Biomechanics of substrate boring by fig wasps

Female insects such as parasitoid ichneumonid wasps must overcome several biomechanical constraints to successfully deposit eggs. These begin with selection of suitable substrates through which the ovipositor penetrates without itself fracturing. The insect must next steer and manipulate the ovipositor to deliver eggs at desired locations and finally retract her ovipositor fast to avoid possible predation. This process is repeated multiple times during her lifetime. Because parasitoid ovipositing behavior involves active interactions of the ovipositor with the substrate, it poses fascinating questions from a materials perspective. Specifically, what are the mechanisms that parasitoid insects use to drill through substrates of variable stiffness without itself buckling or fracturing? What are the properties of the ovipositor and methods used to reduce material wear and increase toughening? These are some of the questions I will address in this talk with a model system consisting of parasitoid and pollinator fig wasps. To characterize the structure of ovipositors, we use scanning electron microscopy with a detector to quantify the presence of transition elements. We also use an atomic force microscope to characterize the material properties of ovipositors. Such methods may be useful for the biomimetic design of functionally graded surgical tools and in the use of novel mechanisms to bore through hard substrates.