The Locust Ovipositor: A Form Follows Function Study of a Unique Digging Apparatus

• Applicant: Professorin Dr. Yael Politi, Ph.D.
• Subject Area: Biomaterials ; Synthesis and Properties of Functional Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 503007430

Ideal digging and burrowing mechanisms and technologies should be compact in structure, energy-efficient and have low impact on the environment. Several studies presented bioinspired solutions, based on digging apparatuses in nature. Promising methods and structures are found in insect oviposition or egg-laying tools. The ovipositor of grasshoppers and locusts, for once, is a highly specialized structure. Grasshoppers and locusts are rare among insects in having ovipositor that work by opening and closing valves rather than by sliding valves upon each other. We propose a form-follows-function study, characterizing the unique adaptations found in the ovipositor of the female locust. We will investigate the presence of structural and material gradients ovipositors valves, and examine their role role in the digging mechanism, using experiments with the animals, materials science tools and computer simulations. Our overarching aim is to understand the biomechanics of the locust digging valves and engineer bioinspired diggers based on the understanding of the natural system. First, we will observe the digging valves as used by the female locust and follow their ontogeny. We will map the material properties of the digging valves using confocal laser scanning microscopy and spectroscopy. Nanoindentation and nanowear tests will provide quantitative measures of the mechanical properties. We will measure friction forces acting on the locust valves, depending on different granular media, and quantify the energy consumption and energy dissipation during oviposition. Next, we will establish guidelines for structural design, mechanical and surface properties forlocust-inspired diggers. We will use finite elements analysis to determine how changes in the structure and material properties influence its performance. Computer simulations will be utilized to elucidate the load distribution in the female locust valve, taking into account the results of measurements of the forces exerted by the organisms under biological relevant conditions. Finally, we will develop bioinspired diggers based on the knowledge gained. we will3D print the valves in different forms and materials in order to examine the suitability of the natural design to its function. The structural and surface properties will be further adjusted in order to improve and extend the performance of the digger, depending on the digging medium. All research will be conducted in a highly collaborative manner, utilizing the complementary expertise of the research groups. The strength of our collaborative approach isdemonstrated by the many preliminary data obtained. We expect that our joit forces will lead to understanding the structure and function of the digging apparatus of the female locust and furthermore to the development of bio-inspired hybrid soft-stiff robotic diggers that will include injection function, resistance to mechanical damage, granular media specificity and energy minimized operation.

• DFG Programme: Research Grants
• International Connection: Israel
• Cooperation Partners: Professor Dr. Benny Bar-On, Ph.D.; Dr. Noa Lachman-Senesh
• International Co-Applicants: Professor Dr. Amir Ayali; Dr. Bat-El Pinchasik