Search results for "Gryllus bimaculatus"
showing 10 items of 11 documents
Ultrastructural changes of the oenocytes of Gryllus bimaculatus DEG (Saltatoria, Insecta) during the moulting cycle
1974
1. The oenocytes of Gryllus bimaculatus are characterized by an abundant smooth-surfaced ER (ATER). In spite of the great cell size the plasma membrane never shows extensive infoldings during the moulting cycle. In addition to mitochondria there are very large numbers of microbodies containing peroxidase but apparently not uricase. Within the second part of the instar the microbodies lie along the clefts which run through the whole cell. 2. The following changes are observed in the course of a moulting cycle: Immediately after hatching the ATER is scarcely developed, some liposomes are located within areas of ATER disappearing some hours later. 20 hours after emergence glycogen deposits app…
Secretion and Metabolism of Ecdysteroids by Oenocyte-Fat Body Complexes (OEFC) in Adult Males of Gryllus bimaculatus DEG (Insecta)
1994
Extracts of whole adult males of Gryllus bimaculatus show distinct maxima of free ecdysteroids on the 8th, 12th and 14th day after imaginal moult at a breeding temperature of 25 °C. Isolated OEFC of 11 days old males secrete in vitro free as well as conjugated ecdysteroids, although the latter predominate. The bulk of free ecdysteroids seem s to consist of E and 20 E according to their retention times in two HPLC systems. Apart from the polar ones, apolar m etabolites appear during incubation. By esterase the apolar metabolites are mostly split into polar ones, partly into 20 E and E. Further treatment of the polar metabolites with helicase leads again to E and 20 E. OEFC transform [3H]E pr…
Land invertebrates of Columbretes Islands : new species
2020
Este artículo se encuentra disponible en la siguiente URL: https://www.mdpi.com/2071-1050/13/4/1776 La fauna terrestre de invertebrados del archipiélago protegido de Columbretes es poco conocida. Además, los pocos estudios existentes se centran en su isla principal, Illa Grossa. Aquí presentamos el listado de espe-cies de invertebrados no registradas, hasta el momento, en el archipiélago, resultados obtenidos mediante una combinación de capturas con trampas de caída, avistamientos y recolecciones aleatorias realizadas tanto en Illa Grossa como en otros tres islotes de este archipiélago. Mediante el primer método se recolectaron un total de 14.830 especímenes entre 2008-2011. La mayor cantid…
An analysis of trade-offs in immune function, body size and development time in the Mediterranean Field Cricket, Gryllus bimaculatus
2005
Summary 1Immune defence has recently been viewed as a life-history trait that shows trade-offs with other life-history traits. However, studies exploring correlations between different components of immune defence and other life-history traits are scarce. 2In this study, two measures of immune function, body size, and development time were studied in the Mediterranean Field Cricket, Gryllus bimaculatus. 3We found no differences between the sexes, but differences in the correlation between the measure of immune function, development time, and body size. In both sexes, encapsulation rate was negatively correlated with body size and development time, whereas lytic enzyme activity was positivel…
Development of the filiform hairs on the cerci of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae)
1978
The filiform hairs, mechanoreceptors of Gryllus, pass through six developmental stages during the last larval stage. The cytoplasm of their sense cells suggests intensive synthesis of protein for cellular metabolism and intercytoplasmic exchange of material via glial evaginations. Ultrahistochemical tests demonstrated acid phosphatase in the lysosomes as well as in components of the Golgi apparatus. There was no significant change in the appearance of the sense cell cytoplasm, indicating a maintained functional state also during molting. The new cuticular apparatus is formed after apolysis by the three enveloping cells. Formation of the replacement hairs is initiated by a cytoplasmic outgro…
Male dominance and immunocompetence in a field cricket
2004
Female preference for dominant males has been found in many species, and it is generally thought that winners of male-male competition are of superior quality. Success in contests probably depends on male condition and overall health. Thus, females could avoid infection and gain genetic benefits in terms of more viable offspring by mating with dominant males. In the present study, we tested whether dominant males of the Mediterranean field cricket, Gryllus bimaculatus, had higher immunocompetence than did their subordinates in experimental trials. We found that dominant males had better immune defense, as indicated by significantly higher encapsulation rate and lytic activity, than did subo…
Morphogenesis of mechanoreceptor and epidermal cells of crickets during the last instar, and its relation to molting-hormone level.
1980
(1) The fine structure of the cercal campaniform sensilla and epidermal cells of Gryllus bimaculatus Deg. (Saltatoria, Gryllidae) was examined, and the ecdysteroid level was monitored throughout the last larval instar. (2) The epidermal cells show changes in shape, cytoplasmic inclusions and differentiation of the apical cell membrane, coupled to the phases of buildup and breakdown of the (cercus) cuticle. (3) The imaginal epicuticle of the epidermal cells begins to form later (by about approximately 6h) than that of the campaniform sensilla. (4) The campaniform sensilla were studied with respect to (a) the morphogenesis of the cuticular apparatus, (b) the inclusion of phenol oxidases in th…
DNA Content and Synthesis in Several Tissues and Variation of Moulting Hormone-Level in Gryllus bimaculatus DEG (Ensifera, Insecta)
1983
The mode of growth of several tissues in Gryllus bimaculatus was investigated during postembryonic development by cytophotometric methods. In contrast to the situation in holo- metabolous insects, the tissues growing by endomitosis reach only moderate levels of polyploidy. In this case the growth of tissues is achieved by mitotic divisions of small cells with subsequent polyploidization. The time courses of DNA synthesis were measured within the 3rd and, for comparison, the 8th larval instar by incorporation of labelled thymidine followed by autoradiography. Hemocytes, cells of the regeneration crypts of the midgut, gonads and nervous tissue showed a continuous incorporation rate; by contra…
Degeneration of moulting glands in male crickets
1998
The degeneration of the prothoracic glands of the male cricket, Gryllus bimaculatus, was analyzed by using an in vitro assay for ecdysteroid release from the moulting glands in last instar nymphs as well as in adult animals, and correlated with light and transmission electron microscopy. Apoptosis was examined by the TUNEL-reaction. The ability to synthesize ecdysteroids reached a peak at the 8th day of the last larval instar, identified as the moulting peak. After adult ecdysis it decreased to barely measurable values. Prothoracic gland degeneration was initiated at the time of the moulting peak, characterized by TUNEL positive reactions, nuclear and cytoplasmatic condensation, a striking …
Courtship song and immune function in the field cricket Gryllus bimaculatus
2003
It has been assumed that sexual ornaments have evolved to reveal males’ health and vigour for females. Choosy females may indirectly use ornaments as an indicator of the presence and effectiveness of genes for resistance against parasites. In this study we tested whether females of the Mediterranean field cricket, Gryllus bimaculatus, can use courtship song as a cue for choosing males with high immunocompetence, measured as encapsulation rate of nylon implants and lytic activity of haemolymph. We found that female crickets preferred courtship songs from males with a high encapsulation rate. Female crickets also had a tendency to prefer courtship songs with high tick rate and long high-frequ…