Mechanical properties of tracheal tubes in the American cockroach (Periplanetaamericana)

Abstract

Insects breathe using an extensive network of flexible air-filled tubes. In some species, therapid collapse and reinflation of these tubes is used to drive convective airflow, a systemthat may have bio-inspired engineering applications. The mechanical behavior of thesetracheal tubes is critical to understanding how they function in this deformation process.Here, we performed quasi-static tensile tests on ring sections of the main thoracic trachealtrunks from the American cockroach (Periplaneta americana) to determine the trachealmechanical properties in the radial direction. The experimental findings indicate that thestress–strain relationships of these tracheal tubes exhibit some nonlinearities. The elasticmodulus of the linear region of the stress–strain curves tubes was found to be1660 ± 512 MPa. The ultimate tensile strength, ultimate strain and toughness were found to be23.7 ± 7.33 MPa,2.0 ± 0.7% and0.207 ± 0.153 MJ m−3, respectively. This study is the first experimental quantification of insect tracheal tissue,and represents a necessary step toward understanding the mechanical role of tracheal tubesin insect respiration.