The efficiency of a new lightweight suction sampler for sampling aphids and their predators in arable land

A petrol driven machine, normally used to collect leaf litter, was modified to be used as a suction sampler for polyphagous predators in cereals and grassy habitats and aphids in cereals. Recovery efficiency of Araneae, Carabidae and Staphylinidae did not differ significantly between winter sampling from Agrostis stolonifera, Dactylis glomerata, Festuca rubra, Holcus lanatus or Lolium perenne although the structure of these grasses was very different. Summer sampling of aphids and their predators in winter wheat showed that the new sampler captured significantly more target organisms per unit area than did a traditional suction sampler. The machine was also lighter, cheaper and much easier to use than a traditional machine.     

A portable suction sampler for rock epibiota

Summary 1. A fully portable suction sampler which can be operated by one diver is described.2. Rock epibiota is removed by a scraper tube which leads, through a collecting chamber, to an air-lift suction chamber and tube. The sample is held in a net bag before reaching the suction chamber. Air is supplied by a cylinder incorporated into the unit.3. The sampler removes all epilithic biota except for the parts of encrusting species cemented to the rock.4. The sampler can also be used for sand fauna.

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Ein tragbarer Saugsammler für epibiotisch auf Felsen lebende Organismen

Kurzfassung Eine Saugpumpe für bestandskundliche Untersuchungen, die von einem Taucher getragen und bedient werden kann, wird beschrieben. Sie besteht aus einer Sammelkammer, in die zwischen dem Schabrohr und der Luftsaugkammer ein Sammelnetz eingefügt wird. Die Saugkammer ist durch ein Reduktionsventil mit einem Preßluftzylinder verbunden. Mit Hilfe dieses Sammelgeräts lassen sich fast alle Organismen von Felsoberflächen entfernen. Es kann überdies auch zur quantitativen Erfassung der Fauna auf Sandböden eingesetzt werden. Vor- und Nachteile dieses Gerätes werden diskutiert.

     

The effects of long-term nitrogen loading on grassland insect communities

Just as long-term nitrogen loading of grasslands decreases plant species richness and increases plant biomass, we have found that nitrogen loading decreases insect species richness and increases insect abundances. We sampled 54 plots that had been maintained at various rates of nitrogen addition for 14 years. Total insect species richness and effective insect diversity, as well as herbivore and predator species richness, were significantly, negatively related to the rate of nitrogen addition. However, there was variation in trophic responses to nitrogen. Detritivore species richness increased as nitrogen addition increased, and parasitoids showed no response. Insect abundances, measured as the number of insects and insect biovolume (an estimate of biomass), were significantly, positively related to the rate of nitrogen addition, as were the abundances of herbivores and detritivores. Parasitoid abundance was negatively related to the rate of nitrogen addition. Changes in the insect community were correlated with changes in the plant community. As rates of nitrogen addition increased, plant species richness decreased, plant productivity and plant tissue nitrogen increased, and plant composition shifted from C₄ to C₃ grass species. Along this gradient, total insect species richness and effective insect diversity were most strongly, positively correlated with plant species richness. Insect biovolume was negatively correlated with plant species richness. Responses of individual herbivores varied along the nitrogen gradient, but numbers of 13 of the 18 most abundant herbivores were positively correlated with their host plant biomass. Although insect communities did not respond as strongly as plant communities, insect species richness, abundance, and composition were impacted by nitrogen addition. This study demonstrates that long-term nitrogen loading affects the entire food chain, simplifying both plant and insect communities. Received: 18 May 1999 / Accepted: 5 January 2000     

Local grassland restoration affects insect communities

1. It is hypothesised that ecological restoration in grasslands can induce an alternative stable state shift in vegetation. The change in vegetation influences insect community assemblages and allows for greater functional redundancy in pollination and refuge for native insect species. 2. Insect community assemblages at eight coastal California grassland sites were evaluated. Half of these sites had undergone restoration through active revegetation of native grassland flora and half were non‐restored. Insects were collected from Lupinus bicolor (Fabaceae) within 2 × 2‐m² plots in spring 2017. Lupinus bicolor is a common native species that is used in California restoration projects, and home and state landscaping projects. 3. Ordination demonstrated that insect community assemblages were different between restored and non‐restored sites. These differences were seen in insect functional groups as well as taxa‐specific differences and were found to be driven by environmental characteristics such as non‐native forb cover. 4. Functional redundancy of herbivores decreased at restored sites, while pollinators became more redundant compared with non‐restored sites. The assemblages of the common species found at restoration sites contained more native insects than those found at non‐restored sites, including species such as Bombus vosnesenskii. 5. Local grassland restoration has the potential to induce an alternative stable state change and affect insect community assemblages. Additionally, it was found that grassland restoration can be a potential conservation tool to provide refugia for bumblebees (Bombus), but additional studies are required to fully understand its broader applicability.     

The Cervex: an ectocervical brush sampler

The performance of a new ectocervical brush sampler--the Cervex--was compared with the Ayre spatula in 280 paired cervical smears. The Cervex smears were superior in quality of spread, transformation zone sampling in all degrees of cervical patency and in detection of histologically proven epithelial abnormalities, with a false negative rate of 10.9% compared with 20% for the Ayre. Improvement in predictive value was noted in atrophic samples, with increased cellularity and transformation zone representation. Difficulty has been encountered in obtaining adequate samples from the older woman and from those with iatrogenic scarring of the cervix. Although two-sampler techniques may be used, submission of high quality pan-cervical material from a single sampler onto one slide is economically and organizationally attractive. The Cervex seems capable of producing such samples and deserves further evaluation for routine screening.     

A new inexpensive suction apparatus for sampling arthropods in grassland

Abstract.

• 1 We describe a new technique for sampling arthropods from grassland and other vegetation, using a modified petrol-driven suction apparatus called a‘Blow & Vac’.
• 2 The new apparatus was tested by comparing its efficiency in extracting arthropods from vegetation with that of a conventional Dietrick, or‘D-Vac’, suction sampler.
• 3 Unimpeded air velocity inside the suction tube was approximately 4 times that of the D-Vac.
• 4 In field trials on semi-natural grasslands, the Blow & Vac caught more individuals of most spider and certain beetle species compared to the D-Vac and approximately equal numbers of Auchenorrhyncha.
• 5 We conclude that the‘Blow & Vac’has considerable potential for sampling arthropod populations. Its low cost and weight make it a suitable alternative to the conventional D-Vac apparatus.

     

Large herbivores facilitate an insect herbivore by modifying plant community composition in a temperate grassland

Large herbivores often co‐occur and share plant resources with herbivorous insects in grassland ecosystems; yet, how they interact with each other remains poorly understood. We conducted a series of field experiments to investigate whether and how large domestic herbivores (sheep; Ovis aries) may affect the abundance of a common herbivorous insect (aphid; Hyalopterus pruni) in a temperate grassland of northeast China. Our exclosure experiment showed that 3 years (2010–2012) of sheep grazing had led to 86% higher aphid abundance compared with ungrazed sites. Mechanistically, this facilitative effect was driven by grazing altering the plant community, rather than by changes in food availability and predator abundance for aphids. Sheep significantly altered plant community by reducing the abundance of unpalatable forbs for the aphids. Our small‐scale forb removal experiment revealed an “associational plant defense” by forbs which protect the grass Phragmites australis from being attacked by the aphids. However, selective grazing on forbs by sheep indirectly disrupted such associational plant defense, making P. australis more susceptible to aphids, consequentially increasing the density of aphids. These findings provide a novel mechanistic explanation for the effects of large herbivores on herbivorous insects by linking selective grazing to plant community composition and the responses of insect populations in grassland ecosystems.     

A self-powered portable insect suction sampler and its use to assess the effects of azinphos methyl and endosulfan on blossom beetle populations on oil seed rape

A new portable insect suction sampler, powered by a small petrol engine, is described. It has been in use for three seasons, and examples given of samples taken from oil-seed rape demonstrate that the suction method is more informative than visual counts or sweep-net sampling for assessing blossom beetle populations.     

The characterization of ferritin in an insect

In mammals, the iron storage protein ferritin is predominantly synthesized on free polysomes and accumulates in the cytosol but some is secreted and circulates in the blood as serum ferritin. In insect tissues, on the other hand, iron-containing holoferritin accumulates in the vacuolar system and can be secreted through the Golgi complex. The midgut can secrete it to the gut lumen and other tissues to the hemolymph.Ferritin was isolated from the midgut and hemolymph of fifth instar larvae of Calpodes ethlius, Lepidoptera, Hesperiidae. This holoferritin is stable to heat (75°C) or in the presence of SDS, proteinase K, or urea, has an Mr above 600,000, contains iron and resembles mammalian ferritins in appearance by electron microscopy. Calpodes ferritin is a glycoprotein having N-linked high-mannose oligosaccharides. It is not antigenically related to horse ferritin but is related to that from Manduca sexta, Lepidoptera, Sphingidae. In its native form, Calpodes ferritin has only 3 isoforms with a pI 6.5–7 suggesting a more uniform subunit composition than that in vertebrates. It has two principle subunits, with relative Mrs of 24,000 (L) and 31,000 (G) and two minor subunits with Mrs of 26,000 and 28,000 all of which cross-react with antibody to Manduca ferritin. The 24 kDa subunit is the only one that is not glycosylated. Iron injections induce an increase in the proportion of the 24 kDa subunit. We conclude that Calpodes has ferritin and that it is glycosylated like mammalian serum ferritin.     

Vegetation heterogeneity caused by an ecosystem engineer drives oviposition-site selection of a threatened grassland insect

Soil-disturbing ecosystem engineers play an important role in plant-species diversity in grasslands as they increase vegetation heterogeneity by creating gaps due to burrowing or mound-building activities. However, knowledge of the ecological importance of these microsites for arthropods is still rare. In this study, we analyse the role of ant-nest mounds of the yellow meadow ant (Lasius flavus) for oviposition-site selection of the silver-spotted skipper (Hesperia comma). Ant mounds were searched for H. comma eggs. Microclimatic and vegetation parameters were ascertained at occupied sites and control sites within the matrix vegetation. Furthermore, we analysed the habitat requirements of L. flavus by means of nest counting and the sampling of environmental parameters within different sites. L. flavus occurred most frequently in abandoned and less steep sites with deeper soils. Mean egg occupancy rates of H. comma on ant hills were 32 %, nearly twice as high as at control sites (18 %). In contrast to the surrounding vegetation, nest mounds were characterized by a lower vegetation cover and litter and a higher proportion of bare ground. Furthermore, they had a higher cover of host plants compared with control samples. These microhabitats offered the following essential key factors for the larval development of H. comma: (1) a suitable microclimate due to open vegetation and (2) a high amount of host plants. This study highlights the importance of L. flavus as an ecosystem engineer within central European grasslands because this species increases vegetation heterogeneity.     

Determination of the collection efficiency of a microbial air sampler

The Biotest RCS Plus air sampler was compared with the well-established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub-micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre-select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro-organisms in a variety of locations.     

Structural analysis of an insect lysozyme exhibiting catalytic efficiency at low temperatures

Bombyx mori lysozyme (BmLZ), from the silkworm, is an insect lysozyme. BmLZ has considerable activity at low temperatures and low activation energies compared with those of hen egg white lysozyme (HEWLZ), according to measurements of the temperature dependencies of relative activity (lytic and glycol chitin) and the estimation of activation energies using the Arrhenius equation. Being so active at low temperatures and low activation energies is characteristic of psychrophilic (cold-adapted) enzymes. The three-dimensional structure of BmLZ has been determined by X-ray crystallography at 2.5 A resolution. The core structure of BmLZ is similar to that of c-type lysozymes. However, BmLZ shows some distinct differences in the two exposed loops and the C-terminal region. A detailed comparison of BmLZ and HEWLZ suggests structural rationalizations for the differences in the catalytic efficiency, stability, and mode of activity between these two lysozymes.     

Modelling efficiency in insect olfactory information processing

The olfactory system of insects is essential for the search of food and mates, and weak signals can be detected, amplified and discriminated in a fluctuating environment. The olfactory system also allows for learning and recall of odour memories. Based on anatomical, physiological, and behavioural data from the olfactory system of insects, we have developed a cross-scale dynamical neural network model to simulate the presentation, amplification and discrimination of host plant odours and sex pheromones. In particular, we model how the spatial and temporal patterns of the odour information emerging in the glomeruli of the antennal lobe (AL) rely on the glomerular morphology, the connectivity and the complex dynamics of the AL circuits. We study how weak signals can be amplified, how different odours can be discriminated, based on stochastic (resonance) dynamics and the connectivity of the network. We further investigate the spatial and temporal coding of sex pheromone components and plant volatile compounds, in relation to the glomerular structure, arborizing patterns of the projection neurons (PNs) and timing patterns of the neuronal spiking activity.     

The structure of an insect chymotrypsin

The South American imported fire ant (Solenopsis invicta), without natural enemies in the United States, widely infests the southern United States, causing more than a half billion dollars in health and agriculture-related damage annually in Texas alone. Fire ants are resistant to most insecticides, so control will require a more fundamental understanding of their biochemistry and metabolism leading to the design of selective, ecologically safe insecticides. The 4th instar larvae play a crucial role in the nutrition of the colony by secreting proteinases (especially chymotrypsin) which digest food products for the entire colony. The first structure of an ant proteolytic enzyme, fire ant chymotrypsin, was determined to atomic resolution (1.7 A). A structural comparison of the ant and mammalian structures confirms the "universality" of the serine proteinase motif and reveals a difference at residues 147-148, which are proteolytically removed in the bovine enzyme but are firmly intact in the ant chymotrypsin, suggesting a different activation mechanism for the latter. Likewise, the absence of the covalently attached propeptide domain (1-15) further suggests an uncharacteristic activation mechanism. The presence of Gly189 in the S1 site is an atypical feature of this chymotrypsin and is comparable only to human leukocyte elastase, hornet chymotrypsin and fiddler crab collagenase. Binding studies confirm the chymotrypsin nature of this novel enzyme.     

The Isaacs cell sampler: an alternative to curettage.

The Isaacs cell sampler was tested in 150 women (102 of them postmenopausal) referred for curettage. The results of cytological testing of material obtained with the sampler were compared with histological findings from curettage performed immediately afterwards. Satisfactory aspirates for cytological diagnoses were obtained in 141 patients and satisfactory material for histological diagnosis in 124. In the 102 postmenopausal patients the cytological method yielded 94 satisfactory specimens, while curettage yielded only 76. All the 17 carcinomas were diagnosed cytologically. Of the 12 cases of premalignant change, nine were diagnosed cytologically; two cytologically diagnosed premalignant cases did not, however, yield satisfactory material by curettage. The Isaacs cell sampler is a simple and reliable way of diagnosing malignancies. Further investigation is needed to define the cytological criteria for diagnosing premalignant cases, but as the material is well preserved accuracy should improve with increasing experience. The method should be valuable in screening women having oestrogen substitution therapy.     

中国西北部草地植被降水利用效率的时空格局

植被降水利用效率(PUE)是评价干旱、半干旱地区植被生产力对降水量时空动态响应特征的重要指标。利用光能利用率CASA(Carnegie-Ames-Stanford Approach)模型估算了2001—2010年中国西北七省草地植被净初级生产力(NPP),结合降水量的空间插值数据,分析了近十年草地植被PUE的空间分布、主要植被类型的PUE,及其时空格局的驱动因素。结果表明:(1)2001—2010年西北七省草地植被的平均PUE为0.68 g C m~(-2)mm~(-1)。在温带草地各类型中,PUE的大小顺序为草甸草原灌丛典型草原荒漠草原荒漠,各类型草地PUE之间差异显著;对于高寒草地而言,高寒草原的PUE显著高于高寒草甸;(2)温带草地PUE的空间分布与年降水量的关系呈抛物线形状(R~2=0.65,P0.001),PUE峰值出现在年降水量P=472.9 mm的地区;荒漠地区植被PUE的空间分布与年降水量的关系同样呈抛物线形状(R~2=0.63,P0.001),PUE峰值出现在年降水量P=263.2mm的地区;对于高寒草地而言,年降水量100 mm以下地区植被PUE变异较大,年降水量大于100 mm的地区植被PUE的空间分布随降水量的变化呈抛物线形状(R~2=0.47,P0.001),PUE峰值出现在P=559.2 mm的地区;(3)不同降水量区域,植被PUE的年际波动与气候因子的关系也有较大差别。在年降水量为200—1000 mm的地区,草地PUE的年际波动与年降水量的变化呈正相关;在年降水量高于1050 mm的地区,草地PUE的年际波动与年均温的相关性较强,相关系数最高可达到0.4。     

The nucleolus during epidermal development in an insect

The fifth stadium of Calpodes has two phases of epidermal cell development corresponding to preparation for intermoult and for moult syntheses. Both phases begin with a period of elevated RNA synthesis and the elaboration of a multilobed nucleolus. The apparent number of nucleoli changes from about two to eight and back to two again within the few hours of elevated RNA syntheses. The nucleolar changes are preceded by elevated litres of haemolymph ecdysteroid. During the two periods of activity, alveoli in the matrix of the nucleoli contain particles believed to be ribosomal precursors. The staining properties of these granules differ according to size in a way that suggests a developmental sequence. Mature granules are about 20 nm in diameter and do not stain with bismuth. They are found at the periphery of the nucleolus, in the nucleoplasm, at the approaches to and within the nucleopores. Perichromatin granules, believed to be m-RNA precursor packages, are up to 60 nm in diameter, do stain with bismuth and are found at the periphery of chromatin, in nucleoplasm and distorted at the approaches to the nuclear pores to fit within the central channel. During these periods of heightened activity the nuclear envelope contains microvesicles that may be free or attached to either nuclear or cytoplasmic surfaces. The structure is appropriate for the microvesicular transnuclear envelope movement of molecules such as the ecdysteroid believed to initiate the nuclear changes.