RESUMEN
Sapygidae is a small family of Aculeata (Hymenoptera), which is divided into two subfamilies Fedtschenkiinae and Sapyginae. The morphology of the skeleton of the sting apparatus in some European species of Sapyginae, which are kleptoparasites of wild bees from the families Megachilidae, Apidae and Colletidae, was examined. Significant differences in its skeletal structure were noted between Sapygina decemguttata and representatives of the genera Sapyga and Monosapyga. The sting of Sapygina belongs to the decurved type, while Sapyga and Monosapyga have a sting close to the coiled type. A comparison of the structure of the skeletons of the sting apparatuses of Sapygina and Sapyga with that of Fedtschenkia (according to other authors) was made. The similarity of the structure of the sting apparatuses of Sapygina and Fedtschenkia was noted. The possibility of using the Sapyginae sting as an ovipositor is discussed.
RESUMEN
The femoral chordotonal organ (FCO) in beetles differs from that in orthopterids in the origin of its apodeme: it originates directly from the tibia in the latter, but amidst the tendon of the extensor muscle in the former. In many beetles, the apodeme pops up from the tendon as a short sclerite (arculum). It turns distally upon bending of the tibia. The turn of the arculum is several times more than the turn of the tibia, and the arculum is connected to the FCO. This system behaves as a high-pass filter with a time constant close to the step period. Various aspects of the arculum have been studied previously, including its shape in various taxa, its biomechanics, matched neural activity in the FCO, as well as evolutionary aspects. The results of previous studies, published in 1985-2003 in Russian, are inaccessible to most foreign readers. However, original texts and the list of studied species (>350) are now available online. Recently, we minimized the system to three components: the proximal tibial ledge, the tendon and the arculum. The elastic tendon contains resilin. In four model species, the arculum readily turned upon stretching of the tendon. Turning was video recorded. The force of approximately 0.005 N, applied to a tendon approximately 0.25 mm in size, is enough for the utmost turn of the arculum. The arculum turned also upon local deformations close to its base. The ability to turn vanished after incision between the arculum and the distal part of the extensor apodeme. A mechanical model of an amplifier is proposed. The apodeme includes optically active structures, which behave differently in polarized light.
Asunto(s)
Escarabajos/fisiología , Animales , Fenómenos Biomecánicos , Extremidades , Fémur/fisiología , Fenómenos ÓpticosRESUMEN
Some flying beetles have peculiar functional properties of their elytra, if compared with the vast majority of beetles. A "typical" beetle covers its pterothorax and the abdomen from above with closed elytra and links closed elytra together along the sutural edges. In the open state during flight, the sutural edges diverge much more than by 90°. Several beetles of unrelated taxa spread wings through lateral incisions on the elytra and turn the elytron during opening about 10-12° (Cetoniini, Scarabaeus, Gymnopleurus) or elevate their elytra without partition (Sisyphus, Tragocerus). The number of campaniform sensilla in their elytral sensory field is diminished in comparison with beetles of closely related taxa lacking that incision. Elytra are very short in rove beetles and in long-horn beetles Necydalini. The abundance of sensilla in brachyelytrous long-horn beetles Necydalini does not decrease in comparison with macroelytrous Cerambycinae. Strong reduction of the sensory field was found in brachyelytrous Staphylinidae. Lastly, there are beetles lacking the linkage of the elytra down the sutural edge (stenoelytry). Effects of stenoelytry were also not uniform: Oedemera and flying Meloidae have the normal amount of sensilla with respect to their body size, whereas the sensory field in the stenoelytrous Eulosia bombyliformis is 5-6 times less than in chafers of the same size but with normally linking broad elytra.
Asunto(s)
Escarabajos/ultraestructura , Animales , Tamaño Corporal , Sensilos/ultraestructuraRESUMEN
Loss of the flight ability and wing reduction has been reported for many taxa of Coleoptera. If elytra are closed, their roots are clenched between the tergum and the pleuron, forces applied to the elytra can not be transmitted to the field of campaniform sensilla situated on the root. That is why it is plausible to assume that the field becomes redundant in non-flying beetles. We examined the relationships between the hind wing reduction and characters of this mechanosensory field in beetles of six families. We measured the size of the elytron, that of the hind wing and counted the number of sensilla in the sensory field. Mesopterous non-flying beetles retain one half to one third of sensilla present in macropterous species of the same body size. Further reduction of the sensory field in brachypterous species is obvious, but sensilla are still present in insects with strongly reduced wings, as long as their elytra are separable and mesothoracic axillaries are present. Complete loss of sensilla coincides with the existence of a permanent sutural lock. However, some beetles with permanently locked elytra and absence of axillaries still retain few campaniform sensilla. A very special case of an extreme wing modification in feather-wing beetles is considered. No sensilla were revealed either on the root of the elytron or on the basal segment of such fringed wings in flying ptiliid species.
Asunto(s)
Escarabajos/anatomía & histología , Animales , Escarabajos/clasificación , Vuelo Animal/fisiología , Sensilos/anatomía & histología , Especificidad de la Especie , Alas de Animales/anatomía & histologíaRESUMEN
In this first of three articles we show the construction of the articular part of the elytron, the root. The root bears a conspicuous field of campaniform sensilla. This field was studied using light and scanning electron microscopes. The diversity of shape of the field among beetles, types of orientation of elongated sensilla within the field, individual variability of their number among conspecifics are demonstrated. Elongated sensilla point to the junction of the elytron with the second axillary plate. Presumably, they monitor twist movement in this junction, which is possible if the elytron is open. The goal of the whole project is to reveal the effect of both structure and function of the hind wings and elytra on the morphology of this mechanosensory field. Our data on allometric relationships between the animal size and quantitative characteristics of the field in normally flying beetles provide an important background for further functional analysis of this sensory organ. We selected 14 series of several species belonging to the same taxon but differing in size from big to small. It is revealed that the area of the sensory field is directly proportional to the elytral area, whereas the number of sensilla is proportional to the square root of the elytral area. Despite the great range in the elytral area (1500 times) in series of selected species the area of an external pit or cap of a single sensillum varies only 25-fold. The density of sensilla per unit area of the sensory field increases with decrease of the elytral area.