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501.
The European spruce bark beetle <Emphasis Type="Italic">Ips typographus</Emphasis> in a national park: from pest to keystone species 总被引:1,自引:0,他引:1
Jörg Müller Heinz Bußler Martin Goßner Thomas Rettelbach Peter Duelli 《Biodiversity and Conservation》2008,17(12):2979-3001
The influence of natural disturbance on biodiversity is poorly known in the intensively cultivated landscape of Europe. As
an example of insect disturbance we studied effects of gaps generated by outbreaks of the spruce bark beetle (Ips typographus) on biodiversity in the area of the National Park “Bavarian Forest” and compared them with openings (e.g. meadows) created
by humans in these forests. Insects were sampled using flight interception traps across twelve ecotones between edges of closed
forest, six bark beetle gaps and six meadows. The diversity and species density of true bugs and of bees/wasps increased significantly
from the closed stand to the edge, and continued to increase inside the openings at interior and exterior edges. Species density
in saproxylic beetles also increased significantly from closed forest to opening, but only across ecotones including bark
beetle gaps. Similarly, the number of critically endangered saproxylic beetles increased significantly in bark beetle gaps.
Using indicator species analysis a total of 60 species were identified as possessing a statistically significant value indicating
preference for one of the habitat types along the ecotones: 29 of them preferred gaps, 24 preferred meadows, three were characteristic
for edges of meadows, three for edges of bark beetle gaps, but only one was typical of closed forest. Most of our results
support the thesis that I. typographus fulfils the majority of criteria for a keystone species, particularly that of maintenance of biodiversity in forests. Our
results emphasize the value for the study and conservation of insect diversity of the policy of non-interference with natural
processes pursued in some protected areas. As a recommendation to forest management for increasing insect diversity even in
commercial forest, we suggest that logging in recent gaps in medium aged mixed montane stands should aim at retention of a
part of the dead wood. Planting should be avoided, to lengthen the important phase of sunlit conditions. 相似文献
502.
Alpers MP 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2008,363(1510):3707-3713
Kuru is a fatal transmissible spongiform encephalopathy restricted to the Fore people and their neighbours in a remote region of the Eastern Highlands of Papua New Guinea. When first investigated in 1957 it was found to be present in epidemic proportions, with approximately 1000 deaths in the first 5 years, 1957-1961. The changing epidemiological patterns and other significant findings such as the transmissibility of kuru are described in their historical progression. Monitoring the progress of the epidemic has been carried out by epidemiological surveillance in the field for 50 years. From its peak, the number of deaths from kuru declined to 2 in the last 5 years, indicating that the epidemic is approaching its end. The mode of transmission of the prion agent of kuru was the local mortuary practice of transumption. The prohibition of this practice in the 1950s led to the decline in the epidemic, which has been prolonged into the present century by incubation periods that may exceed 50 years. Currently, the epidemiological surveillance is being maintained and further studies on human genetics and the past mortuary practices are being conducted in the kuru-affected region and in communities beyond it. 相似文献
503.
Aim Our two main goals are first to evaluate the resilience of the boreal forest according to latitude across the closed‐crown forest zone using the post‐disturbance distribution and cover of lichen woodlands and closed‐crown forests as a metric, and second to identify the disturbance factors responsible for the regeneration and degradation of the closed‐crown forest according to latitude since the 1950s. Location The study area extends between 70°00′ and 72°00′ W and throughout the closed‐crown forest zone, from its southern limit near 47°30′ N to its northern limit at the contact with the lichen woodland zone at around 52°40′ N. Methods Recent (1972–2002) and old (1954–1956) aerial photos were used to map the distribution of lichen woodlands across the closed‐crown forest zone. Forest disturbances such as fire, spruce budworm (Choristoneura fumiferana (Clemens)) outbreak, and logging were recorded on each set of aerial photos. Each lichen woodland and stand disturbance was validated by air‐borne surveys and digitized using GIS software. Results Over the last 50 years, the area occupied by lichen woodlands has increased according to latitude; that is, 9% of the area that was occupied by closed‐crown forests has shifted to lichen woodlands. Although logging activities have been concentrated in the same areas during the last 50 years, the area covered by logging has increased significantly. Outbreaks by the spruce budworm occurred predominantly in the southern (47°30′ N to 48°30′ N) and central (48°53′ N to 50°42′ N) parts of the study area, where balsam fir stands are extensive. In the northern part of the study area (51°–52°40′ N), extensive fires affected the distribution and cover of closed‐crown forests and lichen woodlands. Main conclusions Over the last 50 years, the area occupied by closed‐crown forests has decreased dramatically, and the ecological conditions that allow closed‐crown forests to establish and develop are currently less prevalent. Fire is by far the main disturbance, reducing the ability of natural closed‐crown forests to self‐regenerate whatever the latitude. Given the current biogeographical shift from dense to open forests, the northern part of the closed‐crown forest zone is in a process of dramatic change towards the dominance of northern woodlands. 相似文献
504.
Hong Li William A. Payne Gerald J. Michels Charles M. Rush 《Environmental and Experimental Botany》2008,63(1-3):305-316
Multi-year spatial overlay patterns of plants, insects and soil water may yield insights for management for reducing biotic and abiotic stresses in dryland crops. A study of non-irrigated grain sorghum (Sorghum bicolor (L.) Moench) was conducted in a Pullman clay loam on the semi-arid High Plain of Texas during 2002–2005. The objectives of the 4-year study were to understand the mechanisms of plant spatial and temporal responses to stress from drought, infestations of greenbug, corn leaf aphid (CLA) and maize dwarf mosaic virus (MDMV) disease and soil water content (SWC) heterogeneity, and to reduce plant biotic and abiotic stress using their underlying relationships in space and time. Infrared IRt/c sensed-canopy temperature was measured at 18 or 54 sites along transects in a 6 m × 6 m grid across the years. Greenbugs, CLA, MDMV, SWC and hyperstectral reflectance were determined at each IRt/c site. Natural infestations of greenbugs and CLA on sorghum occurred in early July and insect populations peaked in late July or early August. Insect attacks resulted in plant water stress and sorghum yield loss except a late replanting in early July in 2004. Sorghum grain yield was negatively correlated with canopy temperature, greenbug and CLA (−0.38 < r < −0.75, P < 0.05), and positively correlated with SWC and plant near infrared reflectance (0.25 < r < 0.67, P < 0.05). The IRt/c temperature decreased with SWC but increased with greenbugs and CLA (0.26 < R2 < 0.64). Crosscorrelation analysis showed that these insect, crop, and soil variables were correlated in space within 48–54 m. Late planting in July or spray control in late July or early August would be options to reduce dryland sorghum water stress and yield loss from drought and insect attacks. 相似文献
505.
Lyon D 《Bioethics》2008,22(9):499-508
Governing by identity describes the emerging regime of a globalizing, mobile world. Governance depends on identification but identification increasingly depends on biometrics. This 'solution' to difficulties of verification is described and some technical weaknesses are discussed. The role of biometrics in classification systems is also considered and is shown to contain possible prejudice in relation to racialized criteria of identity. Lastly, the culture of biometric identification is shown to be limited to abstract data, artificially separated from the lived experience of the body including the orientation to others. It is proposed that creators of national ID systems in particular address these crucial deficiencies in their attempt to provide new modes of verification. 相似文献
506.
Carbon dioxide (CO2) has been used for decades to enhance capture of host‐seeking mosquitoes when released in association with traps commonly used by mosquito and vector control agencies. However, there is little published work evaluating the effect of altering CO2 release rates relative to the number of mosquitoes captured in these traps. This study investigated how varying CO2 concentration altered the mosquito collection rate at a freshwater wetlands in southern California. Host‐seeking mosquitoes were captured in CDC‐style traps baited with one of six CO2 release rates ranging from 0–1,495 ml/min from gas cylinders. Species captured were Aedes vexans, Anopheles franciscanus, An. hermsi, Culex erythrothorax, and Cx. tarsalis. A biting midge, Culicoides sonorensis, was also captured. For all species, increasing CO2 release rates resulted in increasing numbers of individual females captured, with the relative magnitude of this increase associated to some extent with known feeding preferences of these species. We found that variation in CO2 release rate can significantly alter mosquito capture rates, potentially leading to imprecise estimates of vector activity if the relationship of CO2 release rate to mosquito capture rate is not considered. 相似文献
507.
The influence of environmental management and animal shelters in vector control of Culicoides (Diptera,Ceratopogonidae) in northeastern Brazil
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Maria da C.A. Bandeira Gustavo A. Brito Adriane da Penha Ciro L.C. Santos José M.M. Rebêlo 《Journal of vector ecology》2017,42(1):113-119
We investigated whether biting midges in peridomestic environments are affected by environmental management practices and the presence of domestic animals. We used CDC light traps to collect midges in 112 residences across 24 locations along tourism routes of Maranhão, Brazil. The collection areas were characterized as follows: i) peridomestic area with domestic animals and without management (dirty); ii) peridomestic with domestic animals and management (clean); iii) peridomestic without animals and with management (clean); iv) peridomestic without animals and without management (dirty). The first two treatments had higher biting midge species richness and abundance, respectively. Generalized linear models indicated a positive correlation between the presence of domestic animals and midge abundance, with an approximate four‐fold increase in Culicoides (Diptera: Ceratopogonidae) abundance in peridomestic areas with animals. The same model showed that domestic animals have no influence on richness. Environmental management does not appear to influence species richness or abundance of biting midges. 相似文献
508.
Food safety is a critical public health issue for consumers and the food industry because microbiological contamination of food causes considerable social and economic burdens on health care. Most foodborne illness comes from animal production, but as of the mid‐1990s in the United States and more recently in the European Union, the contribution of fresh produce to foodborne outbreaks has rapidly increased. Recent studies have suggested that sterilization with nonthermal plasma could be a viable alternative to the traditional methods for the decontamination of heat‐sensitive materials or food because this technique proves capable of eliminating micro‐organisms on surfaces without altering the substrate. In the last 10 years, researchers have used nonthermal plasma in a variety of food inoculated with many bacterial species. All of these experiments were conducted exclusively in a laboratory and, to our knowledge, this technique has not been used in an industrial setting. Thus, the purpose of this review is to understand whether this technology could be used at the industrial level. The latest researches using nonthermal plasma on fresh produce were analysed. These evaluations have focused on the log reduction of micro‐organisms and the treatment time. 相似文献
509.
Ecological consequences of an unusual simultaneous masting of Araucaria araucana and Chusquea culeou in North‐West Patagonia,Argentina
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Fernando A. Milesi María Laura Guichón Martín J. Monteverde Luciana Piudo Javier Sanguinetti 《Austral ecology》2017,42(6):711-722
A simultaneous masting of two abundant species in the temperate forests of North‐West Argentinean Patagonia occurred in 2013 for the first time ever recorded: the semelparous bamboo grass Chusquea culeou (colihue), dominating the understory, flowered and set seed across 1100 km2 while pehuén (Araucaria araucana), an endemic conifer co‐dominating the tree layer had the highest regionally synchronized mast event in the last 30 years. Strong trophic effects were expected as a consequence of this extraordinary amount of seed, such as rodent outbreaks (ratadas) that followed previous Chusquea spp. mast events and included Oligoryzomys longicaudatus, the main reservoir of the Andes virus causing the Hantavirus Pulmonar Syndrome. From March 2013 to May 2014, we sampled relative abundance and activity of seed‐eaters and carnivores at four study sites with different proportions of both masting species. Surprisingly, total rodent capture rates never exceeded 14% in wild habitats and 8% in peridomestic areas showing low overall density in spite of some heavy O. longicaudatus males extending their reproductive activity into winter. Total abundance and relative proportion of granivorous birds peaked at the four sites in winter or spring, when they are usually scarce. Other surveyed organisms (native and exotic seed‐eaters, ungulates and carnivores) showed moderate responses at most, probably through aggregation from surrounding areas rather than reproduction. Seed removal from experimental seed stations varied in time and space though never peaked. The clearest pattern of community responses, though much subtler than expected, occurred at the site where colihue was abundant and pehuén scarce. This is the first systematic study that reports such a simultaneous double masting and our surveys revealed no widespread community consequences. We propose that either contingent events, such as an unprecedented drought, or permanent environmental features or contextual characteristics may explain the lack of a rodent outbreak in this area. 相似文献
510.
Sporadic Creutzfeldt-Jakob disease (sCJD) occurs frequently in the relatively older population, mainly in the groups of 60–69 and 70–79 year-old. Since 2006 when China performed national CJD surveillance, 14 young probable sCJD patients below 40 year-old were identified, counting for 1.93% of all probable sCJD cases. The clinical features of young probable sCJD cases, including the onset feature, the presence of sCJD-associated signs and the clinical duration, are indistinguishable from those of older patients. Special sCJD-associated abnormalities on EEG and MRI were noticed in 7 and 10 cases. CSF 14–3–3 was positive in 7 cases. CSF RT-QuIC showed positive reactive curves in 9 cases, with short lag phases. PRNP sequencing did not find any mutation. Due to low rate of brain autopsy in China, performances of other CJD-associated examinations as much as possible are extremely important for the distinguish diagnosis of young probable sCJD patients. 相似文献