Morphological Study of Insect Mechanoreceptors to Develop Artificial Bio-Inspired Mechanosensors

Mechanoreceptors of the insect play a vital role for the insect to sense and monitor the environmental parameters, like flow, tactile pressure, etc. This paper presents the studies made on the morphology of the mechanoreceptor of the insect Blattella asahinai (scientific name of cockroach) that is a hair-like structure known as trichoid sensilla, by scanning electron microscope and confocal laser microscope. The scanned images show the details of sensilla components in which the hair is embedded in the sockets, which are connected with the cuticle and joint membrane, where the dendrite touches at the base of the hair passing through the cuticle layers. The images also show that the tubular bodies and microtubules are tightly compacted inside the dendrite. This paper presents the details of how the sensilla work when an external stimulus act on them. The hair deflects with the disturbance of the cuticle and joint membrane, and this deformed hair leans on the dendrite, which is attached at the base of the hair that in turn presses the tubular bodies and microtubules, which develop negative ions passing down through the dendrite to the neuron, which provides information as an electric signal to the brain of the insect so that it responds for necessary action. Based on the morphological studies, sensing mechanism, material properties of the components, and design principles will be evolved for the development of an artificial bio-inspired sensor. A solid works model of the sensilla is also presented.

Fine structure of sensilla on the ovipositor of the tephritid fly Urophora affinis

There are four types of sensilla on the ovipositor blade of Urophora affinis Frauenfeld, one more than was observed on three other species of fruit flies studied by other authors. Three of the types, uniporous gustatory pegs, campaniform organs, and tactile short hairs are common to the four species and generally are in similar positions on the blade. The fourth, uniporous gustatory plates, were noted in U. affinis only. The chemosensilla are innervated by three chemosensory dendrites that terminate below the pore and a mechanosensory dendrite with a tubular body that is attached to a basal cuticular apodeme of the covering cuticle. The dendritic tubular bodies of the campaniform organs and tactile hairs terminate parallel to the surface in a right-angular bend, where they are attached to basal apodemes of the covering cuticle. The chemosensilla and tactile hairs have individual outer and inner sheath cells, but the campaniform organs have individual inner sheath cells only. The part of the ciliary dendritic segment that is encased by the dendritic sheath passes through an epidermal cell, often with several sensilla sharing the same epidermal cell in place of an outer sheath cell. The role of these sensilla during oviposition is discussed.

Food capture and ingestion in the large heliozoan, Echinosphaerium nucleofilum

Using its microtubule-containing axopodia, a heliozoan Echinosphaerium nucleofilum feeds on various kinds of protozoans and small metazoans. The present study revealed that food capture and ingestion were carried out in 2 different ways or by a combination of them. The first one was by the rapid contraction of axopodia, by which the food organism was conveyed directly toward the body surface. After such a contraction, many of the microtubules which had been present inside the axopodia degraded and were replaced by C-shaped microtubules. Bundles of tubular bodies were also detected alongside the axonemal microtubules, especially following the use of glutaraldehyde fixative containing ruthenium red. The second method was by means of axopodial flow, by which a food organism attached to an axopodium was conveyed to the body surface along the axopodial surface without accompanying axopodial degradation or contraction. Subsequently the food organism was surrounded by several small pseudopodia to form a food vacuole; many filamentous structures (5-10 nm in diameter) were observed inside the pseudopodia. During the ingestion process many cytoplasmic extensions, including rosary-like filaments, were observed to protrude from the contracted axopodia and the cell body. Mottled dense granules were observed to be discharged from the axopodial surface just when the prey was captured.