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641.
Host-plant green-leaf volatiles synergize the synthetic sex pheromones of the corn earworm and codling moth (Lepidoptera) 总被引:8,自引:0,他引:8
Douglas M. Light Robert A. Flath Ronald G. Buttery Frank G. Zalom Richard E. Rice Joseph C. Dickens Eric B. Jang 《Chemoecology》1993,4(3-4):145-152
Summary The capture of adult male moths in female sex pheromone traps of two key agricultural pests, the corn earworm (Helicoverpa zea) and the codling moth (Cydia pomonella), is enhanced or synergized by a certain group of host-plant volatiles, the green-leaf volatiles (GLVs). Since female adults of both species call and release their sex pheromones while perched upon the leaves of their host-plants, the volatile constituents from the leaves of a number of host-plants were compared. Sex pheromone traps containing one of the prominent leaf volatiles of certainH. zea hosts, (Z)-3-hexenyl acetate, not only significantly increased the capture ofH. zea males but were preferred over traps baited only with sex pheromone. Similarly, traps baited with synthetic sex pheromome ofC. pomonella plus a blend of GLVs captured significantly more males than traps baited only with sex pheromone. Since male moths are not captured in traps baited only with these GLVs, it appears that these GLVs act as pheromone synergists which increase or enhance the attraction or arrestment of male moths in pheromone traps. 相似文献
642.
643.
Frank Dziock Michael GerischMarian Siegert Isabel HeringMathias Scholz Raffael Ernst 《Agriculture, ecosystems & environment》2011,145(1):85-94
Habitat templet theory predicts that habitat provides the templet on which evolution shapes species’ multiple traits and thus their characteristic life-history strategies. By analysing entire trait communities (multiple species and traits) in this framework we can enhance our understanding of how species composition changes as environmental constraints vary across the landscape. Here, we study multiple traits of floodplain Orthoptera communities under the influence of two different sources of disturbance, land use and seasonal flooding.The application of two recently developed statistical techniques - qualitative RLQ analysis and subsequent fourth-corner permutation tests - revealed two different life history strategies in Orthoptera as a response to ecological disturbances, resulting from land use management and seasonal flooding. Orthoptera species seem to have developed two complementary strategies: (i) the high active dispersal-low reproduction strategy in intensive land use situations and (ii) the high passive dispersal-high reproduction strategy in areas with high flood disturbance. Disturbance gradients act as trait filters allowing only particular trait combinations i.e. species with particular preadaptations to survive, whereas others go regionally extinct. Reproduction and dispersal capacity seem to be inversely associated with the disturbance gradients. Ovariole number, taken as the measure for reproduction, showed significant phylogenetic signal, which could potentially confound this relationship. Nonetheless, RLQ analyses coupled with fourth-corner permutation tests proved a powerful tool to reveal and disentangle different evolutionary strategies. 相似文献
644.
645.
Tristan?D.?PearceEmail author James?David?Ford Jason?Prno Frank?Duerden Jeremy?Pittman Maude?Beaumier Lea?Berrang-Ford Barry?Smit 《Mitigation and Adaptation Strategies for Global Change》2011,16(3):347-368
Climate is an important component of the operating environment for the Canadian mining sector. However, in recent years mines
across Canada have been affected by significant climatic hazards, several which are regarded to be symptomatic of climate
change. For the mining sector, climate change is a pressing environmental threat and a significant business risk. The extent
to which the mining sector is able to mitigate its own impact and adapt to climate change will affect its long-term success
and prosperity, and have profound economic consequences for host communities. This paper draws upon case studies conducted
with mining operations in Canada involving in-depth interviews with mining professionals and analysis of secondary sources
to characterize the vulnerability of the Canadian mining industry to climate change. Five key findings are discussed: i) mines
in the case studies are affected by climate events that are indicative of climate change, with examples of negative impacts
over the past decade; ii) most mine infrastructure has been designed assuming that the climate is not changing; iii) most
industry stakeholders interviewed view climate change as a minor concern; iv) limited adaption planning for future climate
change is underway; v) significant vulnerabilities exist in the post-operational phase of mines. This paper argues for greater
collaboration among mining companies, regulators, scientists and other industry stakeholders to develop practical adaptation
strategies that can be integrated into existing and new mine operations, including in the post-operational phase. 相似文献
646.
莱州湾水体中有机磷农药的残留监测与风险影响评价 总被引:5,自引:0,他引:5
研究近年来莱州湾水体中有机磷农药残留情况及对环境的影响.于2005年5月采集了渤海莱州湾及其主要河口地区的水样,用气相色谱(GC-FPD)测定了样品中有机磷农药的含量,并运用化学污染物风险评价公式进行了风险概率评价.结果表明,莱州湾海域水体中有机磷农药的含量范围在0.2~79.1 ng/L,氧化乐果、甲胺磷、马拉硫磷、敌百虫、敌敌畏、乐果、甲基毒死蜱、甲基对硫磷等在研究海域占主要部分.对研究海域水体中有机磷农药的风险评价表明,莱州湾海域水体中的有机磷农药的含量与其他地区相比,污染水平居中,氧化乐果、甲胺磷、马拉硫磷、敌百虫、敌敌畏、乐果等农药对研究海域的生态环境安全已经构成了一定的威胁,应加强该地区该类农药的施用管理. 相似文献
647.
In addition to heat production on the comb surface, honeybee workers frequently visit open cells (“gaps”) that are scattered
throughout the sealed brood area, and enter them to incubate adjacent brood cells. We examined the efficiency of this heating
strategy under different environmental conditions and for gap proportions from 0 to 50%. For gap proportions from 4 to 10%,
which are common to healthy colonies, we find a significant reduction in the incubation time per brood cell to maintain the
correct temperature. The savings make up 18 to 37% of the time, which would be required for this task in completely sealed
brood areas without any gaps. For unnatural high proportions of gaps (>20%), which may be the result of inbreeding or indicate
a poor condition of the colony, brood nest thermoregulation becomes less efficient, and the incubation time per brood cell
has to increase to maintain breeding temperature. Although the presence of gaps is not essential to maintain an optimal brood
nest temperature, a small number of gaps make heating more economical by reducing the time and energy that must be spent on
this vital task. As the benefit depends on the availability, spatial distribution and usage of gaps by the bees, further studies
need to show the extent to which these results apply to real colonies.
M. Fehler and M. Kleinhenz contributed equally to this work. 相似文献
648.
Marshall SC Wilson KG Molnar FJ Man-Son-Hing M Stiell I Porter MM 《Traffic injury prevention》2007,8(3):260-266
BACKGROUND: Methods to study driving patterns and exposure of older drivers have typically relied on surveys or driving diaries. Electronic data logging devices may offer a reliable, alternative method of measuring driving exposure, and global positioning system (GPS) technology may be able to provide further information about driving patterns. OBJECTIVES: The aim of this study was to compare a driving diary with two electronic data logging devices, one of which had GPS capability, in order to identify which method best assesses the driving exposure and habits of older drivers as well as the method most acceptable to study participants. METHOD: In this prospective cohort study we recruited 20 participants aged 70 years or more (mean 78; range 70-85) (15 men and 5 women). The participants' driving patterns were recorded for one week with an electronic data logging device with GPS (FleetPulse), followed by recording for a further week with an electronic data logging device without GPS (CarChip). During both time periods the subjects also completed a standard driving diary. RESULTS: More comprehensive information, including braking and acceleration patterns, duration of driving time, time of day, and maximum speeds, was collected with the electronic devices than with the driving diary. There was excellent correlation between the driving diary data and those obtained with the CarChip (r = 0.9; p < 0.01). The correlation between the driving diary data and the FleetPulse data was moderate (r = 0.56; p = 0.02). The subjects clearly preferred the electronic monitoring devices over the driving diary. GPS data were able to demonstrate driving routes. CONCLUSIONS: Electronic data logging devices are a valid method for recording the driving patterns of older adults. These devices also reduce burden and improve the completeness of data. 相似文献
649.
Madhu Vadali Chao Ma Neil A. Duffie Xiaochun Li Frank E. Pfefferkorn 《Journal of Manufacturing Processes》2012,14(3):307-315
The objective of this work is to predict the final roughness of metal surfaces that have undergone pulsed laser micro polishing. The motivation for pulsed laser micro polishing is to reduce the surface roughness of parts whose surface texture can approach the feature size. Being able to predict the magnitude of the polishing and frequency (wavelength) content of the surface will assist in the design of optimal processing parameters with minimal experiments. Laser pulses are used to create shallow melt pools with a controlled size (e.g., depth) and duration in order to allow surface tension forces to “pull down” asperities with small radius of curvature. There is no ablation occurring in the process being modeled. The melt depth and duration are predicted with a transient, two-dimensional axisymmetric heat transfer model with temperature-dependent material properties. The surface of the melt pool is analytically modeled as oscillations of stationary capillary waves with damping resulting from the forces of surface tension and viscosity. Above a critical spatial frequency, fcr, a significant reduction in the amplitude of the spatial Fourier components is expected. The work described in this paper extends the concept of critical frequency to a physics-based prediction methodology for predicting the spatial frequency content and surface roughness after polishing, given the features of the original surface, the material properties, and laser parameters. The proposed prediction methodology was validated using line polishing data for stainless steel 316L and area polishing results for pure nickel, Ti6Al4V, and Al-6061-T6. The predicted average surface roughnesses were within 12% of the values measured on the polished surfaces. 相似文献
650.
Voluntary exercise at the expense of reproductive success in Djungarian hamsters (Phodopus sungorus)
Energy demands of gestation and lactation represent a severe challenge for small mammals. Therefore, additional energetic
burdens may compromise successful breeding. In small rodents, food restriction, cold exposure (also in combination) and wheel
running to obtain food have been shown to diminish reproductive outcome. Although exhibited responses such as lower incidence
of pregnancy, extended lactation periods and maternal infanticide were species dependent, their common function is to adjust
energetic costs to the metabolic state reflecting the trade-off between maternal investment and self-maintenance. In the present
study, we sought to examine whether voluntary exercise affects reproduction in Djungarian hamsters (Phodopus sungorus), which are known for their high motivation to run in a wheel. Voluntary exercise resulted in two different effects on reproduction;
in addition to increased infanticide and cannibalism, which was evident across all experiments, the results of one experiment
provided evidence that free access to a running wheel may prevent successful pregnancy. It seems likely that the impact of
voluntary wheel running on reproduction was associated with a reduction of internal energy resources evoked by extensive exercise.
Since the hamsters were neither food-restricted nor forced to run in the present study, an energetic deficit as reason for
infanticide in exercising dams would emphasise the particularly high motivation to run in a wheel. 相似文献