Pore-ridged nanostructures on the surface of trichoid sensilla of the male Bombyx mori: Aerodynamic trapping, sensing, and transporting of the pheromone molecules

Authors: SU, JUN - Nanjing Forestry University; ZHAO, BOGUANG - Nanjing Forestry University; Zhang, Aijun; BU, XIAOLI - Nanjing Forestry University; CHEN, JING - Nanjing Forestry University; YAN, ZHANGDONG - Nanjing Forestry University; WANG, SHIFA - Nanjing Forestry University

Submitted to: Arthropod Structure and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/18/2019
Publication Date: 6/19/2019
Citation: Su, J., Zhao, B., Zhang, A., Bu, X., Chen, J., Yan, Z., Wang, S. 2019. Pore-ridged nanostructures on the surface of trichoid sensilla of the male Bombyx mori: Aerodynamic trapping, sensing, and transporting of the pheromone molecules. Arthropod Structure and Development. S1467-8039(18)30167-1.

Interpretive Summary: The mechanism of the high-efficient sensing and transporting of the attractant molecules by insect is studied using a typical moth antenna as model. Three techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and computational fluid dynamics (CFD) simulation, were applied. We found that all the surfaces of antennal hairs have possessed numerous pore and ridge structures and some vortexes on the antennal hair surfaces would be generated by the combined effects of airflow, pore-ridge structures, as well as spontaneous antennal vibration. These vortexes may trap the passing around attractant molecules and provide driving forces and guide them through the pores into the insect antanna and then into the brain. The results may reveal general principles underlying volatile attractant-induced insect behaviors. This information will also provide the basis for novel physical structures of highly efficient and specific adsorbing materials for manufacture of chemical sensor.

Technical Abstract: To understand the mechanism how trichoid sensilla sense the sex pheromone molecules, the micro- and nano-topographic structures on the surface of the trichoid sensilla of the male silkmoth Bombyx mori were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Computational fluid dynamics (CFD) simulation based on finite element method (FEM) was also applied to investigate the impacts of pore-ridged nanostructures on the passing airflow. SEM and AFM images exhibited that all the surfaces except for the basal region of the trichoid sensilla displayed numerous pore and ridge structures. Most of ridges were paralleled around the sensillum, and all pore opening depressions were located at or near the bottoms of ridges regardless of the ridge features. When AFM tip encountered a rapidly rising or falling edge along the ridge hillside, the phase-shifts distinctly increased or decreased, respectively. It was suggested that the variation of phase-shift appearing along the ridge could not be simply attributed to heterogeneity in the lipid surface of sensilla, as the phase-shifts were presented in the same region with the same height of saltation. Laboratory CFD simulation results indicated that the vortexes on the inter ridge surfaces would be generated by the combined effects of airflow, pore-ridge structures, as well as spontaneous antennal vibration, regardless of the up-wing angle to the trichoid sensilla. We hypothesize that the vortexes generated by airflow close to the inter-ridge surface may trap the passing around pheromone molecules, with the surface binding force, providing driving forces for pheromone molecules and guiding them through the pores into the sensillum lumen. We also speculate that the electrostatic charges on the surface of the sensilla produced during moth rubbing its antennae may produce long-range trapping forces to the polar pheromone molecules. The aim of this study is to understand the mechanism of the high-efficient sensing and transporting of the sex pheromone by the trichoid sensilla of male B. mori. The results may reveal general principles underlying pheromone-induced insect behaviors. This information will also provide the basis for novel structures of highly efficient and specific adsorbing materials for chemical sensor.