Cuticular Sac Research Articles

Morphological and chemical composition of the essential oil of the leaf of Schistostephium heptalobium

The morphology of Schistostephium heptalobium was investigated by using electron microscopical examination. The scanning electron microscope revealed that the leaves of this plant are characterized by short, multicellular glandular trichomes and long hairy-fibrous tubular non-glandular trichomes. These trichomes are associated with crystal-like deposits. The Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDX) showed that, Fe, Al, K, Mg and Si are the major components of the crystals-like deposits. The area of the non-glandular trichomes where these crystals-like substances are produced showed Al, Ca, K, Mg, Mo, Na, Pi and Si as major residue when analysed by SEM-EDX. However, the SEM-EDX analysis of glandular trichome sac and the content of the sac showed different results. The anatomical investigation also showed that the ends of the non-glandular trichomes are fibrous and have a tubular base while the glandular trichomes contain cuticular sac. The sac contains by products which are referred to as essential oil. These by-products are regarded as the first line of defence in this plant. Hydro-distillation of fresh leaves of S. heptalobium yielded 2.5% (v/v) of the essential oil. The GC-MS analysis of the oil revealed that the essential oil of S. heptalobium is characterized by α-pinene, sabinene, myrcene, α-phellendrene, 1.8-cineole, γ-terpinen, α-thujone, cis-sabinene hydrate, camphene, terpinen-4-ol, α-terpineol, 2-cyclohexen-1one, geranial, phenol, neryl acetate, β-caryophyllene, β-selinene and caryophyllene oxide. Key words: Glandular trichomes, non-glandular trichomes, SEM-EDX analysis, essential oil composition, Schistostephuim heptalobium.

Ultrastructure of the mesonotal mycangium of Xylosandrus mutilatus (Coleoptera: Curculionidae)

Mycangial structures of female Xylosandrus mutilatus (Blandford, 1894), an Asian ambrosia beetle recently introduced and now established in the southeastern United States, were examined. In addition to the glandular (secretory) mesonotal mycangium located below the scutellum, nonglandular pit mycangia containing fungal propagules were discovered to occur externally on the scutellum. The ultrastructure of the glandular mesonotal mycangium, which consisted of an outer secretory layer covering an inner paired cuticular sac, is described and illustrated. Both secretory and cuticular layers of the mesonotal mycangium were highly tracheolated. Tracheae and tracheoles in association with a Xyleborine mycangium are reported here for the first time. Type 1 secretory cells were identified and observed passing electron-dense material into the glandular mycangium via efferent cuticular ductules, although type 2 secretory cells were not observed. Secretory cells were not observed in association with the nonglandular pit mycangia.

Description of Deleyia gen. n. with a discussion of its phylogenetic relationships to the genera Daubaylia Chitwood & Chitwood, 1934 and Myolaimus Cobb, 1920 (Nematoda: Rhabditida)

AbstractThe new genus Deleyia gen. n., including two new species, D. poinari gen. n., sp. n. and D. aspiculata gen. n., sp. n., is described from terrestrial material (rotting wood and moss) in Ukraine. The new genus is inter alia characterised by the outer cuticular layer being defoliated along most of the body, except for labial region and tail posterior to phasmid, forming a cuticular sheath around the body and a vulval cuticular sac in females, and reduced stoma and basal bulb. Deleyia poinari gen. n., sp. n. is separated from D. aspiculata gen. n., sp. n. by a shorter body (L = 600-831 vs 756-945 μm), a shorter PUS (7-18 vs 44-69 μm), longer tail in both females and males (40-50 vs 32-38 μm and 37-48 vs 35 μm, respectively), and presence vs absence of spicules and gubernaculum. The phylogenetic position of Deleyia gen. n. and its relationships to the genera Daubaylia and Myolaimus are discussed.

Do “glanduliferous” larvae of Galerucinae (Coleoptera: Chrysomelidae) possess defensive glands? A scanning electron microscopic study

Larvae of the chrysomelid taxon Galerucinae, Sermylini, are known to release a fluid from dorsolateral segmental openings when disturbed. The release of this fluid resembles the discharge of secretion from well-studied exocrine defensive glands in larvae of Chrysomelinae, the putative sister group of Galerucinae. Thus, Sermylini larvae have been named “glanduliferous” ones. However, no comparative analyses of the internal structures of the segmental openings in Sermylini larvae have been available prior to this study. Therefore, segmental larval openings in 10 Sermylini species were investigated by scanning and light microscopy. Two types of segmental openings were detected: (1) the opening is visible as an integumental slit which can be opened and closed by muscles. No specific glandular structures are associated with this slit. (2) The opening is covered internally by a cuticular sac which can be everted to the outside. A cuticular duct of a gland is leading into this sac. Haemolymph is discharged from both types of openings. These structures are discussed with respect to reflex bleeding in other taxa. Furthermore, a common origin of the segmental openings in larvae of Sermylini and the segmental exocrine glands in chrysomeline larvae is critically questioned.

Morphology and structural organization of Gene's organ in Argas walkerae.

Electron microscopy revealed that Gene's organ in females of Argas walkerae Kaiser & Hoogstraal (Ixodida: Argasidae) is formed as a double-sac structure consisting of an outer epithelial and an inner cuticular sac. The latter emerges through the camerostomal aperture to the exterior in ovipositing ticks. The epithelial sac forms the corpus and the two blind-ending horns, which pass into the epithelium of the excretory duct of a gland at each side of Gene's organ and envelop the cuticular sac. Both excretory ducts open into the lumen between the epithelial and the cuticular sac. The cuticular sac is folded and consists of a fibrous endocuticula outwards towards the lumen between the epithelial and the cuticular sac and of a smooth epicuticula inwards. Parallel running grooves occur over the lateral epicuticular surface turning medially into cobble-stone pavement-like rises. Tubuli pass through the cuticular sac ending in pores on the epicuticular surface and open into the lumen between the epithelial and the cuticular sac. Muscle fibres pass through the epithelial sac at the horn tips and are inserted to the cuticular sac. In ovipositing females, the glands are fully developed and the lumen between the epithelial and the cuticular sac is filled with an amorphous mass.

Morphology and structural organization of gené's organ in Dermacentor reticulatus (Acari: Ixodidae).

Scanning and transmission electron microscopical investigations revealed that Genés organ in unfed and ovipositing females of Dermacentor reticulatus is formed as a double-sac-structure consisting of an outer epithelial and an inner cuticular sac. In ovipositing ticks the latter emerges through the camerostomal aperture to the exterior. Genés organ in unfed ticks consists of a corpus, two posterior horns and a pair of undeveloped glands at each side, which differentiate in ovipositing ticks to compound, branched tubular glands with a main efferent duct for each gland opening into the lumen between the epithelial and the cuticular sac. Genés organ of egg-laying females corresponds basically in morphology and structural organization to that of unfed ticks. Compared with unfed ticks, however, in ovipositing ticks the corpus and horns are longer and broader, the glands are fully developed and the cuticular sac is evertable. The epithelial sac as the outermost part of Genés organ is continuous with the hypodermis of the basis capituli and the scutum, arises at the camerostomal aperture, forms the corpus and the two blind-ending horns, passes into the epithelium of the main excretory ducts of the glands and envelops the cuticular sac. The cuticular sac passes into the cuticle of the basis capituli and the scutum, arises at the camerostomal aperture, is folded, expands into the horn tips and consists inwards of a smooth epicuticula and outwards of a fibrous endocuticula. Muscles originating from the scutum pass caudomedially through the epithelial sac and are inserted into the cuticular sac. The entire surface of the maximally everted cuticular sac is covered with an amorphous mass. In cleaned samples, ledge-like structures appear on the lateral surface. These ledges turn into balloon-like structures which extend over the medial and dorsal surface. The entire surface including the balloon-like structures and the ledges are provided with numerous cribrate pits.

Modus operandi of oviposition in Dermacentor reticulatus (Acari: Ixodidae).

The process of oviposition in D. reticulatus was observed and found to be a sequence of exactly coordinated, interlocking events independent of the phase of oviposition. The average period of oviposition in the investigated ticks was 31.6 days at 20 degrees C and 95% relative humidity. The number of eggs deposited on each day increased until reaching a maximum on the fifth day of oviposition and then decreased continuously. As a result, most of the eggs were deposited during the initial phase of oviposition. The total number of eggs was proportional to the ticks' weight replenishment. Egg-laying commenced with the lowering of the capitulum and the simultaneous spread of the pedipalps which were lowered to the body wall embracing the genital aperture on both sides. Immediately afterwards the cuticular sac of Gene's organ was pushed out and retracted several times. At the cuticular sac's maximum extension, the vestibulum vaginae prolapsed, forming the ovipositor as an extended tube which handed over an egg to the two horns of the cuticular sac after a brief, but intensive, contact with the cuticular sac. Then the vestibulum vaginae invaginated, the pedipalps closed, and the cuticular sac was retracted. Finally, the egg was transported onto the dorsal area of the tick by means of a vigorous rising of the capitulum. During the course of oviposition most of the events, especially the period of egg embracement by the cuticular sac, were prolonged, as was the total time for laying one egg. Similarly, the intervals between successive egg-laying processes increased continuously. The number of eggs deposited was not dependent on the functional ability of Gene's organ, as shown by similar numbers of deposited eggs from ticks with and without mechanical blocking of the cuticular sac. But the participation of the organ in the process of oviposition proved to be a prerequisite for the viability of the eggs. Larvae developed and hatched only from those eggs which were deposited from ticks with an undisturbed Gene's organ. In comparison, eggs without contact to the cuticular sac of Gene's organ dried up and shrivelled immediately after being deposited and did not hatch. Consequently, it strongly suggests, together with the results from other studies, that Gene's organ covers the eggs with a secretion that prevents the loss of water.

The mechanism of oviposition in Argas (Persicargas) walkerae (Acari: Argasidae).

The process of oviposition in A. walkerae was observed and found to be a sequence of exactly coordinated, interlocking events independent of the age of ticks. Egg-laying always commenced with numerous dorso-ventral movements of the capitulum. The pedipalps were spread during the last dorso-ventral movement and lowered to the ventral body wall embracing the genital aperture on both sides. Simultaneously, the cuticular sac of Gene's organ emerged and immediately everted maximally. Immediately afterwards the vestibulum vaginae prolapsed from the genital aperture touching the cuticular sac. The vestibulum vaginae handed over an egg to the cuticular sac after a brief contact. Then the vestibulum vaginae invaginated, the pedipalps closed and the cuticular sac was retracted. Finally, the capitulum very frequently moved up and down and the free egg was pushed in front of the ticks. The total time of laying an egg averaged 27 min in both 4-week-old and 12-month-old ticks. In 4-week and 12-month-old ticks, egg-laying was preceded by a mean preoviposition period of 6.1 days and 7.5 days, respectively, while the mean oviposition was completed in 14 and 10 days and the average egg totals were 119 and 103.

Larval exocrine glands in the galerucine Agelastica alni L. (Coleoptera: Chrysomelidae): their morphology and possible functions

Larvae of the alder leaf beetle Agelastica alni (Coleoptera: Chrysomelidae) discharge a fluid from openings located dorsolaterally on paired tubercles of the first to eighth abdominal segments, when disturbed. These paired openings have been described as apertures of defensive glands, whereas the discharged fluid ( = tubercle fluid) is often mentioned as reflex blood. Up to now, clear evidence for the presence of glandular cells below the precisely described apertures was lacking, and detailed knowledge of the composition and defensive efficiency of the discharged fluid was not available. In this study, the internal structures around the paired abdominal openings in A. alni larvae were investigated by scanning electron microscopy and histological methods. Additionally, the composition of tubercle fluid and larval haemolymph was compared by microscopy, tlc, and electrophoresis. The effects of tubercle fluid and haemolymph on ants and conspecific larvae were studied by olfactory and feeding bioassays. ¶The morphological studies revealed that A. alni larvae possess sac-like cuticular invaginations which open dorsolaterally from the spiracle on tubercles of the abdominal segments 1 – 8. A single voluminous gland cell (type III) opens into each invaginated cuticular sac. Each sac may be turned from the inside to the outside and retracted by muscles. The discharged tubercle fluid conforms with haemolymph in its pattern of haemocytes and proteins (SDS-PAGE). Tlc patterns of the tubercle fluid and haemolymph differ by a single spot when using a high polarity eluent. Both tubercle fluid and haemolymph significantly deter the ant Myrmica rubra from feeding. Heating, treating by proteinase K, or exclusion of molecules >3 kD did not inactivate the feeding deterrent quality of tubercle fluid and haemolymph, thus indicating that the feeding deterrents are small, non-volatile, non-proteinous molecules present both in the haemolymph and the tubercle fluid. However, the bioactivity of volatiles from tubercle fluid and haemolymph differed, since the volatiles from tubercle fluid act as alarm pheromone for conspecific larvae, whereas volatiles from the haemolymph do not. The function of the glandular cells associated with the segmental cuticular invaginations of A. alni larvae is discussed.

Wax lipid secretion and ultrastructural development in the egg-waxing (Gené's) organ in ixodid ticks

Gené's organ, the egg-waxing organ of ticks, performs an essential function in females by coating the eggs with a waterproofing layer during oviposition, which prevents desiccation of the embryo, ensuring its viability. The organ is a target for control agents and a potential site of virus replication involving trans-oval transmission of arboviruses. The organ is a complex dermal gland, developed to an elaborate degree. The external appendage, the horns, is an evertable balloon-like cuticular sac which manipulates the eggs and coats them in wax. Wax passes through pores in the cuticle from the internal, sub-cuticular lumen. Gené's organ develops in synchrony with oogenesis and oviposition. This paper describes the development of the gland cells and formation of the intra-cuticular lumen and its ultrastructure during engorgement and oviposition in ixodid ticks. The structural basis for wax secretion in Gené's organ is also described.

Glandular pouches of the genital chamber of female Schistocerca gregaria (Forskål) (Orthoptera : Acrididae)

Females of the desert locust, Schistocerca gregaria, have a pair of conspicuous glandular pouches associated with the genital chamber and gonoducts. Each pouch consists of a cuticular sac with an epithelium comprising at least 3 types of cells, namely epidermal cells, vacuolated secretory cells, and duct cells. The vacuole of each secretory cell is connected to the cavity of the pouch by a long, convoluted, cuticular duct some 1 μm in diameter, which runs through the cuticle. Each duct has an accompanying duct cell closely situated. The cuticle is perforated also by numerous fine ducts that do not extend into the epithelium: these appear to be large pore canals. Plates of secretion with a wax-like appearance are found in some pouch cavities, often forming close replicas of the latter. All the major features mentioned above are found in females with undeveloped ovaries as well as those with mature oöcytes: the pouches show little alteration in structure with advancing maturity. The nature of the pouches is compared with that of other Acrididae, and their functions are discussed.

DEVELOPMENT AND BIONOMICS OF CHRYSOMELOBIA LABIDOMERAE (ACARI: TARSONEMINA; PODAPOLIPIDAE), A PARASITE OF THE MILKWEED LEAF BEETLE (COLEOPTERA: CHRYSOMELIDAE)

AbstractAdult females of Chrysomelobia labidomerae Eickwort lay eggs on the upper surfaces of the hind wings of Labidomera clivicollis (Kirby). The eggs hatch in approximately 7 days and male and female larvae feed at the base of the wings and in the meso–metathoracic crevice and swell to about twice their original length. For about the second half of the approximately 7-day larval stadium, the larvae are inactive (pharate adults) and are usually cemented to the undersurfaces of the elytra. Inactive female larvae are accompanied by adult males that apparently copulate with the newly emerged adult females. The pharate adult is enclosed in a cuticular sac that may represent a calyptostatic nymphal instar. Adult females feed on the beetle’s abdominal terga and sometimes also occur on its venter where they do not feed. Females disperse from host to host when the beetles copulate. The species is arrhenotokous. Mites overwinter on the diapausing adult beetles and do not infest the immature stages of their host. Even at high population levels, the mites do not noticeably affect the longevity or fecundity of their hosts.