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At least 145 records · Page 8Linked to original sources
PubMed2003

The behaviour of a multiple sex chromosome system in Dundocoris flavilineatus (Heteroptera: Aradidae: Carventinae) that originated by autosome-sex chromosome fusion.

The nominate subspecies of Dundocoris flavilineatus Jacobs occurs in indigenous evergreen forests over a wide area in KwaZulu-Natal and the Eastern Cape Province of South Africa. It has a chromosome number of 2n male = 28XY, which is the ancestral number for the genus. D. flavilineatus ndabeniensis, which comprises an isolated sibling population at Ndabeni forest in northern KwaZulu-Natal, possesses a multiple sex chromosome system, presumably a X1X2Y system and has a chromosome number of 2n male = 27X1X2Y. The system probably originated when an autosome and the Y-chromosome of the 28XY karyotype fused. In contrast to the situation previously described in the XY1Y2 system of D. nodulicarinus the autosomal and original Y-chromosome parts of the neo-Y chromosome seem to have a reciprocal influence on each other in terms of structure and staining intensity during prophase 1. The autosomal part of the neo-Y adopts a granulate, heteropycnotic, linear structure while the original Y part is less globular than usual in structure. The neo-X chromosome (= X2) behaves like, and stays isopycnotic with the autosomes. It is connected to the neo-Y by terminal association--probably a terminal chiasma. The sex chromosome system is post-reductional and a sex chromosome trivalent is present in all metaphase II cells. The origin and behaviour of the neo-X1X2Y sex chromosome system in D. flavilineatus ndabeniensis are described, discussed, illustrated with photomicrographs and compared to the XY1Y2 system in D. nodulicarinus. Idiograms of the karyotypes of the two subspecies of D. flavilineatus are also presented.

Animals↗
PubMed2003

Cytogenetic and nucleolar meiotic cycle analyses in Dysdercus imitator Blöte, 1931 (Pyrrhocoridae, Heteroptera) from Argentina.

So far, only seven and five species of Dysdercus from the Old and New Worlds, respectively, have been cytogenetically analysed. They all have holokinetic chromosomes and a pre-reductional type of meiosis. In the present study the chromosome complement, male meiosis and nucleolar meiotic cycle of Dysdercus imitator were analyzed. During male meiosis several cytogenetic features are remarkable, namely the presence of a long diffuse stage after pachytene, the finding of one or two ring bivalents per cell in almost all specimens, and the presence of several prenucleolar bodies lasting up to telophase II. The origin and function of these prenucleolar bodies could be related to a particular physiological cycle of the meiocytes.

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PubMed2006

Histological studies of damage by pod-sucking bugs (Heteroptera: Coreoidea) associated with cowpea Vigna unguiculata ssp. unguiculata in Nigeria.

Histological studies were conducted on cowpea pods fed upon by the coreoid pod-sucking bugs, Anoplocnemis curvipes (Fabricius), Clavigralla tomentosicollis Stål, C. shadabi Dolling, Riptortus dentipes (Fabricius) and Mirperus jaculus (Thunberg). Various degrees of tissue and cellular disruption were apparent, especially in the brachysclereids. They were manifested in terms of plasmolysis, cell enlargement and cell wall disintegration depending on the coreoid species involved. The feeding site and its periphery had all the cells of the brachysclereids plasmolysed, with the parenchyma having broken cell walls in the case of A. curvipes. Riptortus dentipes and M. jaculus showed similar patterns of feeding activity but less extensive levels of damage. The Clavigralla spp., however, caused cell enlargement in the brachysclereids, and broken cell walls in both the brachysclereids and the parenchyma. Damage symptoms were observed in cells far away from the feeding sites of the bugs, suggesting the possibility of sucrase activity which has been reported to cause osmotic pump feeding in the Coreidae.

Animals↗
PubMed2006

Effects of temperature on predation by the stinkbugs Picromerus bidens and Podisus maculiventris (Heteroptera: Pentatomidae) on noctuid caterpillars.

Environmental risks associated with the use of non-indigenous organisms for augmentative biological control have received growing attention. In Europe, the native pentatomid predator Picromerus bidens (Linnaeus) has been considered a potential alternative to the North American pentatomid Podisus maculiventris (Say) for the control of lepidopteran, coleopteran and hymenopteran defoliator pests. In the current study, prey consumption and developmental duration of the predatory stages of P. bidens and P. maculiventris were investigated at three temperatures (18, 23 and 27 degrees C) in the laboratory using caterpillars of Spodoptera littoralis as prey. Development time from second to fifth instar was longer for P. bidens than for P. maculiventris, taking on average 17-44 and 14-32 days, respectively, at the different temperatures. Total nymphal consumption of fourth instar S. littoralis caterpillars indicated a greater voracity of P. bidens as compared with P. maculiventris at both the low and high temperatures tested (18 and 27 degrees C). At 23 degrees C, however, the predation rate of P. maculiventris nymphs exceeded that of P. bidens nymphs. Effect of temperature on the functional response of P. bidens to densities of fourth instar Spodoptera exigua was assessed on potted green bean plants. Female adults of P. bidens exhibited a type II functional response at 18 and 23 degrees C but a type III response at 27 degrees C. Searching efficiency was not affected by temperature but handling time decreased from 4.2 to 1.4 h as temperature increased from 18 to 23 degrees C. However, the predator spent twice as much time handling prey at 27 degrees C (2.9 h) than at 23 degrees C. This study indicates high predation rates of P. bidens at a wide range of temperatures and suggests that the species may be a valuable asset for the biological control of defoliating caterpillars, provided that obstacles to its mass production can be overcome.

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PubMed2003

Distribution of NPY and NPY-Y1 receptor-like immunoreactivities in the central nervous system of Triatoma infestans (Insecta: Heteroptera).

The distributions of neuropeptide Y (NPY) -like immunoreactivity (LI) and that of its Y1 receptor (Y1), as well as their coexistence with cholecystokinin (CCK) -LI, were studied in the central nervous system of Triatoma infestans by using immunohistochemistry. NPY-immunoreactive (IR) cell bodies and fibers were observed in the brain, subesophageal ganglion, and thoracic ganglia. NPY-IR somata were seen in the optic lobe and the anteromedial and caudolateral soma rinds of the protocerebrum. Immunostained cell bodies were also found in the lateral edge of the antennal lobe glomeruli as well as in the caudal part of the antennal mechanosensory and motor center. The subesophageal ganglion harbored few NPY-IR perikarya and fibers in the three neuromeres. Positive somata of the prothoracic ganglion were detected near both the cephalic and posterior connectives as well as by the root of prothoracic nerve I, whereas in the posterior ganglion, they were seen by the roots of mesothoracic and abdominal nerves. Coexpression of NPY-LI and CCK-LI was seen in cell bodies of the protocerebrum, the subesophageal and posterior ganglia. Protocerebral Y1-IR cell groups were detected in the anterolateral and posteromedial soma rinds and at the level of the lamina ganglionaris and the external optic chiasma. Numerous positive perikarya surrounded the antennal lobe glomeruli as well as the antennal mechanosensory and motor center. Other immunostained cell bodies were seen in the posterior edge of the esophageal canal and by the roots of the mandibular and the maxillary nerves. Y1-IR cell bodies of the prothoracic ganglion were found near the roots of prothoracic nerves I-II, whereas in the posterior ganglion, they were located mainly in the abdominal neuromeres. Coexpression of Y1-LI and CCK-LI were detected in several brain areas as well as in the metathoracic and abdominal neuromeres of the posterior ganglion. When assessed by immunoblotting, Y1 antibodies detected two protein bands between 34 and 46 kDa. Analysis of the distribution patterns of NPY-LI and Y1-LI suggest that peptide and receptor are mainly involved in the processing of information coming from sensory receptors.

Animals↗
PubMed2004

Distribution of serotonin in the central nervous system of the blood-feeding heteropteran, Triatoma infestans (Heteroptera: Reduviidae).

The distribution of serotonin was studied in the Triatoma infestans central nervous system by using immunocytochemistry. Serotonin immunoreactive cell bodies and fibers were observed in the brain, subesophageal ganglion, and thoracic ganglia. In the brain, serotonin-like immunoreactivity was detected in a limited number of somata, which gave rise to an extensive network of labeled neurites in patterned as well as in nonglomerular neuropils. Immunolabeled perikarya were observed in the optic lobe and in the anteromedial and caudolateral soma rinds of the protocerebrum. Deutocerebral immunoreactive somata were mainly found in the medial layer surrounding the antennal lobe glomeruli, as well as in relationship to the antennal mechanosensory and motor center. The subesophageal ganglion contained serotonin immunoreactive perikarya of variable sizes and moderate to low density of positive fibers. In the prothoracic ganglion, immunoreactive somata were detected near the cephalic connectives as well as in its caudal end. Serotonin immunoreactive somata and fibers were observed in the posterior ganglion of the thorax, with the abdominal neuromeres harboring the highest number of immunolabeled perikarya. These results show that there is a widespread unique serotonergic system in the CNS of Triatoma infestans and suggest that the indolamine could act as a neuromodulator or as a neurohormone.

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PubMed1998

Chemical mediation of egg dumping in the lace bug Gargaphia solani Heidemann (Heteroptera: Tingidae).

We tested the hypothesis that the proximate cue for egg dumping in the lace bug Gargaphia solani Heidemann is a chemical deposited by females on eggs during or shortly after oviposition. The results of this study show that: (1) dumping frequency declines as eggs age but can be elevated to its highest levels by exposure to chemical extracts from young egg masses; and (2) visual cues are not necessary to stimulate dumping. Further data support the hypothesis that the ovipositional chemical is used by egg dumpers as a long-distance signal of an appropriate oviposition site, and is not a mechanism by which guarding females relocate their eggs if separated from them. (c) 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1997

Temperature Regulation of Supercooling and Gut Nucleation in Relation to Diapause of Pyrrhocoris apterus (L.) (Heteroptera)

The heteropteran Pyrrhocoris apterus (L.) does not survive freezing of its body fluids; there is a good correlation between values of survival at subzero temperatures and the supercooling point (SCP), i.e., the temperature at which body fluids start to freeze. The decrease of the SCP and thus the increase in cold hardiness is regulated by photoperiod and temperature. The relative importance of these factors depends on the physiological state of the insect. The SCP is about -7°C at the onset of prediapause and a decrease of about 4-5°C is associated with the development of the diapause syndrome in adults; these processes both are induced by a short-day photoperiod with temperature playing a secondary role. The induction of the diapause syndrome is a prerequisite for the subsequent decrease of the SCP by about 5-6°C during cold acclimation. An intermediate temperature of 15°C, or fluctuating outdoor temperatures and short-day photoperiods, are more suitable for the decrease of SCP than 5°C in continuous darkness. The sensitivity to photoperiod gradually disappears during the development of diapause; after the termination of diapause around the winter solstice the SCP irreversibly increases at a high temperature of 26°C even if exposed to a short-day photoperiod. The SCPs of hemolymph, gut, fat body, and gonads were compared to whole-body SCP. The gut was identified as the primary site of ice nucleation because its SCP value was very similar to the value for the whole body in both short-day and long-day insects. The SCPs of other organs, including the hemolymph, were always lower than the whole body SCP. Food was not a source of ice nucleating agents because the SCP of freshly ecdysed adults remained high after 2 weeks of starvation. In contrast, feeding was a prerequisite for the decrease of the SCP during prediapause. In postdiapause insects, the SCP increased at high temperatures in spite of the absence of food.

Journal Article↗
PubMed1976

Structure and function of prothoracic glands and oenocytes in embryos and last larval instars of Oncopeltus fasciatus Dallas (Insecta, Heteroptera).

1. Active prothoracic glands and oenocytes of last larval stage are both characteristized by well-developed smooth and rough endoplasmic reticulum (ER). Prothoracic glands also show plasma membrane infoldings, but not oenocytes which contain a large number of pleomorphic vesicles. 2. The fine structure of embryonic oenocytes corresponds after blastokinesis with that of active larval and adult cells. Thus, an activity in the late embryo can be assumed. Embryonic prothoracic glands reveal no signs of activity: smooth and rough ER are absent. The subcellular structure resembles that of organ anlagen, i.e. not yet fully differentiated tissue. Hormone synthesis is not likely. 3. Ecdysone titer was determined throughout embryonic development and in mature adults. Although prothoracic glands break down during adult ecdysis, imagines contain in the Calliphora-bioassay active factors: females 0.9 CU/g and males 0.5 CU/g. As sites of synthesis the oenocytes are suggested. 4. A relatively high ecdysone titer of 7 CU/g is measured in newly deposited eggs. The hormone is presumably of maternal origin. Subsequent to blastokinesis the hormone content increases dramatically up to about 180 CU/g, apparently due to endocrine function of the embryo. Oenocytes are proposed as the source of ecdysone during late embryonic development. 5. The function of ecdysone during early and advanced embryogenesis, especially in view of "embryonic molts", is discussed.

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