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ANALISI COMPARATIVA ULTRASTRUTTURALE DELLE GHIANDOLE RIPRODUTTIVE ACCESSORIE MASCHILI IN BACTROCERA OLEAE E CERATITIS CAPITATA (DIPTERA: TEPHRITIDAE)
No full textNotes on the biology and ethology of Luperomorpha xanthodera, a flea beetle recently introduced into Europe
No full textThe life cycle, host plants and damage caused by Luperomorpha xanthodera (Fairmaire), a chrysomelid recently introduced to
Europe, are described. In Tuscany (Italy) L. xanthodera completes 2 generations per year and all stages may overwinter in soil. Adults fly and feed from March-April until autumn. Females oviposit in the soil where larvae complete their development on radicles and pupate. Adults are polyphagous, chiefly anthophagous, causing damage on plants belonging to 23 genera of 19 botanical families
Comparative fine structural analysis of the male reproductive accessory glands in Bactrocera oleae and Ceratitis capitata (Diptera, Tephritidae)
No full textThe morphology and ultrastructure of the male reproductive accessory glands from Bactrocera oleae and Ceratitis capitata were comparatively investigated. In both insects, there are two types of glands, mesoderm- and ectoderm-derived, which open in the ejaculatory duct. The mesoderm-derived glands are sac-like in B. oleae and very long tubules in C. capitata, whereas the ectodermic glands, generally branched finger-like structures, are longer in B. oleae than in C. capitata. Despite their different morphology, the ultrastructure of the two types of glands is quite similar in both Tephritids. The epithelium of the mesoderm-derived glands consists of binucleate and microvillate secretory cells. In C. capitata, but not in B. oleae, the secretory cells contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The gland lumen is filled with a dense or sometimes granulated secretion. The ectoderm-derived glands undergo a cycle of maturation, by which their epithelial cells form a large subcuticular cavity filled with an electrontransparent secretion. Electrophoretic analysis of accessory gland secretion reveals in both species the presence of low molecular weight protein bands. A major band of about 29 kDa or 30 kDa in B. oleae and C. capitata, respectively, is
revealed
Ultrastructure of the midgut and the adhering tubular salivary glands of Frankliniella occidentalis (Pergande)(Thysanoptera: Thripidae)
No full textThe ultrastructure of the midgut and the tubular salivary glands of Frankliniella occidentalis (Thysanoptera:Thripidae) is described. The microvilli have 2 different types of glycocalyx: in the anterior part of the midgut they are surrounded by a myelin-like membrane; in the posterior region, the microvilli have numerous rod-like projections arranged to form a continuous layer. Microfilaments longitudinally cross each microvillus; the microfilaments contain F-actin. Tubular salivary glands flank the midgut but do not fuse with it. The distal part of these glands have microvillated cells containing large amounts of electron-transparent material. The cells of the proximal part are lined with a thin cuticle
Functional morphology of the female reproductive apparatus of Stephanitis pyrioides (Heteroptera, Tingidae): a novel role for the pseudospermathecae
No full textAt mating, female insects generally receive and store sperm in specific organs of their reproductive tract called spermathecae. Some Heteroptera, such as Cimicomorpha, lack a true spermatheca; some have receptacles of novel formation where sperm cells can transit or be stored. In Tingidae, there are two sac-like diverticula, the "pseudospermathecae," each at the base of a lateral oviduct, which previously were considered to function as spermathecae. However, this role has never been documented, either by ultrastructural studies or by observations of sperm transit in the female reproductive tract. In this article, we investigate the morphology and the ultrastructure of the female reproductive apparatus in the economically important tingid species Stephanitis pyrioides, focusing our attention on the functional role of the pseudospermathecae in an evolutionary perspective. Each ovary consists of seven telotrophic meroistic ovarioles, the long pedicels of which enlarge into a bulb-like structure near the terminal oocyte. The ovarioles flow into two long lateral oviducts, which join to form a very short common oviduct. Basally, each lateral oviduct is connected through a short duct to one of two pseudospermathecae. The ultrastructure of the ectodermal epithelium of the pseudospermathecae is dramatically different in sexually immature or mated females. In virgin females, cells delimit a very irregular lumen, filled with a moderately electron-dense granular material. The large nucleus adapts to their irregular shape, which can have long projections in some regions and be flattened in others. After mating, epithelial cells generally elongate and display an apical layer of microvilli extending beneath the cuticle, often containing mitochondria. In the lumen of the pseudospermathecae there is a dense brownish secretion. No sperm cells were ever found inside this organ. After mating, sperm move upward along the lateral oviducts and the ovarioles, accumulating in the bulb-like structure of the pedicels, and proceeding into the distal region between the follicle cells surrounding the oocyte and the ovariole wall. The egg, most likely fertilized in the bulb-like region of the ovariole, moves through the lateral oviduct, entirely enters the pseudospermatheca and is smeared with its secretion just before oviposition. We exclude a function of sperm storage for the pseudospermathecae, and instead suggest a novel role for these organs as reproductive accessory glands
The ultrastructure of Malpighian tubules and hindgut of Frankliniella occidentalis (Pergande)(Tisanoptera, Thripidae)
No full textThe ultrastructure of the western flower thrips, Frankliniella occidentalis (Pergande) (Order: Thysanoptera), has 4 Malpighian tubules that are free of the intestine as they leave their junction at the pyloric region. The tubules consist of an epithelium with a single type of microvillated cells; proximally, the cells are lined by a thin cuticle. Numerous mitochondria, basal infoldings of the plasma membrane and vesicles with varying densities suggest active transit of fluid in the cell for osmoregulation. Two of the Malpighian tubules are bent posteriorly and closely adhere to the hindgut in the region of the rectal pads where the 2 epithelia are separated only by a basal lamina. The ultrastructure of this region suggests possible fluid reabsorption from the gut lumen
The ultrastructure of the spermatheca in Ceratitis capitata Wied and Dacus oleae Gmel (Diptera: Tephritidae)
No full textThe spermatheca of two economically important insects, Ceratitis capitata and Dacus oleae (Diptera, Tephritidae) was studied by scanning and transmission electron microscopy.
The organization of this organ is very similar in both species: it consists of an apical receptacle where spermatozoa are stored and a long duct opening in the vagina. The apical receptacle is characterized by a secretory epithelium structured as in insect ectodermal glands, lined by a cuticular intima. The secretory cells have an asynchronous secretion cycle, more evident in Ceratitis capitata.
Two types of secretions have been observed in Ceratitis: one has a microtubular appearance, the second is glycoprotein in nature.
The spermathecal duct consists of two ultrastructurally distinct parts: the distal one shows cells with microtubular bundles anchored to the opposite sides of the cell membrane; this organization is able to resist to mechanical stress during the transport of spermatozoa. The proximal tract of the duct is characterized by cells involved in osmoregulatory functions
Fine structure of the hindgut and the rectal pads of Frankliniella occidentalis (Thysanoptera:Thripidae)
No full textThe fine structure of the rectal pads of Frankliniella occidentalis is described. Each pad consists of four types of cell: the principal cells, characterized by many apical infoldings of the plasma membrane and many scalariform junctions associated with mitochondria, are involved in active uptake from the intestinal lumen; the sheat cells wich surround the pad; the basal cells forming a basal cavity, and the central cells forming an axial duct in the pad. The rectal epithelium is simple and reveals structures suggesting water uptake
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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