bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interspecific competition between Eupelmus vuilleti and Dinarmus basalis, two solitary ectoparasitoids of Bruchidae larvae and pupae
Authors: van Alebeek F. A. N. , Rojas‐Rousse D. , Leveque L. 
Published: April 2011

AbstractCoexistence of two solitary ectoparasitoids of bruchids may be the result of counter‐balanced competition. Some strategies in interspecific competition at the extrinsic level of female behaviour are identified. Dinarmus basalis (Rondani) (Hymenoptera; Pteromalidae) has adapted an evasion strategy to avoid competition. Females of D. basalis show interspecific discrimination against hosts parasitized by Eupelmus vuilleti Crawford (Hymenoptera; Eupelmidae) and lay fewer eggs in the presence of females or hosts parasitized by the latter. Eupelmus vuilleti has adapted an aggressive strategy. In contrast to D. basalis, E. vuilleti concentrates her ovipositions on hosts already parasitized by D. basalis. Females of E. vuilleti preferably use oviposition holes made by other parasitoids, and are able to kill eggs and larvae of D. basalis selectively by thrusts of their ovipositor (ovicide and larvicide). Furthermore, E. vuilleti can act as a facultative hyperparasitoid on older larvae of D. basalis. The number of E. vuilleti offspring is not affected by the presence of D. basalis on a host. Our study does not provide insight in the process of larval competition.RésuméCompétition interspécifique entre Eupelmus vuilleti et Dinarmus basalis, deux ectoparasitoïdes solitaires des stades larvaires et nymphaux de BruchidaeLa coexistence de deux ectoparasitoïdes solitaires de Bruchidés peut resulter de compétition contrebalancée (Zwölfer, 1971). Quelques stratégies en situation de compétition interspécifique ont été identifiées au niveau (extrinsèque) du comportement de femelles. Dinarmus basalis (Rondani) (Hymenoptera; Pteromalidae) a développé une stratégie d'évitement de la compétition. Les femelles de D. basalis montrent une capacité à reconnaître les hôtes parasités par Eupelmus vuilleti Crawford (Hymenoptera; Eupelmidae), et pondent moins d'œufs en présence des femelles d'E. vuilleti ou des hôtes parsités par cette espèce. Eupelmus vuilleti a adapté une stratégie aggressive. Au contraire de D. basalis, E. vuilleti concentre sa ponte sur les hôtes déjà parasités par D. basalis. Les femelles d'E. vuilleti utilisent préférentiellement les orifices de ponte pratiqués par les autres parasitoïdes. Elles sont alors capables de tuer grace à l'ovipositeur les œufs et les larves de D. basalis (ovicide et larvicide). De plus, E. vuilleti est capable d'hyperparasiter les larves de dernier stade de D. basalis. Le nombre de descendants d'E. vuilleti n'est pas affecté par la présence de D. basalis sur un hôte. Notre étude expérimentale n'a pas permis l'étude du mécanisme de la compétition larvaire.
Control of diapause and supercooling by the retrocerebral complex in Pyrrhocoris apterus
Authors: Hodkova Magdalena , Hodek Ivo 
Published: April 2011

AbstractEffects of external (photoperiod, temperature) and internal (retrocerebral complex, diapause condition) factors on supercooling were studied in Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae) adults. An increase in supercooling capacity is associated with the induction of diapause by short‐day photoperiod or cardiacallatectomy of long‐day non‐diapause insects in spite of a high temperature of 26 °C. The induction of diapause is a prerequisite for a further increase in supercooling capacity by cold acclimation.Post‐diapause adults show low values of the supercooling point also in late January or early February, although their developmental potential is fully restored. Evidently the ability to supercool associated with diapause induction is maintained by a low ambient temperature in spite of diapause termination. The supercooling point increases rapidly when these adults are transferred to a high temperature of 26 °C and cold re‐acclimation is then no longer possible. The inhibition of morphogenesis (maturation of gonads) by cardiacallatectomy does not prevent the supercooling point from increasing in post‐diapause adults at the high temperature.
Trichogramma egg parasitism of Helicoverpa armigera on short‐duration pigeonpea intercultured with sorghum
Authors: Duffield S. J. 
Published: April 2011

AbstractThe levels of egg parasitism by Trichogramma spp. (Hymenoptera: Trichogrammatidae) on populations of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) were recorded on sorghum (Sorghum bicolor L.) and on two flushes of flowers on short‐duration pigeonpea (Cajanus cajan L.). H. armigera oviposition was concentrated on the early flowering stage of sorghum and the flowering and early podding stages of both flushes of pigeonpea. Parasitism on sorghum increased rapidly as egg density increased and reached a peak of 74.6%. Parasitism on pigeonpea was concentrated on H. armigera eggs laid on the first flush of pigeonpea flowers with a maximum of 69.2%. These high levels of parasitism on pigeonpea coincided with the period of parasite activity on sorghum. The levels of parasitism then declined rapidly and only very low levels were detected on a second flush of flowers. This rapid decline resulted in the overall egg mortality caused by Trichogramma on pigeonpea to be low, with a maximum of 7.8% caused by parasitism, compared to 34.4% on sorghum. The pattern of parasitism suggests that a transfer of parasites occurred from sorghum to pigeonpea. The rapid decline of parasitism on the pigeonpea indicates that parasite populations cannot be sustained on pigeonpea once the influx from sorghum stops. The results are discussed in terms of a possible method of encouraging the transfer of parasites from sorghum to short‐duration pigeonpea by producing a more continuous cropping environment.
Responses of the sheep blowfly Lucilia sericata to carrion odour and carbon dioxide
Authors: Wall R. , Warnes M.L. 
Published: April 2011

AbstractThe nature of the responses of the sheep blowfly Lucilia sericata Meigen (Diptera: Calliphoridae) to carrion odours and carbon dioxide were examined in a windtunnel in the laboratory and the attractiveness of carrion‐bait was examined in the field. In the wind tunnel, gravid 9‐day‐old females increased both the number and duration of their flights, in response to carrion odours. In addition, linear velocity was reduced and the sinuosity of flight increased in the presence of these odours. With 3‐day‐old females, the response to carrrion odour depended on previous exposure to proteinaceous material. Protein deprived females showed kinetic responses to carrionodour which were similar to those of gravid females. No such changes were observed in protein‐fed females. No responses to CO2 were observed. In the field, the importance of olfactory cues in bait location was demonstrated by the absence of L. sericata from sticky targets lacking an odour bait. Increased bait concentration did not affect the age, sex ratio or ratio of L. sericata to other Lucilia spp. caught, but did increase the numbers caught. Analysis of the reproductive status of females caught, indicated that a greater number of gravid females were caught than expected, while a lower number of females in the final stages of vitellogenesis were caught than expected. The results show that the responses of L. sericata to odours are complex, and are dependent on both exogenous and endogenous stimuli, the latter including the stage of ovarian development.
Effect of trap background on cabbage root fly landing and capture
Authors: Finch S. 
Published: April 2011

AbstractPieces (600 mm × 800 mm) of coloured board, plastic sheeting and woven materials, placed beneath water traps prevented the traps from becoming soiled during rainy weather. Such backgrounds are not recommended for use with traps for monitoring populations of the cabbage root fly (Delia radicum L. ‐ Diptera:Anthomyiidae), however, as, instead of increasing trap catch they reduced the numbers of female flies caught by 70%–90%. The main effect was that the visually attractive stimuli from the introduced backgrounds competed with those from the trap. A white background competed with a white trap on a direct fly/unit area basis. Green backgrounds stimulated males to land and the vertical stems of both real and artificial grass induced trivial flights that resulted in greater numbers of males entering traps resting on short grass. Most females were caught over bare soil. To minimize the variation in catch between traps used for monitoring cabbage root fly populations, the background beneath each trap should be similar. For maximum capture, the background should be of grass for male flies and of bare soil for female flies. Care is required if data from traps within mulched crops are used to make pest control decisions, as they will underestimate considerably the numbers of flies in such crops.
Spectral reflectance from a broccoli crop with vegetation or soil as background: influence on immigration by Brevicoryne brassicae and Myzus persicae
Authors: Costello Michael J. 
Published: April 2011

AbstractLight reflectance in five wavebands of the spectrum was measured from broccoli (Brassicae oleracea var. botrytis [L].) interplanted with leguminous cover crops (cover crop background) or broccoli grown as monoculture (bare soil background), and fertilized with compost or synthetic fertilizer. Alate Brevicoryne brassicae (L.) and Myzus persicae (Sulzer) (Homoptera: Aphididae) were monitored in yellow pan water traps and on broccoli leaves. Reflectance intensity was higher with a background of bare soil at all wavebands except blue (400–455 nm) in the early‐season. Intensity decreased as broccoli canopy cover increased at all wavebands except blue and green (515–550 nm), declining‐most dramatically in the yellow (550–590 nm). Highest late‐season intensities were in plots with bare soil background and fertilized with compost (those stressed for nitrogen). Few differences in spectral composition, expressed for each waveband as a percentage of total intensity, were recorded. Numbers of alatae were lowest in cover crop background plots in the early season, reached equivalency with bare soil background by mid‐season, and showed highest positive correlations with intensity in the yellow (550–590 nm). Results correspond to laboratory findings that aphids are attracted to higher intensity light, especially in the yellow waveband, and support a phototactic explanation for aphid orientation in the field.
Within‐patch foraging behaviour of the aphid parasitoid Aphidius funebris: plant architecture, host behaviour, and individual variation
Authors: Weisser Wolfgang W. 
Published: April 2011

AbstractThe influence of plant architecture, host colony size, and host colony structure on the foraging behaviour of the aphid parasitoid Aphidius funebris Mackauer (Hymenoptera: Aphidiidae) was investigated using a factorial experimental design. The factorial design involved releasing individual parasitoid females in aphid colonies consisting of either 10 or 20 individuals of Uroleucon jaceae L. (Homoptera: Aphididae) of either only larval instar L3 or a mixture of host instars, both on unmanipulated plants and on plants that had all leaves adjacent to the colony removed. Interactions between the parasitoid and its host were recorded until the parasitoid had left the plant. The time females spent on the host plant and the number of eggs laid varied greatly among females. Host colony size significantly affected patch residence time and the number of contacts between parasitoids and aphids. Plant architecture influenced the time‐budget of the parasitoids which used leaves adjacent to the aphid colony for attacking aphids. Female oviposition rate was higher on unmanipulated plants than on manipulated plants. No further significant treatment effects on patch residence time, the number of contacts, attacks or ovipositions were found. Oviposition success of A. funebris was influenced by instar‐specific host behaviour. Several rules‐of‐thumb proposed by foraging theory did not account for parasitoid patch‐leaving behaviour.
The effects of a phagostimulant and a deterrent on the microstructure of feeding by Manduca sexta caterpillars*
Authors: Bowdan E. 
Published: April 2011

AbstractCaterpillars of the hawkmoth Manduca sexta Johan. (Lepidoptera: Sphingidae) were offered discs of agar containing one of a range of concentrations of sucrose or of quinine, and the microstructure of the resulting feeding behaviour was quantified. As sucrose concentration increased caterpillars ate more by increasing the rate of biting and the lengths of meals. Bite frequency increased, after a latency of seconds to minutes, over the entire range tested (0.005 M to 0.5 M) whereas meal length reached a maximum at 0.1 M. Larvae spent less time feeding on agar containing 1 mM quinine than on quinine‐free agar. This was accomplished by a reduction in the size of meals; numbers of chewing bouts in meals were lower. No other feeding behaviours were affected. In addition there was no orderly relationship between quinine concentration and changes in feeding behaviours. These observations suggested that postingestive effects were important in decreasing feeding.
Mechanical and Impact Properties of Needle Punched Nonwoven Composites
Authors: Lee Sung Ho , Kang Tae Jin 
Published: April 2011

The effect of changes in fiber structure on the mechanical properties of nonwoven composite with different punching densities was studied through the testing of tensile, bending, impact, compression after impact, fatigue, friction/wear and mode-I interlaminar fracture properties. The tensile strength and mode-I interlaminar fracture toughness of nonwoven composite was increased with increasing punching densities due to the increased fiber entanglement. The flexural, impact, fatigue and wear properties were decreased with punching densities due to the damage to fibers during the punching process which resulted in the reduction of fiber length. The impact resistant properties showed its maximum at the punching density of 30 penetrations/cm2. The tensile modulus and the compression strength were determined from the orientation of the reinforcing fibers which was affected with the punching densities. The mechanical properties of nonwoven composite showed rather isotropic properties with increased random distribution of the fibers at high punching densities. In the range of adequate punching densities, the nonwoven composite showed substantially improved mechanical and impact properties compared to the woven laminate composite. The nonwoven composite showed improved properties of flexural and compression strengths as well as mode-I interlaminar fracture toughness.
Effect of Extrusion on Fiber Orientation and Breakage of Aluminar Short Fiber Composites
Authors: Kang C. G. , Kang S. S. 
Published: April 2011

The short fiber reinforced aluminum composite material was fabricated by the stirring method, and extruded at high temperature at various extrusion ratios. The hot extrusion load of volume fraction 15% metal matrix composites and base alloy A17075 has been compared. The fiber length distribution, fiber breakage and fiber orientation are investigated to determine the fiber behaviour before and after hot extrusion. The tensile strength of the hot extrusion billet was experimentally determined for different extrusion ratios, and compared with theoretically calculated strength.
The Effective Thermal Conductivities of Composites with 2-D Arrays of Circular and Square Cylinders
Authors: Lu Shih-Yuan 
Published: April 2011

A boundary collocation scheme suitable for calculation of the effective thermal conductivity of 2-dimensional periodic arrays is developed. Investigated 2-dimensional arrays include the square arrays of infinitely long circular and square cylinders and hexagonal arrays of infinitely long circular cylinders. The effective thermal conductivity is studied subject to variation in two system parameters: the inclusion volume fraction, f, and the conductivity ratio of the inclusion to the matrix, k2/ k1 (= σ). The parameter domain investigated is complete, ranging from 0 to the close packing in inclusion volume fractions and from 0 to ∞ in conductivity ratios. The effectiveness of different configurations in improving (if k2/ k1 > 1) or reducing (if k2/ k1 < 1) the effective thermal conductivity of the composite is studied with the three arrays. With enhancing (insulating) inclusions, the square array of infinitely long square cylinders is found to be the most efficient configuration in improving (reducing) the effective thermal conductivity of the composite among the three arrays for f below a first crossing volume fraction, f c1, around 0.56 For f greater than fc1, the square array of infinitely long circular cylinders becomes the most effective configuration. Contour plots of the relative effective thermal conductivity, k eff/ k1, in the f - log (σ) space are obtained, which can be used to infer values of σ from measurement of k eff/ k1 at some given f.
Thermally-Induced Shapes of Unsymmetric Laminates
Authors: Peeters L. J. B. , Powell P. C. , Warnet L. 
Published: April 2011

Models to describe the shapes of unsymmetric laminates produced with a flat mould have been already developed by several researchers. These models are reviewed and on some points theory is extended. The experimental work done so far to confirm the developed theoretical models is rather limited. This especially applies for angle-ply laminates, on which no experimental work has been reported yet. This paper presents new experimental work that has been conducted both on cross-ply and angle-ply laminates over a wide range of laminate dimensions. The experiments show that the influence of the side length on the curvature is very well predicted both for cross-ply and angle-ply laminates, also the bifurcation point behaviour is clearly observed. Possible causes of differences between theory and experiment are outlined. The theoretical predictions are especially sensitive to the transverse thermal expansion coefficient of the individual layers.
Can the Compressive Response of Fiber-Reinforced Composites be Modelled by Means of Layered Arrays?
Authors: Weitsman Y. Jack , Chung I. 
Published: April 2011

The validity of some basic premises employed in modelling of the compressive response of fiber-reinforced composites is examined in the present article. It is shown that the deformation fields associated with the compression of layered media yield inadmissible results when applied to hexagonal and square arrays of circular fibers. Consequently, predictions of compressive strength, which derive from the prevailing representations of layered geometry may not apply to realistic circumstances.
Modelling Lamina Longitudinal Compression Strength of Carbon Fibre Composite Laminates
Authors: De Morais A. Balacó 
Published: April 2011

The determination of the lamina longitudinal compression strength remains an unsolved problem. Non-valid failure modes are commonly observed in compression tests of unidirectional specimens. Micromechanical modelling has also proven to be a difficult task. It is believed that failure is initiated by fibre microbuckling, and that non-linear matrix behaviour and fibre misalignments play a major role. The main obstacles are thus the non-linear nature of the phenomenon and the scarcity of material data. Here 2D and 3D Finite Element models are presented. The Finite Element Method can easily deal with non-linear problems. The models are computationally inexpensive and can be easily implemented on a commercial code. A sensitivity analysis was performed using realistic input data. The model predictions are well above the unreliable experimental values so far available. Further, the most important variables were found to be the fibre misalignment angle and the matrix yield stress. The fibre spatial arrangement also affects the predicted results. Reliable strength data are essential to validate the models here presented. Nevertheless this study shows that accurate predictions should be expected to prove difficult, mainly because of the complex matrix stress-strain behaviour and the statistical nature of fibre misalignments and spatial distribution. In addition, the important role of the matrix in model results raises the question of the existence of a unique lamina longitudinal compression strength (LLCS). Lay-up dependent transverse and shear stresses acting on the load aligned laminae should accordingly yield lay-up dependent LLCSs, which is confirmed by experimental data.
Bearing Failure of Bolted Composite Joints. Part II: Model and Verification
Authors: Hung Chang-Li , Chang Fu-Kuo 
Published: April 2011

An investigation was performed to study the bearing failure and response of a mechanically fastened laminated composite joint. The experimental work of the study was presented in Part I, and this paper summarizes the analytical work. An accumulative damage model based on the damage mechanisms observed from the experimental study was developed to simulate the bearing failure in the laminated composite joints. The model consists of two parts: damage prediction and constitutive modeling. Damage accumulation criteria by modifying Hashin criteria were proposed to predict the mode and extent of bearing damage as a function of the stress state, and the relationships between material properties and bearing damage were established based on failure mechanisms. A nonlinear finite element analysis based on the model was developed. Data obtained from this study and existing literature were used to validate the model. Overall, the predictions agreed with the data very well.
Spin Burst Test of Carbon-Carbon Composite Disk
Authors: Kogo Yasuo , Hatta Hiroshi , Kawada Hiroyuki , Shigemura Takashi , Ohnabe Hisaichi , Mizutani Tomoaki , Tomioka Fumiki 
Published: April 2011

In order to establish design criteria for a turbine disk made of Carbon-Carbon (C/C) composites, spin burst tests were performed on quasi-isotropically laminated C/C composite disks. Un-notched and notched flat disks were prepared to evaluate the effect of stress concentration on fracture behavior. Strain measurements during rotation tests revealed that deformation of the C/C composite disks with or without notches was in agreement with analytical or finite element calculations in the elastic region, which suggests that the test fixtures of the spin tester have a negligible effect on the deformation of C/C composite disks. In the spin burst tests, the un-notched C/C composite disks burst at an average rotation speed of 25000 r.p.m. with a peripheral velocity of 393 m/s. A comparison between the mean hoop stress averaged over the radius and the tensile strength of smooth specimen suggests that the burst of the un-notched C/C composite disks obey the mean stress criterion. On the other hand, the fracture toughness criterion was shown to be applied for the notched specimen. The difference in the fracture criterion between the un-notched and the notched C/C composite disks is believed to correspond to that between the double edge notched specimens and specimens with a hole in the static tensile tests, (which was explained by the difference in the magnitude of the damaged zone where the stress concentrations would be relaxed).