Ultra-Morphology and Mechanical Function of the Trichoideum Sensillum in Nabis rugosus (Linnaeus, 1758) (Insecta: Heteroptera: Cimicomorpha)

SIMPLE SUMMARY: Nabis rugosus is a representative of the Nabidae family belonging to the heteropteran group. It is a predator of tiny insects and has different sensory receptors that detect environmental changes. The present study focuses on the antennal sensilla of N. rugosus, mainly on the trichoideum sensillum as mechanoreceptors for detecting various tactile factors surrounding the insect. The morphology of trichoideum mechanosensillum in N. rugosus was modelled as a three-dimensional structure from the derived data sets using SEM and TEM. Specific inner features of the sensillum are also presented, which will be useful to build a biosensor for detecting physical environmental parameters. ABSTRACT: The present study aims to investigate the morphological features of the antennal sensilla by using SEM and TEM. The construction of a 3D model of trichoideum sensillum using Amira software is presented in this paper. Five sensillum types, namely trichoideum, chaeticum, campaniformium, coeloconicum, and basiconicum, were recorded. This model exhibits the mechanosensillum components, including the embedded hair in a socket attached by the joint membrane and the dendrite connected to the hair base passing through the cuticle layers. TEM images present the dendrite way, micro-tubules inside the dendritic sheath, and terminal structure of the tubular dendrite body and so-called companion cells included in the receptor, e.g., tormogen and trichogen. The parameters noted for the external structure and ultrastructure of the mechano-receptor indicate that they are specific to a particular type of sensillum and would be useful in developing the model for a biosensor. Results show that bio-inspired sensors can be developed based on morphological and ultrastructural studies and to conduct mechanical studies on their components.