Evaluating the modulus of flying insect thoraxes with nanoindentation


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


22-1  Sat Jan 2  Evaluating the modulus of flying insect thoraxes with nanoindentation Yager, CC*; Casey, CB; Vahidi, G; Jankauski, MA; Heveran, CM; Montana State University, Bozeman, Montana; Montana State University, Bozeman, Montana; Montana State University, Bozeman, Montana; Montana State University, Bozeman, Montana; Montana State University, Bozeman, Montana ccyager99@gmail.com

Insect flight is the product of hundreds of millions of years of evolution. However, little is known about the microscale structure and material properties of the insect thorax, a flexible exoskeleton structure that is central to the flight drive train. The objective of this research is to evaluate the thorax material properties across different insect species and within a single insect species using nanoindentation. We chose to compare thorax properties for Manduca sexta, a synchronous flier, and Apis mellifera, an asynchronous flier. Thoraxes for each type of insect were embedded in poly(methyl) methacrylate, sliced and polished in a transverse plane, and nanoindented to create modulus maps spanning the cuticle thickness in multiple locations along the thorax.Our results show that the M. sexta thorax has a mean modulus of 7.26 GPa ± 0.88 and that the A. mellifera has a mean modulus of 7.69 GPa ± 1.00. These modulus values agree with previously reported cuticle moduli for other insects ( eg. Coleoptera spp).M. sexta also had moduli around the wing-hinge that may be unusually high for insects (~40 GPa). We imaged the thorax nanoindentation sites using Raman spectroscopy and Confocal Scanning Laser microscopy to provide insight into what may be driving these results, especially the areas with very high moduli. Preliminary results suggest that this is not the result of protein crosslinking but may be related to differences in material composition of these areas. The results of this project will help drive understanding of how thorax material may enable efficient insect flight and how material properties might change between synchronous and asynchronous lineages.

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