrook