| effects of the pyrethroid fenvalerate on the alarm response and on the vulnerability of the mosquito larva culex pipiens molestus to the predator notonecta glauca. | previous studies have shown that mosquito larvae retreat from the surface of water as an alarm response to sudden changes in light intensity. we investigated the effects of the insecticide fenvalerate on this alarm response in larvae of the mosquito culix pipiens molestus and on the related vulnerability of these larvae to the predator notonecta glauca. for the alarm response, after 1h of exposure to fenvalerate, no immediate effects were observed. however, after a 5-h postexposure period follow ... | 2011 | 21543050 |
| [ultrastructure of the olfactory gland in the back swimmer notonecta glauca l. (notonectidae)]. | | 2015 | 4393166 |
| acrosome formation during spermiogenesis in notonecta glauca l. (heteroptera). | the giant spermatozoon of notonecta glauca has a 1 mm long acrosome. it has the shape of a stiff needle with round cross section and contains several different components. morphogenesis of this simple form proceeds by very complex changes of both the internal structure and the outer shape. surrounded by a great number of individual dictyosomes the acrosome is attached to the anterior nuclear pole where it grows to a sphere measuring about 20 microns in diameter. in its interior differentiations ... | 2012 | 3370612 |
| bioaccumulation and trophodynamics of the antidepressants sertraline and fluoxetine in laboratory-constructed, 3-level aquatic food chains. | although reports of pharmaceutical bioconcentration in aquatic organisms are increasing, less is known about trophic transfer in aquatic food webs. the bioaccumulation and trophodynamics of sertraline and fluoxetine, 2 selective serotonin reuptake inhibitors (ssris) frequently detected in aquatic environments, were tested by exposing constructed aquatic food chains to ssris under controlled laboratory conditions. both of these ionizable, weak base pharmaceuticals showed lower bioaccumulation fac ... | 2017 | 27696515 |
| the distribution and function of microtubules in nutritive tubes. | the density and distribution of microtubules in the nutritive tubes of three hemipteran insects, corixa punctata, notonecta glauca and dysdercus cingulatus, were analysed from electron micrographs by computer. both parameters varied amongst all three species, the density of microtubules in corixa being approximately three times that seen in dysdercus. the density and distribution of microtubules within the nutritive tubes correlated directly with the size of particle transported by them, suggest ... | 1977 | 929581 |
| sublethal effects and predator-prey interactions: implications for ecological risk assessment. | ecological risk assessments tend to focus on contaminant effects on single species in isolation. however, additional effects from interactions between species (e.g., predator-prey interactions) may also occur in natural systems. the present study investigated the consequences of sublethal contaminant effects in prey on predator-prey interactions, particularly the interaction between prey behavioral changes and predation by predators with different hunting strategies. ambush (ischnura elegans van ... | 2009 | 19572771 |
| effects of glycerol and freezing on the appearance and arrangement of microtubules in three different systems: a freeze-substitution study. | effects of glycerol and freezing on microtubules in three different systems viz. the ovaries of notonecta glauca, the sperm tails of notonecta glauca and the hyphae of the fungus phanaerochaete velutina have been studied by means of freeze-substitution. the protofilamentous substructure of microtubules is visible in positive image whether or not the tissues are treated with glycerol prior to freezing, suggesting that it is the freezing which allows this by the weakening of hydrophobic bonding be ... | 1986 | 18620162 |
| effects of water depth on choice of spatially separated prey by notonecta glauca l. | in laboratory experiments, the predator, notonecta glauca l., was exposed to varying densities of surfacedwelling culicine mosquito larvae and the bottom-inhabiting isopod, asellus aquaticus l., in either shallow or deep water at 20° c. at this temperature n. glauca spends most of the time at the water's surface, so, by changing water depth the accessibility of asellus to the predator was manipulated relative to a consistent culex presence.all n. glauca spent more time submerged in shallow (75 m ... | 1984 | 28310723 |
| geometric optics of the corneal lens of backswimmer, notonecta glauca. | various sets of equations describe the geometric optics of the corneal lens of backswimmer, notonecta glauca. | 1989 | 20555448 |
| geometric optical optimization of the corneal lens of notonecta glauca. | the optimal shape of the corneal lens of the water bug backswimmer (notonecta glauca) and the optimal shape and position of the thin transition layer between the distal and proximal units of its cornea are theoretically determined. using a geometric optical method, first the shape of a geometric interface between the lens units is determined, which eliminates the longitudinal spherical aberration. this interface is investigated for differently formed thick lenses when the medium in contact with ... | 1989 | 2615380 |
| high molecular weight microtubule-associated proteins within testes of hemipteran insects. | results presented here indicate that the high molecular weight microtubule-associated proteins isolated from the ovaries of the hemipterans, oncopeltus fasciatus and notonecta glauca, while absent from nervous tissue, are present in the testes of the respective species. here they are seen to be located to extensive microtubule aggregates within the cells surrounding the sperm, but not obviously to the sperm themselves. | 1992 | 1628319 |
| on the possible function of the proximal lens unit of notonecta glauca. | the water bug notonecta glauca has doublet lenses corrected for spherical aberration. the proximal lens unit constitutes a refractive index transition between the distal lens unit and the crystalline cone. it inevitably reduces the reflectivity of the eye. such correction for spherical aberration, however, could also be simply achieved by means of an aplanatic singlet lens. therefore it seems possible to suppose that the proximal lens unit might produce both decreased reflection and increased tr ... | 1993 | 8249323 |
| pupil adjustments in the eye of the common backswimmer | the pupil mechanism in the acone apposition eye of the semi-aquatic common backswimmer notonecta glauca (hemiptera) was investigated with infrared reflectometry of the pseudopupil. this method allows non-invasive continuous measurements of pupil responses in the living animal. the dynamic range of the pupil sensitivity is about 7 log units during daytime and 6 log units at night. during the day, the sensitivity range of the pupil covers the normal daylight intensities in the animal's habitat, ju ... | 1995 | 9317362 |
| poly(a) mrna is attached to insect ovarian microtubules in vivo in a nucleotide-sensitive manner. | in ovarioles of hemipteran insects, rna passes from anteriorly positioned nurse cells to the chain of developing oocytes via extended nutritive tubes. these intercellular connections may reach several millimeters in length. each nutritive tube is comprised of many thousands of parallel microtubules. we have extracted microtubule bundles from isolated nutritive tubes of notonecta glauca and, using hybridization techniques, provide evidence of poly(a) mrna attachment to microtubules in vivo. we al ... | 1999 | 10379840 |
| the c-banded karyotypes of the four british species of notonecta l. (heteroptera: notonectidae). | chromosome preparations were made from mid-gut and ovarian cells of adult notonecta glauca l., n. obliqua thunberg, n. maculata f. and n. viridis delcourt, using the acetic acid dissociation, air-drying method (crozier 1968) with giemsa staining. c-banding was obtained by treatment with barium hydroxide and salt-sodium citrate (2xssc). the karyotypes of the first three species are very similar, with 11 pairs of autosomes plus xy sex chromosomes (plus sometimes a small 12th autosome pair in n. gl ... | 2004 | 15061791 |
| use of carbon and nitrogen stable isotope ratios to assess the effects of environmental contaminants on aquatic food webs. | in this study, the value of carbon (delta13c) and nitrogen (delta15n) stable isotope ratios were determined in nymphs of a top-predator, the common backswimmer (notonecta glauca l.), collected in 18 m3 outdoor freshwater mesocosms used to assess the fate and ecotoxicological effects of a diphenyl ether herbicide, fomesafen, applied alone or in combination with agral 90 (mixture of polyethoxylated derivatives of nonylphenol). both treatments had a negative effect on delta13c values which may refl ... | 2006 | 16199117 |
| superhydrophobic surfaces of the water bug notonecta glauca: a model for friction reduction and air retention. | superhydrophobic surfaces of plants and animals are of great interest for biomimetic applications. whereas the self-cleaning properties of superhydrophobic surfaces have been extensively investigated, their ability to retain an air film while submerged under water has not, in the past, received much attention. nevertheless, air retaining surfaces are of great economic and ecological interest because an air film can reduce friction of solid bodies sliding through the water. this opens perspective ... | 2011 | 21977425 |
| modality matters for the expression of inducible defenses: introducing a concept of predator modality. | inducible defenses are a common and widespread form of phenotypic plasticity. a fundamental factor driving their evolution is an unpredictable and heterogeneous predation pressure. this heterogeneity is often used synonymously to quantitative changes in predation risk, depending on the abundance and impact of predators. however, differences in 'modality', that is, the qualitative aspect of natural selection caused by predators, can also cause heterogeneity. for instance, predators of the small p ... | 2013 | 24245584 |
| large variation among photoreceptors as the basis of visual flexibility in the common backswimmer. | the common backswimmer, notonecta glauca, uses vision by day and night for functions such as underwater prey animal capture and flight in search of new habitats. although previous studies have identified some of the physiological mechanisms facilitating such flexibility in the animal's vision, neither the biophysics of notonecta photoreceptors nor possible cellular adaptations are known. here, we studied notonecta photoreceptors using patch-clamp and intracellular recording methods. photorecepto ... | 2014 | 25274359 |
| predator-induced defences in daphnia longicephala: location of kairomone receptors and timeline of sensitive phases to trait formation. | the freshwater crustacean daphnia adapts to changing predation risks by forming inducible defences. these are only formed when they are advantageous, saving associated costs when the defence is superfluous. however, in order to be effective, the time lag between the onset of predation and the defence formation has to be short. daphnia longicephala develop huge protective crests upon exposure to chemical cues (kairomones) from its predator the heteropteran backswimmer notonecta glauca. to analyse ... | 2015 | 26400980 |
| dry under water: comparative morphology and functional aspects of air-retaining insect surfaces. | superhydrophobic surfaces prevent certain body parts of semiaquatic and aquatic insects from getting wet while submerged in water. the air layer on these surfaces can serve the insects as a physical gill. using scanning electron microscopy, we investigated the morphology of air-retaining surfaces in five insect species with different levels of adaptation to aquatic habitats. we found surfaces with either large and sparse hairs (setae), small and dense hairs (microtrichia), or hierarchically stru ... | 2011 | 21290417 |
| nepomorpha, gerromorpha and leptopodomorpha (hemiptera: heteroptera) of the tuscan archipelago (italy). | this paper provides the first checklists for nepomorpha (12 spp.), gerromorpha (10 spp.) and leptopodomopha (5 spp.) of the tuscan archipelago; summarizing and updating the knowledge for this area. the presence of the family micronec- tidae is recorded for the first time in the archipelago, as well as six species: nepomorpha - micronecta scholtzi (fieber, 1860), sigara selecta (fieber, 1848), s. stagnalis (leach, 1817), s. lateralis (leach, 1817); gerromorpha - gerris asper (fieber, 1860); lepto ... | 2013 | 26312344 |
| phenotypic plasticity of daphnia pulex in the presence of invertebrate predators: morphological and life history responses. | morphological and life history traits of two clones of the cladoceran daphnia pulex were measured in the presence and absence of size-selective insect predators, the midge larva chaoborus flavicans, which preys on small daphnia, and the water bug notonecta glauca, which preys on large daphnia. the aim was to detect predator-induced phenotypic changes, particularly the effect of simultaneous exposure to both types of predators. other work has shown that in the presence of chaoborus americanus, da ... | 1992 | 28312604 |
| non-interactive multiple predator effects on tadpole survival. | interactions among and within three species of predators were estimated in terms of their effects on prey survival using short-term predation experiments. the prey were tadpoles (rana temporaria), and the predators were dragonfly larvae (anax imperator), newts (triturus alpestris), and backswimmers (notonecta glauca). mortality rate per predator imposed by triturus and notonecta did not decline with predator density, whereas the predation rate of anax was strongly reduced when the number of pred ... | 2012 | 22159918 |
| the organization of the lamina ganglionaris of the hemipteran insects, notonecta glauca, corixa punctata and gerris lacustris. | neuronal elements, i.e. first and second order neurons, of the first optic ganglion of three waterbugs, n. glauca, c. punctata and g. lacustris, are analyzed on the basis of light- and electron microscopy. eight retinula cell axons, leaving each ommatidium, disperse to different cartridges as they enter the laminar outer plexiform layer. such a pattern of divergence is one of the conditions for neuronal superposition; it is observed for all three species of waterbugs. the manner in which the rec ... | 1979 | 455401 |
| reflection-polarization patterns at flat water surfaces and their relevance for insect polarization vision | it has recently been shown that horizontally polarized ultraviolet light reflected from the surface of water is the main optical cue for habitat finding by insects living in, on, or near water. what are the polarization properties that make the skylight reflected by water attractive to flying water insects in nature? in this paper, as an approach to this problem, the patterns of the degree and direction of polarization of skylight visible over a flat water surface are computed for unpolarized li ... | 1995 | 9441813 |
| biophysical properties of photoreceptors in corixa punctata facilitate diurnal life-style. | measurement of evolutionary adaptations of a visual system to its visual and operational ecology requires comparison of visual function in different species with similar morphologies and visual ecologies, occupying the same habitats but displaying differences in visually-guided behavior. the goal here was to document the biophysical properties of photoreceptors in the lesser water boatman corixa punctata, which shares many features with the previously studied aquatic predator water boatman backs ... | 2015 | 25913025 |
| uptake and depuration of pharmaceuticals in aquatic invertebrates. | the uptake and depuration of a range of pharmaceuticals in the freshwater shrimp (gammarus pulex) and the water boatman (notonecta glauca) was studied. for one compound, studies were also done using the freshwater snail planobarius corneus. in g. pulex, bioconcentration factors (bcfs) ranged from 4.6 to 185,900 and increased in the order moclobemide < 5-fluoruracil < carbamazepine < diazepam < carvedilol < fluoxetine. in n. glauca bcfs ranged from 0.1 to 1.6 and increased in the order 5-fluorour ... | 2012 | 22226124 |
| a staufen-like rna-binding protein in translocation channels linking nurse cells to oocytes in notonecta shows nucleotide-dependent attachment to microtubules. | in drosophila melanogaster the staufen gene encodes an rna-binding protein that is essential for the correct localization of certain nurse cell-derived transcripts in oocytes. although the mechanism underlying mrna localization is unknown, mrna-staufen complexes have been shown to move in a microtubule-dependent manner, and it has been suggested that staufen associates with a motor protein which generates the movement. we have investigated this possibility using notonecta glauca in which nurse c ... | 1999 | 10444389 |
| effect of vertebrate and invertebrate kairomones on the life history of daphnia magna straus (crustacea: branchiopoda). | the history of selection of daphnia magna populations living in north african temporary ponds may differ from populations inhabiting permanent ponds. laboratory experiments were conducted to examine the effect of fish gambusia holbrooki and invertebrate notonecta glauca kairomones on the life history traits of the freshwater cladocera daphnia magna straus. with fish kairomones, daphnia reproduced early and had a significantly smaller size at first reproduction (sfr) and a smaller size of neonate ... | 2010 | 21146140 |
| importance of prey and predator feeding behaviors for trophic transfer and secondary poisoning. | hydrophobic contaminants accumulate within aquatic sediments, hence pelagic predators may have limited direct contact with such compounds, but can be exposed via their benthic prey (i.e., via dietary exposure). here we examine the importance of feeding behaviors of both prey (sediment ingesters or noningesters) and predators (piercers or engulfers) in determining the extent of dietary exposure and toxic effects. a freshwater macroinvertebrate system was used, consisting of two predator species, ... | 2009 | 19921914 |
| does freeze-substitution reveal the hydrophobic nature of interprotofilament bonding in microtubules? | the massive system of microtubules in the ovarioles of notonecta glauca has been prepared for electron microscopy by means of freeze-substitution. with this technique the protofilaments comprising the microtubule walls can be observed in positive image, indicating that the procedure provides a valuable method for observing microtubule substructure. surprisingly though, the cryoprotectants, which are an integral part of the method, caused a rearrangement of the microtubules from their usual patte ... | 1985 | 4042167 |
| zonation of the optical environment and zonation in the rhabdom structure within the eye of the backswimmer, notonecta glauca. | in the compound eye of notonecta glauca, the backswimmer, there is a small ventral region in which the rhabdoms differ in structure from those in the other parts of the eye. here, among other unusual features, there is a special orientation of the microvilli of the central rhabdomeres, i.e., in most of the median eye region that has been examined, the microvilli of the two central rhabdomeres are aligned with one another, at an acute angle to the transverse axis of the body. in the small ventral ... | 1983 | 6883440 |
| [energy turnover of water bugs]. | 1. this study concerns the energy turnover of the water bug species naucoris cimicoides (naucoridae), notonecta glauca (notonectidae) and ranatra linearis (nepidae). the results refer to the conditions in the reed belt of the lake "neusiedler see" in eastern austria. 2. population density was, using various methods, quantitatively determined for each test species. in summer the values were as follows: naucoris 8, notonecta 2 and ranatra 0.5 individuals per m2 in the closed reed belt. abundance i ... | 1976 | 28308654 |
| | from photographic recordings the distribution of individuals of the back swimmer notonecta glauca in natural and artificial populations of various densities and sex ratios were analysed. the distances between each animal and its nearest neighbour were measured and compared with calculated data from population models with known dispersion patterns. it was shown that each back swimmer population with a higher density than 6 animals per m2 follows a random distribution. varying the ratio of males t ... | 1975 | 28308704 |
| chloride cells of larval notonecta glauca and naucoris cimicoides (hemiptera, hydrocorisae). fine structure and cell counts at different salinities. | the chloride cells of the larval waterbugs, notonecta glauca l. and naucoris cimicoides l., ultrastructurally resemble the caviform chloride cells of other aquatic insects as well as those of teleost fish. the predominant features are abundant mitochondria, basolateral plasma membrane infoldings and an apical cavity possessing numerous microvilli. after histochemical precipitation of chloride, dense deposits of silver chloride are present in the apical region. the cuticular area overlying the ch ... | 1975 | 1120337 |
| experiments on the efficiency of the "physical gill" (hydrous piceus l., naucoris cimicoides l., and notonecta glauca l.). | | 1951 | 14902483 |
| experiments on the respiration of some aquatic insects (hydrous piceus l., naucoris cimicoides l. and notonecta glauca l.). | | 1950 | 14829311 |