Micromorphology of the Fibers Behind the Frons Plate and its Adjacent Regions in the Oriental Hornet (Hymenoptera, Vespinae)

The present study describes the fibers occurring in the space extending behind the frons plate, or the region between the ocelli and the clypeal plate of the Oriental hornet. These fibers connect to the brain in the anterior part of the head in a zone which is demarcated by an imaginary line traversing the upper part of the two omrnatidia. Static fibers are present in the upper part and in the center of the space. These static fibers do not move with acceleration of the structures attached to the head. They are perpendicular to the frons plate, are relatively numerous and usually short. In contrast, the fibers in the lower part are directed toward the organ with which they connect, are few in number, have triangular fastenings and are longer. All of the fibers are branched, especially near their point of attachment to the substrate. On the surface of these fibers, there are occasionally coin or bob-like protuberances or other dilations. As seen in serial sections, proceeding from the top down to the base of the space, the fibers are longer at the center of the frons and gradually shorten toward its margins. We propose that the interaction between the fibers and the various structures in the head to which they are attached, having a harp-like appearance, is responsible for the proprioceptive sensing in hornets including the detection of gravity in the course of comb building

Subcuticular microstructure of the hornet's gaster: Its possible function in thermoregulation

The present study set out to elucidate the structure and function of the large subcuticular air sacs encountered in the gaster of the Oriental hornet Vespa orientalis (Hymenoptera, Vespinae). Gastral segments I, II, III, together with the anterior portion of segment IV, comprise the greater volume of the gaster, and inside them, beneath the cuticle, are contained not only structures that extend throughout their entire length, like the alimentary canal, and the nerve cord with its paired abdominal ganglia, situated near the cuticle in the ventral side, but also the heart, which is actually a muscular and dorsally located blood vessel that pumps blood anteriorly, toward the head of the hornet. The mentioned structures take up only a small volume of the gaster, while the rest is occupied by air sacs and tracheal ducts that also extend longitudinally. Interposed between the two air sacs, there is a hard partition and above it, at the center – a paired tracheal duct that extends the entire length of the air sacs. The endothelium of the air sacs is very anfractuous, thereby enlarging and strengthening the surface area. In each gastral segment there is an aperture for the entry of air, namely, a spiracle. Additionally, in each segment, in the antero-lateral aspect of its tergum and situated between two successive segments, there is an intersegmental conjunctive bearing parallel slits of 1–2 microM in width and 10–30 microM in length. The latter are arranged concentrically around bundles of tracheae that traverse the cuticle from segment to segment. From the upper rims of the slits are suspended downward fringe-like structures or "shutters" ranging between 3–10 microM in length. We discuss the possibility that the Oriental hornet resorts to internal circulation of air, along with a thermoelectric heat pump mechanism, in order to achieve cooling and thermoregulation of its body

Proteins in Venoms of Two Wasps, Polistes Comanchus Navajoe and Vespa Orientalis

1. By means of gel electrophoresis the basic proteins in venoms of Polistes comanchus navajoe and Vespa orientalis were resolved into 6 and 5 proteins respectively, all of molecular weights \u3e 15,000. 2. Several proteins appeared to be similar in both venoms. 3. The main component of P. comanchus venom responsible for hemolysis was isolated, and data concerning its thermolability, molecular weight (approximately 26,000) and amino acid composition show that unlike the cytolytic components of bee and ant venoms which are small peptides, the corresponding functional entity of P. comanchus venom (polistin) is a protein having the characteristics of an enzyme

Micromorphology and Maturation of the Yellow Granules in the Hornet Gastral Cuticle

The yellow granules in the gastral cuticle of the Oriental hornet Vespa orientalis (Hymenoptera, Vespinae) are located in yellow stripes. In the present study, we focus on the micromorphology and formation of the yellow granules from their inception to their spread in the regions which are destined to acquire a yellow color. The cuticle was observed with several methods of electron microscopy. The results showed that the yellow granules comprise a layer which is 40-45 µm thick, within the total cuticular thickness of 40−45 µm. In the mentioned regions one can see, from above, many apertures of about 0.5 µm in diameter which extends into a peripheral photoreceptor cell. In each yellow granule, one discerns a myoid envelope inside which there are 9 fibrils arranged in a circle. Yellow granules maturation process involves infiltration of canals that give rise to the incipient ball-shaped primary granules which increase in number (as a result of continues budding off the walls of a canal) as the cuticle matures and transform into secondary barrel shaped granules, becoming elongated and then splitting into shorter barrels that fill up the entire area. Preliminary examinations have suggested liver-like function activity within the layer of yellow granules